KLR 650 Dyno Results

JAN 2004 TO June 2007 ( UPDATED )


The KLR 650 seems to be a fairly popular "cult" type of bike in the Dual purpose world, and there seems to be some standard modifications that people perform on it almost as soon as they buy one. Concerning power mods, a pipe or slip-on silencer, a high flow air filter, and a jetting change ( of course ) is often the norm.

So in an effort to see what a stock bike produces, and to see how these bolt on mods might effect you, the Saturday afternoon mechanic, I bolted some of this stuff on and displayed the charts below.

Now understand, this is for reference only and is by no means the standard. Just an idea of how a mod will effect your power and jetting. Unless the jetting is dangerous, I'm gonna leave it where the DynoJet people suggest so that those of you without a dyno and gas sniffer can see what happens with each change.

In this test I used a 2004 KLR 650 with 500 miles in it.  I chose the Big Gun exhaust system for it's complete package ( Quiet series silencer and header ) and for it's long lasting coating. The standard in jet kits is the DynoJet kit and so the stage 1 and 2 kit was used here per DJ instructions just as you the consumer would, along with a new K&N filter

It was my intent to find out where the bike performed in "bone stock" trim, and then to add the modifications, starting with the jet kit, and plotting the best results from each mod ( after rejetting for each mod of course if it was way outta wack ).

So...on to it.

Notes about how to read my notes...The Legend

Blue lines you see are the best of 6 runs ( I used run #6 for the comparison ) in the stock as delivered configuration. All I did here was to break in the bike, change the oil and filter, clean the air filter and warm it up on Chevron Supreme 93 octane fuel, which was used for the remainder of the test. I may tri it again later with regular 89 octane, as 93 is a waste on a bike with the low compression this one has.

Red lines were runs with the recommended jets installed for a stock bike with stock airbox and filter and stock pipe...which is how I ran it...nothing but the jet kit on a stock bike. ( a note here, DynoJet recommends a 136 main, along with a new needle in the 3rd clip position, drilling a larger vacuum lift hole, and 3.5 turns out on the pilot fuel screw. The stock bike comes with a 148 main, and though I question the use of a 136, I wanted to do it the way you would do it...per their instructions. Still stock pipe and air filter.

Green runs were the stage one jet kit, switching back to the stock 148 Main Jet, and pulling the airbox snorkel and adding 4 one inch holes across the top of the airbox. Still with stock pipe and air filter.

There was a pink run, run #18 it added the Big Gun pipe and the 150 main jet, I lost the rpm sensor and it wasn't plotted on the first graph, you'll see it on the second graph, but I had to change to Speed figures on the bottom to compare all the runs, as the computer won't allow me to plot a run without RPM against a run with RPM so in order to get the #18 run plotted along with the rest, I had to change from rpm to mph. Note however that in this case speed almost coincides with rpm so a comparison can still be made. Changes to the pink run were the adding of the Big Gun pipe and a richer main per DynoJet to a 150... the 150 was too rich so on run #20 ( the purple one ) I finally added the last part the K#N filter to try to bring it back a bit leaner...it only helped a bit.

The purple run is with "everything", as I said above, I am now using the DJ kit, the Big Gun Pipe, and the K&N filter.

Air Fuel...the only thing that really matters.

All ya need to know for now is that higher on the chart is leaner, and lower is richer, and that the yellow band is where ya wanna be.   When ya first open the throttle the mixture shoots way lean, as rpm increases it gets on the needle and starts to come into a better spot, as the rpm increases further you transition onto the main for the duration. We could talk about this all day, but for now, just figure the pilot won't show on this chart cause I didn't start my run until 2000 rpm. The needle is showing leaner than it really is because of the rapid throttle opening. Figure the needle can be read from about 3500 rpm to 4500 rpm then it's the main, though they actually overlap in that area. ( on this chart )  As for the main jets, the green run is the best. The red run is too lean, the blue too rich, the purple close, but still too rich.  But as I said I'm not finished yet, the final run #20, shows the needle too lean, the 150 main a bit too rich and since DynoJet doesn't include any pilot jets, I'll have to grab some today and try to fix the bottom end lean issue. Max power is about what it's gonna be though. I'll go back to the 148 main, richen the needle and the pilot and get back with ya.

