Your risk from exposure to these chemicals varies, depending on how often you do this type of work. Cold the cylinders are barrel shaped and this is why you need torque plates to do any measuring or boring. The World Products Merlin IV block is bored and decked to size with our new Centroid touch probe machine. Depending on the year, make and model of a car, horsepower ranges from approximately 145 to more than 370. If you do need it bored to a larger size, just take the cylinder down to a shop. Big bore kits are commonly sold in 44mm (63cc), 47mm (72cc), 50mm (81cc), and 52mm (88cc). Before you reinstall a good camshaft, remove the minor surface defects on the cams and the camshaft by using crocus cloth or a fine stone. How to use bore in a sentence. NOTE: The tool will appear oversized. Running a cylinder head intended for a larger bore size can result in valves crashing into the block. Whether you're rebuilding a street engine or building a high-performance racing engine, consider this your starting point. If the clearance is alright the very least I would do is to de-glaze the cylinders with a ball hone. Depends on the ridge and the piston ring style. This intensive, 100% rebuild with paint, polishing, re-chroming & many new parts = 34 labor hours. It is not necessary to remove the engine from the scooter. Specialty Tools for Performance Engine Building Your ability to do an exceptional job, can sometimes be hampered by the quality of the tools you have available. An engine parameter is some number which describes a physical characteristic of the engine. i would just like to know what all i would HAVE to do to make this work. First you need to decide on the cylinder bore size. The process is quite intensive and requires the disassembly of the engine. if you dont want to spend the money then get a hone job. When Do You Need To? - Duration: 9:17. Barr and I were always saying how we would do it if we ever design a new engine. Depending on the year, make and model of a car, horsepower ranges from approximately 145 to more than 370. What do you think the positive aspects of faith are? Share your opinions with us down below. Our case boring is done to the highest standards, with a stepped bore to maximize case strength for full piston and cylinder support. Small Block Chevy Head ID; Engine RPO Numbers: These are also located on the drivers side of the engine, at the back of the head on the transmission mounting flange. You can also tell when disassembling an engine by looking at the existing bearings and their wear pattern. Especially if you have. 001 for expansion. Also a lot of measurements must be performed, which may introduce errors. The advantage of running the 2. Get the block surfaced and bored. After the engines are cast the rough holes for the cylinders are bored out and finished. ” When it comes to choosing an engine oil and filter to protect your Yamaha, this couldn’t be more true. After all, how many busts do you need to see (no jokes) before they all start to look the same? And frescoes are all well and good, but you can only see so many of them before neck cramp starts to set in. 00-inch bores. you need to read, research and feel comfortable that you have a basic understanding of every step before you even touch a wrench. When you have an engine "bored and honed", the cylinder is basically cut wider (boring) and then polished inside (honing). Harbor freight has a set that is usually on sale, I think I got my set for $7. If the bore size is between standard Flex-Hone sizes, the next larger standard Flex-Hone should be selected. You'll use a big 4. Extreme Boost 35lb+ Gas, Alky, E85 Bore x. just go to a local parts store and rent a hone and hone it. For a nitrous or blown racing engine, the top ring end gap should be opened up to as much as. Running a cylinder head intended for a larger bore size can result in valves crashing into the block. It may be 0. Marine Engine has been online since 1999 providing boat motor repair information and services to boat owners and mechanics. A good machinist can check the crank bearing bore for alignment with a straight edge. 0L Jeep engine and gain an idea of what questions you NEED to ask. How do you tell if your pilot jet is too lean, rich, or just right? The pilot jet is sized correctly if the fuel screw setting falls between 2. 000-inch stroke, and even though the block can be bored as big as 4. 