A couple of technical questions

[Hired_Goon]

I own 2 78 E's. One is the good bike for weekends and the other is the daily work hack.

The work hack has an oil leak in the head so I ripped the motor out and put the spare motor from my parts bike in it while I get the leak fixed.

The questions.

The motor I pulled out has a G stamped on the pistons. No other markings. Are these standard??

Anybody ever successfully welded up a crack in the bore section through the cam tunnel???

Clutch in the parts bike is the wierdest thing. No matter where I adjust it to the bike will creep forward when I put it in gear. I can feel it start to engage fully as the lever is about halfway out. Give it some gas down the road and it will slip like crazy.

Now the slipping I can handle as it's only in there for a couple of months, but the creeping is annoying. Any suggestions? 20/50 oil too thick?


It's a fairly sturdy motor but has an unknown history. Sat for a long time and was used as a paddock basher before that. Oil I dropped out was pretty thick and black so will do a few changes every 100 miles or so to flush it clean.

Won't bother with the jumping out of first either. Will use it for dog undercutting practice one day when I have time.

[Snow]

I don't have all the answers you are looking for, but I have a couple suggestions:

Pistons - I don't recall much in the way of markings on the pistons - the Wisecos have all sorts of info on em, so I'd have an educated guess they are stock. Where is this "G" printed?

Clutch - just another guess, but I'd wager your fibers and/or steel bands are warped. A *little* bit of creep from oil...somethingorother...isn't out of the ordinary, but slipping means the clutch is worn. 20/50 should be fine as long as it's not the energy conserving variety. What oil are you running?

Don't bother welding up the crack in the cyinders - just get a different set, perhaps from Andreas. I got a set from him for $50 including shipping.

Jumping out of first could be bent/worn shift fork - I'd consider checking it out before something nasty happens.

[mro]

Piston

Pretty sure 78/79 stock piston have no markings

80/81 have 3H5 on em

Not going to look at the big bore pistons on the hot rod so haven’t a clue what could be on after market ones


mro

[goldcoastguy001]

Not sure bout the Pistons and wouldnt want to lead you astray, I wouldnt recommend welding the crack if you intend to keep the engine for a long time, however I know of people who have had similar cracks welded and it sems to work so long as it is done by someone good (I just dont like the thought of it). The clutch plates sound warped, maybe thru abuse in the paddock. The oil is fine but change it a few times may be abit of drag thru gummy oil. Take the clutch plates out and clean and inspect then do an oil change. The dogs on the first gear issue will only get worse, Practise on them if you wish but remember if you get it done now on the spare engine at least you'll have a set of good ones for later down the track if you need them......cheers

[Hired_Goon]

Thanks all.

May have to get the verniers out and check the piston size before i put it all back together. The bores are in exceptionally good condition for a bike this old and high mileage. No lip whatsoever and looking at the bottom of the bore where the piston doesn't hit it looks like recent hone marks. Maybe it has a set of oversize pistons.

I do know some good alloy welders so am confident on a good job. Gotta do something with it cos the leaks on the driveway are bugging SWMBO.

The clutch I'll just live with for now I think. The engine I'm fixing needs plates as well so I don't want to cough up for two sets.

Only slips when the main jets start working anyway. The creeping can be handled with the front brake.

Cheers
HG