Rob123
Thrash Merchant
Posts: 382
|
Post by Rob123 on Oct 18, 2020 10:13:53 GMT 1
I had a slight weep of coolant after rebuilding the top end after having the barrels ported. After around 150 miles of running in new pistons I decided to take the head back off to sort the weep. I was going to put a bit of gasket sealant on the gasket and bolt it back up. The compression ring on the right hand side cylinder appears to be rippled/indented slightly. There are similar marks on top of the cylinders. When fitting the head I had the bike up right and not lent over so I'm pretty sure the head went on inline. The compression ring diameter measures 65.75 ish . Pistons are 65.5. I've ordered a genuine head gasket to replace it. Anyone seen this before any cause for concern? Cheers Rob        |
|
|
|
Post by midlifecrisisrd on Oct 18, 2020 10:29:14 GMT 1
I'd say it's just the way the ring has compressed on tightening
Dodgy gasket probably
Steve
|
|
Rob123
Thrash Merchant
Posts: 382
|
Post by Rob123 on Oct 18, 2020 10:54:11 GMT 1
Cheers Steve
Just looking at the old gasket (pictured).
There is an indentation albeit more uniform around half the ring on one side.
It looks like the piston has been hitting it causing a perfect piston shape dent in the ring.
I'm pretty sure I'd of felt that tho.
Its like the gasket is on the limit when used with 65.5mm pistons.
|
|
|
|
Post by JonW on Oct 18, 2020 12:51:09 GMT 1
I dislike this style of gasket, Yam went to this design and then went back to the multileaf design for the LC, thats said something to me.
|
|
|
|
Post by flames on Oct 18, 2020 12:51:33 GMT 1
I had similar head gasket in mine a while back that blew completely. Split the metal ring and the material around it. Think my compression was too high because I tried to get a tight squish and neglected to check compression etc.
I fitted genuine after that with no problems.....I did increase the squish to be safe as well.
|
|
|
|
Post by Tobyjugs on Oct 18, 2020 12:58:08 GMT 1
I agree with Steve, in the past I've had issues with the head gaskets using 2mm+ pistons.
I now use four cylinder head bolts with the heads cut off to hold the gasket in place then you can visually check how it fits before sliding the head on and tightening up properly .
|
|
|
|
Post by 4l04ever on Oct 18, 2020 15:28:01 GMT 1
I agree with Steve, in the past I've had issues with the head gaskets using 2mm+ pistons. I now use four cylinder head bolts with the heads cut off to hold the gasket in place then you can visually check how it fits before sliding the head on and tightening up properly . To save cutting the bolts, you could just put the gasket on the cylinders loosely and locate it by putting the head bolts in a few turns without the head fitted. You can then check if the gasket is over hanging the cylinders, which may only be on one side if the bores are not central in relation to the head bolt holes. |
|
|
|
Post by 4l04ever on Oct 18, 2020 15:30:41 GMT 1
The leak may be caused by the top of the cylinders not being flat or not being parallel and level with each other. I bolt mine on with no head and use spacers under the head bolts, then can check with a straight edge. If they are not level, my engineering man can skim them as a pair using my jig plate.
|
|
Rob123
Thrash Merchant
Posts: 382
|
Post by Rob123 on Oct 18, 2020 17:44:37 GMT 1
I'll try again once the new gasket comes 🙂 👍
|
|
|
|
Post by Tobyjugs on Oct 18, 2020 22:21:26 GMT 1
I agree with Steve, in the past I've had issues with the head gaskets using 2mm+ pistons. I now use four cylinder head bolts with the heads cut off to hold the gasket in place then you can visually check how it fits before sliding the head on and tightening up properly . To save cutting the bolts, you could just put the gasket on the cylinders loosely and locate it by putting the head bolts in a few turns without the head fitted. You can then check if the gasket is over hanging the cylinders, which may only be on one side if the bores are not central in relation to the head bolt holes. It also helps guide the cylinder head down with very little movement to disturb the gasket. I find it easy and precise. |
|
|
|
Post by steeley on Oct 19, 2020 8:28:01 GMT 1
Hi ,did you check that the base gaskets didn't over lap in the center i had this some years ago .
|
|
Rob123
Thrash Merchant
Posts: 382
|
Post by Rob123 on Oct 25, 2020 20:59:00 GMT 1
I fitted the new genuine head gasket today using the methods mentioned on here.
Leak free cheers guys 👍.
Put gasket on dead central,dry no sealant
Warmed the bike up without coolant in
Let it cool down re tourqed to 20 ft lbs
added coolant.
I noticed the pattern gasket bolt holes have alot more play in them then the genuine gasket,
Thus making it easier to put it on not central.
Barrels were both dead level i checked using the spacer method 👍
|
|
