|
|
Post by miker1bike on Apr 16, 2014 15:35:56 GMT 1
Am about to change head gasket for the third time my fault really using pattern gasket didn't seal ! Used pattern gasket with blue hylomar sealed for a short time but started smoking from left cylinder and bubbling through header tank so now have a genuine gasket ready to fit
My question is do I fit it dry start engine with no water to get gasket hot so it seals or fit it dry torque it down leave overnight torque again & fill with water or fit it torque it fill it with water get a couple of heat cycles and torque again before I ride it ? I also have some loctite 3020 gasket spray I bought from pjme with the gasket should I spray this on first and try that ?
Thanks mike
|
|
|
|
Post by midlifecrisisrd on Apr 16, 2014 16:01:55 GMT 1
i have never used sealant on a head gasket, that is what the black coating on the gasket is for. i have also had good results from a pattern gasket.
i would say the biggest prob is either barrel deck heights sligtly out, warped head or uneven torqued base bolts as you cant use a torque wrench without the special tool
best advice is not to tigted the base bolts first. fit them loosely then fit the head and torque the head down. then tighten the base bolts. this makes sure the head to barrel faces are seated perfectly and the base can take up any slight variance
i would not start the motor dry either to stop hot spots and uneven expansion
steve
|
|
|
|
Post by messer on Apr 16, 2014 18:54:57 GMT 1
What is the general consensus on having the heads o ringed?
|
|
|
|
Post by looey on Apr 16, 2014 19:26:47 GMT 1
I did a load of research on here before doing my first YPVS head gasket and there's so many differing opinions it's almost no help... lol  I ended up using a genuine head gasket (dry metal leaf type), which I've now used twice with no leaks or system pressurising either time. What I did was..... Fitted barrels but only did the 8 nuts up as tight as I could by hand (fingers, no tools) Applied the absolute thinnest application of clear RTV Silicone sealant to both sides of the Head Gasket (so little, you can only just see the surface is wet as a result) Torqued to 24 pounds in progressive stages Left an hour and re-chequed the torque (they tighten slightly) Then did the 8 barrel bolts up spanner tight Ran it up dry but only for long enough the for barrels to get some heat in them (certainly not anywhere near hot) Left if to cool overnight and re-torqued again (again they tighened slightly) Filled it up with coolant and rode it a few gentle miles Left it to go cold again and re-checked the torque settings (bolts didn't move this time). Like I said, that's how I decided to do it after reading all the advice and opinions on here, you'll have to do the same I think, listen to all the opinions and make your choice. You could always try it dry then try the sealant option if it doesn't seal ?. Good luck. |
|
|
|
Post by Denzil on Apr 16, 2014 20:40:49 GMT 1
This is how I did mine (LOOEY). The only exception I did was NOT run it dry. And I also torqued down in stages. 20 lb sq ft, 22 lb sq ft, 25 lb sq ft with four heat cycles between re torquing. Job all good Genuine Yam gasket every time.
|
|
|
|
Post by bare on Apr 17, 2014 2:55:43 GMT 1
IMO Midlife is correct.
It's not a gasket quality or likely even a Tq method issue... but the cyl barrel heights being mismatched.
For god only knows what underlying reason.
Fairly simple to have a barrel set height match machined. Cheap insurance against a nonstop sealing issue.
|
|
|
|
Post by 4l04ever on Apr 17, 2014 10:22:39 GMT 1
I had a special plate made so that I can get LC and YPVS barrels skimmed as a pair. It is 25mm thick and has been surface ground on both sides.
If anyone needs any doing, let me know.
|
|
|
|
Post by midlifecrisisrd on Apr 17, 2014 11:33:22 GMT 1
What is the general consensus on having the heads o ringed? got mine o ringed. just single inner ring, bit of rtv around the water jacket sorts the rest excellent re usable solution steve |
|
|
|
Post by tygertung on Apr 17, 2014 11:36:26 GMT 1
I don't think you should use any sealant on the head gasket, it is designed and will work best dry. The special paint will seal it all up. I have tried using part of the head gasket with lots of sealants, different types, but it didn't work.
|
|
|
|
Post by looey on Apr 17, 2014 13:25:32 GMT 1
Do the latest genuine gaskets have special paint or a black coating ?.
A few years ago they used to have like a shiny tar like finish but all the genuine head gaskets I have purchased over the last few years are just dry metal leaf type ?.
|
|
|
|
Post by tygertung on Apr 18, 2014 11:40:44 GMT 1
I have brought two recently and they both had special black paint coating..
|
|
|
|
Post by looey on Apr 18, 2014 11:55:20 GMT 1
I have brought two recently and they both had special black paint coating.. For a YPVS 350 ?. Could you by any chance put a pic up of one, so I can compare it to the one I bought ? |
|
kjellg
Weekend rider
Posts: 60
|
Post by kjellg on Apr 18, 2014 15:38:25 GMT 1
I have brought two recently and they both had special black paint coating.. For a YPVS 350 ?. Could you by any chance put a pic up of one, so I can compare it to the one I bought ? Here is a pic of one I acquired from bob_yp  |
|
|
|
Post by looey on Apr 18, 2014 17:00:42 GMT 1
Aaaarh right, so they have a dry black painted surface. I take it that finish is either soft enough to act as a sealant when torqued down, or gets sticky the first time it gets hot  . Maybe not on the YPVS but on the 125 & 350LC they used to have a sticky (like tar) finish and used to stick so hard they were difficult to get off !. |
|
|
|
Post by arrow on Apr 18, 2014 17:04:33 GMT 1
The "black painted surface" sticks like concrete after the head has been torqued down. Nothing else is required.
|
|
|
|
Post by looey on Apr 18, 2014 17:36:13 GMT 1
Well it's worth knowing. I've never had a problem with a 125LC or 350LC head gasket but have with a YPVS 350 in the past
|
|
|
|
Post by lb on Apr 20, 2014 10:18:35 GMT 1
Bob_yp also sells the 250 oem gaskets....
|
|
|
|
Post by tygertung on Apr 21, 2014 0:18:45 GMT 1
There are the ridges on the outer shims which help to seal the combustion chamber.
|
|
.
