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Post by flames on Aug 6, 2013 19:54:18 GMT 1
I just cant seem to catch a break.you may or may not of read of the problems I was having with my piston eating lc.well,i thought I had finally got it all sorted.new gasket set from norbo,fitted and torqued down,no leaks.which is a first,i should've known it was too good to be true.ran sweet,sounded really crisp,and popped wheelies in 1st on the band.left her in the garage for a cuple of days as weather been cack. just been out for a quick 3 or 4 mile ride to make sure everything was sweet before I used her for work tomorrow.left the village,and went to overtake an audi a3 and wotever was in front of him,went down a couple of gears ready,but a3 man had other ideas and got on the gas before the car coming the other way got to me.red rag bull and all that jazz,i caned the ol gal for all she was worth,sitting on a3's bumper for a couple of miles b4 I had to turn off.turned off,gave her a handful,got about 1/4 of a mile and the I lost thr r/h/cylinder.nothing to suggest I had eaten another piston,so I figured my plug,cap or lead was to blame,so I limpd home on one cyl.got in garage to find the cooling system completely drained.it appears ive blown my head gasket within 10 miles of fitting it.i checked plugs,r/h/s was a lovely biscuit brown,l/h/side looked brown beneath the wetness.which was strange coz this was the side that was still running.anyways,probed the piston crowns with a bit of solder,dosent appear to be any damage,but wont know for sure till I lift the head.but I think it is only gasket........unless the head has fell apart that is.ho hum.now thinking of going for one of nk racings copper gaskets.at least they can be re used if you anneal them.or so im lead to believe,but stand to be corrected.
one day I hope to have her running long enough to use a full tank of fuel without having to strip her down!!!
I will let you know if it ever happens.
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Post by arrow on Aug 6, 2013 20:24:10 GMT 1
That's bad news mate, you have had a long run of bad luck. Have you done all the checks before on barrel height(s) and head for flatness etc? Also are you lubricating the barrel studs and both sides of the head washers with a smear of grease?
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Post by molegripper on Aug 6, 2013 20:27:55 GMT 1
Was it a genuine head gasket? And did you re torque after the first time you got it up to temp.? I haven't has any issues with gen yam head gasket but other aftermarket stuff - well that's another story and it always involves coolant leaks.
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Post by flames on Aug 6, 2013 20:31:54 GMT 1
yes mate.barrels check out.head has been skimmed,but checked volume and that checks out within tolerance.
grease in the threads you mean? no i haven't.i put copperslip round the outside of the head bolts and the studs(not on thread tho).nothing round the washers tho.i used silicone on the gasket (not gen yam) as a precaution,but im guessing as its pressurised the cooling system,its blown around the metal rings.
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Post by flames on Aug 6, 2013 20:34:54 GMT 1
Was it a genuine head gasket? And did you re torque after the first time you got it up to temp.? I haven't has any issues with gen yam head gasket but other aftermarket stuff - well that's another story and it always involves coolant leaks. not gen yam,it was Athena kit,from norbo.so wouldn't imagine this to be the prob.i re torqued after a heat cycle.then re checked after another.only torqued to the specified 17lb a ft.normally I goto 20lb,have been to 25lb on account of water leaks,but this was down to cheapo head gaskets I think.i didn't go over 17lb as I didn't have any dribbles. |
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Post by steve h on Aug 6, 2013 20:37:15 GMT 1
If it wasn't for bad luck, you would have no luck at all  |
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Post by flames on Aug 6, 2013 20:42:57 GMT 1
this is true.
and if I didn't have elsie,i wouldn't have a bad back from keep having to push her about.she gunna have to think on soon,coz when im old,and she is powering my wheelchair,i wont be able to push no more!!!
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Post by arrow on Aug 6, 2013 20:46:11 GMT 1
Lubricated threads and the same torque value as standard will pull the head down much better, but I use 25Nm on mine.
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Post by molegripper on Aug 6, 2013 20:47:08 GMT 1
Was it a genuine head gasket? And did you re torque after the first time you got it up to temp.? I haven't has any issues with gen yam head gasket but other aftermarket stuff - well that's another story and it always involves coolant leaks. not gen yam,it was Athena kit,from norbo.so wouldn't imagine this to be the prob.i re torqued after a heat cycle.then re checked after another.only torqued to the specified 17lb a ft.normally I goto 20lb,have been to 25lb on account of water leaks,but this was down to cheapo head gaskets I think.i didn't go over 17lb as I didn't have any dribbles. Can't recall the make but I had to go way over the 17 foot pounds to stop the non yam gasket leaking as well. Put a gen one on at the normal torque setting and never had any issues. Not cheap but I picked a few up on eBay from Malaysia - normally go for £26 - worth it IMHO. Wish I applied the same principle to crank seals! |
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Post by flames on Aug 6, 2013 21:02:01 GMT 1
not gen yam,it was Athena kit,from norbo.so wouldn't imagine this to be the prob.i re torqued after a heat cycle.then re checked after another.only torqued to the specified 17lb a ft.normally I goto 20lb,have been to 25lb on account of water leaks,but this was down to cheapo head gaskets I think.i didn't go over 17lb as I didn't have any dribbles. Can't recall the make but I had to go way over the 17 foot pounds to stop the non yam gasket leaking as well. Put a gen one on at the normal torque setting and never had any issues. Not cheap but I picked a few up on eBay from Malaysia - normally go for £26 - worth it IMHO. Wish I applied the same principle to crank seals! that ol chestnut hindsight. its a wonderful thing so they say.i say its a pain in the ar5e for not showing itself sooner. will try the grease on threads thing next time gary. cheers guys. |
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Post by arrow on Aug 6, 2013 21:08:48 GMT 1
Lubrication for torqued threads is important so you don't get any tight ones or loose ones on the same job. Not as important with angle tightening as the bolt will move down by a precise amount due an exact movement of the threads (angle), if that makes sense.
