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Post by ruffneck247 on Sept 2, 2014 15:55:39 GMT 1
Hi,
My head gasket failed on left cylinder. I have now replaced and re-assembled the bike. Now runs hot and smokes a lot from left exhaust. Any ideas why this might be?
Cheers
Chris
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Post by muttsnuts on Sept 2, 2014 17:16:23 GMT 1
which head gasket did you use, a genuine one or a pattern one, also did you clean the head and barrel faces up and removed any crud etc, did you use any sealant when you re-assembled it etc, have you torqued the head down, done a heat cycle and then re-torqued it down, TBH there are a good number of variables that need to be narrowed down first
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Post by ruffneck247 on Sept 2, 2014 18:43:26 GMT 1
Cleaned head and barrel faces perfectly. Used a pattern head gasket with no sealant and torqued in correct order to 24Nm.
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Post by muttsnuts on Sept 2, 2014 20:02:06 GMT 1
ok cheers, if you used a pattern head gasket, then did you run it up first with no water and then let it cool down and then re-torqued the head as otherwise they tend not to seal until they have a done a heat cycle as the "shirlac" on the gasket needs to melt and seal to the head and barrels, once that has happened you can fill it with water, do another heat cycle and recheck the torque settings
if you put water in before doing a "dry" run heat cycle then there is every chance that the gasket will leak as water stops the "shirlac" from melting and sealing properly
so you could have water geting into your barrel(s) ad hecne all of the white smoke and running hot etc
HTH
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Post by stusco on Sept 2, 2014 20:21:32 GMT 1
I've never heard about doing dry runs before ,how long would you run it for
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Post by muttsnuts on Sept 2, 2014 20:39:54 GMT 1
I run them until I can't hold my hand on the barrels for very long, normally around 3 to 5mins on a slightly fast tick over (1800 rpm) - but no longer, then I leave it to cool down over night ideally, then re-torque the head, never had a pattern head gasket leak when i do that, had plenty leak if I don't ! - if you use a geniunie head gasket you don't need to do that though as thjey seal a completely different way
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Post by 4l04ever on Sept 2, 2014 23:07:15 GMT 1
Check the water level in the radiator and overflow bottles. If it is going down, then the new head gasket could be leaking. The smoke will be greyish if it is steam, just like a kettle!
If it is blue grey then it will be oil burning, which is usually okay. I have seen quite a few bikes where there is more smoke from one side than the other.
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Post by stusco on Sept 3, 2014 15:03:52 GMT 1
Are Norbo's pattern or genuine I can't remember what I bought
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Post by stusco on Sept 3, 2014 15:04:38 GMT 1
The gasket is thin sheets of black metal
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Post by bare on Sept 3, 2014 19:45:50 GMT 1
Interesting .. The thin sheets of metal type (didn't know they were available for an LC though)
are far Less critical to being aftermarket than the fibre /comp ones OEM onna LC.
Might not be the HG then ?
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Post by stusco on Sept 5, 2014 19:07:28 GMT 1
Sorry it's a ypvs
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Post by muttsnuts on Sept 5, 2014 19:57:29 GMT 1
ah, that puts a different complexion on things ifn its a YPVS and not an LC
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Post by looey on Sept 6, 2014 10:16:29 GMT 1
When I do my YPVS top end, I fit the barrel nuts just hand tight, then do the process as Muttsnutts does. Obviously once the head it torqued down for the first time, then tighten the barrel nuts.
When I re-use a head gasket, I fit it with the thinnest possible smear of clear RTV silicone sealant (just enough to give a shine) and not had any probs with that either. Put any more on than that and it will squash out and start to block the water jackets.
Some say use sealant, some say absolutely not, but in my experience not had a problem either way. Certainly wouldn't use any on first time use on a genuine head gasket though.
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Post by rich on Sept 6, 2014 13:07:10 GMT 1
I think the most important thing is to run the engine up to full temp before riding and then let it cool right down overnight. Retorque the bolts when it's stone cold, even if you need to back them off slightly first. The reason for this is the head expands when hot and will squash the gasket slightly and you will lose some of the clamping effect when it cools down. I reckon this is where a lot of people go wrong, rather than the pattern vs genuine gasket debate. Not really had much trouble with pattern gaskets, or reusing genuine ones. I also use a light smear of sealant unless the gasket is brand new and still has the rubbery black coating.
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Post by bare on Sept 8, 2014 17:33:15 GMT 1
One fellow who has Some respect. Always sprays his head gaskets, both brand new and recycled, with Rattle can Laquer.
Claiming this is a Very good sealant. His success record suggests that there may be truth in his technique
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Post by looey on Sept 8, 2014 17:52:43 GMT 1
One fellow who has Some respect. Always sprays his head gaskets, both brand new and recycled, with Rattle can Laquer. Claiming this is a Very good sealant. His success record suggests that there may be truth in his technique Can see how that could work. Is there any more detailed info. on using that process ?. Would be a lot easier to dust both sides with a spray than applying a very thin coat of sealant  |
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Post by steeley on Sept 8, 2014 20:02:31 GMT 1
I would like to know more about that also.while being a believer in dry head gaskets.always room for new ways/ideas.interesting.
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Post by ruffneck247 on Sept 14, 2014 17:51:49 GMT 1
Thanks for all your help, it turns out to be that the bolts weren't torqued down properly as my torque wrench wouldn't go as low as 24NM so I had to guess initially, but when I bought a lower torque value one - problem solved!
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Post by steeley on Sept 14, 2014 19:29:41 GMT 1
glad you got the job sorted out and it was just a torque job ,happy days.
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