Big problem this time - bike sounds like a sewing machine and no power

[xwhatsit]

What state is the battery in?

Have you tried a new plug? Is it possible that with all the drama with the cracked head that the carb settings have been maladjusted . Specifically, the cracked head would have tended to make the machine run lean - so someone may have wound the pilot jet adjustment in (or out, whichever way your one goes ) to richen the mixture. Now without the leak it's too rich

If you are getting a good spark and a new plug I doubt it is spark (your method of testing is fine).

Once running does it idle reliably and well, about 1000-1200 rpm? Respond cleanly to the throttle?

Nooo... well... I've been treating the starting symptoms before and after rebuild as a group. As far as I can detect, there's no difference between how it was before and how it is now. The carb may well be up the tree. In the past I have tried new plugs, with good success -- typically, putting a new plug in would make it start on the first or second kick (once, rode to Repco, bought a plug, tried to start with the old start but not even bump starting would do it -- put in new plug and it started straight away). EDIT: and as far as I can recall, it idled much better with the new plug, and started well for maybe two or three days before it would turn to shit again.

It won't idle to save it's life. I've noticed after the rebuild (good compression, maybe?) it is happier at low revs, but eventually it'll just conk out without warning, and I don't want that to happen with the starting issues the way they are so I keep blipping the throttle so it revs around 2Krpm. It sort of responds well to throttle around 1000-1200, but sometimes it'll stall when I twist it.

Battery is fully charged, appears to be holding up well. Got a bit more than 12V in it, maybe 12.5 or something. It's probably not in best condition, after being discharged a couple of times, but would it still cause issues?

[Ixion]

If the battery is reasonable it is probably sufficient for a kickstart bike - no voltage drop from the electric starter to worry about.

Definately sounds ike the carb needs tuning.

I'd suggets another new plug (you imply I think that you haven't replaced it since the "old' motor) - the cracked head may have been stuffing them up so a new one may last well now.

And see if you cna get it to idle, if it will idle OK it will probably start OK

[xwhatsit]

Nup, haven't replaced plug since did motor. Have a brand-new looking slightly different model plug (but still in the same series) that came in the box of bits with the parts bike. Will give that a whirl.

I'll have a play with the carb. I know it's pretty clean inside, hopefully the idle circuit isn't blocked as that looks a bastard to clean out. With a bit of luck the pilot mixture may be the only thing I need to do.

The plugs always look the same after they've run for a bit -- white/light grey electrode, but dead clean, no deposits or any shit. I just pulled the plug out now, the insulator is white with maybe a slight orange/brown spot or two.

Will follow the procedure in Haynes of how to set pilot mixture tomorrow. I have a spare carb too... it's probably pretty stuffed though.

The oil leak is worrying me though. Would that goopy orange silicone crap be a good idea?

[Ixion]

Hm. Mr Motu will have something to say about the goopy orange crap. Try to get a better one, Loctite do a good range. Check the cover for warping if you can .

The plug should NOT look white (like a new one looks) It should be a choclate brown , about the colour of fruit and nut chocolate. A whiteish grey plug definately indicates a lean mixture. But I assume that your comment about colour is based on plugs running with the old cracked head - as I said that will certainly have made for a lean mixture. The orange brown spots may indicate that the mixture is more correct now (it takes a few hundred kilometres for the full clolour to show). Deposits are not really what we are worried about here.

Definately has been running lean in the past. And a greyish plug usually indicates that its been overheated (the effect of lean mixture) and ruined. Definately replace it.

Replace plug, see how it gos , if it still won't idle or start, look at the carb. More likely to be fiddled settings (in a vain attempt to compensate for the elanenss), rather than anything blocked.

[xwhatsit]

Hahaha yeah I know the goopy orange crap's reputation, but that'd be better than my engine giving off smoke at the traffic lights. It's not a two-stroke, you know . I'll check out Loctite, then.

Ooooh ok, chocolate brown, then? Well I'll give the new plug a shout tomorrow then, and try and get the pilot mixture right. Hopefully it will stay good for a while.

Thanks for the help.

[xwhatsit]

Well I've had a bloody frustrating morning. Put the shiny plug in, started third kick or so despite the shitty weather. Idled quite well, even without choke, and right down to the recommended 1200rpm +/-100. Went for a short ride to get her up to temperature, came home and followed the method outlined in the manual on how to set pilot mixture. Thought I got it right, so went for a short ride again. Bike stalled while idling at an intersection, could not for the life of me get her started again, even though I could start her just before when hot. Flooded engine trying to start, finally managed to bump start her but wouldn't idle at all any more. Came home, sweat pouring off me from the effort to start her, pulled out the plug and it was all grey like the other one.

Now, the manual doesn't say, but if I'm screwing it in, does that make it leaner or richer? I've made up my mind that carbs are a bitch. Horrible fiddly pieces of shit and now I'm feeling pissy. How much are those exhaust analyser thingies I've heard references about? Would make things a hell of a lot easier.



Oh and a while back I talked to my Dad, he mentioned he'd put straight pipes on his cruiser and then took it to the shop to have it put on the dyno and the carb tuned. It cost him $100 in Australia. Is it comparable here? Almost wouldn't mind just dumping a weeks wages on getting this frigging thing right.