Way too rich, heavily farkled, high elevation, stumped - Kawasaki KLR 650 Forum
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post #1 of 11 Old 06-19-2013, 07:26 PM Thread Starter
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Way too rich, heavily farkled, high elevation, stumped

Just installed a 685 kit on my 2011 KLR650. After my initial break in, I'm finally ready to rev over 4-5k and the engine keeps dying. Cause appears to be 30% [10:1 AFR] too much fuel. While it will run in the 2500-3500 RPM range with this ratio, any higher and it jumps, bogs, and applies power again after a 14.7:1 AFR is reached. So I'm getting too much fuel... can't figure out why.

Location: 5500 ft

I have a lot of mods to increase air flow:
L-mod, K&N filter, snorkel removal, high flowing exhaust tip.

Data Acquisition: I installed an Innovate LC1 to read my O2 levels. To prevent a misreading, the fresh air injection system was deleted. This device allows me to know that I'm getting 30% too much fuel anytime I'm off idle.

I have the same issue with OEM needle shimmed, or Dynojet needle. I do feel like the bogging was higher in the RPM band with the OEM though. New plug since install, not sure if I gapped it...

Mixture Screw: Out 1, 1.5 & 1.75, no real decrease in total off throttle fueling.

Jetting
145 main [stock]
40 pilot [stock]
- Just ordered 137.5 & 140s along with a 38 to put in. I expect a step down of 2 sizes, which is appx 15-20%. This is required for a proper tune; however, I wouldn't expect those to make me run 30% too rich.

Carb Cleaning: Was disassembled 3 times over the last few days for a complete cleaning with air & fluid. All vent lines were removed, cleaned & reattached. The diaphragm has been checked, needle collar there, washers on top of needle, orifices cleared, etc...

Any ideas y'all would like to toss my way? I'll be sure to keep this updated when I swap in the replacement jets. I made so many mods during my last tear down that this is like starting from scratch on a whole new bike. Hope it will feel like a new bike after I'm done...
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post #2 of 11 Old 06-19-2013, 09:25 PM
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Originally Posted by engimuneer View Post
Just installed a 685 kit on my 2011 KLR650. After my initial break in, I'm finally ready to rev over 4-5k and the engine keeps dying. Cause appears to be 30% [10:1 AFR] too much fuel. While it will run in the 2500-3500 RPM range with this ratio, any higher and it jumps, bogs, and applies power again after a 14.7:1 AFR is reached. So I'm getting too much fuel... can't figure out why.

Location: 5500 ft

I have a lot of mods to increase air flow:
L-mod, K&N filter, snorkel removal, high flowing exhaust tip.

Data Acquisition: I installed an Innovate LC1 to read my O2 levels. To prevent a misreading, the fresh air injection system was deleted. This device allows me to know that I'm getting 30% too much fuel anytime I'm off idle.

I have the same issue with OEM needle shimmed, or Dynojet needle. I do feel like the bogging was higher in the RPM band with the OEM though. New plug since install, not sure if I gapped it...

Mixture Screw: Out 1, 1.5 & 1.75, no real decrease in total off throttle fueling.

Jetting
145 main [stock]
40 pilot [stock]
- Just ordered 137.5 & 140s along with a 38 to put in. I expect a step down of 2 sizes, which is appx 15-20%. This is required for a proper tune; however, I wouldn't expect those to make me run 30% too rich.

Carb Cleaning: Was disassembled 3 times over the last few days for a complete cleaning with air & fluid. All vent lines were removed, cleaned & reattached. The diaphragm has been checked, needle collar there, washers on top of needle, orifices cleared, etc...

Any ideas y'all would like to toss my way? I'll be sure to keep this updated when I swap in the replacement jets. I made so many mods during my last tear down that this is like starting from scratch on a whole new bike. Hope it will feel like a new bike after I'm done...

A K&N filter has been shown to flow less air than the OEM. Have you tried running the bike without an aircleaner?

RPM's aren't really relevant when talking about the carb. It's the throttle postion that determines which jet circuit is involved. Couple of good resources: Carburetor Tuning - Keihin CVK40

My guess is that the needle jet circuit is too rich. You say it's OK off idle and once it gets wound up. Have you tried the OEM without the shims? Raising the needle richens the mixture. Higher elevation = less air = richer right? Did you buy the Dynojet kit and specify your elevation?

Sorry don't mean to ask you dumb questions but need some baseline.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #3 of 11 Old 06-19-2013, 10:17 PM Thread Starter
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What would no air filter prove, even if raises AFR? It's not the choke point.

MC Mod was performed (exhaust cam rotated toward engine one tooth, CCW).

There is no top end. 16.75%+ throttle all bogs once around 3500-5000. Can't rev beyond that. Makes enough power off the idle circuit to 50 mph for my commute.

Doesn't bog until 4-5 seconds of 10:1 fuel is applied (>17% TPS). Drops to stoichiometric for 1 sec, rinse, lather, repeat give/take 20%.

Diaphragm looks good after repeat examinations. Can't verify whether slider is moving well.

3 different settings on the DJ needle (kit came with bike). 2 on OEM. Moves stall out RPM up a little bit. Not the issue.

Mixture screw is 1-1.75 out.

