It olso dosent want to idle , it seams like rear cylinder quits how ever at above 1700 rpms it runs fine but sputers from time to time on rear cylinder at the same timerear cylinder is runing allot hoter thean front olso the plug in back is alot cleaner thean front one
On pretty much ALL Harley's (and all other air cooled V-Twins), the rear cylinder runs hotter because the front cylinder tends to semi-block the airflow coming to it.
You have only one carb, so if it was jetted right for one cylinder, the other cylinder wouldn't be too far off.
Most likely from your description (rear cylinder quits how ever at above 1700 rpms, sputters from time to time on rear cylinder, rear plug is a lot cleaner than front one), I would look at an air leak (common on Harley's) where the intake manifold joins the rear cylinder head, and/or an exhaust leak at the rear pipe.
Testimonial: "i due think that i have an excoust leak and i orderd new intake seals the rear cylinder turned my pipe blye in 10 min and i couldint touch the head it was so hot compare to front as i cal hold my hand on it"
ps thanks
If the seals are bad, it causes a lean mixture. It IS possible for only one seal to be bad, leaning out just that one cylinder.
ok i took it apart and eaven thou everything looked good on the outside the seals on the intake to the head were deafeanatly trashed theay apeard like an old vacum hose on a car from 60s they crumble to touch and lost ther elastycyty olso the seal ring on the carb has a small ring grove on the inside so im going to replace all of that and will let you all know in a mean time thanks for all the coments
Yeah, over time, from the heat and just any smog in the air, the rubber pieces wil deteriorate.
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May hav vacuum leak-chec hoses for condition--rear cylinder runs hot because front gits more air-----plugs may not b the same-see if they match--also the cables wear inside causes bad firing-----carbs mite need ajust------an air cooled engine will last twice as long if u blow a fan at cylinders for an hour after riding--heat kills motors
Testimonial: "thanks everybody i wil cheack all that in next couple days"
SOURCE: HD 1200 Sportster 1997 model misfiring on rear cylinder
hi paul here,
the coil on my bike turned out to be the problem after checking wires, connections and plugs. brought a used single fire.
tried it out after being told that coils usaully go all bad not just half.
have not had the problem since and i was conteplating buying ignition and coil combo for hundreds.
good luck
SOURCE: misfire forward cylinder
First you'll need to get a jet kit from West coast star. Then you'll need to jet the carbs to run equally. This may take some trial and error. Another thing that worked on my bike was the upgraded coil kit they sell. It's almost double the voltage of the stock coils and comes with better insulated wires for a more uniform resistance. I haven't had this problem since. It'll make the cylinders fire evenly and save you from those pestiferous fouled plugs. I hope this helps.
SOURCE: 2003 Harley Davidson Sportster 1200 Custom Tachometer kit
The only idea that i can come up with is that you dont have a good ground..or the guage was bad when you bought it..i hope this..Keith
SOURCE: 2003 Harley Davidson XL 1200 C Sportster Custom
vapour lock in fuel line caused by leak below filter to carbs , replace lines and vacume. had same prob and after many attempts and dangerous situations found minute cut in line . when it happens release line to tank and let fuel flow re connect. will happen faster second time. 3 miles or so
SOURCE: Runs on back cylinder but front cylinder pops a little when idlin
This particular model uses a BS36ss carb for the # 1carb or back as you are calling it. there is an input and output as a pass through to the second carb intergrated into the fuel delivery system of the # 1 carb. the # 1 carb draws fuel from this port also. check for obstructions at this point where the 2 carbs intersect and in the transfer line to the front carb remember this is a neg. pressure regulated fuel system so any leaks at carb 2 (Front Carb) or Balance Tubes Between cylinders and it wont function . vacuum is the key
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would wrogly jeted carberator cause overheating on one cylinder only
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