blah sick of this help plz

[400EXtreme]

okay well recently my bike needed a new piston so i put it all in correctly and everything. Problem was the piston from wiesco, where you put the wristpin in was a little bit higher than the stock one.(found this out after putting it in :/ ) So i thought of an idea to raise the cylinder a little bit by putting 3 gaskets instead of 1 under it. Would that have anything to do with it? I cleaned carb, carb was fine, it has spark, its getting me so fustrated and all i wanna do is ride :(. Any little help will very appreciated.

Thank you,
Mark

[cdrookie]

if the piston isn't the same you need to return it and get the right one! but since it's in i doubt they'll take it back...

[F-16Guy]

You can't put the wrong piston in a 2 stroke and expect it to run. If the pin height is different, the port timing will be totally changed and the bike probably won't start. If it does start, it will run like crap. Take the piston out and call Wiseco. If they sent you the wrong piston, you may be able to get partial credit or a full refund. Make sure you know for sure what year and model it is and get the correct piston and gasket set.

[400EXtreme]

thank youu

[400EXtreme]

Originally posted by F-16Guy
You can't put the wrong piston in a 2 stroke and expect it to run. If the pin height is different, the port timing will be totally changed and the bike probably won't start. If it does start, it will run like crap. Take the piston out and call Wiseco. If they sent you the wrong piston, you may be able to get partial credit or a full refund. Make sure you know for sure what year and model it is and get the correct piston and gasket set. wait you said pinston height. The pistons are identical besides the fact that where you put the wristpin in its 2mms higher than the stock one. So without 2 of the gaskets it would hit the cylinder head.

[miken]

Most likely adding three gaskets measureably changed your compression. Gotta have the right parts.
Mike -

[400EXtreme]

Yea i sent the piston back so hopefully they will give me the right one this time.

[pro-rider46]

you never said what your problem was, and i dont think stacking gaskets is good, but idk for sure.

[660r2a400ex]

the bigger the gasket, or the more gaskets, you lose compression (HP) its not good

[John451]

Originally posted by 660r2a400ex
the bigger the gasket, or the more gaskets, you lose compression (HP) its not good

In his case, It would not lose compression because it would be raising it to make it so it fits right. He has too much compression basically so he's trying to lose compression so hes back to stock compression. It's gaining the height lost by the taller piston if that makes sense to any of you. It would work. I did it on my rm250 after having too much of the head cut because the compression was igniting it then it was sparking. But it works fine with an extra head gasket.

[660r2a400ex]

sorry, i just dont get it :( build the bike right, build with proper parts, i just dont like rigging stuff up and thats what it sounds like, sorry, hope i dont affend anybody. pull it back a part, take your time and make sure you have the correct parts, good luck

[400exrider707]

Originally posted by John451
In his case, It would not lose compression because it would be raising it to make it so it fits right. He has too much compression basically so he's trying to lose compression so hes back to stock compression. It's gaining the height lost by the taller piston if that makes sense to any of you. It would work. I did it on my rm250 after having too much of the head cut because the compression was igniting it then it was sparking. But it works fine with an extra head gasket.

Actually if you read what he said, the location of the wristpin is higher in the piston, meaning the piston is going to sit lower in the cylinder, and by adding more base gaskets, it's even lower on top of that in the cylinder... at least according to what he said in his original post, I'm not sure if this is what he actually did or not.

[660r2a400ex]

correct, also is this a flat top or domed piston?

[John451]

Originally posted by 400exrider707
Actually if you read what he said, the location of the wristpin is higher in the piston, meaning the piston is going to sit lower in the cylinder, and by adding more base gaskets, it's even lower on top of that in the cylinder... at least according to what he said in his original post, I'm not sure if this is what he actually did or not.

Haha o ya. wow... But i got the hint about that because it said the piston was hittin the head.

[wilkin250r]

Actually, the theory is sound. It's very common on the 250r to use the 86 piston with an 89 crank, which causes the piston to sit 5mm higher than normal. Using a 5mm spacer plate brings everything back to normal, with the port timing being close enough to stock that no modification to the ports are needed for normal operation. Like I said, it's very common.


However, that is a method that has been tried and tested, and spacer plates made specifically for that combination. I wouldn't recommend jimmy-rigging your own with a few extra base gaskets. These sort of clearances need to be exact within about 0.005" (about the thickness of 2-3 sheets of paper). I'm not sure you're going to have that level of precision.

I think you're on the right track just getting the proper piston. I know you're eager to ride, but it's your engine. Don't monkey around with it, do it properly.

[400EXtreme]

thanks wilkin so just correct me if im wrong. Since the piston isnt the right size and i added 2 base gaskets instead of one that causes the port timing to be off right so it wont start.

[wilkin250r]

Originally posted by 400EXtreme
thanks wilkin so just correct me if im wrong. Since the piston isnt the right size and i added 2 base gaskets instead of one that causes the port timing to be off right so it wont start.

The port timing will be almost identical.

But this would assume that you have an exact match, that the added thickness of the extra base gaskets exactly matches the piston pin offset. That's rather doubtful, most likely you have a little bit of a mismatch.


Basically, my post was saying that it COULD work, but it would require a lot of error-checking and a whole list of issues to look out for that I won't bother posting each and every detail. With a lot of work, it could be possible, but it's just not worth the hassle. You would be a whole lot better off just getting the proper piston.

[400EXtreme]

so is that why its not starting? I was thinking my stator is shot. Going to check today