stumbling at off idle

[BigDick]

I was cruising around town today getting lost and I roll on the throttle and my bike starts stumbling, like a miss. I turn off the main road and go down a bit to turn around and it magically starts running perfect. I blow it off and keep rolling and about 10-20 minutes later it does it again. Just out of the blue, it idles along just fine but as soon as I give it any throttle it stumbles and chokes, almost like it's running out of fuel. This is the first time it's done this. do I have carb problems or electrical problems? I was thinking pickup wires maybe?

[tarzan]

Maybe crap in the fuel.Or water.Do you have filters on it?

[BigDick]

Yes I have inline filters, put new ones on a couple months ago. Also not the rubber automotive fuel lines, I'm running the clear plastic/nylon/stuff fuel lines, and it did rain the other day but my bike is always under the carport, so it's very unlikely that any water got into it.

[petejw]

Hey BigDick
Wont hurt to check the pick up wires, take the side cover off
and give the wires a wiggle while the engine is idling.

[TopCatGr58]

Hey Dick,

Your signature shows special, do you still have the OCTY? If so, it could be faulty, or vac. leak going to it, so it's not opening completely causing too slow of fuel flow??

You didn't say what gear, what rpm you were trying to do the roll on?

Also, possibly clogged gas tank cap vent?

Can't remember what all maintanence you've done, like cleaned carbs, tuned with colortune or by ear, etc.?
T.C.

[BigDick]

the Octy went bye bye a long time ago.

It did it once when I was cruising in 3rd at ~40 when I was just giving it a little bit of throttle it was fine, but as soon as i cracked it a little further open it started missing and stumbling. I slowed down and turned to go home so I wouldn't get stranded across town and it started running correctly. I went for a little while longer and then it started missing again, same situation except i was in second running about 30.

something I've been wondering in the back of my head, at that low of rpms would I be putting enough charge through to the battery? Could i have drained the battery enough for it to misfire?

I'll check the gas cap vent, the underside of my cap is fairly rusty but doesn't look like anything flakes off.

the last synch was quite a while back, never been colortuned.

it sounded like only two cylinders were cutting out, maybe coil problems? I still have the stock coils on.

[rpgoerlich]

Running with the same problem on the XS11G. Stutters just above idle, once into it around 3k it clears up. Thought about removing the TCI and re-soldering the connections as it sounded like a problem I had with a Virago. I've cleaned the carbs thoroughly and installed inline fuel filters from day one. Pickup coils have been repaired in place as it still has the original bolt holding the timing plate installed.Timing is right on.
Everything is stock, including air filter. Carbs adjusted and re-synced 2 days ago. I rode it into work today to see how it runs before I possibly make that run to Hurst,TX. It's ok on the highway, just from a stop.

Hoping to ride this one up to MOTM and get some input there.

[BigDick]

Real quick, when you guys say take off the left side cover, you mean the aluminum engine side case correct? I've always referred to the plastic covers under the seat that cover the battery and fuse box as the side covers.

[rpgoerlich]

Yes, Aluminum one, Just in front of your left foot when on it.

[BigDick]

good opportunity to change the oil while I'm in there. It needs done too.

[dbeardslee]

Sounds a lot like a problem I just tracked down on Betsy. I kept looking at carbs, fuel, etc. It wound up being bad Mikes XS coils. They weren't getting enough juice to fire with 12.5v going to them, but when the rpm's rose to 2K (where the alternator is putting out the full 14.2v) they worked fine. I'd get out the old digital multimeter and check your pickup and ignition coils.

[BigDick]

Sounds a lot like a problem I just tracked down on Betsy. I kept looking at carbs, fuel, etc. It wound up being bad Mikes XS coils. They weren't getting enough juice to fire with 12.5v going to them, but when the rpm's rose to 2K (where the alternator is putting out the full 14.2v) they worked fine. I'd get out the old digital multimeter and check your pickup and ignition coils.

Good excuse to get new coils with a nice hot spark I had figured either the pickup wires, coils, or tci were most likely.

[dbeardslee]

Big - I just installed green Mikes XS coils last week and I'm lovin' 'em. Haven't determined yet what kind of headaches you might run into with them on a special installation though. I'm going to assist some other members this coming Saturday installing a new motor in a special, so I'll have an opportunity to eyeball it good. They're tight on a standard, so be thee aware. Here's a link to a thread with more info on the install (pics towards the bottom of the page).

Could be the pickup coil wires causing the problem when the advance moves. Probably a good idea to run some tests before acquiring parts. Then again, those green coils are sure nice .

[dbeardslee]

Big - I got a real close look at an 81SH today and it looked like there's pretty much the same amount of room for coils as there is on my standard. The 81 has a little bracket for the plastic steering neck cover that attaches to the front coil mount, but it didn't look like it would be a problem. Still looks like it may require a minor (although warranty-voiding) modification to the green coils to get 'em mounted though. Maybe someone else will figure out how to fab a bracket for them, but I'm pretty happy with the way I've got mine mounted.

[MickT]

Stumble at off idle

Hi
Ive just been having this same problem, had a trip to Germany, when it started to rain it would miss and pop and bang, at one point it stoped running altogether, got back home after the 24th inernational rally, had a run out as you do started to rain, started doing the pop bang thing again, was on my way home anyway, so tank came off, and found water dripping out of the coils so took the coils off the bike, cheap after market coils....rubbish.. fitted some spare good coils of a MNS I have, to which I have fitted the DYNA coils, seems to me the off idle stumble lies with the coils or HT leads, that how I ended up with cheap after market coils due to failed HT leads


MICKT