Mr head meet Mr piston

britincali · Post by **britincali** » November 11th, 2008, 1:06 pm

Looks like the dome/squish was machined a little of center, I dug up the old cracked piston and found the same thing.

I dropped the head off at a buddies to have him machine the head a little, on a positive note I think this is why it was blowing gaskets

fastkart · Post by **fastkart** » November 11th, 2008, 2:49 pm

I'd be for getting ahold of Glen and asking for his thoughts. I just went out to take a peek at the dome of the piston in my GSS and it looks alright, but I don't have it on a bottle either.

britincali · Post by **britincali** » November 11th, 2008, 2:55 pm

The head has been completely reshaped, its a 2mm part of the squshband on the intake side that is hitting the piston, it looks like it was machined slightly off center.

My guy is gonna put it in a mill and cut off the offending bit of ally

100hp honda · Post by **100hp honda** » November 11th, 2008, 5:26 pm

dont tell me you had somebody shave the top of the cylinder down ?

. edit i checked my numbers and piston is is right

britincali · Post by **britincali** » November 11th, 2008, 5:43 pm

Glen decked the cyl last time it popped the gasket and cracked the piston, and no the piston aint in backwards

100hp honda · Post by **100hp honda** » November 11th, 2008, 5:46 pm

britincali wrote:Glen decked the cyl last time it popped the gasket and cracked the piston, and no the piston aint in backwards

ya piston is right i just double checked with mine. when i had that cylinder it was supposedly brand new, i dont see how it could be cracking pistons. whats the head look like ?

britincali · Post by **britincali** » November 11th, 2008, 5:53 pm

Head looks fine damage wise.

Where the squishband meets the flat surfce of the head there is a small lip from say 12oclock to 3pm where it wasnt quite centered when machined, it wasnt an issue when I got the motor from you as IIRC you ran the fatter cometic gasket, when I put it together I used the thin single layer honda jobbie then after the piston cracked I had the head/barrel decked which compounded the problem and gave it an even bigger hit.

Im gonna get the head back tomorrow from the guy removing the bit of material then reassemble it with a copper headgasket and go from there.

Crank feels tits BTW.

100hp honda · Post by **100hp honda** » November 11th, 2008, 5:59 pm

did you notice it loosing coolant into the piston area ? did you feel the piston hitting the head ?

britincali · Post by **britincali** » November 11th, 2008, 6:02 pm

It blew the headgasket bigtime last trip to dumont, it was leaking coolant all the way around. It lasted pretty well tho as this was the 3rd trip with probably 20 gal of gas and 10lb of juice total.

When I pulled the head you could see it had been going inside and out as there were tracks on the gasket and rust on the sleeve.

I dint feel it hitting, it probably dented the piston the first time I fired it.

Gotta love self race clearancing

100hp honda · Post by **100hp honda** » November 11th, 2008, 6:06 pm

britincali wrote:It blew the headgasket bigtime last trip to dumont, it was leaking coolant all the way around. It lasted pretty well tho as this was the 3rd trip with probably 20 gal of gas and 10lb of juice total.

When I pulled the head you could see it had been going inside and out as there were tracks on the gasket.

I dint feel it hitting, it probably dented the piston the first time I fired it.

Gotta love self race clearancing

that sucks. hope you get it figured out

britincali · Post by **britincali** » November 11th, 2008, 6:11 pm

Nothing to figure out, cut head a little and re-assemble!

Go hammer the fuk out of it and break something different

http://www.youtube.com/user/500bigbore · November 12th, 2008, 8:03 am

hey, i just noticed this post and was trying to explain it in another! that piston is proud to change the port timing of the jug! I've had to use stock 91+ heads and thin cometic or oem head gaskets, or 90- heads with the thick 88 style gasket to achieve the right compression!

100hp honda · Post by **100hp honda** » November 12th, 2008, 5:04 pm

brit read this. says if your squish velocity is wrong it can break the piston, maybe your squishband was wrong design ?. piston hitting the head may have been the culprit also. im not sure shaving the cylinder is helping either, maybe you need 2 base gaskets now

http://www.2strokeheads.com/tech1.htm

britincali · Post by **britincali** » November 12th, 2008, 5:30 pm

Its going back together tomorrow.....

100hp honda · Post by **100hp honda** » November 12th, 2008, 7:01 pm

i still dont see how that shit could of happened

. i thought the flat part of the head was never in contact with the piston

LOVEMYCR500 · Post by **LOVEMYCR500** » November 13th, 2008, 9:21 am

I'm no expert but if I were running nitrous I would want to keep my compression but make sure my piston to head clearance was .050 or more. Since your motor was probably set up just to run gas before the clearance was tighter. Everything expands at a greater rate running the juice but you probably knew this. It's probably a bit of an art to cutting a nitrous dome because you want to keep your compression up, you want to keep detonation down and squish band width and angle comes into play but you want a larger piston to squish clearance so when you hit the juice for a prolonged period it doesn't expand everything and hit. I would have someone cut the head that has prior experience.

britincali · Post by **britincali** » November 13th, 2008, 10:55 am

Its come to a point where I can't trust anyone to do anything right anymore, the gasket I ordered from the copper gasket "pro" is fuked up, the muppet that was gonna fix the head hit it with a dremel (I could have done that and done a better job). So tonight im gonna sit down with the trusty dremel and fix all the fuked up shit myself.

Im fukin hot as hell this morning, if you want something doing right do it yourself.

http://www.youtube.com/user/500bigbore · November 13th, 2008, 11:47 am

if i were even 1/2 as far away as i am i'd be on it for ya! what do you need to resolve the headgasket situation?

http://www.youtube.com/user/500bigbore · November 13th, 2008, 11:48 am

any pictures of that head? how much chamber is left? what thickness of gasket are you looking for?

britincali · Post by **britincali** » November 13th, 2008, 11:52 am

The offending bit of material is like a sliver of moon about 2mm thick, the dipship machinist removed most of it with his trusty dremel but there is still some material left. Im gonna hit it tonight and clean it up, im re-using the stock gasket with a heafty bead of 1211.

It just sux that between the head and the gasket in $45 out for complete shit work

It'll get done.

dannygraves · Post by **dannygraves** » November 13th, 2008, 12:24 pm

hey, if you want, call my buddy dewayne, he cut my head and he is absolutely meticulous.
Trust me, there IS a reason I do almost everything myself besides being a cheep asshole

pstoffers · Post by **pstoffers** » November 13th, 2008, 3:45 pm

Put a stock head on it!!!!!!!!!!! And let'er buck.......

britincali · Post by **britincali** » November 13th, 2008, 3:48 pm

pstoffers wrote:Put a stock head on it!!!!!!!!!!! And let'er buck.......

Ive got one in the garage and Ive been seriously considering it, the only question is drill the head for the bigger studs or put old studs back in the jug and buy a new gasket. ?????

pstoffers · Post by **pstoffers** » November 13th, 2008, 3:50 pm

britincali wrote:
pstoffers wrote:Put a stock head on it!!!!!!!!!!! And let'er buck.......

put old studs back in the jug and buy a new gasket. ?????

britincali · Post by **britincali** » November 13th, 2008, 3:52 pm

Im gonna grind on this head tonight and see how it turns out (fuk im sounding like clyde now!)

BannedCR500Riders.com

Mr head meet Mr piston

Mr head meet Mr piston