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Misfire and breakdown

PostPosted: Sat Aug 01, 2020 10:35 am
by hbr341
Hi all
I am still having problems with my 1256 hb I've been out a few times no problems a few weeks ago I had been driving about 15minutes the car started to misfire under load and I had to stop it will tickover fine but no power to pull off switch it off for 10minutes and its ok I've checked it and everything is perfect fitted a new condenser been out a few more times all ok then the other day did the same thing started with one misfire and then a breakdown on a bad bend I do think it's an ignition problem as the carb is new and their is plenty of fuel anybody got any ideas please.


Re: Misfire and breakdown

PostPosted: Sat Aug 01, 2020 9:18 pm
by lancsamb
i had a very similar problem, i discovered that if i removed the breathervpipe that goes from the crankcase to the airfilter this reolved thevproblem. The cause is that hot oily fumes are being sucked into the carb and flooding the engine. i havevput a small filter on the end of this pipe and thats fine for now but in the winter i will take the head of and sort out the valves hopefully. if you look at the facebook site for the club i put a video of this fault.

Re: Misfire and breakdown

PostPosted: Sat Aug 01, 2020 11:29 pm
by dazza
Had a similar issue with a faulty coil, it was brand new aswell.
The mechanic that diagnosed it said it would be overheating and failing. Replacement cured it straight away.

Re: Misfire and breakdown

PostPosted: Mon Aug 03, 2020 7:02 pm
by hbr341
Hi guys
Thank you for your replies, I did change the coil this made no difference. I think I may have sorted the problem, I made a metal plate, to go between the carb and the exhaust manifold, I then took the car on a long drive,there were no problem. When I got home,the plate was very hot but the base of the carb was cool. So I think it was caused by the heat of the manifold. I have a long road run on Sunday, so fingers crossed.
Regards Chris