Losing 1 cylinder at idle...

TeK9iNe wrote: When you "cleaned" the carbs, did you squirt carb cleaner thru the pilot jet passage in the carb, and visually confirm its flow by watching it fire into the carb bore?

Sounds to me like you have a clogged pilot passage in a the carb itself.

If everthing worked fine put away, its something thats been added to the equation - like fuel grunge plugged up in that shit.

Good luck!

Pull pilot jet. Squirt cleaner up there. Watch it come out all small holes in carb bore. Done.

I did make sure fluid came through the pilot but I was thinking the same thing... maybe crud got in there or I didn't get one as clean as the others?

Didn't sync the carbs yet either. They did appear to open fully and close at the same time or very nearly so, but I didn't actually measure or adjust.

Thanks for all the tips guys. Didn't have much time to work on things this weekend. Rebuilt my front brake master cylinder, but don't have it re-installed yet. Z1E got my parts here for the weekend, I just didn't have time.

New kid coming this Friday, so I may be done for a while. Bike runs. I'll keep working on fixing it up as time allows. Should have it good to go before good riding weather. I'll keep running the little dual sport 'til then.

Made some progress since last posting to this thread. Thought I had it licked. Valves clearances were off, 6 of 8 were out of spec tight. Fixed that and things fired up much better. Also had an issue with my timing, but that's been resolved. Most recently, I installed new coils and plugs (wasn't maintaining spark when wet after I washed it). Rode the bike about 40 miles and all seemed right with the world. There was a little stumble toward the end of my ride between 3-4k rpm's, but I didn't think much of it at the time.

I've now got a dead cylinder due to a fouled plug, I think.

Rode to work Friday, excited to be on the bike and enjoying the cruise. Starting to really like the seating position and get a feel for things. Work isn't far, about 8 miles through the county roads to town.

Everything seemed fine. Bike fired right up at home, ran well 90% of the way. Just before I got to work, seemed like I had a cylinder dropping out at idle occasionally. Didn't think too much about it. Seems if I kept the rpm's up, it ran great. Possibly some issues below 3K rpm's.

After work, the bike fired up, but not easily and it was only running on 3 cylinders. Couldn't get the 4th (cylinder 4) to kick in. I may have over-choked it, but only cylinder 4 was dead. I'm kick-start only at the moment. Decided to call for a ride rather than limping home on 3 cylinders.

Came back Sat. morning with some tools hoping to pull the plug, swap it with one of the other cylinders, and ride it home. No dice. Pulled all the plugs. 1 & 3 are lightly black on the ceramic near the center, I would guess about right. 2 was almost white, too lean. 4 was black. After I swapped plugs with cylinder 2 and it still wouldn't go, I pulled cylinder 4 again to find it wet with fuel. There was fuel in 3 of 4 vacuum port caps on the intake boots but I'd been using the choke.

I have some ideas about what might be wrong, but I'm not sure. Would a choke plunger failure cause this? Seems like cylinder 4 must be getting too much fuel all the time. I have the opposite problem with 2, but it is firing. Probably an adjustment to be made on 2, but 4's way off. My other thought is that the float level is too high in the bowl on 4 and maybe too low on 2.

Does that sound reasonable? If I pull the carbs back off, how do I tell if the choke plunger is bad? I plan to do a good mechanical synchronization this time. First go around, I didn't move them hoping the PO had it close. I'm not sure that's the case.

Is the choke plunger something that suddenly fails (if that's even it)? Or was a just running well before because of new plugs? I'll need to check the float level before I pull the carbs.

I agree with a plugged pilot jet or fuel & air passage to it and the idle air mixture. It would be a mricale if the tank & carbs were clean after sitting for years. The pilot jet passges are tiny and it will keep plugging them up unless the tank is cleaned

mtkawboy wrote: I agree with a plugged pilot jet or fuel & air passage to it and the idle air mixture. It would be a mricale if the tank & carbs were clean after sitting for years. The pilot jet passges are tiny and it will keep plugging them up unless the tank is cleaned

I appreciate the help, but my problem has changed. Maybe I should have started a new thread?

No longer a dry cylinder, I'm drenching cylinder 4 which fouls the plug and leaves me with only 3 working pistons.

Idled pretty smooth 'til it fouled the plug, I just have to figure out why it's so rich there.

If not already done, would perform the clear tube test, to determine whether the fuel level is correct.

Good Fortune!

Patton wrote: If not already done, would perform the clear tube test, to determine whether the fuel level is correct.

Good Fortune!

Is it possible to do this without the $70 specialty tool?

LukeMacPU wrote:

Patton wrote: If not already done, would perform the clear tube test, to determine whether the fuel level is correct. Good Fortune!

Is it possible to do this without the $70 specialty tool?

Is it possible to do this without the $70 specialty tool? YES!

Here's an example depicting clear tube of appropriate outside diameter as self-threaded/wedged into the float bowl drain hole, whereby the special tool is unnecessary.
Some minimal leakage won't affect the results, as fuel volume entering the bowl exceeds any leakage.




Good Fortune!

Thank you. I'll definitely give that a check before I pull the carbs all off.

If running pod air filters, maybe the #4 is over-oiled or dirty.

Good Fortune!

Patton wrote: If running pod air filters, maybe the #4 is over-oiled or dirty.

Good Fortune!

I've got stock air-box & filter.

I think I found my problem. The float in the number 4 carb was way off relative to the others. Fill level was above the top of the bowl. I would guess fuel level was about 1/4" high. I must have bent the float when I had it apart the first time. That or one of my three garage helpers got it for me. We've got 4 kids 4 & under. The oldest three all love to come out to the barn to "help" Daddy work on stuff. I don't mind most of the time, but it's not always great.

I did a mechanical synchronization while I had them off. The number 3 carb was definitely off, the others were pretty good.

Ran out of time for the night before I got it all buttoned back up. Pulled my right-hand switch cluster and found it full of rust/corrosion. I'll be ordering a replacement, ASAP. As bad as that switch is, I may have electric start again after replacing it. Picked up some new plugs at Autozone. If all goes well, I'll have it buttoned up in the morning and see if I've really fixed anything.

Thanks again for all the advice. I feel silly now that I think about it, but I hadn't realized how much of an impact float level has on these carbs.