So here's the numbers

 Horsepower goes up and down. rpm to the left and right. For instance look at the bottom of the chart, for an rpm, say 3200, then go up to the place where the red line dips down a little. Go to the left and read the HP figure, in this case 16 HP. continue to go up to the pink line also about 3200 rpm, and notice that at 3200 rpm that, if you again look to the left, the pink run is about 18 HP. Now you can look down at the same rpm on the air / fuel chart and see where the fuel mixture was for that moment ( rpm ) and see how it relates to power.

Have fun, I'll give ya more later and when I feel like it's accurate I'll post it as a page on my regular web site.


Here's one with torque, read it on the right, they are the plots ( lines ) that are higher ( actually printing over my "Dynorun legend ) on the left side of the chart, tapering off to the right, you can still pick an rpm, ( like 3500 ) and see that on the purple run, torque was way high... at that moment  almost 34 ft/lbs, also at that moment ( 3500 rpm ) horsepower on the purple run, was also higher about 23HP compared to about 19 or 20 on the blue run ( stock ). remember that in 3rd gear where I was running that rpm and speed are close so you can almost compare chart to chart...but not quite.  Remember that on the second chart I left out #18 and the color legend has changed slightly as well.

 This one shows HP figures only so it's easier to read., And I left out the rpm and so I could use run #18 as I told you, it lost rpm sensing on #18. But it shows all mods without the K&N. And then the K&N was added on run #20

And finally this one here that I did this evening.  In order to verify that the big boost in low end power was not due to faulty jetting, I went back and ran the bike nine more times, in addition to the twenty I ran yesterday. So what ya see below is Dyno run 29 where I held the bike at a steady ( well kinda steady ) 2800 to 3500 rpm for about ten seconds, this allowed the gas sniffer to get a good grip on how the lower mid range is jetted, right at the spot where the Big Gun pipe gives all the boost. As it turns out the jetting is right around the 13.5:1 mark, and I can live with that. I also went back to the stock 148 main again to bring the fuel air ratio that you saw in run #20  ( above ) back up to about 13.3:1 so now what you see is a very slow throttle opening for 9-10 seconds and a fairly flat fuel delivery schedule. Oh and on the last run of the day ( this one...#29 ) we forgot to type in the change to the main, it still says 150, should be 148.

So that's it.  The fuel delivery schedule is fairly flat at an average of 13.5 to 1.  I got about a 17% boost in very usable power right where we want it ( between 2500 and 5800 rpm ). I'm not really interested in power above that range anyway.  The final setting were as follows

 Fuel screw out 3.25 turns.  DJ needle in 3rd groove from top.  Drilled slide with 1/8th drill bit.  148 ( stock ) main. Removed air box snorkel and baffle, and drilled 4 one inch holes in top.  Installed Big Gun Quiet series header and silencer. And installed K& N filter.

Could I have gotten more bang for the buck?

Maybe.  You could've adjusted your fuel screw at no cost. And drilled your slide. You could've even put a couple of shims under your stock needle, and even made the air box mods...for little cost and you'd have the "green" run #14. More power everywhere. Quicker and smoother throttle response. All for about a dollar. ( for needle shims ). Do ya need the DynoJet kit?  Well, like I said, you could make a damned good run without it. I'd buy it for the adjustability it offers when I head out to the mountains or to Death Valley. Adjustability is what ya buy here.  I'm not really sure that in the case of the KLR that the K&N is worth it's price. While it may flow better than stock in almost every other case, I think the steel plate that comes with this one, causes the K&N to give up about 30% of it's surface area to the stock filter, and so it showed very little gain ( .4hp at 7000 rpm ).  While not proven here, I think a good TwinAir could beat it.  Now comes the pipe. $450 retail. Nothing else showed the single biggest gain in usable horsepower ( and monster torque ) like the Q series pipe from Big Gun. No other silencer looks a good as this baby either, and loosing eight pounds that is carried up high on the bike is certainly worth something. Do ya need it? Your call. 








