Bought bottom end from Boy Go Fast, should I be worried?

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Theon

New Member
Jan 20, 2014
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FNQ Australia
I can't answer his question if the slant head will have to much compression if I don't know what squish he ended up with.
Or if he is more likely to have a 38 or 40mm crank.
Just trying to help.
I guess I was taught to do things properly,
If people just want to slap things together, then why be on here asking questions?
just do it, see what happens,
better luck next time?
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
I can't answer his question if the slant head will have to much compression if I don't know what squish he ended up with.
Or if he is more likely to have a 38 or 40mm crank.
Just trying to help.
I guess I was taught to do things properly,
If people just want to slap things together, then why be on here asking questions?
just do it, see what happens,
better luck next time?
I have been running, tinkering and building these engines for the last four years, Im one that doesn't get to technical with things and I've had great results with my engines, I know you have excellent intentions and are only trying to help but if you try to teach algebra to a three year old in a language they dont speak what benefit will it be to them?

You obviously know more than I do about performance building the engine, but I can tell you that I have 45+mph bikes that have never had squish measured, a fairly good balan ed lower along with a properly tuned NT carb and the right gearing with a good flowing exhaust will get most people to the point they want to be with there bike in my experience.

You obviously take the time to try and help and myself and others really do appreciate that, its just a bit much to be asking noobs about whether or not they have done more technical mods and processes when they have no clue what any of it is.

Map
.wee.
 

Theon

New Member
Jan 20, 2014
1,440
6
0
FNQ Australia
It's not hard to measure the squish.
And not a bad idea, at least you know that you don't have .2mm squish and the piston will hit the head eventually.
Things like checking your squish are just good engine building practices.
and if he's got a 38mm crank then there is nothing to worry about.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
So guys, is it ok for me to run a milled slant head on a 40mm stroke as long as the piston does not hit the head or plug? (it doesn't) That's all I want to know.
Yes it is fine to run the milled slant head with a stock head gasket and as long as the slant head has not been milled beyond the height of the raised sealing ring that the heads have, it is a good idea to leave the spark plug out and roll the bike forward or backwards with clutch engaged so the engine will spin over just to make sure the piston doesn't contact the head.

I have shaved the slant heads down until all of the sealing ridge ring is removed and as long as the head gasket is a stock thickness of 0.018+ I have never had the piston contact the head.

Map
.wee.