| Author | Message | ||
     Bobd |
Ok, here goes. I have this niggling peeve with my '98 race kit equipped S3T. At partial throttle, (down hill, low speed cruising in town in a lower gear.) The engine stutters and stammers until a load is placed on the engine then it runs fine. I have rebuilt the carburetor, checked and cleaned the plugs and checked the exhaust manifold gaskets. All to no avail. I have also noted this phenomenon on Harley V-twins. Some tell me it is just the nature of the beast. I beg to differ. Could a better carburetor solve this annoyance? Any ideas? | ||
| Firemanjim |
What rpm are you running,too low and you will get some symptoms like that?Try running one gear lower,they like being above 3500.What carb and how is it jetted?Ignition stock?From my experience a single fire ignition smoothed out my S-2's low speed running.YMMV. | ||
| Tramp |
before you get involved in too much part-changing, check for exhaust leaks... NOT just at the manifold, either. check the junctions of your headpipes to your muffler- this is actually the most frequent cause of sputter that i see in my shop... 'cause folks don't really check for it.... | ||
| Tramp |
i wasn't disagreeing with jim's (as always) wise post...just putting a diagnostic thought out there from which to start... | ||
| Bobd |
Firemanjim, I am running a stock Keihin carb, race kit ignition module. I don't know the jet sizes. Same symptoms at higher rpms. Where can I find more info on the single fire ignition? Tramp, I have changed out the exhaust port gaskets and have checked there for leaks. I will check junction between the exhaust header and the muffler. Thanks all for your help. | ||
| Firemanjim |
Stock carb can run really well but comes jetted very lean.Check knowledge vault for tips but at minimum a slow jet change and make sure idle mixture screw has been exposed and adjusted.Stock there is a lead plug covering the screw. I run a Dyna 2000 module on both my S-2's. | ||
| Tramp |
how are your intake gaskets and the seals? those rubber seals can give you the same issues. start with a 185 main and a 48 pilot. that's a decent starting point. as firemanjim said, make sure the mixture screw's exposed. i start with it turned out 3x. i noticed you didn't mention intake seal and gasket checks, those are really crucial in these sleds. dyna's my favourite ignition, personally. they seem to be the most bulletproof. | ||
| Jackbequick |
What Tramp said!! The #48 jet and mixture screw setting (I used 2-1/2 turns on my stock M2) made a miraculous difference on my not race kitted bike, which was running pretty much like yours. "..intake seal and gasket checks..." Tramp, those checks are what, spraying WD-40 on the inlet tract seals with the engine at 2,000 RPM or so? Tell me what happens if there is a suction leak. Jack | ||
| Bobd |
Thanks guys for all the additional tips. I will tackle them one by one until I notice a marked improvement. I have already exposed the idle mixture screw and adjusted it to three turns open. Seems to idle a little better. Next, I will check the jet sizes and change out to the recommended 185 main and 48 pilot. Then check for leaks at the intake seals. (WD40 @ 2000 rpm?) As a last resort, I will go to a single fire ignition system. (Dyna 2000) (Message edited by Bobd on September 20, 2005) |