30 over and you won't need to file fit the rings. Do I need custom pistons? A. Tell the counter person you need it for a Magnum engine. If you want to hone and rering an engine yourself without proper measuring tools, remember to only make about 6 strokes per cylinder. We will deck this block to the exact specs you need. There is no need. 05-inch bore as the 390. if the car still runs good youll prolly only need to hone it. if it isnt too worn you can just hone it and rering. It can also be found in everything from 240SX drift cars to Mustang drag cars. A 5" bore 24" stroke at less than 20 GPM will make for a long cycle time. Barr and I were always saying how we would do it if we ever design a new engine. If this is your first visit, be sure to check out the FAQ by clicking the link above. 060 inch, and possibly more after proper thickness testing. Tap the accelerator in a diesel car and you get instant, satisfying response. 007 inches times the bore diameter. This is because I'm shifting at 6000 and not the Victor upper limit of 8500. Here is a list of common signs that tell you that you need to rebuild your car's engine. Your engine does not care, and neither do you, what the throttle bore size is. Remove the circlip and push the wrist pin out with a screw driver. H series bearings should be used if contact patterns obtained with P series parts are too narrow. 25 stroke engine series. For a nitrous or blown racing engine, the top ring end gap should be opened up to as much as. It is a good idea to mildly load the engine as soon as you can. Some parts are a given like gaskets, seals and the parts I called out in the previous pages. Because the components of a stroker kit are all precision balanced together, once a kit is ordered, specific parts in the kit cannot be returned or exchanged. I do recommend checking your engine with a leak down tester and that will give you an idea of the condition of your rings and cylinder. 5000 inch, but these values can varies when the cylinder is bored for oversize pistons or cylinder sleeves. RealStreetPerformance. You need to measure the bore and the stroke to know for sure. We need your cylinder back as a core to bore and re-plate for the next customer. You should be able to bore out the S10 rod end to 0. If you don’t have access to an impact wrench or don’t want to use one, a socket and braker bar of your choice will do. This method is simple and of sufficient accuracy if you do it carefully. ” When it comes to choosing an engine oil and filter to protect your Yamaha, this couldn’t be more true. I'm a little rusty on numbers but I think that anything more than 4 thousandths (. If you get it wrong it will be very ugly as the liners won’t seal properly. Do you need to bore the engine for new pistons? I was just wondering if you actually had to bore out the engine for custom pistons and have the pistons fitted to the block, or if they can be made to slide right in. Re: How do you know when you need to get bigger pistons when honing? Phil--don't laugh--I will need a set of pistons for mine over the winter and havent decided if I'm going to bore mine--I'm going to do the same basic thing youre doing-rebuild the block--are you also replacing the bearings or just the pistons and rings??? good luck--Steve. you need to read, research and feel comfortable that you have a basic understanding of every step before you even touch a wrench. Maybe you can bore over. Set the micrometer to the bore size you need, then place the gauge between inside the mic and rock the gauge back and forth, and side to side. A good machinist can check the crank bearing bore for alignment with a straight edge. Valve size is limited to 0 - 4 inches. Big Bore, High compression (10. You can do this without a meter, but it is a bit tougher. With a diesel engine, you get more power. In an interview with Bored Panda , Pastor Ron Garner of the Wantagh Memorial Congregational Church explained the inspiration for the witty signs and talked about the role of religion in the 21st century. If you’ve got an engine problem, you’ve got a car problem. Repeat until you see no grey on the white cloth. If this occurs, the engine will likely require complete disassembly and fresh honing. 