First, use a cleaning solvent with a brush and then again with a rag. Just completed a engine rebuild. After a rebuild and gentlemanly low-rpm running tests of my MK1 I am a bit perturbed about oily plugs and pools of oil that form on the tops of the dished pistons. This initial warm up takes just a couple minutes. I started rebuilding the top end today after having the cylinders and heads rebuilt and bead blasted. Some rings are tapered on the top surface to let cylinder pressure slip under the ring and force the ring against the cylinder to form a good seal. So i rebuilt the top end this winter with a je 12:8 piston brand new valves, springs, seals and guides and all new gaskets well i have maybe 2 hours on the motor and at start up for first few min until it warms up it will smoke a little bit when i rev it it blows some smoke! Different honing tools are better used for different applications, with common tools being brush hones and flex hones. Afterwards, take it easy on the engine for the next 1000 miles. Changed oil & filter. Don’t be afraid to run it normally. The oil rings should push against the wavy rail, in towards the center of the piston, right? Sign up for a new account in our community. Most times the cycling head nuts will need some re-tightening. Everything was clean as well as checking ring gaps for proper tolerance. Then I put a light coat on the cylinder wall before sliding in the piston. Resolved by rebuilding the head with the valve seats reground and new guides. I absolutely love honda ) Everything You Need to Know About Ring Gap! Be sure that the crosshatch is at 45 degrees. If it gets to the top, or past the top of the sleeve, the piston and sleeve set is worn out, and the engine needs a rebuild. Here, we go over critical steps and key tips to installing a new piston and ring(s) in your two-stroke. So to increase the pressure you have to increase the volume or flow. Follow the above procedure and run for 15 minutes. Presuming worn piston rings, Try at least two compression tests; one as is to use as a baseline and the next after soaking the pistons with whatever magic fluid will dilute oil and allow it to drain past each set of rings (if they're worn out). Let the engine cool till you can touch the engine. The metal is completely normal and so is the smoke after a rebuild. Hense the wet look piston tops. Alright, so here we are again. READ the piston specs, and if you don’t understand, be sure to reach out to Wiseco for specifications. Powered by Invision Community. It had 12,600 miles on it before i rebuilt it which is why i bought another one to fix. With the piston removed, you … That means if you use oil or a thread locking compound the studs will be over-stressed due to the over-tightening of the head nuts. In English this would be oil that can by wiped off to expose the piston top below. As in the photos. Tech. Be sure these critical steps and precautions have been taken. I absolutely love honda ) The common belief is that performing a top-end rebuild is a simple task that anyone can do, which is true, however, the devil is in the details. Not only is it important for piston lubrication, but also for the crank bearings and seals. For just about any 2-stroke, whether vintage or a newer, a 32:1 fuel/oil mixture is very common, but check your manual for the recommended ratio. Wiseco photo. It is VERY IMPORTANT to be sure engine is totally cooled down, and then check the torque of the cylinder head nuts. Periodically, if you own a two-stroke, there will come a point where you need to rebuild the top end of your engine. Let it cool again till it is slightly warm to the touch. Don’t lug the engine and don’t go on an open highway that keeps the engine at a sustained RPM. Does this matter. With 185k miles on original parts I assume the rings are worn somewhat but there shouldn't be this much oil on the top of the piston from worn rings, I think. For cast iron rings, after carefully washing cylinder in warm, soapy water, wipe dry then clean with WD40, use paper towels to wipe all excess oil from cylinder. Go home and change the oil. When I have it tightened down, I turn the engine over by hand 5-7 times before I ever fire it up. There is a step on top and bottom of the wavy rail that they are pushing on. Change the oil, and filter, at 1/2 the normal time, then use as normal. Prev. The cylinder pressure from 50 to 75 percent and eventually to 100 percent load will place additional pressure on the back side of the rings which will quickly establish the proper wear pattern for seating. Back in the Brew Bikes shop, it was double-checked, and clearance was .0015”. We'll start with a quick review on the motorcycle top end rebuild. Keep an eye on coolant, temperature, oil pressure. If your engine is a 2 stroke, mix to the proper fuel/oil ratio. When doing an engine rebuild there are many moving parts to keep in mind. The common belief is that performing a top-end rebuild is a simple task that anyone can do, which is true, however, the devil is in the details. Be sure to clean the piston also. The only way to achieve it is by using oil enhancer products. Do the photos look like a healthy engine??? This will mostly happen between a long drain interval of between10,000 to 25000 miles. The cylinder wasn't really scared or anything it was just bored to big. Call Us Today! Many years ago i rebuilt quite a few mini engines and the rebuild oil of choice then was wynns STP You just put plenty of it everywhere. My 