What does it feel like when a spot is rich or lean??

Hi,

The petcock is freshly rebuilt and is operating correctly. Float level was set to the stock settings, but I recently raised it about 1.5mm or to see if that would help. No difference could be felt.

I'm sure you already know this but I thought I'd mention it.

If you raised the float height while the carbs were upside down, then you have actually lowered the fuel level in the bowls. When you lower the float height (when checking upside down) then the fuel level in the bowls will be higher.




Thank you for your indulgence,

BassCliff

[49er]

The petcock is freshly rebuilt and is operating correctly. Float level was set to the stock settings, but I recently raised it about 1.5mm or to see if that would help. No difference could be felt.

I'll admit, it DOES feel like it's running out of fuel supply, but there seems to be plenty of supply there... I'll double check it again, just to be sure.

Dynojet also mentioned something about the float-bowl breathers needing to have the lines removed and the outlets turned down. I've done that. I've also tried adding lines and routing them to a place with non-turbulent airflow, etc... All to no avail.

I'm left to think that it may be ignition related, so I'll try to rule that out for now. One would think that SOMETHING I've done to the carbs would have made some move towards a difference, better or worse, but thus far, the problem remains. Verifying the ignition system seems prudent at this point.

After re-reading your earlier post, your plug colour is classic leanness. If it was an electrical issue, I would expect the plugs to have darkened due to partially burnt vapours in the chambers.

Are you running an additional inline fuel filter? These often cause fuel starvation problems.

You can eliminate fuel starvation from the list by shutting off the engine when it starts playing up. Put the bike on the centre stand and remove one of the outer carb drain plugs to see how much fuel runs out. If fuel gushes out, and you collect equivalent to 1/3 to 1/2 a bowl of fuel, you don't have a fuel delivery problem.

Have you checked the fuel flow through your petcock? I'd remove it, clean it and check that the filter in the tank isn't clogged up reducing flow. Also, are you sure that the float levels are correctly set? If they are set too low, you will also experience the problem you have described.

The petcock is freshly rebuilt and is operating correctly. Float level was set to the stock settings, but I recently raised it about 1.5mm or to see if that would help. No difference could be felt.

I'll admit, it DOES feel like it's running out of fuel supply, but there seems to be plenty of supply there... I'll double check it again, just to be sure.

Dynojet also mentioned something about the float-bowl breathers needing to have the lines removed and the outlets turned down. I've done that. I've also tried adding lines and routing them to a place with non-turbulent airflow, etc... All to no avail.

I'm left to think that it may be ignition related, so I'll try to rule that out for now. One would think that SOMETHING I've done to the carbs would have made some move towards a difference, better or worse, but thus far, the problem remains. Verifying the ignition system seems prudent at this point.

[49er]

Well, guys... I put the needles back to the 3rd slot, and installed 170 mains... very little effect! The stumble is still there, and I'm a little frustrated...

HOWEVER, I shall persevere!

I've had every main in there from 155 up to 175, and had needle settings from 2 down from middle, to 2 up from middle, and NONE of this seems to have an overall effect on the severe WOT stumbling I'm getting.

SO, I'm going to go through the entire wiring harness, or at least those parts affecting the ignition, including cleaning up the fuse box, as BassCliff recommends. I'm also going to pick up a relay tonight and do the relay mod for the ignition. I'll test the voltage to the coils, and make sure the plug boots are sufficiently low resistance.

Going to make sure that the ignition system is delivering full spark throughout the RPM range and see if perhaps THAT is the issue.

What I discovered yesterday is that at full WOT, the bike pulls to 5000, and then starts stumbling/cutting out. It actually seems to do this at anything over about 1/2-2/3rds throttle, but is quite obvious at WOT. I DOES rev right up to around 8500 or so in the gears where that is possible to do without opening the throttle up that far, but even then, at some point you have to open it up further and then the stumble starts...

I may end up right back at jetting, but since it seems to happen at exactly the same RPM, regardless of gear or load, I suppose it could be a weak ignition. Time to eliminate that possiblity, anyhow...

Darin, I'm not ruling out electrical issues as others have suggested but to me your symptoms sound like the engine is getting starved of fuel when it is under high demand. Doing a plug chop at that time should reveal a lean condition. If the plugs are sooty then it probably confirms an electrical issue.

Have you checked the fuel flow through your petcock? I'd remove it, clean it and check that the filter in the tank isn't clogged up reducing flow. Also, are you sure that the float levels are correctly set? If they are set too low, you will also experience the problem you have described.