JAN 2006 More KLR650 Goodness.

OK I've made a few mods here and I'm gonna show 'em to ya in no particular order. First on the following chart is a combination of the most significant runs from above and then the addition of a new 685cc big bore kit offered to me by Cary at Schnitz racing. He's done a helluva lot of work with this KLR engine and is probably one of the sharpest tuners and fabricators I know. 

Look at the chart...I think it says more than I could. But gimmie a few days and I'll put up a more in-depth report.

Now for those of you who wanna see more technical stuff than this chart, below here's the result of the last ten or so dyno runs on this kit, as I was trying to dial in the jetting. You can see,  the fuel delivery curve was a bit jagged after I first installed the "fat piston" kit. Peak power was still a substantial gain over the non-kitted engine at 37hp ( I actually had 38.14 on run #7 not shown here but it was still just a bit too lean for my liking, though not dangerous or anything at 14.5:1 ). 

You can see on the fuel air chart in the middle, that I managed to get the fuel delivery schedule about as good as one can get a carb, it almost looks like an injected bike. It's averaging 13.6 to 1, makes 37.86 hp, and has a beautiful fat torque curve...nice!  I think there's more power still, just a bit anyway. If you look at the fuel curve at the very bottom, say 3500 rpm, and look at the torque curves at the same place, you can see where it was lean on the fuel curve that it produced an additional 2 ft/lbs of torque ( 3350 rpm ) I may try one more run just for a tiny tweak to lean it the smallest amount way down on the bottom...just to see. Also Cary has been doing some pipe work as well, and while the Big Gun pipe I'm using produces excellent low and mid range torque, the internal baffling of the quiet series silencer inhibits the top end even more than the stock pipe ( check the green line versus the red line above ).

I'm gonna stay with the Big Gun pipe, but I'd sure like to see what an open core silencer would do for the top end on this engine. The problem with that is, that it may diminish the low end, and since that's where we all ride ( 3500 to 5500 rpm ) the Big Gun's Q series is actually perfect for this engine. Unless you take yours to the dragstrip!

Will you feel the difference? No doubt. You wont have to squint your eyes, or cock your head over to tell. It's there. You'll get what you pay for. You will smile.

Does the lighter piston fix the vibration? Not completely. But you will notice a slight difference at a stop light, and at steady state cruise. I can put my glasses on the seat with the bike running, and they wont vibrate off while I put my helmet on.

Does it affect gas mileage? I'm not completely sure on this one yet. I've rejetted a few times. Sometimes for power, sometimes for cooling, sometimes for economy. In the end, I think if your bike was properly jetted before, you won't see enough of a margin to matter. What I'm actually seeing is about 46mpg and this is GPS mileage, not speedo mileage. On the speedo I'm still seeing about 49-50mpg.

Will it make the bike run hotter? Again proper jetting can determine the delta between hot and cold, and more power generally means more heat, but I'm really not seeing it. Until I rejet for the summer heat ( tonight ) and dyno it again tomorrow I wont have accurate results, but I'm gonna say again, no. Not so much as you'd notice.

Does it detonate? My kit came with a choice of several base gaskets, I chose to use the stock thickness and have seen no signs of any detonation with mid grade fuel ( just a single tank test ) or with my usual Chevron Supreme fuel. No. No detonation.

37.98 ft/lbs @ 4700 rpm. Up from 32.20 @ 4700 from the "before runs".  ( Stock was only 31 at that rpm )

Horsepower, nearly 38 peak, up from 33.4 before the fat piston. 

  Now I've got some good mods on my scoot to start with, but still, 10% torque and top end horsepower is what I'm seeing. And I can get more! I actually have it jetted "safe and reliable" and am using the "safe and reliable" base gasket.   I could've got a bit leaner on the bottom and used a thinner base gasket to produce more torque, but that's not what we're about here.