19) Re-install the coolant plugs on the block and refill the coolant system. If you really do need much more than say 240hp from a Holden 6, it may prove more practical and cheaper in the long run to use a Jzed/Duggan style head. Someone told me all i needed was the rods and crank out of a 400 small block and to bore it 30 over, but if I did that wouldnt I need differant heads. Why do you need to file fit a ring set? The reason a compression ring is file-fit in a high performance engine is because the gap affects performance. If you need to, reclaim the register area of the cap and mill the register face back to a dimension that will keep the cap good and tight in the block register. Now if this is an oil consumption issue, you do have the cheap alternative of simply running a thicker oil with the worn engine. You cannot undo the reborn and certainly do not want to have to redo it again. I was thinking i would need a gasket set, 4mm crank, and spacer. you're going to need a top compression. Some mild big bore pistons are available that are installed via an overbore, but you’ll still never get more displacement than 58cc unless you spend thousands on a 150cc GY6 engine swap. If you do not wish to prime the engine, crank the engine for 15 to 20 seconds WITHOUT PUMPING. Fill the cylinders with diesel and let it sit for a few days. Bore was 93 mm (3. In case you haven't seen one, it's like a toilet brush with balls of abrasive stuck on the ends of the bristles. Calculators to find 1/4 mile ET and MPH. You'll need a way of keeping the engine at 2,000 rpm's for the break-in. See Below for explanations of the fields required. The LQ4 piston is dished where as the LQ9 is a flat-top increasing compression to 10:1, and HP to 345 factory. If you let the issues go unfixed, you run the risk of ruining the engine completely, requiring you to do a complete rebuild anyways. You can get a bored out cylinder that's 144cc's, but to actually perform like a 144 it will need some tuning. range and is designed for years of trouble free service. But i would go for. 9 L (2935 cc/177 in³). Oil smoking first appears during engine cold starts. It's diameter influences air velocity into the engine. Of course swapping a 400 is nice to but you cannot bore a 350 cc inot a 400 cc motor its not gona happen. When you test the methanol jetting be sure to make several passes before you settle on a particular main jet size and power jet setting, it will take a few passes for the engine to come up to operating temperature, if it doesn’t detonate on the first run it may do so on the third or fourth so proceed methodically. The 332 and 352 had 4. Wiseco photo. com has a complete inventory of UTV engine parts so you can spend more time riding and less time looking for the parts you need. Few machine shops have a machine of this accuracy. 4L Engines You need to have clear performance goals, a detailed list of proposed machine work, and a definite budget when you arrive at the machine shop with your Modular engine. Core charge: We do have a core charge on this cylinder. When you disassemble an engine and can feel any lips the block needs a rebore. Running a cylinder head intended for a larger bore size can result in valves crashing into the block. Our stock bore is 87. RealStreetPerformance. There is no need. I am wanting to go back to the stock 125 but I don't know if you have to bore out the engine case for the bigger piston or not? I read that certain big bore kits you will and some you don't. For a 4" bore CIRCLE TRACK engine, use a 330 Heavy Duty Block. When selecting pistons for a boosted engine, you need to consider compression ratio, material, type of construction, ring type and material, top ring land location relative to the crown, clearances to bore relative to skirt size, and coatings. If you look at the inside of the cylinder you can see the metal changes colors about an 1/8" in from the bore. It's a somewhat cumbersome process that requires heat in addition to tools, and knowing how to dial everything in to create the right fit is a skill. Then you can either take it to a small engine (up here a snowmobile shop) and pay $60 per hole, or preferably use a lathe and 4 jaw chuck. It's that feeling you get when you twist the throttle. 4120 OE 01. SO its up to yuo swap a 455 or 400 and last but not least bore the 350 tio a 383 stroker. 25 stroke engine series. There is no other product on the market like this. 700" Rods, ARP 8740 Bolts Mahle pistons 10:44 compression Competition valve train Crane gold full roller rockers Competition Hyd Cam 284xe. Bare Engine Blocks Whether you’re building a new engine or recovering from an under-the-hood incident you’d rather soon forget, explore our large selection of aftermarket bare engine blocks to complete your new power plant project. Now what?Time to make sure you have the specialized tools to do the job. Engine Case Machining , BIG BORE, 88mm, 90. Then inspect the cylinder surface. If the cylinder bore is worn and can't be re-bored to a uniform diameter, the external piston ring diameter should be the same as the smallest diameter of the bore (usually crank shaft end) - to avoid possible ring breakage due to an insufficient expansion gap. Usually you will be quoted for the