Performance Mods - Kawasaki KLR 650 Forum
KLR & Other Motorcycle Related Discussion Grab a seat and discuss whatever you like about the KLR or other related topics. Within reason.

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post #1 of 14 Old 09-08-2017, 12:39 PM Thread Starter
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Performance Mods

Im fairly knew to the KLR and it is the smallest displacement bike I have had for many years. I'm not expecting a hot rod but to me my bike is pretty gutless. I bought the bike at sea level and live at 5000 feet. I'm assuming re-jetting is in order and probably exhaust. Just wondering what you experts have done? I'm not looking for extensive mods just the best bang for my buck....

And now for a really dumb ?.....where is the tool kit on this bike?

Thanks! John
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post #2 of 14 Old 09-08-2017, 02:05 PM
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The oem tool box is recessed into the forward portion of the rear carrier rack.

As to performance, all normally aspirated internal combustion engines loose about 3% power per 1000 ft of altitude. So you have about 15% loss. I also live at 5357ft and normally ride up to 10,000 ft. A stock KLR650 will still pull above 80 mph up-hill in 4th gear at 10,000 ft. albeit slowly.
You will get used to it.

Adding 4, one inch holes in the top of the air cleaner box, behind the battery will help more than leaning the carb jetting. Adding AIR instead of reducing Fuel. And it is a FREE Improvement.

pdwestman
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post #3 of 14 Old 09-08-2017, 03:29 PM
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The KLR is no powerhouse and can't really be made into one. The "common recommended mods" will give you a bit more power, help throttle response and correct the poor factory jetting:

- KLX Jet kit - Eagle Mfg & Eng and follow the instructions
- snorkle-ectomy

Optional:
- L-mod or 4 1" holes in the airbox lid
- UniFilter (eaglemike again)
- silencer of your choice.

.....after that it's the big bore kit (685 from EM is my recommendation) but I'd only do it if the bike was burning oil or needed top end work. Next up would be head porting, then cams, increased compression, etc. etc. ....but your then spending serious money and the returns start to become questionable - you can get 10X the functional improvement spending the same money on suspension for eg.

I have two fairly identical KLR's and I was able to do all the recommended mods on one and compare it to the bone stock one and I was happy with the difference....but again, horses for courses....if you want a hotrod, a KLR ain't it!

Cheers,
Dave
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post #4 of 14 Old 09-08-2017, 04:04 PM
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I am at sea level and often travel off road in the 4,000' - 6,000' range.

It's my "humble opinion" that most of the Air Box and Exhaust modifications do more to add noise and volume more than any actual performance increases. But while I don't think that these modifications do anything positive; they certainly will not do anything to hurt the performance of the bike either, so . . . . your call. I replaced my stock exhaust to eliminate the Tweety Bird sound they are known for, and to save a few (very few) pounds. But I can't say it noticeably (Butt Dynometer) improved the performance of the bike at all.

The single best performance modification I did was to replace the original 15 tooth Drive Sprocket with an aftermarket 14 tooth sprocket. If you shop around (eBay) this modification can be had for less than $20. The downside to this modification is that extended travel at anything over 50/60 mph will rapidly become somewhat tedious. But it will definitely get there in a hurry, that's for sure. Here on L.A. Freeways I can maintain 70/75 mph, which is needed to stay with the flow of traffic. But other than getting from Point A to Point B, I can't honestly recommend it.

I also did what they call the 22 cent modification which involves adding a shim under the Main Mixture Needle (richer) and the enlargement of a pressure transfer port. Google the phrase "klr650 22 cent mod" and you'll come up with all sorts of explanations and U-Tube videos on how to do this. The impact of this modification is probably more noticeable the lower your altitude is.

If it turns out to be an oil burner (apparently a lot of them are), as is said, "there's no replacement for displacement" A 685 kit will almost certainly increase the performance of the bike. However, I'd not do this modification solely for the purpose of increasing the power from the engine. It's $$:HP ratio seems fairly steep to me. Of course YMMV.

My perspective is that it would be difficult for me to sink a lot of money into engine power increasing modifications on a KLR 650 before I'd have to seriously consider replacing the KLR with a different bike that makes more power to begin with.

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post #5 of 14 Old 09-08-2017, 04:36 PM
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I agree with most of that, particularly the "it would be difficult for me to sink a lot of money into engine power increasing modifications on a KLR 650 before I'd have to seriously consider replacing the KLR with a different bike that makes more power to begin with." part

....but I do firmly believe that the airbox is the biggest restriction in the KLR's "air pump". personally I can see zero downsides to the airbox mods (never noticed ANY noise difference, not that I'd care) but the potential upsides are cleaner air (pulling from the lid area rather than the snorkle location) and better flow.

For those that haven't seen it:

A lot of missunderstanding with airbox issues.

First, the screen. Airflow gains are not linear. Removing the screen with an otherwise stock KLR airbox will only gain you 2 cfm. The engine won't know the differance. However, with a heavily modified airbox, the gain from removing the screen is 8 cfm. Depending on what else is done to the engine, you may make more power. I doubt that you'll feel it, but a dyno will show it. Butt-dyno's can detect very small low rpm changes, but don't detect higher rpm changes very well at all. You'll likely not detect it, but that does not mean it's not there.

