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[Geraintosaurus]

Oh, sorry, I missed your question about the backfiring. I only get smoke through the carburettor when trying to kickstart, occasionally. Otherwise it's a sort of low rumble from the exhaust.



Having just put my head next to the cylinder, the noise is coming from there I think but now I'm wondering if perhaps it's just the ignition itself... hard to say but it sounds vaguely more like a pop now than a metallic clang. I just noticed it suddenly one day and so assumed it was a problem but I might be over-reacting.

[Adrian]

No, not really applicable. This is more in the line of Whitworth spanners, Brylcreemâ„¢ and black and white public information films (come on Alan R, you know you want to!).



As you seem to have been struggling with this quite a bit, is there a friendly vintage or classic club that meets anywhere near you, local branches of the Royal Enfield Owners' Club included? I think you will find most are helpful and will realise that not all of us started mucking about with old bikes in our teens over 40 years ago.



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[Adrian]

Our replies crossed.



The odd backfire through the carb when starting isn't unknown, if it has developed in the exhaust on over-run it's most likely an air leak, you can remove the silencer and exhaust pipe, clean all the carbon off the exhaust port in the cylinder head and on the pipe/silencer inlet, and carefully reassemble the lot with a good smear of nothing more special than ordinary bathroom silicone RTV paste. Wipe off the excess, leave it to set and that should hold it.



It sounds like your Bullet could actually use a proper service if you have someone nearby who is competent with old bikes.



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[Lord-Toady]

I need to check the timing, the tappets and clean the carb on mine, mine is a bu**er for spitting back through the carb when trying to start it. I found it started better if I gave it a bit of gas while kick starting but I found it would spit back through the carb and the kickstart would vibrate violently with the kickback. I have now started trying to kick it over and give it a tiny bit of gas just after I have finished the kick while the flywheel still have a bit of momentum left in it and then it normally starts but if I give it gas while kicking it spits and kicks back.

[Leon Novello]

Fix the kick-back problem first; too many kick-backs will strip the teeth in the oil pump spindle, thereby wrecking the engine.

[p]

Two things come to mind;
one: check for air leak between carb and cylinder head - easily done with can of aerosol.... look through forum to find out about it.
Two: engine runs, so timing somewhere near right - remove points cover and mark backplate to rim of casing with a thin pencil line or scratch, (now you know you can always go back to that), now slacken the two "long nuts" slightly and experiment moving backplate a tiny bit either way by trial and error to try and eradicate problem (you can leave the cover off for now and go and play on a nice quiet bit of road until you have found a position where all runs smoothly - a tiny clockwise movement may retard ignition enough to solve your problem.

[Mark B]

I found Pete Snidal's Bullet manual to be a very useful book, explaining things in a simple way, giving practical advice even on the basics such as how to ride a bike, and talking about maintenance, repairs and upgrades in language that lay people like me can understand.

[Geraintosaurus]

Thanks guys, this advice is great! About to try all this out. One more question: if my timing backplate won't move any further clockwise, is there something I can do about that?

[Geraintosaurus]

I've bought some silicone sealant and as I understand it I need to seal the part indicated in the picture below:







I sprayed WD40 onto the bit between the carb and the cylinder and the revs did increase, so clearly I need to reseal something there - I just replaced the rubber bit so I don't think it's that. So question is can I use the silicone sealant to seal the manifold to the cylinder (see picture below)?

[Adrian]

Yes regarding the silicone RTV and the exhaust port, you will also need some around the other end of the exhaust pipe where it fits into the silencer. If the exhaust pipe is a very loose fit in the head a strip of alloy cut from a beer can and wrapped around the end of the pipe will take up much of the slack, but it will still need the RTV.



On the inlet side you have now successfully identified a leaking inlet gasket which needs replacing. The answer here is to remove the carb and unbolt the alloy stub, carefully clean off any remains of the old gasket or sealant from the joint face on the cylinder head inlet port and on the alloy stub so that they are both spotless, and check the stub's joint face with a straight edge to make sure it isn't distorted. You will then need a new gasket from out hosts:



http://accessories.hitchcocksmotorcycle ... ges%2F1868



Rather than RTV I would use a dedicated automotive gasket jointing compound on this such as Wellseal, not loads but a good thin even film all round.



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