basic job and after inspection of the components you will get a call back with a more accurate estimate. In many cases the engine can be worked on while installed in the scooter, but the frame design of some scooters prevents big bore kit installation while the engine is still in the scooter. What kind of shock oil do you use? If this is your first visit, be sure to check out the FAQ by clicking the link above. One of the most important parts of a well operating engine is a good piston and bore to keep compression high and transfer that power to the back wheel. Check out our guide to understanding the Toyota 2JZ-GTE for everything you'll ever want to know about one of the greatest production engines in history. For example, your 125cc dirt bike engine is 54mm bore, the Wiseco piston is designed just for that bore size, and does not require any specific adjustments to fit properly. It will have a bunch more torque. You can gage progress by cleaning both parts and determining how far the piston enters the bore. Axtell Big Bore Kits - From $1120 107ci for 1999-2006 Models, 117ci for 2007-Present Models. Start off with an improved air intake to let the engine breath better. The problem boils down to this: When you bore a carb in a conventional fashion (straight through the carburetor), the bore becomes larger very rapidly at lower throttle settings. 060 inch, and possibly more after proper thickness testing. All you need to do is place the bike on a stand then start the engine and allow it to run at a low speed (just keep it running) until it has fully warmed up (~15 minutes), then allow the engine to cool fully and repeat this process for a total of 3 times. If you have an internal crack, you'll likely have symptoms similar to a blown head gasket. On top of that, there's bound to be additional components that have dry rotted or broken during disassembly. You can dip a cast iron cylinder head in a hot caustic solution but don't dip an aluminum cylinder head in it!. You can also tell when disassembling an engine by looking at the existing bearings and their wear pattern. Here the block deck is getting cut with a fly cutting head. Now that you have a better idea of what Gen III and IV LS small-blocks are and whether the engine you’re looking to rebuild falls within the family, it’s time to decide whether an engine rebuild is really something that you want, or need, to do. Before you reinstall a good camshaft, remove the minor surface defects on the cams and the camshaft by using crocus cloth or a fine stone. if you dont want to spend the money then get a hone job. Now what?Time to make sure you have the specialized tools to do the job. They should be measured for your preference. Some parts are a given like gaskets, seals and the parts I called out in the previous pages. If you want to get rid if it and are not ready to do an overbore/full engine overhaul, rent or borrow a ridge reamer and be done with it in a few minutes. Every now and again the gaps do line up – and once lined up there is a tendency for them to stay lined up at least until the vehicle hits the next pothole in the road when one or other will rotate and break the line. The bore & stroke of this engine is the perfect combination of performance, reliability and driveability. Re: How do you know when you need to get bigger pistons when honing? Phil--don't laugh--I will need a set of pistons for mine over the winter and havent decided if I'm going to bore mine--I'm going to do the same basic thing youre doing-rebuild the block--are you also replacing the bearings or just the pistons and rings??? good luck--Steve. It has been around since the fifties ( there was a product back then called tuf-block ). This will ensure adequate bond time which will prevent leaks. How much the cylinders need to bored depends on how much oversize you go and what kind of piston (cast or forged) you want to use. The 911 engine can be a loud, noisy engine, and if you havenâÂÂt listened to a whole lot of them, your imagination can get the best of you. Your risk from exposure to these chemicals varies, depending on how often you do this type of work. How do you determine if the block should be bored? see above. You would have to pay the 100% refundable core charge. NOTE: If you use a dyno with a brake, it's critical during break - in that you allow the engine to decelerate fully on it's own. The theme here is big displacement in a small-block made of aluminum, re-engineered with modern technology and race driven design. Take a look at the spark plugs, too. Machine Shop Guide to Rebuilding Ford 4. ) (Don't use the dyno brake. Bore was 93 mm (3. Puffs of blue smoke out the exhaust means the engine is burning oil. What you and your engine do care about is how much air the throttle body can flow. we’ve already developed several new products for the 4. I am wanting to go back to the stock 125 but I don’t know if you have to bore out the engine case for the bigger piston or not? I read that certain big bore kits you will and some you don’t. 0L engine, you'll need a top-end as mentioned in the 300rwhp section plus some sort of power adder. 