| Author | Message | ||
     Scdobber |
Well,this issue goes back to day one of owning my stock M2 with low rpm issues,it tends to cough through the carb and does not run very even "surges" below 2500 rpm,regardless if in town or highway cruising at say 45 mph with a occasional annoying hiccup,it runs great other than that with plenty of power throughout,it even idles fine.The previous owner said it started doing it with him at 1200 miles with him one day after exiting off the interstate and continued till now,he though the carb was gummed up from lack of riding,it now has 1600 miles.I drilled out the cap and adjusted the mixture 2.5 turns,now at 2 3/4 turns with no big change.I checked for vacuum leaks and found none which I'll recheck again.Back in November I cleaned the carburetor and installed a 45 slow jet which seemed to improve the issue some but I lost horsepower in the mid rpm range,really a overall power loss,I don't see how just by changing the slow jet but I'm new to the CV.I can live with the issue at highway speeds where I can keep the rpm up but around town under 20 mph is aggrivating with the surging.Any tips would be great,perhaps this is common with the Buells at slow speeds | ||
| Rjn |
can it have something to do with your fuel/air mixture ?? i had also a dip in my power range with my M2. This was with a stock exhaust and race airfilter. After installing a race exhaust, K&N air filter ( Big Blow ) and re-ajusting the carb the problem was gone. now she pulls from low RPM's all the way into the red with no power loss or power dip in the mid-range RPM's. | ||
| Buellistic |
Scdobber: Hopefully you still have the OEM needle ... Raised mine 0.050 of an inch ... This is how "i" have my 1997 S3T set up: "ADD" Have my ACCELERATOR PUMP disconnected !!! M2 OEM needle raised 0.050 of an inch ... Slide RADIUS'ed ... #200 High Speed Jet ... #48 Low Speed Jet ... Low Speed Mixture screw 2 1/2 turns from seat ... CARB. jetting was set in the REAL WORLD using a FUEL/AIR GAUGE ... Timing Mark set just coming into the rear of the timing plug hole ... Top End and Cams are OEM ... Air Intake System: Econo Force with a K&N RC-3680 air filter inside Air Box so that "i" can ride in the RAIN ... "MAY THE LONG LASTING BUELL BE WITH YOU !!!" (Message edited by buellistic on January 17, 2010) | ||
| Scdobber |
Yes I did try shimming the needle at exactly .050 with 2 washers but it killed the bike with fuel,it would idle but as soon as throttle was applied it would puff black fuel smoke and die unless I released the throttle,remember I'm 100% stock | ||
| Daveswan |
Crud blocking the slow jet holes and slow jet - blow out with compressed air. An intake leak, check with spraying wd-40 etc. around the seals. jets and needle positions should remain stock since that hasn't changed. Seems there is extra air getting in or fuel being prevented from getting in.. float setting? crap beneath the viton needle there> fuel line clog or junk in the screen not allowing enough fuel to keep up with it's consumption? Just throwing stuff out there. | ||
| Buellistic |
Scdobber: Check your timing as to where you TIMING MARK appears in the timing plug hole ... Stock setting(timing mark) is in the center of the timing plug hole, "BUT" it will run better if it is just coming into the rear of the timing plug hole ... Drop the needle to a 0.030 of an inch shim on the needle. Low Speed Jet #45(you've got), and the idle mixture needle 2 turns out from the seat(always set your idle RPM at 1000 RPM)... It is a hard guess with out hearing you engine and test riding your M2 ... Remember: All engine are created equal, "BUT" they do not run that way ??? | ||
| Scdobber |
Thanks for the pointers,maybe it will be warm next week so I can check some of the things mentioned,I'll post my finds | ||
| Richsm2 |
Buellistic, doesnt the pump need to be disconnected to run a 48? or poof goes the spark. | ||
| Guell |
The accel pump on his s3 is dissconnected. | ||
| Scdobber |
I did recheck for vacuum leaks at the carb boot and intake seals with wd-40 and what carburetor cleaner I had left but found none.Just for future reference,how many turns out on the idle mixture screw can I go before determining if I need to go up on the slow jet possibly 3-4 turns out from lightly seated?? | ||
| Guell |
anything past 2.75 turns out and i go up a jet size. 3 to 4 is way too much | ||
| Buellistic |
"THANKS", Richsm2 and Guell ... "YES", my ACCEL. PUMP is disconnected (which was from the beginning) ... You do not need the ACCEL. PUMP unless you can not keep the the engine on the cam ... Lets say your engines Torque/Horse Power starts at 2500 RPM, "WELL" if you are not on the cam at 2500 RPM and open the throttle too much your engine will bog down as in QUIT ... The ACCL. PUMP was put on the later SPORTSTER CARB's. do to new riders of which a lot of them were Ladies ... On the Fuell Injection Models, this is taken care of with the TPS(throttle position sensor) which works better for every rider ... (Message edited by buellistic on January 18, 2010) | ||
| Richsm2 |
