Forum

[JTL]

Simon, I believe it was the decomp (maybe head gasket too)... Summery: almost new (400 km only) tuned head from Mr. H meaning ok valves, brand new piston (8:1) with rings in need of proper bedding, trying the 1 mm solid copper gasket fitted with Blue Hylomar and the old decomp just screwed back onto the head. First run after reassembling I lost compression after 500 m; engine died. Back home top end was pulled and put back on. This time with the composite gasket and a brand new copper sealing for the decomp. And now the bike runs great. I'm still in the process of running in the piston/rings with small outbursts of heavy accelerating/deaccelerating... all the best Jacob

[simon]

Yes. The solid gaskets can be tricky. I've made a few of my own at .5 mm to give me more compression. Even annealing them thoroughly they can be hit and miss. I finally fitted this one with wipe of silicone and all is well. Don't chuck it out but remember you have to heat them all over to cherry red to ensure they are nice an soft before re use. S:)

[PeteF]

JTL,
Glad you're sorted,
BUT
Your last post contained one of the major pitfalls of curing any mechanical problem.
Quote; "almost new (400 km only) tuned head from Mr. H meaning ok valves" unquote.
Sorry, it means no such thing. All it means is that the new head has only run for 400km.
I've been sorting mechanical problems for a living for 40 years and the number of times that the problem was caused by the last "new" part installed runs into thousands. I'm sure Mr H does a wonderful job and in this case it wasn't the valves but dodgy parts get through any system. This is one of the reasons that it's a good idea to only ever change one thing at a time if at all possible.

[JTL]

PeteF, you are absolutely right about what the 400 km run time mean: 400 km run time and nothing else. Writing (correctly) about technical issues are not an easy thing. At least it is difficult to make it short. And the deduction that because Mr H makes quality products (most of the time) then the valves are ok is a mental shortcut. I guess I was just a little lazy in my writing not mentioning what I have been listening for/looking at at wich part of the engine. Well, bottom line is that the bike is up and running with the old composite gasket. The copper gasket has to wait for better times... My only problem now is myself. I'm too impatience for a proper running in of the new piston and rings. Too much speed and for too long time. Most of the time it is in the city, so speed limits and queueing are my little helper here... all the best Jacob

[Beezabryan]

I used a solid copper gasket once for just one day, since then it has been an ornament hanging from a nail on the garage wall. Odd really, use a composite gasket on our Flash & it will weep oil, use a solid gasket & all is well. Just the opposite with the Infamous Bullet. The joys of old mo'cycles !

[PeteF]

Jacob, I wasn't meaning to be pedantic but I've seen countless hours wasted (a lot of them my own) by assuming that new parts are OK. As someone said "to assume is to make an;
ass of u and me"

[JTL]

PeteF, I know what you mean. Assuming doesn't bring anyone anywhere; knowledge does. As I do not want to waste peoples time by not describing any problem correctly I will try to make a better job explaining what the situation can be. Based on knowledge of course. Which mean I have to make a better investigation on the situation. Wich in the end will make it somehow easier to fix any problems. Being a home mechanic with an urge to ride the bike instead of too much tinkering your comment is absolutely well taken... About the copper gasket: one day I will learn. For now it might go on the wall as Beezabryans... all the best Jacob