005″ and utilizing a 4. If any are out then it will have to be bored. You can also calculate Calculate Bore from Engine Size, Stroke, and Number of cylinders, or, Calculate Stroke from Engine Size, Bore, and Number of cylinders by entering the required values and clicking on the proper Calculate button. Then, remove the entire carburetor. since you only need to measure to within 0. For instance, if the crank journals do not need to be ground undersized, then they aren’t. Maybe you can bore over. Most of the time, it’s the people who buy just a cylinder kit that give bad feedback. We do also offer complete kits if you need pistons and gaskets. I have a recommended engine page now that recommends 3 different vortec 350 engine configurations which are affordable and makes at least 300hp with bored throttle body and good exhaust setup. you need to read, research and feel comfortable that you have a basic understanding of every step before you even touch a wrench. Golen tells us, "The very bottom of the cylinder walls on LS engines need clearanced 60 to 80 thousandths when you are building a stroker, because. The smaller the intake valve size, the more torque your engine will have. Besides, all you'll do is "punch out" the block as far as it can go and you won't be able to rebuild it again because you've already bored it as far as you could go. When you have an engine "bored and honed", the cylinder is basically cut wider (boring) and then polished inside (honing). Or checkout the Briggs & Engine Buying Guide. How do you determine if the block should be bored? see above. We have read everything from magazine articles to Pilot Operating Handbooks, Ser-. Extreme Boost 35lb+ Gas, Alky, E85 Bore x. 165 so you don’t need custom pistons. 600" BORE MACHINED 10. Set the gauge to just over the diameter, using the correct extensions. It may be 0. (Don't use the dyno brake. As soon as you are sure you have the bore cleaned out completely, wash it 5 more times! When checking ring end-gap, if you need to open the gap, we used to clamp a fine file in a bench vise so both cutting surfaces are verticle. You cannot undo the reborn and certainly do not want to have to redo it again. Engine Displacement. In many cases the engine can be worked on while installed in the scooter, but the frame design of some scooters prevents big bore kit installation while the engine is still in the scooter. Q If I bolt these heads onto my block, will I have enough piston to valve clearance. i need to be able to pick multiple options. The sleeves can be pressed into place, or they can be held in by a shrink fit. Re: when do you need to shave the rave valves? Originally Posted by laylo27300 I built a 787 last month bored it 1mm over and did not shave the raves put about 50hrs on it since then it is in a 98 speedster boat, should I pull those and grind those too, I dont have any problems with the engine. Shop cell 503-551-4263 Your Full Service Small Engine Cylinder Repair Facility. we’ve already developed several new products for the 4. After all, how many busts do you need to see (no jokes) before they all start to look the same? And frescoes are all well and good, but you can only see so many of them before neck cramp starts to set in. Specialty Tools for Performance Engine Building Your ability to do an exceptional job, can sometimes be hampered by the quality of the tools you have available. Most modern engines are detuned through the PCM. Make sure that the engine has good oil pressure as its running. This means the counterweight in the crankshaft must carry additional weight, known as the bob weight, to compensate for the heavier piston. In addition, you will need the following:. The stock carburetor is a little small for high performance applications but it works quite well on a "mild" blaster (pipe, airbox lid removed, new air filter, jetted properly). I want to rebuild the 1340 Evo engine. The bore is basically what the diameter of the cylinder is. Hey guys, My truck came with a 305 from the factory, we replaced that engine a few months ago at 284,000 miles with a brand new 350 crate 2 bolt main Before my