check your float level by looking into the carb at low throttle setting , if you are getting droplets than it is too high . | ||
| Blake |
#45 slow jet and a few turns out give or take worked great on my Cyclone when it was stock and even now, a little rich even. | ||
| Rickie_d |
A bike with only 1200 – 1600 miles can have more that normal blow-by than a well broke in and sealed motor. The excessive oil vapor expelled by the crank case vent under this condition can attribute to fuel/oil pooling in the ports for the low and main air jets} at the base of the carb venturi. The not ridden much part can turn this mixture into a restricting or clogging varnish unless these jets receive attention during the cleaning process. This in many cases is overlooked as the source of such symptoms and is just compounded by additional fuel. | ||
| Scdobber |
makes sense to me,maybe things will improve after I get some miles on the bike (Message edited by scdobber on January 18, 2010) | ||
| Buellistic |
BUELLers: IMHO, 8.75 oz. of STP Gas Treatment(with a full tank of gas) every 5K miles is good for your engine ... "ADD" this also helps keep your CARB. lean !!! In the days of the PAN HEADS the valve guides would get so dry they would actually "SQUEAK" and H-D's answer was their CHERRY JUICE top end additive ... In 108,822.1 mies as of the last ride, no dry valve guides or MYSTERY tappet noise ... "ADD" Plus no dirty CARB. prblems !!! "MAY THE LONG LASTING BUELL BE WITH YOU !!!" (Message edited by buellistic on January 19, 2010) | ||
| Rickie_d |
I am not sure what Buellistic is addressing, however I am sure it has nothing to do with what I am trying to convey! With that said, the air jets will most likely (never) not clear themselves with mileage; you will have to clean them to clear up your problem. | ||
| Buellistic |
Rickie_d: Check my add's on post in question ... | ||
| Rickie_d |
(Message edited by buellistic on January 19, 2010) Does not “add” to your credibility...especially when every thing else in your post has nothing to do with clarifying the originators problem relevant to the topic of carb jetting and part throttle response issues described!! Even though I have worked on flat-heads, knuckles, and the predecessors to your "PAN HEADS”, I don’t think I can help you attach your issues with this problem. | ||
| Rickie_d |
correction...:"as" the predecessors to your "PAN HEADS”... | ||
| Daveswan |
I second the clogged air jets... When I got my old M2 I didn't realize how bad varnish could get! I also had a small wasp nest inside the air cleaner - it hadn't been ridden for quite awhile and was slated to become a mutant chopper! I saw what was called "carb cleaning tool" which was actually nothing more than Acetylene torch cleaning wires - very fine twisted wire... used very carefully to help remove crud as needed after the jets have been removed, plus carb cleaner to soften it up. I made sure each passage was clear by blowing compressed air through each and every passage. | ||
| Scdobber |
Ricky,part throttle issues are correct,as mentioned it has a perfect idle and revs from idle fine with no popping,it's really only a issue at low speeds/rpm and it's very jumpy or rather has a hesitation with occasional pops in the airbox under 20 mph in town so I tend to clutch more.I've checked the tank strainers which were clean,it has a new air filter,airbox seal & gaskets to carb as well as new intake seals & carb boot I installed back in November when I cleaned the carburetor which I think I neglected to clean or check the air jets,my focus at the time was all in the bowl,so that may very well be the issue.I'll pull the carburetor again this week and focus on cleaning everything again including the air jets and see if it helps. | ||
| Rickie_d |
Dave described the procedure perfectly, that is exactly what I do when addressing these jets. | ||
| Scdobber |
Got everything cleaned,as far as the mixture screw,the correct order is the spring followed by the washer,then the o-ring? the o-ring and washer fell out so I'm assuming the o-ring is last | ||
| Rickie_d |
Just to make sure we are clear: With the needle pointing up, drop the spring over the needle, then the washer, then the o-ring, and install into the carb body. | ||
| Scdobber |
Thanks | ||
| Scdobber |
Well I gave the carburetor a good cleaning which I found no blockages in any of the passages.I gave it a 20 mile test ride and had no change in low rpm conditions,I found this thread interesting on some issues that I'm having http://www.badweatherbikers.com/cgibin/discus/show .cgi?tpc=3842&post=109691 (Message edited by scdobber on January 21, 2010) | ||
| Rickie_d |
I just saw your note, but I have to take off for a few hours. What year is the bike and are there any mods to the ignition circuit? I will respond later tonight… By the way, at most, a malfunctioning TPS will only allow for slight hesitation if there is a high demand for power from a low RPM for a given gear selection. (Message edited by Rickie_d on January 21, 2010) | ||
| Dave_02_1200 |
Does an M2 have a TPS with a carb? |
