TOPIC:

I recently rebuilt the top end of my 1976 KZ900. I sent everything to PitStop performance. Joe bored the cylinders for MTC 1015 pistons, put in some APE 410 cams and did some mild head porting. Joe's work is very good and his turn around was pretty short.

I installed APE HD cylinder head studs because I heard they were necessary with the bigger pistons and more compression rate. I have the bike back together and I have done a few heat cycles and road the bike about 30 miles. Now the base gasket right behind the #1 piston is leaking. :/

I was very careful to clean and prep everything when I put it together, used new gaskets and torqued to specs. I ordered a new base gasket and head gasket from PitStop because I was thinking I need to take the top end off and try again.

Considering how much work this I thought I would pose the questions.

Is there something I can do to make sure this leak doesn't happen a second time? Any help would be greatly appreciated.

I would use a good gasket seaIer, personally use gasanitch on my gaskets. It seems to really help them seal. It wants to rip the gaskets every time you remove them. But before you tear it back apart read this. I always run cometic gaskets when available.

kzrider.com/forum/2-engine/590842-engine-case-studs#605011

Best check the head nut torque. Always recommended after a few heat cycles since the gaskets compress and relax. Hope you used quality gaskets too, not crap like Athena.

Head nuts torqed to specs and checked and torqued again. I used cometic gaskets. It's what Joe recommended. Is there something better?

SeattleKZ wrote: Head nuts torqed to specs and checked and torqued again. I used cometic gaskets. It's what Joe recommended. Is there something better?

I think Cometic is okay. Just know Athena's green base gaskets suck big time, and Vesrah is better, but not of OEM quality. Sorry, not sure what to suggest.

SeattleKZ wrote: I recently rebuilt the top end of my 1976 KZ900. I sent everything to PitStop performance. Joe bored the cylinders for MTC 1015 pistons, put in some APE 410 cams and did some mild head porting. Joe's work is very good and his turn around was pretty short.

I installed APE HD cylinder head studs because I heard they were necessary with the bigger pistons and more compression rate. I have the bike back together and I have done a few heat cycles and road the bike about 30 miles. Now the base gasket right behind the #1 piston is leaking. :/

I was very careful to clean and prep everything when I put it together, used new gaskets and torqued to specs. I ordered a new base gasket and head gasket from PitStop because I was thinking I need to take the top end off and try again.

Considering how much work this I thought I would pose the questions.

Is there something I can do to make sure this leak doesn't happen a second time?

3-bond

Nessism wrote:

SeattleKZ wrote: Head nuts torqed to specs and checked and torqued again. I used cometic gaskets. It's what Joe recommended. Is there something better?

I think Cometic is okay. Just know Athena's green base gaskets suck big time

+1 The green ones failed on my rebuild, had to tear it apart and replace them. Not fun.

I am taking mine apart this week and was curious what was the turn around time from pitstop on your head and cylinder.

I use Permatex copper coat, the kind you spray on all my base gaskets and never had a leak. The stuff works great and when you have to remove the gasket it comes right off.

He was around 3 weeks or so. He gave me an estimate of lead time and did it in the time he said he would. Not the most conversational guy but he knows his stuff and gets the job done right.

Thanks baldy110 I was thinking I would use the copper coat when I replace the gasket. The gasket is black so I'm sure it is vesrah. I'm going to torque the cylinder head bolts again and ride some more before I take it apart but I have my doubts that that will work.

Just "fog" on spray copper coat.
A small spray can of that will list you the rest of your life.
There is NO WARE else to use it on your bike.

Mike

PS make sure you didn't get an O ring out of place.