Red Rimshot Posted May 8, 2020 Share Posted May 8, 2020 Hello everyone, I trying to start my Son's 1938 RT100 (98cc). If it starts it will run very lumpy (as if on choke). It has ran in the past, but not now. So last week I removed the barrel and piston- all good. Removed flywheel, removed and cleaned points and so on. Woodruff key good. All good. Nice spark. Plugs getting wet. Tried different plugs - still the same??? I'm wondering if it's a timing issue. Tomorrow I'm going to have another look. Is the timing adjustable ? Any advice please ? Thanks all, Kingsley Quote Link to comment Share on other sites More sharing options...
david1212 Posted May 10, 2020 Share Posted May 10, 2020 Is the fuel fresh ? Quote Link to comment Share on other sites More sharing options...
jenkinov Posted May 10, 2020 Share Posted May 10, 2020 Good call ..always worth using fresh fuel.... I regularly use high octane fuel to get vehicles that have been stood to fire then revert to standard octane Jenkinov Quote Link to comment Share on other sites More sharing options...
Red Rimshot Posted May 10, 2020 Author Share Posted May 10, 2020 Hello, thanks. Yes, fuel is ok. I didn't see any obvious method to move timing and I'm not in front of the bike now. It runs, sometimes, but not well. My lad rode it in Arnhem last yr and had it going well (he races motocross !!!) so I put it down to lack of compression, after a few days worth of thrashing about !!!- but it's not that. I reckon it's slipped timing or crank case seal. Quote Link to comment Share on other sites More sharing options...
jenkinov Posted May 10, 2020 Share Posted May 10, 2020 There's a old thread on the an RT100 where quite a few hmvf members advise they own one ..plus welbike a regular contributor puts in extracts of a large book. .. If they don't spot this thread ..I would suggest sending personal messages to them via hmvf as owners they make have suggestions Jenkinov Quote Link to comment Share on other sites More sharing options...
mtskull Posted May 11, 2020 Share Posted May 11, 2020 It is very unlikely to be a timing issue causing the problems you describe, especially if it was previously running well. Might be worth replacing the condenser -a nice spark in the open air doesn’t always equate to the same thing under compression. Likewise, wet plugs do not rule out a fuelling issue; too rich a mixture (maybe due to leaky float valve or stuck float) might cause the symptoms you describe. Also, always a good idea to check that the silencer isn’t blocked with carbon deposits. First though, there’s a very simple test to narrow the cause down before you do anything else: Drain the carburettor and turn the fuel off. Then, with the throttle wide open, give it a generous squirt of Easy Start. Try to start it: if it runs any better on Easy Start, you have a fuelling issue. If it is no better, look at ignition or, as you suggested, crankcase seals. Quote Link to comment Share on other sites More sharing options...
Red Rimshot Posted May 11, 2020 Author Share Posted May 11, 2020 Hello all, thanks for the replies. It's sorted. Runs ok on a Champion plug, but not on an NGK or a Lodge. My mates Triumph trials bike is the same ??? I don't know why. Thanks again. Quote Link to comment Share on other sites More sharing options...
No Signals Posted May 12, 2020 Share Posted May 12, 2020 i don't know about Lodge plugs, but the world is awash with Chinese replicas of NGK plugs. None of which, reputedly, last more than a few firings; so maybe you have one of them. The NGK copies are so good visually that even NGK cannot tell the difference! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.