Comparing screen removal to other models is wrong, particularly with the newer sportbikes. With them, the screen often serves another purpose as well. Air distribution in a 4 cyl sportbike can be a real problem, particularly with "ram air". Removing the screen on them can cause very real losses, depending on the model. That does NOT apply to the KLR.

Same thing with air filters. There is only about 2 cfm differance from the best filter (UNI), to the worst (K&N). With a modified airbox, that differance grows to 9 cfm.

Here is the flow chart:

Completely stock - 64.8cfm
Same - Remove snorkle - 74cfm
Same - With UNI filter - 76.2cfm
Same - Remove screen - 78.6cfm
Same - Small "L" cut - 85.1cfm
Same - Large "L" cut, open snorkle area further - 92.4
Same - Remove door - 103.2

Alternate - UNI filter, No snorkle, With screen, No door, No "L" cut - 95.4

All at 2" of water, tested at 1 1/2" and 3" and averaged to 2"

To answer the larger question, how much air can the KLR really use?
....................
A stock KLR about 70-80cfm. With a good pipe about 75-90cfm. A modified motor about 90-100cfm. Having a bit more capacity than you you need will not hurt anything. The effects are not linear though. Going from 65cfm to 75cfm you will likely notice, but going from 75 to 85 cfm you likely won't.

Part of the confusion might be due to the effects of the carb shimming. Since that mod is for a stock needle, the snorkle removal serves not just to add air, but to lean out the top end. The stock KLR till 07 is rich on the top. ( The 08 has a smaller main jet.) Airbox mods have much more effect on top end mixture, so, with the stock needle it also helps straighten out the fuel curve.

Finally the airbox door. You've got to carefull there. You don't have clean air there. It's flowing past that door when riding. You can easily create a partial low pressure area there, depending on wind direction, and where you place your leg!

Cary"


I do not recommend removing the backfire screen (PITA) or running without the airbox door for reasons that should be obvious.

Though a KLR isn't going to have a bunch more power no matter what you do, a KLX kit combined with the snorkle-ectomy and L mod or 4 - 1" holes will have it running properly. don't bother with the little 1" foam filters if you drill the holes - they are useless.

Cheers,
Dave
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post #6 of 14 Old 09-08-2017, 04:42 PM
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And another airbox read (though I don't like some of the recommendations in it); https://www.klrchris.com/kawasaki-klr650-airbox-mod/


....at the end of the day; either KLRCary and others are right and opening up the airbox improves airflow and performance and assists with proper jetting OR they're wrong, the test data is incorrect....but even if that's true, the mods have little to no downsides IMO.

- and on the 22 cent mod; it helps correct the partial throttle lean condition but the shape of the needle is far from optimal; the KLX needle was designed by Kawi's engineers when they were NOT constrained by the EPA and is a much better shape/design......unless one is short the extra $44.73 (44.99 less 22 cents!) then I recommend the KLX kit.

JMHO for discussion purposes; cheers all

Dave
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post #7 of 14 Old 09-08-2017, 04:44 PM
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If you're considering an aftermarket silencer:

A subjective topic but to recap recent discussions;

I don't like loud but I've replaced the stock silencers on both KLR's for several reasons, namely; lighter weight (5 - 7 lbs), better tone, better looks. .....I wouldn't recommend it thinking there will be a noticeable increase in power, nor would I put much faith in manufacturer's that claim much in the way of HP increases (with no other changes).

After much research and some testing, I like the LeoVince X3 which is relatively quiet at 94db, doesn't require repacking (the only one that doesn't AFAIK, except for the ridiculously expensive Staintune out of Austrailia), looks decent and has a spark arrestor and USFS compliance. Runner up would be the Lexx with the optional trail insert; also around 94db but it does require periodic repacking. I also like the FMF Q4 but it is a bit louder (though still trail compliant) at 96db (keep in mind that the increase in decibels isn't linear).

There are a great many aftermarket silencers on the market that are far too loud IMO and you'd do best to avoid them.

Good luck,

Dave
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post #8 of 14 Old 09-09-2017, 03:45 AM
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Ain't nobody gonna answer the OP's question (tell him where to find his tools)?

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post #9 of 14 Old 09-09-2017, 11:11 AM
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Quote:
Originally Posted by Damocles View Post
Ain't nobody gonna answer the OP's question (tell him where to find his tools)?

Damocles, did you not read all the postings?
That was the 1st thing I responded to.

Quote:
Originally Posted by pdwestman View Post
The oem tool box is recessed into the forward portion of the rear carrier rack.

As to performance, all normally aspirated internal combustion engines loose about 3% power per 1000 ft of altitude. So you have about 15% loss. I also live at 5357ft and normally ride up to 10,000 ft. A stock KLR650 will still pull above 80 mph up-hill in 4th gear at 10,000 ft. albeit slowly.
You will get used to it.

Adding 4, one inch holes in the top of the air cleaner box, behind the battery will help more than leaning the carb jetting. Adding AIR instead of reducing Fuel. And it is a FREE Improvement.
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pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #10 of 14 Old 09-09-2017, 11:17 AM
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Maybe he bought the bike used and the previous owner installed a top box over the tool box?

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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