Why does the KLR engine suck in HP

[larryboy]

Originally Posted by Mikef5000

Every dyno's different, but I got my #'s here:
http://www.motorcycle.com/manufactur...iew-91450.html

"Compared to the G650’s 50 crankshaft horsepower at 6500 rpm, the TR650 cranks out a purported 58 ponies at 7250 rpm, a 16% improvement.... Our dyno testing of the BMW revealed 44.2 hp at 7200 rpm, so the TR should produce just over 50 horses at the wheel."

Yeah, I've read that. We don't get to measure HP at the crank like the mfg, so we get to estimate. Common correction factor for most dyno's is 20%, they give you back 20% after a dyno run...this is actually crank HP. So if we go off the claimed 58 BHP we get 46.2 HP at the wheel, it's extremely difficult to get 6 more HP out of any single and they are speculating...Husky mods for an extra 2 HP at the wheel is realistic.

[Grinnin]

Originally Posted by beergut

A number isn't what I'm striving for, better drive ability is the better way of putting it.

If you haven't put in a KLX needle and leaner main jet, I recommend it. The KLR main jet has a lean spot just off idle that really screws driveability then they put in a too-rich main jet to compensate. http://www.schnitzracingstore.com/catalogs/catalog.asp?prodid=4929812

It's not an accelerator pump (or a larger piston), but it does improve off-idle response.

[Grreatdog]

Speaking of KLX, the KLR650 needs that whole motor. It is a pretty strong runner. My 640 has flat out spanked every DR, XRL or KLR 650 I have ever ridden with. But my buddy's old KLX650 was almost as fast on acceleration then beat me on top end. At 90 mph on gravel I was glad to be on my 640 since the suspension and weight on the KLX650 are still in crap territory. But it has a pretty impressive motor. I have no idea why Kawasaki neutered it for the KLR650.

[Off the grid]

It's not just the anemic engine, it's the fucking atrocious suspension and dangerous brakes.

[OldPete]

Intake valve closing in the most important valve event.
Close it early and low rpm torque is up but high rpm breathing/HP is limited.
Close it late and low rpm torque is down but high rpm HP figures go up.

With late closing, compression can be increase because effective c/r is low at low rpm.

With state of the art ECU, fuel & ignition timing can be such that a late closing intake can still have good low rpm grunt.

[Mikef5000]

Which leads us to this:

[Kommando]

Originally Posted by beergut

KTM 640adv:
625cc, 54hp

KLR 650
649cc, 20hp

Honda XR650
644cc, 30-35hp

Suzuki DR650
644cc, 43hp

All of these are estimated and from QUICK google searches and are unmodified engine ratings. One thread said the XR can hit the 45-50hp target pretty easily, the DR isnt far off and the KTM makes everyone laugh.

WHy does the KLR suck so bad? What can make serious improvements?

Your numbers are a bit off. Some are crank figures and some are wheel figures. That said, some engines have WAY more volumetric efficiency than others.

The KLR likely has a lower compression ratio, worse flow (through the intake, head, and exhaust), a less-aggressive cam, longer stroke, poor spark placement, poor carbing, or more parasitic drag. It's also heavier than most.

I see a similar difference in power between my GF's Suzuki SX4 and a Honda Civic SI. Both are 2.0L, DOHC, 16V motors. The SX4 makes about 140-145HP at the crank and is a little over 2700lb. The Civic SI is rated for almost 200HP and is a few hundred lb lighter.

If you want to make power with a KLR, improve the flow (intake, head, and exhaust), bump up the compression, put in a more-aggressive cam, use a lighter piston, and dial in the carbing. Other than that, you could increase the displacement with a big-bore kit, and/or add forced induction (turbo) and/or nitrous. A kit exists to make 50+WHP with a WR250R/X, via turbo. Forced induction and/or nitrous can add crazy power. It can also obliterate your engine's internals and your driveline parts.

Forced induction is especially nice at high altitudes.

[OldPete]

Originally Posted by itsatdm

Funny you should mention that. Lacking a dyno, I used a 2/10 mile segment of a hill to test my mods. I started at 50mph and saw what increase the latest mod made. Started at 67mph for stock and ended with 77mph as something that was a compromise between HP and low end torque.

My latest untested change was setting intake valves at the lowest lash spec and retarded the exhaust valves by using max spec. Another compromise as it "feels" like more hp at the top end, not too much loss at low revs. It is good to have a hobby Sound right?

Google/youtube camshaft lobe centers. Muzzy has a long how to on it.

Advancing the intake closes the intake sooner=better bottom-end. Retarding later=better top-end. At best it is only about a 700rpm movement in the peak.
On DOHC engines with large valves at wide included angles, care must be exercised or the in. & ex. can tangle at overlap... I did it on a GS1000 Suzi.

Looks like the KLR cam gears are woodriff keyed to the cams. I've used offset keys on Chev small blocks.

Worn cam chains in proper tension retard the cam/s.

[kojack]

Originally Posted by Off the grid

The KTM 690 makes 61hp stock.

Yep, it does, but its a high strung crack head that od's a lot. The klr will just trudge on my after the ktm has shit the brick.

Sent from my ARCHOS 80G9 using Tapatalk 2

[NovaMoto]

+100

This engine was built to run at lower speed for a long time with more usable, less intimidating power/torque delivery.

Originally Posted by OldPete

Intake valve closing in the most important valve event.
Close it early and low rpm torque is up but high rpm breathing/HP is limited.
Close it late and low rpm torque is down but high rpm HP figures go up.

