im lookin to rebuild my top end. ebay has a couple of different aftermarket brands including yamaha eom, namura, wiseco, wsm etc. which should i go with? i believe my motor is still stock bore. thanks
yamaha oem vs aftermarket top end kit
- Thread starter blastermessiah
- Start date
the cometic gaskets have worked great for me as well, wiseco gaskets im not too fond of however.
As far as pistons go, Wiseco is your best bet for a stock bore engine.
As far as pistons go, Wiseco is your best bet for a stock bore engine.
thanks for the input guys...somone rebuilt the top end wrong and supposedly kicked it over and piston skirt broke off, cylinder looks good, so ima just hone it and rebuild it. what do yall mean by 'cosmetic gaskets'? is that oem?
its not cosmetic its cometic and its a brand name of some really nice gaskets, i use thier EST series and looove em I:I
cometic gakets are better than stock.
i was gonna say if your cylinder was wrecked get a vito's big bore kit.
definately worth the money.
yeah wiseco is what i use, i dont really like namura personally.
i was gonna say if your cylinder was wrecked get a vito's big bore kit.
definately worth the money.
yeah wiseco is what i use, i dont really like namura personally.
Cometic is a brand of aftermarket gasket. I like them OK, but you can't go wrong with using OEM gaskets for rebuilding an engine to stock spec. If they work well enough for the factory, they will work just fine for you. Cometic makes good stuff, though, and I wouldn't hesitate to use their gaskets, especially on modified engines.
Just a thought: Check your cylinder bore with a bore gauge, or have a machine shop do it for you and compare it to spec, before assuming all is well and putting a new piston back in. A broken piston skirt usually results from piston slap...basically what happens when even a new piston is fit into a cylinder which has been worn out-or-round or tapered or both. If you just throw a new piston into a worn cylinder which 'looks OK', you may be right back at the same place you are now in a couple months.
Oh, and don't forget to pick up ALL broken pieces of piston skirt from inside the crankcase. Leave a chunk in there, and it will wreak havoc on main bearings.
Just a thought: Check your cylinder bore with a bore gauge, or have a machine shop do it for you and compare it to spec, before assuming all is well and putting a new piston back in. A broken piston skirt usually results from piston slap...basically what happens when even a new piston is fit into a cylinder which has been worn out-or-round or tapered or both. If you just throw a new piston into a worn cylinder which 'looks OK', you may be right back at the same place you are now in a couple months.
Oh, and don't forget to pick up ALL broken pieces of piston skirt from inside the crankcase. Leave a chunk in there, and it will wreak havoc on main bearings.
lol sorry, ok i will look up 'cometic' gaskets, any tips on where to get best price?....i have another question? previous owner tore down top end so i have no idea what happened to broken pieces....should i just flush out bottom end or do i have to split the cases?
Power Sports
u can order all the gaskets direct from cometic. flushing the bottom end should be sufficient without taking the cases appart. dont forget to get that cylinder checked.. good luck
u can order all the gaskets direct from cometic. flushing the bottom end should be sufficient without taking the cases appart. dont forget to get that cylinder checked.. good luck
Myself as well as most engine builders who frequent here prefer OEM gaskets. If you need a good place to find gaskets cheap go to cheapcycleparts.com . It might take a week to get your order but excellant customer service and cheaper than the dealership for sure.
how am i supposed to properly flush engine?...i was told to do this but i dont really know how exactly 
if motor is off the bike u can just pour gas and dump it. i dont know brake cleaner will eat up yamahabond or not?
i would just stick with mixed gas (gas/oil mix). It will get rid of all the particles and wont leave the bearings dry. Brake Cleaner can cause surface rust which will wreak havoc with anything that is steel (crankshaft, bearings, etc) if left in the engine. It can also damage seals.
If you pull the cylinder off, you can get a syringe (or a filler bottle for a nitro RC) and pour gas into the crank case then suck out the fuel with the syringe or filler bottle. Be careful not to rotate the crank assembly while doing this to avoid damaging the bearings (little bits of metal get in them then you rotate the bearings and i think you can see where this is going). Repeat this process until you dont see any metal flakes in the fuel you put into the crank case. Also, use fresh fuel (stuff with no metal in it) for each time you fill the crank case. When the fuel appears to be free of debris, make sure to get ALL excess fuel out of the crank case.
The fuel bottle makes this job very easy IMO, they only cost around $5 and you can also use them to manually prime the engine.
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