truck was slow as hell with all those miles, but I never cared about performance, just cruising and straight pipes. It has been around since the fifties ( there was a product back then called tuf-block ). The theme here is big displacement in a small-block made of aluminum, re-engineered with modern technology and race driven design. The only real way to know for sure what engine you have is to locate the engine codes and reference them to a reliable source. Then start the engine. Harley Cylinder Problems – Including Some You Never Thought Of Hi to everyone Some riders of classic Harleys might have found problem with your classic OEM Harley cylinders in the past, either with smoking, oil blow by, or lost compression, just to name a few. Instead of a 5w30 or 0w30, step to a 5w40 or 0w40. Examples of engine parameters are cubic inch displacement (CID), bore, stroke, valve size,rod length, rod/stroke ratio, bore/stroke ratio, etc. I ordered new 0. The other thing people overdo is hone. To have a machinist suggest to bore an engine to the boundary of the factory maximum, is quite ridiculous for a street engine. Cover sensors, exposed wiring, the distributor, and spark plug openings. 001 mm -- measurement. When you take the heads off you will see the cross hatching from the factory. Diesel engines are more technologically advanced, more durable, and more powerful than ever before. The RPM entered should be the maximum RPM the engine is to run (you know that RED LINE on your tachometer). A simple compression test or leakdown test will give you at least some idea on the health of your engine. I had him order all of the parts, that way if he got the wrong size anything he had to reorder and he never was waiting on me to supply parts. If you have a large area that didn't clean up, its time for a bore. When Do You Need To? - Duration: 9:17. ) For any changes needed, just call and we will build a custom engine package for you with the horsepower you want. 407-695-7223 www. I really don't need my engine to redline any higher and would prefer not to mess with it even though I have found them used for under $500. 300”, with a groove diameter of. stacks, etc. 3 readily available and you can get on the road again in under a week, I'd say go for it. No need to bore or even split the cases, just do the cylinder and piston swap. Likewise, if you're building a high performance engine with close tolerances, you don't want any misalignment in the main bores or cam bores. You'll also need an oil pump, which is an easy item to choose - if the car is turbo charged, you need a 30mm pump, if not, then you need a 26mm pump. Marine Engine has been online since 1999 providing boat motor repair information and services to boat owners and mechanics. Our primary goal is to engineer crankcase upgrades to combat the motor company cost reduction directives. this roughs it up into a crosshatch pattern instead of being completely smooth (glazed) so the oil lubricates properly. These will bolt to the big block and will allow the engine to sit in the exact same location relative to the frame as it would have in a factory installation. This can be done using Vauxhall XE pistons. Bore definition is - to pierce with a turning or twisting movement of a tool. So go ahead and give it a try. You must measure. Measuring the cylinder bore at multiple heights within the cylinder shows you whether the cylinder is out of round or tapered. From the classic Sprint, ST, LX and Revival to the modern motorcycle styling of the Streetmate, Tomos' devotion to quality is evident throughout. Puffs of blue smoke out the exhaust means the engine is burning oil. A boiler explosion, even in miniature, can result in serious injury. So this means you will have to remove the valve cover if it is not already off. For example, the bore dimension of a. Ok guys, I need to know how to go about building me a 383 Stroker. The formula for calculating how much CFM (cubic feet per minute) an engine requires is: CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456. We offer kits to suit every need, some with just the basics and others with every bell and whistle you can think of. Which kit is up to you really, they all should mesh just fine with a +4mm stroker. Not only will you get the peak horsepower, you'll get a wider powerband. Between 1954-1962, Chevrolet produced their famous full oil pressure 235 cubic inch six cylinder in trucks and it soon proved to be one of the greats among engines. Rather, it would have been nice to have an engine with a removable cylinder so big bore kits that add serious power are an option. Reassemble all parts and start the engine. There are boring machines to fit every engine bore size so you need to know what type of work you do most. All you need, though, is a small hand brush to do the job. 8 in) for a total displacement of 2. 