So I bought a boost bottle, now I'm baffled.

Txsandman

Member
Joined
Apr 11, 2016
Messages
32
Yeah so I put my new offset intake with boost bottle on.... Went to take a test ride. As soon as I start the bike it lunges forward and almost pops a wheelie, also felt like the throttle was stuck or the motor was idling to high. So I cut engine and turn the idle screw out. Try to go again and motor just shutters and runs like sh*t. So I pull my head off and find that the piston hit the head so hard it set my spark plugs gap to .000. Anyone want to explain wtf happened?
 


GreasyChris

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Joined
Jan 3, 2019
Messages
1,275
that is really strange, the intake should have no effect on why the piston hit the head. sometimes if your squish gap is set to close once the engine gets hot and things expand the piston will hit the head. is anything loose inside? did you remove a base gasket or head gasket?
 

GreasyChris

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Joined
Jan 3, 2019
Messages
1,275
not all head gaskets are the same thickness, i have some copper head gaskets but mine are actually thicker than the stock aluminum ones, however i think the copper ones compress more. really you should get some soft 1mm solder and tape it across the piston from side to side and put it back together then rotate the engine, pull it apart and measure how thick the solder is after. this is your squish gap. it should be about .8mm anything lower than .5mm and the piston will most likely bounce off the head.
 

LewieBike

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Joined
May 21, 2014
Messages
811
This is a hairy dog story..

The only possible way a spark plug ground electrode could be hit by the piston is if someone..(*) installed an extra long spark plug and didn't check the clearance to the psiton.

It also would have been very evident before the engine even got started as the piston would have been banging on the spark plug's electrode while pedal starting it. Would make a hella loud clanking noise.
 
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