 I figure we want as much power as we can get "safely", even if were in podunk  town somewhere where there's no premium fuel.  Besides that, the added compression of a thinner base gasket, may have produced a higher low end torque number, but the added resistance of the extra compression would have taken away my top end gains to some extent.

  The big bore kit is the way to go. No doubt.  In order no to make a fool of myself and have someone debunk my findings, I've run it on two different dynos on four different weekends over a 2 month period, and there's no doubt in my mind, that for the price of a pipe, or less, that there's good reliable power here. It may be a little more or less on your bike but remember, "There's no replacement for cubic displacement"!!

 Anyway. I say it's a "go" and ready for market.

Is there more? Sure is, I've got some cool airbox mods I'll show ya directly. But right now I'm on a suspension project.


 OK Time to get serious.    Cary also offers a Big Valve head, that has stainless valves that are slightly oversized, along with some mild port work for a good flow. In fact if ya call him up at Schnitz Racing, he'll explain the several stages of head mods he has for this bike. You can send him your head, and he'll custom make a set of valves for it, install 'em and port the head just a bit.

 I installed this mod, and as you can see from the chart below, there was a boost to be gained ( after proper jetting of course.


 But there's more. I've been running the Q Series pipe all this time ( Quiet series ) in an effort to be more neighborhood friendly, but as a final power mod, I installed another of Cary's mods, a Big Gun muffler with a modified "Box Section" core.  Which is to say, a box section instead of typical round core silencer. He's added just a couple of "V" shaped baffles to bring the noise down.   I gotta say that this muff made a big change on the top end power of the bike. And I think that I've finally got it where I want it. It will easily run max RPM with stock gearing anf will clock over a hundred miles per hour, and that's GPS speed not that stupid speedometer that comes stock.

Anyway, I've put this easier to read chart up for you to browse.  The top three lines show the big bore kit in blue, addition of the big valve head in pink, and after you have enough exhaust gas flowing to make a difference...the box core exhaust in red. BAM! Now that's the way this bike shoulda been delivered from the factory!

                                                                             KLR650 with Custom Muffler

That is all of the power stuff...for now.

 Last update  07 DEC 06

                     NEW UPDATE ( again ) MAY 30 2007


    Well it seems the people at Schnitz Racing, and more to the point, Cary Aspy have gone a step farther still.

       Ya see, the 685 kit pushed the safe limits of the KLR's cylinder bore in the stock cylinder casting. So we kinda thought that was the end, without going drastic. And so drastic is what's happened.

      Ever heard of a process called Cryogenic treating?  In it's simplest terms, it's where you take a piece of metal and freeze the hell outta it for a while, then let it warm back up, and in the process the metal becomes much...uh..."tougher" I guess would be the word. ( I'll explain more later, we used to do it to our clutches )

 Anyway, Cary had some sleeves made, had 'em cryo treated and now feels they're strong enough, and distortion free enough to bore 'em to a 703.5cc configuration.

I got the first one. You'll soon see the results here, and on my favorite KLR website www.KLRWorld.com.


Another guy there Marty, got the second kit right after I got mine ( nana nana boo boo ) and will post his impressions there as well.

 Anyway this kit comes with piston, moly coated of course that is 14 grams lighter than the 685 piston which was several grams lighter than the stock piston, so vibration may be affected a bit. It also comes with the cylinder, and pre sized head gasket, and two sizes of base gaskets so you can alter the compression. I'll be running premium fuel, and so I'll be using the highest compression to see what the bike can do with the new "biggest" bore kit, the "Fat Head" cylinder head, and the custom box core pipe.

 It shouldn't be long, I'll try to get it installed this weekend, torture it for a few weeks then dyno it and put the results here.

 Today is the 31st of May 2007...


 Today is 19 Sep 07.  The 705 kit is still in the testing mode. we're forging ahead here with some new stuff that includes higher compression and altered cam timing to see what this beast will do.

 I've beat on the Cryo-Treated 705 cylinder pretty hard and oil consumption is nill, and power is good.

 I'm gonna wait just another week or two and head to the dyno room again and I'll post when it's done.