klr engine and head porting - Kawasaki KLR 650 Forum
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post #1 of 11 Old 03-24-2015, 03:45 AM Thread Starter
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klr engine and head porting

Ls and Gs

Please forgive me if this is in the wrong place or commonly answered. Two questions.

1. There are lots of threads about port profiling in association with the big bore mods. Are there benefits to having the head worked on without upgrading the ccs?

2. There is at least one excellent description of a gentleman swapping a Versys motor into a KLR frame. What about a DR motor/gearbox into a KLR? Is this physicaly possible? Seems you'd get more power and a comfortable ride with a good size tank!

Thanks all!
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post #2 of 11 Old 03-24-2015, 08:43 AM
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1. Gains from porting/polishing with an otherwise stock engine are, IMHO, minimal, and realizable only at highest rpm and considerable flow rates. On the diminishing benefit-to-effort side of the performance curve. YMMV.

2. According to Motorcycle Consumer News magazine's annual performance index issues, for all current production motorcycles, the KLR650 yields more rear wheel horsepower than does a DR650. Yet, the difference is no more than that found between Lewis Carroll's Tweedle-dum and Tweedle-dee. The conversion appears to me to be a laborious effort for no significant benefit.

Dropping a Versys engine and drivetrain into a KLR chassis? Another matter altogether; extra gear and about double the horsepower!



My opinions only; I respect conflicting viewpoints, humbly await corrections and clarifications.
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post #3 of 11 Old 03-24-2015, 09:17 PM
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What, no CONTROVERSY?

No CONTRADICTIONS?

What must I do, to get a RISE out of someone?

Revisit the PCV valve mod? The Thermo-Bob? The "MC" mod?

If I get away with this, I may express MORE uncontested opinions!

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post #4 of 11 Old 03-25-2015, 01:57 AM Thread Starter
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No controversy, but follow up!

Damocles,

thanks for your reply. Everything i read claims 38HP for KLR and 46HP for DR650, a bit more than 20% more. Is Motorcycle Consumer news different?

regards

Mike
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post #5 of 11 Old 03-25-2015, 04:51 AM
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How about that RFVC Honda XRL 650?

I used to have an '83 XL600R and it wheelied easier and had
much more usable punch that either my '95 DR650S and now
'09 KLR650E.

Best bang for the buck is probably the 702cc big bore kit and
maybe cams. Any head will benefit from a good exhaust port
polish but it's probably not necessary unless you go over 6,000
rpms often. (Gotta agree with Damocles on this one.)

Ride 'em if ya got 'em,
Cheeeeeeeeeeeeeeeeeeeeeeeap

This is my son, with whom I am well pleased." ----God
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post #6 of 11 Old 03-25-2015, 05:35 AM
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Suzuki does claim 46 horsepower for the DR650SE in its official "Specs."

Curious, I wandered to a discussion on a dsriders forum where this question was posed by a European rider wanting to know "why all the Americans keep talking about 34-36 hp?"

Those participating in the discussion seem to have reached the concensus that the DR horsepower is measured by Suzki at the crank, not the rear wheel.

True? I dunno, but having ridden both, if the Suzuki's engine has 20% more horsepower, it is somehow squandered long before reaching the rear wheel.



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post #7 of 11 Old 03-25-2015, 06:53 AM
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Quote:
Originally Posted by jonesm1 View Post
Damocles,

thanks for your reply. Everything i read claims 38HP for KLR and 46HP for DR650, a bit more than 20% more. Is Motorcycle Consumer news different?

regards

Mike
Motorcycle Consumer News runs independent dynamometer tests of rear wheel horsepower.

KLR650: 36.1 HP
DR650: 35.6 HP

You can Google the Motorcycle Consumer News article on annual performance indexes.

Save you some research effort: http://www.mcnews.com/mcn/articles/2...rfInd_0214.pdf

Last edited by Damocles; 03-25-2015 at 06:58 AM.
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post #8 of 11 Old 03-25-2015, 01:17 PM
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Quote:
Originally Posted by jonesm1 View Post
Ls and Gs

Please forgive me if this is in the wrong place or commonly answered. Two questions.

1. There are lots of threads about port profiling in association with the big bore mods. Are there benefits to having the head worked on without upgrading the ccs?

2. There is at least one excellent description of a gentleman swapping a Versys motor into a KLR frame. What about a DR motor/gearbox into a KLR? Is this physicaly possible? Seems you'd get more power and a comfortable ride with a good size tank!

Thanks all!
Q#1,
I read Years Ago, that Proper porting is beneficial to Any Engine! Even on otherwise stone stock engines. I will tend to agree with that basic statement. There should be benefits to be had. And any gains are permanent! But also Any Losses are Permanent!
Proper porting still seems to be a 'Black Art'. (And Proper Porting changes with other Mods!)
I did do a little 'cleaning-up' on my personal bike, 40,000+ miles ago. I hope it helped. No way for me to tell. Can't afford a 'pro' job and who is he?

I've ridden with / raced with friends on older KTM 620, XR650L, DR650, DRZ400R, many other KLR's 1987-2012, even 2 '09s with Schnitz 685's. My bike holds its own quite well in drag-race, roll-on and top speed. On asphalt or dirt.
Of course, I only weigh 150 lbs. freshly dried. ( I like 'wet-weight' #'s for a bike .)

Q#2,
I do not have the skills to switch to a Versys engine. And the oil drain plug hangs too low for my Rocky Mountain Rock Pile.

pdwestman
Modify at "YOUR OWN RISK"!

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

Last edited by pdwestman; 03-25-2015 at 01:23 PM. Reason: Added (proper porting changes with other mods)
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post #9 of 11 Old 03-26-2015, 01:53 AM
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I have ported a few engines but never in a bike. Gains are to be had im sure... but use caution. Results are final and may not always be for the better. I had a friend that ported and polished his heads and it ran like crap. Too smooth. Fuel and air needs a little bit of turbulence to mix it all up like it should be. My buddy made heads and manifold for a 8000 rpm engine. Not what he needed. However with a 650cc single, I doubt it would hurt it much. Could help some too! Hard to tell when your done Im sure. I would try a little if it were mine. But I have had some experience with it too. Whats life without a little risk?
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post #10 of 11 Old 03-26-2015, 08:58 PM
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Legend has it one former poster on this forum (something of a legend in his own mind, IMHO) "ported" his way into the water jacket of his KLR650 head; then blamed the profound, true expert who had instructed him, for the "amateur night" mistake.

Porting and polishing remains to a degree an art, as well as a science. Top professional engine-builders sometimes use FLOW BENCHES, at least to get ballpark knowledge of cause-and-effect results.

Finally, a correctly ported/polished head may yield power gains at 6,000 rpm; at 3,000-4,000 rpm, typical KLR650 service-life operation? Not so much, IMHO. In fact, as Klahowya41 mentions above, without sufficient turbulence at certain rpm/flow rate operation points, a ported-and-polished wonder may yield LESS power than a stocker.

Similarly, OVER-CARBURETION is POSSIBLE; a too-large venturi cannot permit adequate flow velocities and fuel-atomization turbulence to produce optimum power, compared to a properly-sized carburetor. [IMPOSSIBLE to convey this concept to someone enamored with the, "Bigger is ALWAYS better!" mindset, in my experience.]

Finally, miniscule gains in power (without measurable, repeatable data, and/or drag strip/speed trial runs), remain largely a function of, "head-space between the ears," of the tuner/rider, IMHO; YMMV!
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