Pre 685 & free flow exhaust, bike ran great. I now have 18% less air pressure, 5-20% more airflow, and 145 (1.34-1.36mm) jetting for OEM sea level, down from DJ138 (lowest kit offering). Additional airflow should have leaned out any richness to within 15%. Will update once new jetting arrives, have a few more tricks still up my sleeve.
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post #4 of 11 Old 06-19-2013, 10:36 PM
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Quote:
Originally Posted by engimuneer View Post
What would no air filter prove, even if raises AFR? It's not the choke point.

MC Mod was performed (exhaust cam rotated toward engine one tooth, CCW).

There is no top end. 16.75%+ throttle all bogs once around 3500-5000. Can't rev beyond that. Makes enough power off the idle circuit to 50 mph for my commute.

Doesn't bog until 4-5 seconds of 10:1 fuel is applied (>17% TPS). Drops to stoichiometric for 1 sec, rinse, lather, repeat give/take 20%.

Diaphragm looks good after repeat examinations. Can't verify whether slider is moving well.

3 different settings on the DJ needle (kit came with bike). 2 on OEM. Moves stall out RPM up a little bit. Not the issue.

Mixture screw is 1-1.75 out.

Pre 685 & free flow exhaust, bike ran great. I now have 18% less air pressure, 5-20% more airflow, and 145 (1.34-1.36mm) jetting for OEM sea level, down from DJ138 (lowest kit offering). Additional airflow should have leaned out any richness to within 15%. Will update once new jetting arrives, have a few more tricks still up my sleeve.

Sorry just trying to offer some ideas. The DJ numbers don't correspond to Keihin's but you probably knew that.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #5 of 11 Old 07-17-2013, 09:51 AM Thread Starter
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Currently have OEM needle with 1 shim and 137.5 jetting. While the bike runs very well. I can feel a decrease in power from prior with WOT. I'm also getting 10.6:1 AFR at that position. Anyone know what part could fail that would allow so much extra fuel to get in? I don't see how the jetting can be too big still, since I dropped it from the OEM 145.
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post #6 of 11 Old 07-17-2013, 10:27 AM
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Captain Obvious would say that a really clogged (and that could be a clean air filter loaded with too much oil) could cause that condition.

Other than that, the carb is so dead simple that there's not much that can go wrong or break outside of a mis-assembly of some sort.

Can you remove the air filter and the door and rig up some sort of light and mirror arrangement to insure that the slide is moving up and down with the throttle as it should? If there is a burr on the slide or a twist in the diaphragm the slide might hang and essentially operate the needle and jet in the wrong range for the throttle opening.

And, yes, I'm grasping at straws. I had to work to get the fuel mixture down to 13:1...

T

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“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -Philip Marlowe

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post #7 of 11 Old 07-17-2013, 10:28 AM
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you didn't say whose main jet you are running. DynoJet and Keihin have a different numbering system and the DJ's are considerably larger with the same #. If I were you I would leave the stock pilot in and run a 142 Keihin main with the mix screw out 2 to 2 1/2 turns. Interesting problem, I have not seen a CVK running so rich that it bogs at acceleration or WOT. What exhaust do you have? Are you sure there are no restrictions in intake or exhaust? Put the O2 meter away for now and get back to basics until you are close. here is a conversion chart for main jets.
Dynojet/Keihin Conversion table:
122 135
124 138
126 140
128 142
132 145
134 148
136 150
138 152
142 155
144 158
146 160
148 162
Hope this gets you on the right track
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post #8 of 11 Old 07-17-2013, 10:42 AM Thread Starter
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Im running Keihin jets. OEM 145 got reduced to 137.5. I previously ran the DJ needle with DJ138 jetting, waaaaay to rich for my elevation.

I also changed the pilot from 40 down to 38.

I no longer bog upon acceleration. The bottom 3 circuits all behave appropriately and give AFRs in the right range. WOT is the current issue, which means mains for the most part.

I like your mirror idea. The K&N air filter has been cleaned but not reoiled recently. Not sure if I"ll be able to see anything with the spark arrestor still installed but still worth giving a try. I could see a diagphram issue or burr causing the problems based on the behavior.

I'll also remove the air filter for a run or two, see how it affects the AFRs. The exhaust is super free flowing with my newest exhaust tip.
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post #9 of 11 Old 07-17-2013, 10:54 AM
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OK, I misread when I responded. I didn't understand it was only a WOT issue

First, the K&N flows less air than stock. That seems primarily due to the reduced area it has because of the hard cap. Most prefer the stock or Uni filter over a K&N.

Second, the stock needle has a very reduced profile at the tip and will go stupid rich at WOT. I think it's a fail-safe sort of thing to ward off building a lean grenade at WOT and to act as a sort of RPM limiter. ;^)

You will likely find better results in your tuning efforts with a KLX needle; I certainly did.

T

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem
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post #10 of 11 Old 07-17-2013, 11:07 AM
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Tom just said everything I was thinking. Ditch the K&N (probably not the issue here, but they don't belong on a KLR) and like Tom I am leaning(pardon the pun) toward a needle issue. Even at your elevation that seems like an awful small main. I always ran the KLX needle with great results. When you are talking "tip" I take it you just modded the stock exhaust? I don't want to get into the exhaust thing here cuz some are TRUE melonheads and are on my ignore list.....
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