changing exhaust pipes
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Intermediate
Joined: Apr 2007
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changing exhaust pipes
all summer my 80 sporty was running fine I have the stock exhayust pipes on it and a S&S carb. so I decided to go with open pipes bad mistake. got about 20 miles down the highway bike began to back fire turned the pipes blue near the exit and bike died. waited about 30 minutes bike started again got as far as the harley dealer changed plugs( real fouled) and proceeded to go home got about three blocks and the damn thing hapened again.so now i pushed the bike home and it was real heavy. plugs fouled again. so now i put the stock pipes on it and no problems.when I was sitting by the front wheel i rolled the throttle and noticed the excelerater pump was not engageing I took it apart and the guy who had it before me put the thing together wrong spring was on the top. and one of the two check ***** was missing. now it runs real fine( notice all summer even when the bike was hot I had to give it choke thought that was just the way the carb is. now I can start it up with out choke and when its warm even better. SO HERE IS MY QUESTION IF I RUN THE DRAG PIPES WITH BAFFLES IN IT DO I HAVE TO CHANGE THE JETTING? AND IF SO WHICH JET? the idle or the main? my friends say I have to do that so she wont run rich.. can any advise thanks all merry christmas LARRY
Tourer
Joined: Apr 2006
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RE: changing exhaust pipes
I'd get in touch with S&S and tell them what you have going on. Give them the carb model, what kind of pipes, etc., and they should be able to get you going. Yes the intermediate and main jets should be replaced.
Road Warrior
Joined: Nov 2006
Posts: 1,427
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From: Heart of Dixie
RE: changing exhaust pipes
It's generally known that most drag pipes hurt performance except at high rpms (the length of the pipes determines the sweet spot). If you make an exhaust change and your bike runs too rich, I guarantee that you're throwing performance out the window just to make noise. Baffles will help some, but the best low-buck setup is the stock headers (with crossover) with aftermarket slip-on mufflers. You get increased power and more noise - the best of both worlds.
To answer your question, with the open drags, I'll bet the low speed circuits/jet could be leaned out a little and it would be fine without messing with the main jet.
To answer your question, with the open drags, I'll bet the low speed circuits/jet could be leaned out a little and it would be fine without messing with the main jet.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
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From: Houston Texas
RE: changing exhaust pipes
'all summer my 80 sporty was running fine I have the stock exhayust pipes on it and a S&S carb. so I decided to go with open pipes bad mistake. got about 20 miles down the highway bike began to back fire turned the pipes blue near the exit and bike died. waited about 30 minutes bike started again got as far as the harley dealer changed plugs( real fouled) and proceeded to go home got about three blocks and the damn thing hapened again.so now i pushed the bike home and it was real heavy. plugs fouled again. so now i put the stock pipes on it and no problems.'
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Well, I just have to say that in my opinion, changing out your pipes had absolutely nothing to do with your bike problems and pipes turning blue (20 miles down the road I might add).
In 50 years of riding and wrenching, I have changed out all kinds of pipes on both British and American machines and not a single bike has stopped running because of the pipe change. Just ain't gonna happen.
The result you can expect to see when you change out a style of pipes is in the performance of the engine. This change may be increased performance or decreased performance. The machine is then put into proper balance by re-jetting the carb, perhaps changing the ignition timing etc.
I rather think your problem may have come from riding the bike all summer with the some choke on (because the acel. pump was not installed correctly) and perhaps it all came to a head when you changed out the pipes. It is called coincidense.
SO HERE IS MY QUESTION IF I RUN THE DRAG PIPES WITH BAFFLES IN IT DO I HAVE TO CHANGE THE JETTING?
That will depend on a number of factors. Just install the pipes with the baffles.
Fire up the engine and let it warm up.
Did it start easy?
Does it idle smoothly and without miss?
Roll on the throttle at idle, opening the throttle slowly to 1/4 throttle.
Does it run steady?
If the answer to the above questions is yes, then the low speed adjustment is fine.
For checking the high speed adjustment (jet size) just take the bike out on the highway (not with cops around) and let go of the reins. From a rolling start, open the throttle in first gear and run the engine up to 6000 rpms. Does it miss?
Shift to second and again run it up to 6000 rpms in 2nd. Does it miss?
If it does not miss then the jetting is fine.
If it does miss, then the jet is either one size too small or one size too large, as a guess. Just buy one of each and try them. That is the easiest way to determine the correct main jet size in my experience.........pg
************************************************** *************************
Well, I just have to say that in my opinion, changing out your pipes had absolutely nothing to do with your bike problems and pipes turning blue (20 miles down the road I might add).
In 50 years of riding and wrenching, I have changed out all kinds of pipes on both British and American machines and not a single bike has stopped running because of the pipe change. Just ain't gonna happen.
The result you can expect to see when you change out a style of pipes is in the performance of the engine. This change may be increased performance or decreased performance. The machine is then put into proper balance by re-jetting the carb, perhaps changing the ignition timing etc.
I rather think your problem may have come from riding the bike all summer with the some choke on (because the acel. pump was not installed correctly) and perhaps it all came to a head when you changed out the pipes. It is called coincidense.
SO HERE IS MY QUESTION IF I RUN THE DRAG PIPES WITH BAFFLES IN IT DO I HAVE TO CHANGE THE JETTING?
That will depend on a number of factors. Just install the pipes with the baffles.
Fire up the engine and let it warm up.
Did it start easy?
Does it idle smoothly and without miss?
Roll on the throttle at idle, opening the throttle slowly to 1/4 throttle.
Does it run steady?
If the answer to the above questions is yes, then the low speed adjustment is fine.
For checking the high speed adjustment (jet size) just take the bike out on the highway (not with cops around) and let go of the reins. From a rolling start, open the throttle in first gear and run the engine up to 6000 rpms. Does it miss?
Shift to second and again run it up to 6000 rpms in 2nd. Does it miss?
If it does not miss then the jetting is fine.
If it does miss, then the jet is either one size too small or one size too large, as a guess. Just buy one of each and try them. That is the easiest way to determine the correct main jet size in my experience.........pg
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