With late closing, compression can be increase because effective c/r is low at low rpm.

With state of the art ECU, fuel & ignition timing can be such that a late closing intake can still have good low rpm grunt.

[Grreatdog]

Originally Posted by NovaMoto

+100

This engine was built to run at lower speed for a long time with more usable, less intimidating power/torque delivery.

So was the engine in my lawn mower. It doesn't make me want to ride the damned thing for fun.

[beergut]

My thought:
http://klrworld.com/forums/modificat...r-mods-report/

I have a guy in AZ who does a lot of cage engine head porting and has done a few Honda motorcycle heads. I will likely be sending him my head and I will also be installing a little larger valve. I am also considering doing a ceramic coating on the faces of the valves to help with heat.

At the end of the day, I will likely have all of this into a bike that will still be a KLR.


***this is on a pre-08 bike***

If you dont have access to the site, it summarizes that the 685 with a ported head and larger valves nets extra power. Patman went from a stock 34hp to 46hp with a very nice power curve to 6300 rpms. It falls of drastically at about 7100rpms.

Patman says "The 685 kit is a pretty good boost even to a stock bike and has the added benefit of lessening the vibration through a lighter piston. Also the kit I got, and I'm not sure on the production kits ) cut oil consumption by...welll 100% I guess. I haven't used any yet."

KLR Cary who built the engine says "The head is a "Stage-2". That runs about $585.00. The valves are oversize, but will clear even with the stock piston. There are options that can add, or deduct from that price. I feel that it is a practical place to stop. There is an afull lot more that can be done to the head, but the returns for the dollar start to fall off steeply. Total cost for both, if you do the assembly is just under $1000

Some other things you shoud know:
The exhaust noise level will increase a good amount, no matter what system your using.
Jetting is more difficult, and what worked before will no longer do. The piston alone won't change it. The head WILL. Slide lift hole must not be bigger than 7/64". The difference in lift hole size makes a much larger change. I'm running a stock size lift hole in mine. It will also require the KLX needle. The DJ needle will work in some situations, but the KLX needle is more likely to make it easier to jet. The stock needle will not work!
Heavier clutch springs are wise. Stock is OK, but borderline, though that depends somewhat on how you use it.

Cary"

I have spoken to Schnitz and they advised me to ship my head to
http://www.mtechmotorcycles.com/perf...5-705-kits.htm

[XDragRacer]

Originally Posted by itsatdm

People do not understand the relationship between HP and Torque, there is a formula for it. HP=T x RPM divided by 5252rpm, where they are always the same. Both display a curve on a dyno. Even past torque peak the engine can make more power if it spins faster. When the HP line peaks due to design, it is all down hill.

I'd just note; maximum torque and maximum horsepower do not occur at the same rpm.

One can calculate horsepower at maximum torque, and torque at maximum horsepower, but . . . two different rpm values are involved . . .

[Kawidad]

I agree with those that mention the heavy weight of the KLR. I think that's the main reason it is slow compared to other 650 singles mentioned. The power to weight ratio is poor.

I've owned all of the aforementioned bikes and honestly, the KLR does not feel down on power related to the other bikes. I even owned the XRL and the KLR at the same time. The XRL is not more powerful. It is more abrupt and has a cruder more dirt bike like engine character, whereas, the KLR is much smoother and thereby makes it feel slower, but it's not.

I have a 2000 model and have stripped it down to a reasonable level, but could go much further if I wanted. I estimate I've taken between 20-30 lbs off, but really it's still going to be much heavier than the stock XRL or DR.

Now having said that, I've been searching and researching performance mods for the motor that are reasonable and practical. (By my estimation) Things that can be done that fall in this category are as follows: (in no particular order, but done together) Porting, aftermarket cams, bigger valves with better springs, the 688cc (Wyman) kit, and lighten the flywheel, and switch out the carb. IIRC, the compression ratio on the stock motor is acceptable, somewhere around 11:1, so I wouldn't try decking the head or anything else to bump up the compression, although you could if you wanted to. Then you need to make some modifications to the cooling system to compensate.

Patman and KLRCary did great work, but that was all done 5 years ago and since they were pioneers, others have seemingly built upon their work, but the documentation is spotty.

Food for thought.

[elsalvadorklr]

I agree wholheartedly with the above post

having owned an 08 and then selling that to fund an 88 xr600 rebuild I can compare both honestly and objectively

the klr has tractor torque UNRIVALED right off idle, in fact they are famous for this and can idle pretty much up anything...the klr in fact has more torque at idle than both the xrl, and xr, aaaaaaaaaaaaaand dr.

now midrange and topend is different but the internal gearing of the higher gears and final gearing give me a higher topspeed on the klr...again gearing

in any case the figure of 20hp of a klr is wrong at the rear wheel I remember being at 28hp and at the crank in the area of 34-36hp depending on who you ask very very close to the xrl...in fact some places put the klr as having more hp, especially the older models

power to weight ration went down even more when they upgraded the 08 and up models...gaing an estimates 30lbs give or take...again hp and torque being completely different animals especially in the case of the klr

lastly weight and how the bike handled(supsension) especially on dirt are the only detrimental points one could argue against the KLR objectively, having said that I did some funky and gnarly stuff on the klr when it was my only bike...

lose weight and improve the suspension before doing any engine mods

this applies to most budget dualspots and dirt bikes even the mights xr.

cheers