poor running when warm.

[buddylove]

hey guys, im putting this out to see if your expertise can assist me. I bought my t25 back in may for a very reasonable amount but i bought it with what i was told was a piston issue so was sold as spares. Its a 1982 air-cooled 2.0 litre. I live in the midlands and had to collect from south London, the guy who owned it said it probably wont get me home, however it did and i have traveled another 3500km since my ownership, however at the end of the season last year i took it out and it seemed to start misfiring very badly but only when warm, from cold its just as normal. i had the engine checked over by a local camper garage prior to this issue and they said it was fine and a very tidy example. then this problem developed and i cant work out what it is, but when i remove one breather line to the left carb it runs ok, but i dont think its a air blockage, im getting so confused as to what it may be!! can you help??? it is going to be looked over next week but id like an idea of what it could be. cheers guys!!!

[BOXY]

If the misfire goes away when you disconnect the pipe from the air box it can only be a mixture issue. Disconnecting the pipe is just going to let more air into the carb weakening the mixture. When did you last change the air filter? If the air filter is blocked less air will be getting to the carbs and the mixture will be overly rich. Once the engine warms up it could be rich enough to flood one of the plugs and start the misfire.

[The Bobdogs]

Have a word with fullsunian over in Grantham, he's the Aircooled fella and will be able to sort it out.

[buddylove]

maybe then it could be then the timing or fuel mixture, but i am struggling to make 40mph, when this van will happily cruise at 75 without an issue, even tho i have been told its broken i have had 125kph out of it, which i assume is good for a decent engine???so could it possibly be a piston problem or just something simple???how would it react with a piston down??? thanks for your help guys!!!

[BOXY]

If you've got a piston / cylinder problem the engine will be down on power and you'll probably get smoke out of crankcase breather if you pull the hose off the air-box, or blue smoke out the exhaust. You really need to do a compression check to see if there's piston problem.

If the compression check is ok, try shorting out each spark plug in turn to see if the engine revs drop or the engine stalls. If shorting a plug doesn't effect the engine you'll know that plug or HT lead isn't coming to the party.