I went through something similar with my 1000G. Turned out the Ignitor was toast. Basically you would ride along & then it would hit a wall, no more power, just a constant flat blah... (hard to describe).

Would be one of the things I would check out - a hell of a lot of "carb problems" are electrical...

I think I've read that here before. I'll check it out. Going to be kind of hard to diagnose a faulty/intermittent ignitor though, eh??

Why do I see me having to explain the purchase of a Dyno-S system to my wife in my near future???

[salty_monk]

I went through something similar with my 1000G. Turned out the Ignitor was toast. Basically you would ride along & then it would hit a wall, no more power, just a constant flat blah... (hard to describe).

Would be one of the things I would check out - a hell of a lot of "carb problems" are electrical...

sorry for the hijack darin

No worries! That's why I'm having this stuggle in "public"! Hopefully someone else can learn from me asking all these dumb questions!

thanks mike i will be using that from now on---been wondering for a while--sorry for the hijack darin

is there a way to save or bookmark threads?

I have a "subsribe to this thread" link in a "thread tools" pull down in the upper right (under the main menu bar). Then there's a "subscribed threads" link under Quick Links.

Good thread--good descriptions--let us know if its ignition related when you figure it out----is there a way to save or bookmark threads?--ive just been commenting on the ones i want to find again--thought there might be an easier way

Well, guys... I put the needles back to the 3rd slot, and installed 170 mains... very little effect! The stumble is still there, and I'm a little frustrated...

HOWEVER, I shall persevere!

I've had every main in there from 155 up to 175, and had needle settings from 2 down from middle, to 2 up from middle, and NONE of this seems to have an overall effect on the severe WOT stumbling I'm getting.

SO, I'm going to go through the entire wiring harness, or at least those parts affecting the ignition, including cleaning up the fuse box, as BassCliff recommends. I'm also going to pick up a relay tonight and do the relay mod for the ignition. I'll test the voltage to the coils, and make sure the plug boots are sufficiently low resistance.

Going to make sure that the ignition system is delivering full spark throughout the RPM range and see if perhaps THAT is the issue.

What I discovered yesterday is that at full WOT, the bike pulls to 5000, and then starts stumbling/cutting out. It actually seems to do this at anything over about 1/2-2/3rds throttle, but is quite obvious at WOT. I DOES rev right up to around 8500 or so in the gears where that is possible to do without opening the throttle up that far, but even then, at some point you have to open it up further and then the stumble starts...

I may end up right back at jetting, but since it seems to happen at exactly the same RPM, regardless of gear or load, I suppose it could be a weak ignition. Time to eliminate that possiblity, anyhow...

You asked about the difference in feel between too lean and too rich.

When an engine is moderately too lean, there is a hesitation/stumble on the throttle. When it is excessively lean the bike will have a severe bucking hesitation, which is the precursor of holed pistons.

When moderately too rich, there is a flat throttle response to acceleration (commonly called running fat). When excessively rich you get a pungent smell, black sooty smoke from the exhaust and often fouled spark plugs.

One of the most helpful posts I have seen in ages. Thanks for this.

You asked about the difference in feel between too lean and too rich.

When an engine is moderately too lean, there is a hesitation/stumble on the throttle. When it is excessively lean the bike will have a severe bucking hesitation, which is the precursor of holed pistons.

When moderately too rich, there is a flat throttle response to acceleration (commonly called running fat). When excessively rich you get a pungent smell, black sooty smoke from the exhaust and often fouled spark plugs.

Thanks... that's what I was really looking for...

From your description, combined with the chop I did tonight, I'd say it's too lean. I had moved the needle UP one notch to the 2nd notch, and it made the problem worse.

The plugs were pretty white with almost no color in the center and on the electrode... there was some dark color around the outside, but I think that was from some of the idling and partial throttle stuff. I also couldn't get it to rev up to the 8500 like I could before.

I have a set of 170 mains ready for it that I was thinking about trying, since it really seems like it's lean in the mains at WOT. I'll get that right first, and then figure out the needle from there.

[49er]

You asked about the difference in feel between too lean and too rich.

When an engine is moderately too lean, there is a hesitation/stumble on the throttle. When it is excessively lean the bike will have a severe bucking hesitation, which is the precursor of holed pistons.

When moderately too rich, there is a flat throttle response to acceleration (commonly called running fat). When excessively rich you get a pungent smell, black sooty smoke from the exhaust and often fouled spark plugs.

[chef1366]

If it is jetted with a DJ kit correctly I'd check out the ignition.