PJR Posted May 9, 2020 Report Share Posted May 9, 2020 Some thoughts please as to why this may have started to happen. I have checked the jets and settings on the carb but to no avail. Is running rich, a little, so any thoughts there would be good also Look forward to any help and replies Peter Quote Link to post Share on other sites
John L Posted May 9, 2020 Report Share Posted May 9, 2020 Peter I think you need to tell us a bit more about your setup Has the engine been rebuilt,? Is this first time running with these carbs? Was it running fine before, what's been done since? John Quote Link to post Share on other sites
Motorsport Mickey Posted May 9, 2020 Report Share Posted May 9, 2020 ^ + 1 Also are you running an air box, socks or open trumpets. Mick Richards Quote Link to post Share on other sites
PJR Posted May 9, 2020 Author Report Share Posted May 9, 2020 Had been running fine - really started when coming out of hibernation. Have changed plugs, just in case, no difference - and HT leads. It has electronic ignition. Air box filters Quote Link to post Share on other sites
PJR Posted May 9, 2020 Author Report Share Posted May 9, 2020 Just wondering whether to bite the bullet and re-setup all 3 carbs from scratch!! Quote Link to post Share on other sites
Oddball Posted May 9, 2020 Report Share Posted May 9, 2020 Also... are you using an electric fuel pump and a pressure regulator and at what pressure. Is this the first or last carb to get fuel. Did you check the float height by removing the main jet, should be 25mm from the jet housing or 41mm from the top cover Cameron Quote Link to post Share on other sites
Oddball Posted May 9, 2020 Report Share Posted May 9, 2020 4 minutes ago, PJR said: Had been running fine - really started when coming out of hibernation. In that case, fresh fuel and a good thrashing might do the trick Quote Link to post Share on other sites
Rob Salisbury Posted May 9, 2020 Report Share Posted May 9, 2020 Hibernation? ... how old is the petrol? Cheers Rob Quote Link to post Share on other sites
PJR Posted May 9, 2020 Author Report Share Posted May 9, 2020 Thanks all - think you're right. With the fuel just sitting there over the winter it may have deteriorated. I did have it running stationary over the winter just to keep it "warm" . Quote Link to post Share on other sites
Motorsport Mickey Posted May 9, 2020 Report Share Posted May 9, 2020 So why is it just affecting the nearest to bulkhead carb ? Is that the last or first fed.? Mick Richards Quote Link to post Share on other sites
PJR Posted May 9, 2020 Author Report Share Posted May 9, 2020 First feed Quote Link to post Share on other sites
ntc Posted May 9, 2020 Report Share Posted May 9, 2020 23 minutes ago, Motorsport Mickey said: So why is it just affecting the nearest to bulkhead carb ? Is that the last or first fed.? Mick Richards Good question Mick just been helping someone with this I await the answer as that may help have you checked for **** in the tank and filters Quote Link to post Share on other sites
John L Posted May 9, 2020 Report Share Posted May 9, 2020 Could be one of the 2 idle jets with a bit of blockage, or some water in that carb. I wouldn't touch any settings until you have given it an Italian tune up. John Quote Link to post Share on other sites
Tom Fremont Posted May 10, 2020 Report Share Posted May 10, 2020 I second the Italian tuneup suggestion. I've never had this problem in 24 years and 135,000 miles with triple DCOEs on my '250s. They never really hibernate, though, getting exercised year round provided the roads are neither wet nor salty. So at most 3-4 weeks. I use a highly acclaimed fuel additive too: Seafoam. As for clogging the jets, nothing small enough to pass the screens in the fuel inlets can possibly do so. Not sure how water would get in there, but appreciate how it corrodes aluminium - and nuggets of this crud would be past the screens. I've never done it, but pulling the idle jets and running a tiny wire through them might bear fruit. Great suggestion by Cameron; the height is like a closely guarded secret ( though really, who out there cares except us afflicted? ). For what it's worth, both of mine are lower than 25mm by 2mm in one case and 3mm in the other. 25mm may be the highest practicable setting; there the main jet system will come in the soonest possible. Sameness between the carbs is sublime! Finally, as most carburetor problems trace back to the ignition I wouldn't be surprised if it applies here. I'm not a fan of the electronic types, as mine don't miss a beat with points and the reliability is excellent. I did have a fling with a Crane / Allison setup that lasted for a few years, then when a chronic low speed miss was cured by fitting a worn out points distributor I had on the shelf I saw the light. Tom Quote Link to post Share on other sites
PJR Posted May 10, 2020 Author Report Share Posted May 10, 2020 Thanks all for the comments - will try and find the time to go through each one and eliminate accordingly Will do the Italian tune up first though!!! Quote Link to post Share on other sites
PJR Posted May 18, 2020 Author Report Share Posted May 18, 2020 the Italian tune up - at 4000 rpm in 2nd the whole thing "wobbled" seemed to calm down and was as smooth as silk at 2000rpm upwards but at low revs still spitting and spluttering Quote Link to post Share on other sites
PJR Posted May 26, 2020 Author Report Share Posted May 26, 2020 Just had another "go" at the spitting! Discovered that the distributor clamp was not tightened and as a consequence had caused the timing to go off!! Have done a quick "tune" and already the spit seems to have gone - going to do a "concentrated" tune tomorrow to see if I can eliminate it once and for all Thanks to everyone for their inputs and ideas Peter Quote Link to post Share on other sites
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