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Post by wallcraft on Aug 6, 2013 22:11:54 GMT 1
I had the same issues as you, I solved this problem by
O ringing the head and barrels and sandwiched with copper gasket to maintain my squish . 1500 miles no probs.
mark.
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Post by 47x on Aug 7, 2013 9:45:44 GMT 1
wouldn't be using sealant on the head gasket neil...should be dry use,get genuine one from maylaysia..and torque to 25nm..  |
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Post by flames on Aug 7, 2013 20:53:21 GMT 1
heres what I found when I removed head....     so.... any ideas as to why this happened? or are we all still agreed its more to do with pattern gasket? |
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Post by flames on Aug 7, 2013 20:55:23 GMT 1
as you can see in the top 2 pics,it has blown at the rear,but the front has started to go egg shaped aswell.other side is as it should be.
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Post by kevsypvs on Aug 7, 2013 21:14:20 GMT 1
cheap shitty pattern gasket mate get a good one from norbo ,and torque correctly no more probs then mate
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Post by LC_BOTT on Aug 7, 2013 21:18:01 GMT 1
What sort of squish are you running, as there doesn't look to be a lip on the head at all now, is the motor tuned etc and have you checked the crank for twisting?
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Post by arrow on Aug 7, 2013 22:07:08 GMT 1
I'm going to say something here that might/might not be relevant. Years ago a fitter told me the strongest type of gasket was metal on metal. By putting sealer on there are you preventing this from happening? Just a thought.
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Post by blyth1970 on Aug 7, 2013 23:06:37 GMT 1
Has the head been skimmed or just cleaned up with a block and wet and dry, this will cause the lip on the edge to tapper down, there does not look like much of a lip, what is your squish set at ?
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Post by steve h on Aug 7, 2013 23:12:14 GMT 1
Stick a genuine yam head gasket on. Looks like that pattern one was made from lead and rice paper.
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Post by flames on Aug 8, 2013 5:38:36 GMT 1
head has been skimmed,0.75mm removed which is why there is no lip.squish is 1.2mm with the gasket torqued to 17lb a ft.this is how it came on the bike when I bought it 21 yrs ago,so I don't know how it was done,but I would gues its been lapped.but not had a prob with this before.the gasket doesn't sit inside the lip as I have checked that on another head I have.i haven't used the other head as the ring damage is bad.there is ring damage on this head in the other pot,but not as bad.crank has been checked and is within tolerance,tho I didn't do this myself as I don't have the gear to do it.and altho I used sealant,it was a lite smear only on the paper part around the water ways as I had one that leaked slightly a few yrs ago that allowed water to escape down one of the stud holes and made it go rusty.i have pm'd norbo with regard a gen gasket,but I am also seriously considering trying a copper one.are the genuine yam gaskets made as 1 piece? or is the ring crimped on as the pattern gasket?
thanks for the replys peoples.
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Post by tygertung on Aug 8, 2013 6:02:09 GMT 1
They are 3 piece, seem to be three layers of steel with a black sealing paint. They have a raised portion ring around the water galleries and head, sort of embossed.
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paulo
Thrash Merchant
Posts: 406
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Post by paulo on Aug 8, 2013 7:27:05 GMT 1
I know how you feel M8, had head gasket problems with my YPVS motor.
What I can't work out is, when we were 17 / 18 years old, I bet non of us used gen yam gaskets / parts with no problems - I know I didn't, £25 a week wage.
So with my latest engine rebuild, cleaned piston infected crank up in my bench parts washer, bearings felt ok, side to side gap of rod at top spec but f**k it I thought, cleaned up badly scored rh barrel with flexhone, not perfect, new pistons (£50) a pair from Japan, pattern gasket set and 1000 miles down the road, the old girl is still going !.
Best of luck, but to me it looks like a faultly head gasket, that's 21 years experience working in the car manufacturing business - seen this when the unitshop test chaps have stripped motors down for fault investigation !.
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Post by Delbert on Aug 8, 2013 7:31:56 GMT 1
If Thats a multi layer gasket you have there , then with out a question of a doubt Thats your problem , we have had no end of trouble with them on cars and bikes & dont use them any more , as said use genuine and should sort it ,, best of luck mate sounds like you can do with a break !
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Post by Norbo on Aug 8, 2013 9:15:08 GMT 1
I do my heads down to 20 or 22 however it may to High compression for the head gaskets on a standatd head it may have been ok . I recently had the same problem have the head skimmed as it was not flat but in the end it turned out to be over compression in 1 pot blowing the gasket every time I went out must have done 3 head gaskets and scuffed the barrel a little before I found the problem
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Post by midlifecrisisrd on Aug 8, 2013 9:18:17 GMT 1
I would check the compression. As Norbo says it may be too high.
Squish is one thing but if there is not enough volume in the head it will cause problems.
Steve
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Post by yamaha341 on Aug 8, 2013 10:13:11 GMT 1
baaaddd 11 luck mate right enuf BUT,,, what is that goo your putting on with the head gasket is it RTV as in instant gasket//
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Post by kevsypvs on Aug 8, 2013 10:24:33 GMT 1
get another descent head with new genuine gasket bung it on and go
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Post by 4l04ever on Aug 8, 2013 15:26:52 GMT 1
Check the volumes in your domes. Should be at least 18.5cc each side. If any smaller, you will be running too high compression. I had the same problem and was pushing a copper head gasket out in the same places.
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Post by flames on Aug 8, 2013 15:57:27 GMT 1
its clear sealant I was using,tho it doesn't look very clear now.domes are 18cc each side,not including gasket.
will do a compression test and got from there.whats the highest compression I can hope to get away with?
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