Need help with topend rebuild
- Thread starter bullman926
- Start date
Depending on where you bought the top end kit from you should be able to exchange it for a different size. You never want to bore the cylinder anymore than needed because once its bored out then you have to buy a new sleeve ( usually around $100 ) and get the new sleeve pressed into your cylinder ( usually around $150). I would strongly suggest trying to exchange the piston/top end kit for the appropriate size, your mechanic/shop should be able to measure your cylinder walls and have a good idea of what size piston you will need after the bore.
A 67 MM piston would require a new sleeve? I thought the sleeves were what was bored?
your existing sleeve can be bored to fit a 67mm piston.
he was saying above, to not go bigger than needed, as the sleeve can only be bored so many times until a new sleeve is needed.
Ok thank you. Yeah that had me scared because what I had read was that the stock sleeve could be bored up to 68mm before it would need to be replaced. The shop that has my jug said that it would need to be bored .010 at least to clean up the scarring and I would need to go probably one size up on the piston. Well me not knowing what that meant at the time I ordered first and asked questions later. (Lesson learned). I then began to read up on it and then so many questions followed my readings which is why I joined the forum. You guys have been crazy helpful. Very glad I joined up. Here is to hoping that the build goes smooth and lasts awhile. I am thinking I will stay with the 67mm only because I've already received it and I'm not sure about amazon's exchange policy. So at best I have 4 more rebuilds on it. Which I'm not sure of the life left on the bottom end but I'm thinking if the bottom end gives out before the top end cannot be bored again then I'm going to go all out with a big bore stroker. But let's just hope that can of worms is far in the future... Thanks again for everyone's help and a huge thanks to everyone for not criticizing my lack of experience. I:II:II:I
Quick question on the plug chopping and this will be a dumb question I think but I'm going to ask it to be safe... Is it safe to do the plug chopping before the break in period is complete on the new topend or should I give it some easy ride time prior to the chop?
do the heat cycles and retorque the head and base nuts before doing the plug chop.
you shouldn't be revving it past 3/4 throttle during that time, so the main jet does not effect anything (main jet works from 3/4 - full throttle)
heat cycles:
http://www.blasterforum.com/engine-13/blaster-engine-break-44174/
recommended break in:
http://www.blasterforum.com/engine-13/la-sleeve-ct-racing-recommended-engine-break-50702/
we've all walked in those same shoes before, reading and asking on here is far better than learning the hard way
I read this thread again and I was wondering what all mods are done to the Quad, and what all do you plan on doing to it when you get your Jug back? You said you plan on buying an exhaust, any ideas on what Brand?
When your ordering your top end gaskets, Its recommended by most to only use OEM Yamaha or Cometic base gaskets. The green paper ones should be avoided.
The lack of experience thing, there is no shame in that. We've all been there!
When your ordering your top end gaskets, Its recommended by most to only use OEM Yamaha or Cometic base gaskets. The green paper ones should be avoided.
The lack of experience thing, there is no shame in that. We've all been there!
like awk and dirty said weve all been there.The only way to get experience is to do it.Better to do it with the advice of 1s who have been there.So no shame
Thank you. I didn't order the gaskets separately, they came with my wiseco piston. I have been in the hospital with my son and my piston just arrived yesterday but I haven't been able to check it out and look at the gaskets. But the kit I purchased was the Wiseco topend rebuild kit with all the gaskets, wrist pin, bearing etc included. Should I not use these?
And as for the exhaust, as of right now I just want to get it running. Once I get it running and become confident in the motor I am looking to get an FMF Fatty pipe and Powercore muffler. It is my understanding that at that point I will need to rejet my carb so I'm assuming I will need to do another plug chop at that point?
Hope your son is ok. I'm not familiar with the wiseco gasket sets. Maybe take a picture of them and put them up and we will let you know.
View attachment Capture.jpg
It looks like paper gaskets, so I should order new gaskets from cometic I'm guessing?
just order a single OEM base gasket, from ebay
or ken oconnor racing...............
OEM Yamaha Blaster Parts
The rest of them should be ok. Just the base gasket is the one. Awk pointed you in the right direction!
You can lose them all quick if you don't get everything right. Rebuilding .25mm is only for engines that are well maintained. Since it's not already been said and you might not already know; air filter maintenance is of the utmost importance. Remember that anything that gets through a 2 strokes air filter goes through the engine not just across the top of the piston of a 4 stroke. The good news is if you do your rebuild right, break in and jet properly, maintain your air filter and keep it leak free......the little engines are near bullet proof.
So I installed my new topend today... Unfortunately I just can't get this thing to start. It has fire, gas, and compression. It just won't start. I'm not sure what I've done wrong. It will hit a lick once or twice every about 10 kicks but never really starts. The stator that I purchased prior to the topend rebuild seems to be able to adjust the timing... Is it possible I installed that wrong? The stator that came off did not have the adjustment that I could tell.
By saying "fire" do you mean spark? On the adjustable timing plate there is numbers from -10 to +10 with corresponding lines. One the cases behind the flywheel there is a nub at 3 o clock or so,the bottom of that nub should line up with zero on the adjustable plate.
Also is the carb clean? Did you try starting it with the chocke on? What does the new top end have for compression?
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