0 SOHC engine for you power adder guys. If you need further assistance with replacing the piston rings in your engine, then seek out a professional, such as one from Your Mechanic, to help you. When you take the heads off you will see the cross hatching from the factory. Start with the factory jetting and proper float levels. Also a lot of measurements must be performed, which may introduce errors. Most Pontiac blocks can tolerate an overbore up to. We will deck this block to the exact specs you need. When setting the engine to TDC on the compression stroke for cylinder #1, you must realize that the crankshaft rotates twice for every single rotation of the camshaft. ) and then try the piston in the bore. Starting at $150 ea. Everything you ever wanted to know about the LQ4/LQ9 engines! OP PONTIAC SLEEPER, theturboforums. If someone tells you that an older cast iron block Kohler engine isn’t worth repairing or rebuilding and repowering your garden tractor or small engine equipment with a new engine is the way to go, then they obviously is lying to you, don't know much about older Kohler engines or is trying to make a lot of money by selling you a new repower kit. In Europe, this engine was commonly fitted with the Bosch L-Jetronic fuel injection system, married to Ford's EEC-IV engine management. 10 shorter, also do they ever machine the register surfs?? Or do those surfs stay put?. You need to use Plasti-Gauge to determine how much clearance you have, then contact a dealer about bearing sizes needed. If you need to resize any one cylinder in a multi-cylinder engine, you must resize all cylinders to the same oversize. The process is quite intensive and requires the disassembly of the engine. 383 is the limit of your existing motor. If you have a large displacement fuel injected engine with throttle-by-wire, you need an S&S Throttle Hog from Star Racing! The new Throttle Hog huge bore EFI throttle bodies for late model Harley-Davidson® big twins are available in three sizes: 58mm, 66mm, and the giant 70mm. 7 in) and stroke was 72 mm (2. I have a recommended engine page now that recommends 3 different vortec 350 engine configurations which are affordable and makes at least 300hp with bored throttle body and good exhaust setup. If it's an external crack, that's easy enough. You must measure. 99 or something.  Here are 7 tools you'll need if you plan on rebuilding your Kohler K Engine. If you manage to turn the engine through two full revolutions without finding any point where the priming lever works, the linkage inside the lift pump has broken - not uncommon, and you will need to replace the lift pump. 005", which you would need to anyway if you went. The Forgotten 261 6 Cylinder Engine. You may lightly tap it but if the pin is in too tight, you will need to pull it with a wristpin puller. If you have a helper, one of you can sit in the car and do this via the gas pedal. since you only need to measure to within 0. 0015" feeler barely fit. The advantage of running the 2. One, you need to bore the cylinder oversize and two, you are sadly lacking in your maintenance. Re: Rust in cylinder bore Here is an old trick that still works. Your carburetor or EFI will need to be corrected to compensate for how differently the engine now breaths. Upgrade kit for GY6 139QMB 49cc four stroke engine, you get everything needed to do the upgrade, The upgrade works great on the four stroke 139QMB engine giving you speeds up to 50mph, to achieve this alittle more air is needed, a good spark plug gapped correctly some good gas and a fine tuned air mixture, we are looking for better air filters that will help these kits along and we are almost. You could do the whole job yourself (requires special tools), buy a complete engine (bit pricey), have a mechanic do it (do not do this unless you like to be ripped off), or like me, buy a short block, get your head rebuilt, and buy the rest of the gaskets/timing set/pumps that you need, and any performance parts and piece it together yourself. Do I need to fill out a Work Order? Do you line-lap Evolution cases? What guidelines do you use to bore cases? What specifications does Darkhorse follow? What guidelines do you use to install crankshafts? Where do you measure crankshaft total indicated run-out? Do you work on motorcycle heads or cylinders?. Big Bore Kits for Harley I have a 1994 Dyna Wide Glide I'm customizing this winter.