| Author |
Message |
    
Gazz
| | Posted on Monday, September 23, 2013 - 01:13 pm: | 
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I picked this up about a week ago and now that it registered and insured, I have been riding it about town and then some. Most of the time it runs quite smoothly but every now and then it will cough through the intake, sometimes multiple coughs or a series of coughs and then it will run fine for a bit. I drained all the gas and tried some high octane gas (110 octane racing fuel) as a friend suggested it might be low octane fuel causing it but that did not help. I have sprayed some gumout in the carb while it was running and have also added some mystery oil to the tank but there has been no change. Right now I am running a mix of 110 octane and 97 (?) octane gas in it and of course the problem is still there. I also took apart the fuel petcock on the bottom of the gas tank and it looked fine - no crud or anything that might cause a problem. Does this mean I have to pull the carb off and clean and adjust it? This bike has been sitting around, like maybe a couple of years so I am guessing that there is some junk somewhere. Anybody have any ideas or suggestions on what else I might do? Thanks for your comments. |
Randomguy3
| | Posted on Tuesday, September 24, 2013 - 09:10 am: |
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I have no idea, but mine does this as well sometimes. I have a 2002 Cyclone that coughs when it is cold, and sometimes still when it is warm (out of the blue). I run no higher than 93 octane. My buddy told me it's "a H-D thing" and apparently H-D motors running like crap is "normal". I've been looking for a culprit as well. I look forward to hearing some more comments on this. |
Randomguy3
| | Posted on Tuesday, September 24, 2013 - 09:12 am: |
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Oh yeah, congrats on your new bike! |
Gazz
| | Posted on Tuesday, September 24, 2013 - 09:45 am: |
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Thanks for the congrats and the response!
Yesterday, I took it for a quick putt to the farm stand and it coughed a bunch. I don't think the motor was able to get up to normal operating temperature and it makes me wonder if there is some kind of vacuum leak or leak in the intake part of the motor. A friend of mine who is a long time Harley guy thinks the coughing is from to lean a fuel mixture. I wonder if the "leak" closes up a bit as the engine components get warm and expand. But I am just guessing and hope to hear some good sound advice on how to fix it. |
Sparky
| | Posted on Tuesday, September 24, 2013 - 03:39 pm: |
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These are symptoms of a too lean idle jet. If the idle jet is the stock one, it's going to be too lean for today's gasoline, and it may be partially gummed up which makes the stock lean idle even leaner.
If it were me I'd take the carb bowl off and replace the idle jet with a #45 from your H-D dealer. Then if you can get to the idle mixture screw (under a soft aluminum plug in the back of the carb) adjust the idle halfway between too lean and too rich. |
Ocbueller
| | Posted on Tuesday, September 24, 2013 - 06:33 pm: |
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As Sparky said and additionally I would pull the intake manifold and replace the seals. They commonly harden and will start to leak especially when cold. Lots of write ups on jetting and manifold seals on this board.
SteveH |
Bluzm2
| | Posted on Tuesday, September 24, 2013 - 09:00 pm: |
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Sparky and Steve are dead on.
45 pilot jet, - check
Good intake seals - check
Bike running better - CHECK! |
Gazz
| | Posted on Tuesday, September 24, 2013 - 10:10 pm: |
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Thanks for those responses!
Today I took the plugs out to have a look at them (they look fine) and while doing that, I do notice some kind of stuff is escaping around the flange of the manifold where it meets the rear cylinder and thought I should look at that a bit closer or maybe change them. So that is on the list of things to do. The other day I did try to drop the float bowl but I could not get enough pressure on the Philips head screws that hold it on with the carburator in place. I suspect there is junk in there as I always have to clean the one out on my tractor after it has sat for a while. I am a bit nervous about taking the throttle linkage stuff off though. I never could get the derailleurs on my mountain bike to work properly after taking them apart. |
Buell_bert
| | Posted on Wednesday, September 25, 2013 - 12:26 am: |
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Mine is stock. Jets and all and it does not cough at all and has all the torque these bikes are known for . I would think it is the intake seals also. I have had to change the intake seals and clean and put a carb kit in it as well a couple years ago. |
Harleyelf
| | Posted on Wednesday, September 25, 2013 - 01:40 pm: |
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If the carburetor is not at fault and the fuel is not at fault, and the fuel flows clean without obstructions... perhaps the issue is not in the fuel system.
Fuel...compression...spark. Compression is good because it sometimes runs well. Fuel is moving through the system at least some of the time, so probably all the time (for the purpose of diagnosis).
Check the cam position sensor. They often smell fried after they fail. And when they fail intermittently, no amount of carburetor adjustment will make the engine run smoothly. An after market Sportster part should work. |
Buell_bert
| | Posted on Wednesday, September 25, 2013 - 10:47 pm: |
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If the seals are old and dried out they may leak cold or warm or both. The cylinders expand and contract thru the heat cycle. Use Silglyde or something like it to lube the seals. They will install easier and allow movement as they heat up and cool down and protect the seal. I am not saying it is the problem but it sure sounds like it to me. It sure helps to have the proper wrench as well as a friend to hand you tools. Good luck and keep us informed. |
Gazz
| | Posted on Sunday, September 29, 2013 - 10:13 am: |
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Yesterday, I rode the bike about 50 miles one way it did not cough or backfire the entire way there and was a joy to ride. I visited a friend and let him take the bike for a ride and it ran perfectly for him as well. Riding back was a different story though. It coughed and backfired the entire way back.
I also received the manual and it states that the engine will run fine on 10% ethanol fuel. This week I will buy the new seals and hopefully get them installed to see if that clears it up. I'll also drop the float bowl on the carburetor and look for junk while it is off.
Thanks for all the suggestions. |
Buell_bert
| | Posted on Sunday, September 29, 2013 - 09:47 pm: |
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Here in WI we have premium that has no ethanol. I use it in all the toys (bikes, boat engine, 4 wheeler, lawn mower, generators, minibikes etc.). My daily drivers get only regular because of the price. Anything that may sit for awhile gets premium WITH OUT ETHANOL. |
Randomguy3
| | Posted on Thursday, January 09, 2014 - 01:21 pm: |
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Update on M2: Replaced the 42 to a 45 jet and changed the intake seals. Left the stock 195 jet. Cleaned out the carb and put in gaskets etc. from a rebuild kit. Hoping this solves the problem, but I haven't gotten it back together to test it out. It's too damn cold. |
Gilmorew07
| | Posted on Tuesday, June 17, 2014 - 01:59 pm: |
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I just picked up a '99 S3 and after riding it around town for awhile, I have noticed the same cough. Any update on the changed jets and intake seals? |
Harleyelf
| | Posted on Tuesday, June 17, 2014 - 03:20 pm: |
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Your '99 has injectors, no carburetor.
Change the intake seals and then look to the cam position sensor. |
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