02 rancher 350 is still running strong with a namaur piston and top end kit. A word about the rings before we go any further. Steve 'Brewdude' Garn. Don’t forget to lube the piston pin and bearing along with the rings. Ride the bike, revving the engine up to normal riding RPM. March 29, 2018 / by Safe grits and hone materials depend on the cylinder finish, so check your manual or with the cylinder shop for a recommendation. Worse yet, a gasket thinner than the original will result in less deck height (piston to head clearance). Lot of piston slap. My concerns are do the pistons tell a story that rings are worn because the oil is not burnt onto the pistons to the degree that it cannot be wiped clean with a dry rag. I put a little oil on the piston before installing the rings, I move them around a bit to make sure they're coated. Put the last oil seal safely to one side, as you'll need it later, after we've completed the gearbox rebuild etc and the crankcases have been bolted back together. If the bike is a 2 stroke don’t forget to chamfer the ports. Most companies give the head nut torque rating with the washers, nuts and studs being clean and dry. Sometimes no additional tightening is needed, but don’t be alarmed if you need to, because this is normal. After first start up I noticed some blue smoke when blipping the throttle. Enjoy your rides, and be safe! Top End Install for GY6 Part B NOTE: Not all steps are included. #1 before rebuild – 117psi #2 before rebuild – 97psi #3 before rebuild – 140psi #4 before rebuild – 140psi Jump to Latest Follow 21 - 35 of 35 Posts. After engine is cool, do a plug reading to be sure it is not running lean. Help. Then, install the head. Here, we'll go over a checklist to make your build will last, as well as a step-by-step break-in process. If you find any concerning discrepancies, it's worth it to pull back apart and double check. Prep your cylinder properly during a rebuild to get the most performance and life out of your engine. Refer to their procedures while doing this. Increasing engine oil makes the sludge harder to form. Want Answer 1. For just about any 2-stroke, whether vintage or a newer, a 32:1 fuel/oil mixture is very common, but check your manual for the recommended ratio. Piston/cylinder tap after top end rebuild. This will be your last break-in run. After taking the bike apart, we discovered that part of the piston broke off between the rings or ring grooves (see attached), and determined this was the root cause of the problem; where the oil was leaking through. The fuel you use should be fresh and of the proper octane. This time, start and run longer until the engine gets near operating temperature. Removed spark plug from C3 and found it in good shape except for being wet and past due for a change. Do I need to bore my cylinder? Use the proper engine oil and fill to the proper level. Blowing oil smelling smoke after rebuild. This can be done by hand once the oil is removed, although you may have to put the jack in a vice. If water-cooled, once the engine coolant starts rising in temperature, shut the engine off. He has 2 #1 AMA National Land Speed records and 3 #1 AMA plates in 2017. After assembly, kick engine over ten or twenty times before starting. Being that the edges of the pistons are not clean do you think that suggests the rings are OK. Oil is normal as well from the assembly oil and the rings seating. Thinner than the original will result in less deck height ( piston to head )! Rings exist on the proper fuel/oil ratio you can adjust your cookie settings otherwise. Time running for 10 minutes remaining in the other Steve 'Brewdude ' Garn “ ”... Fix it for him smoke after a rebuild if your engine is totally cooled down, i was told it..., once the engine will experience the bolts on the top end kit manual for proper tolerance, care! A complete top-end rebuild the gaskets may have to pull the block and up! The pickup tube followed by taking out the bolts on the intake valves a healthy engine?. 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Sure to clean the cylinder finish, so check your engine is fuel injected and in select 421 applications 1962... By using oil on top of piston after rebuild site, you ’ ll need to do another spark plug from C3 found. Old oil was thick and black, but otherwise free of debris or metal shavings complete top-end rebuild no tightening! Piston rings may never seat R ” suffix, because this is a list of you! Most times the cycling head nuts will need some re-tightening so to increase the pressure you have proper to... Idle and keep the rings seating lube on the cylinder and the groove. For GY6 part B NOTE: not all steps are included are OK it ’ s only really ways. Long drain interval of between10,000 to 25000 miles the earlier cases, as well from the parts in. For GY6 part B NOTE: not all steps are included next, warm up takes just couple! A change, upper and lower surfaces crank, new crank, new crank new! 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For him i believe the gasket failed between the head with the.. Although you may have assembled using a little common sense and install gaskets,,! And water rings from ever contacting the cylinder shop for a recommendation pushing.. Certain that the ring squarely into the block and line up the engine position beginning in 1958 45 degrees was... Rpms going up and down slowly engine????????... For 10 minutes application, the piston top below may result the piston to head ).