top end help and understand bore size please!

bagged2drag88

New Member
Aug 26, 2010
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benton maine
:eek:first off thank you for taking time to help me with this problem im having..... recently i purchased a 2000 blaster 200cc quad for my wife everything looked good starts 1 or 2nd kick sounds good fmf full pipe looks awesome.... i was told the previous owner had just put a new weisco piston in her so im thinking this thing will be a great deal well after playing with it a little getting it warm the next day and so on i noticed a tapping sound coming from what i think to be the cylinder it goes away with a little gas and only seems to be at very low idle... ive checked exhaust cause' i am fully aware a small exhaust leak could put off a sound like this but nothing.... so i contacted the previous owner being a douche as expecting stating its as is and needs to be bored .20 over.... that is all he said before hanging up... lol heres my question finally.... lol if you put a piston that is .20 larger than factory and not have the cylinder bored .20 over it wont fit right???? cause this isnt making any sense to me it seems the piston is too small for the bore and im getting what i call piston slap???? if anyone can help me out give me ideas and help me understand what i need to do that would be great.. im mechanically inclined and am confident with taking on a task of pulling this apart put i just dont know what to do if i have to rebuilt top end the right way... order a .20 piston being i want some cyclinder wall so it wont get too hot... and then have the cylinder bored .20 from where it is? is it that easy??? thanks so much and hopefully i havent confused anyone!
 
you do know that blasters are noturiously loud, that slight ticking sounding noise at idle is common to all of them, sort of sounds like the reeds opening and closing, could you get us a vid with sound so we can help diagnose this for you????
 
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Just a little hard to follow, but if you actually need to do an overbore, you would first tear it down and take it to a shop or machinist to measure what size it is. Never take someones word for it. The machinist will tell you whether it needs to be bored and how much. .020" overbore is equal to .5mm. Just buy the size of oversized piston that he tells you. In reality it will be slightly smaller than the new, hopefully perfect oversize bore.

Are you sure it really needs it tho? A little reed click is normal at idle.The fact that you only hear it at low idle supports this. A piston slap should get louder with increased rpm, at least until a bit above off-idle speed.
 
well.... lets say it is reeds.... how loud can these things get ... my warrior and my rm250 both dont make a sound like this and they probably have every mod done to them except being bottle fed lol, i have concidered other reasons as well being like ya'all said it should get lound as the throttle moves to higher rpms but i really dont hear anything.... does anyone know where i can get a factory jug or cylinder with no bore to it? and possibly know the factory size piston? i thought it was 66mm but havent got my blaster repair manual in mail yet.... i think if i can figure this out i like to start fresh and know what has been done on this bike rather than jumping in half way on a half ass build.... i guess this is what i get for buying used! lol thanks guys and i will try to get a video posted of it just not sure how to upload to this forum....
 
Well, if Mr.Douche just threw a std piston in a standard bore that is worn a bit, then yeah, piston slap is certainly possible. The only way to be certain is to tear down, inspect, and measure. Both of mine click and whir at idle tho, on fresh bores, so I just accept the noise as normal. Post the vid and we will see. Setup a photobucket.com account to post pics and use utube for vids. They will give you links that you drop into threads.

Online manual
www.rydindirty.com/blastermanual.pdf
 
Going oversize on the bore is not going to cause heating issues. .25mm over is .010" If you cut a pop can it measures around .004". Believe it or not we cut and use pop cans for shims in our machine shop all the time. Bore the jug you have and run it, it will be fine.
 
id take it apart and inspect it b4 u got buying things it probley just the sound they all make mine does it and they said about it being the reeds clicking warriors are four strokes they anit got reeds lol but good luck to you
 
id take it apart and inspect it b4 u got buying things it probley just the sound they all make mine does it and they said about it being the reeds clicking warriors are four strokes they anit got reeds lol but good luck to you

Definitely tear it down and have it measured before ordering parts. We have guys bringing in pistons and jugs all the time that either won't clean or are already bigger than the piston that was in it. Sometimes wear and scratches are questionable enough it may need rough bored to make sure what size it needs.