Kawasaki KLR 650 Forum - Reply to Topic
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

Thread: Elevation and effect on carb/exhaust mods Reply to Thread
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  Topic Review (Newest First)
03-12-2017 03:43 PM
Jhawker23

Huge improvement! Pulled snorkel (seemed a small change for any improvement - it's only about 4"), and drilled out the 4 1/2 one inch holes in the air box cover, and added the washer to the needle.

It's a different bike!

Oh, and upgraded to pro taper EVO's...

I appreciate all of the help and insight!!!
03-12-2017 11:16 AM
Jhawker23 Well, in the break in period, I'm pushing to 4K.
03-12-2017 09:02 AM
Damocles Are you lugging your bike? Operating in a gear too highj-ratio a gear for adequate power to develop with rpm?

An operational KLR650 will turn a quarter mile from a standing start in about 15 seconds. If yours won't, something's amiss. Shifting at rpm above the power peak, you should be able to post a similar elapsed time.
03-12-2017 07:55 AM
Jhawker23 Thanks again for the help!

So I'll do my best to describe it..... but maybe I should just GoPro it. Maybe this is normal (but doesn't feel like it should be).

2nd, 22 mph and accelerating to 30+: average 8 - 10 seconds to increase to 33/34. It's a steady speed increase, not slow to rapid acceleration. It feels like nothing changes, whether I'm 2/3 throttle or WOT. It says "I have one speed, you can mess with that throttle all you want but this is how I'm going to do it".

So, I'm closing in on 4k RPM and shift to 3rd, and then it's close to the same slow rate of acceleration to hit 40+.

Does that description make any sense? The feedback is nothing changes after mid-throttle. I understand it's not a powerhouse but WOT in 2nd gear and it slowly accelerates with no change between mid throttle and WOT?
03-12-2017 12:03 AM
justjeff JHawker,
Well something you could try is reinstalling the factory muffler and see if your acceleration comes back. Or you could try the 22cent mod and see if richening the carb helps at all. This could give direction to future adjustments. If you go in the carb, record what main jet is in there.
Regards,
JJ
03-11-2017 10:46 AM
pdwestman
Quote:
Originally Posted by Jhawker23 View Post
So I only drilled the slide based upon the recommendation that the elevation may negate the need for shimming the needle. I've not done anything else other than the exhaust. I've not touched the idle screws.

This is the plug after the first 20 miles. About the last 13 are after the exhaust change.
Does the engine run normal as it used to from idle to 2000 RPM? 2500 RPM? 3000 RPM? 3500 RPM?

Does it run Worse the harder you try to accelerate?
03-11-2017 04:03 AM
Damocles A difficult concept to convey: Drilling the slide does ABSOLUTELY NOTHING to alter air/fuel ratio. NOTHING! The air/fuel mixture remains EXACTLY the same, before, during, and after slide-drilling.

(I sincerely believe this statement to be true, REGARDLESS of what one might read on the Internet.)

Shimming needle fuel-enriches mid-range operation; stock needle WOT mixture is plenty fuel-rich.

Trick muffler alone fuel-leans mixture slightly from stock; ain't no big thang, IMHO; no need to over-think it.

================

As to plug reading; a plug reading remains valid only if: The throttle is chopped immediately (at the level of interest), the ignition killed, and the bike coasted to a stop. You read only the plug condition at the last moment the engine was running, reflecting whatever air/fuel ratio was combusted at the time.

If the engine is permitted to idle immediately before a plug reading is made, the reading will reflect the mixture condition at IDLE; if the throttle is chopped at WOT and the ignition killed before the bike coasts to a stop, the mixture at WOT will be read. And so it is, throughout the throttle-opening range . . .

Further, plug reading as compromised nowadays by ethanol and other chemical in gasoline; ain't like it was in the "bad old days."

The above: What the big boys on the playground said, from the days of my misspent youth to the present.

================

If truly, sincerely, and critically interested in precise air/fuel mixture, unleashing an exhaust gas analyzer on the bike offers a chance of plausible measurement; plug reading has always been more of an art than a science . . .
03-10-2017 09:01 PM
Jhawker23 So I only drilled the slide based upon the recommendation that the elevation may negate the need for shimming the needle. I've not done anything else other than the exhaust. I've not touched the idle screws.

This is the plug after the first 20 miles. About the last 13 are after the exhaust change.
03-10-2017 11:55 AM
pdwestman
Quote:
Originally Posted by Jhawker23 View Post
The lexx exhaust is on and I'm happy with the improvement in tone. But now I have weak acceleration all around. I can open the throttle in 2nd gear and slowly accelerate to 30 mph. It's running like a big, heavy scooter.
Jhawker23,
Did you do the 22 cent mod to the mid-range carburetor needle at the same time as the muffler change?
03-10-2017 10:35 AM
justjeff Hi JHawker,
Was there anything else you did at the same time? I ask this to try and isolate the cause of the result.
JJ
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