Edit: My bike:
09 KLX 351SF
TM36-68 Jetted to MY perfection. Usually 60 mpg.
15/39 gearing
My own muffler mod
Lid on , lid off KDX snorkel in , snorkel out.......
4,000 miles on 351, 8,000 miles on bike.
Oil changed every 1,000 miles, filter changed when the spirit moves me.d



I wrote some in the original thread, but.....

So here is what I found.

First, I only did the intake cam. I adjusted the valve timing to be 1/2 tooth advanced. This means the intake valve opens and closes 10.5* sooner.

Bike did not run any better, more like worse. I run with the KDX snorkel cut off inside the air filter lid, so its just a duct to divert the noise away from me. I pulled the lid and bike ran better, about as well as before. Intake noise was really loud.

Then I was thinking (ut oh) If an exhaust valve does not open for what ever reason, it pops back through the intake. SO I pulled the exhaust cam, marked and realigned the ACR. I retarded the exhaust cam by 1/2 tooth or 10.5* like in the instructions. Now exhaust valve opens 10.5* later and closes 10.5* later.

Bike started and ran like it should except less power on the top end and a little more in the mid range.

I was hoping this advertised extra horse power would make it lift the front wheel in second gear. It tries, but no luck. Nothing gained there.

It was hot out and bike was pinging, so I filled it with 93 octane and pinging went away.

Power was a little smoother
Fuel mileage went down about 5 mpg.
Bike did seem to pull better at 6000 rpm and was all around a little more mild mannered and stable.

THEN yesterday I was at an ice cream stand and left I tried to do my usual wheelie. The bike runs out of power too soon so the front wheel does not stay up, I am embarrassed.

Today on my way to work, 4th gear, wide open throttle, top speed 73 mph about 9,000 rpm. It was all she had in 4th. I shifted into fifth. The bike started accelerating again. It started to develop a head shake so I backed off.


SO today after work, I put the cam timing back to stock.

 

Intake and exhaust back to original timing. I did not mess with the ACR.

Bike starts as good or better than before.

On my way home from work, 4th gear wide open top speed 79 mph, 10500 RPM. I cranked it wide open while going 62 mph in 6th gear. It climbed to 85. That was close to all it had. I backed off thinking about the headshake this morning. Probably all it had anyway.

I got my baby back!

I had no other problems like valves hitting the piston, hot starts, cold start were all fine before and after the mod.

In the end, I think all I really did is move the power band lower, not create more power.

I hope this answers a lot of questions.
Yes I used a torque wrench, YES my valves are properly adjusted. I tried a 125 and 130 main jet. It made no difference width the lid off.
David

 

Wow, interesting. I'll wait a while longer and see how things go between the cam mod, the 351, and so on. Good thing I'm broke right now.

Rob

 

Huh...your post disappeared?

Wonder what the differences in set up between your bike and the OP of the cam retiming thread. What jetting changes did you have to make?

Because I'd like to get more midrange power w/o the loss of top end. The 350 kit helped tremendously, but currently using close to the stock gearing 14 x 45.

 

No, my post did not disappear.

Pulling the lid leaned it out a little, so I tried a 125 main instead of the 130. No significant difference.

I forgot earlier, Backfire screen is gone and has been.

David.

Edit: yes, my post did disappear.

 

Funny how stock D model bikes made 32+ hp with the stock cams and timing!

 

My original post in the original thread disappeared.
This one may too.

Original poster of the cam mod thread still claims I did the mod wrong way. Pictures of the timing are posted, posts have been edited not by me.

MY bike is back to normal running like a raped ape just like before.

It did not work for me, but try it for your self.

David

 

WOK, I realize those are not your personal dyno results, and I respect your posts and opinions a lot on the forum...but...I don't believe those horsepower numbers out of any relatively stock KLX250. I don't think any amount of timing alteration is going to make that kind of horsepower difference. Plus, what I can see, the D models used a 32mm carb instead of the later 34mm carb. All use the same cams and cam timing. They are all 11:1 compression. There are not enough elements in the D model to justify a very large horsepower increase like that.

I think we're looking at either optimistic figures published back in the early 90's when that type of thing was more common, or maybe we're looking at horsepower at the crank...not rear wheel.

 

All valid opinions, and yes I suspect they are crank figures. Kawa put the D model out as a competition model and it runs the same cams as the late model. This in itself shows the OE cams have potential for more hp gain on the late model bikes, combined with some other changes. 25 hp, dyno, (I don't know how that translates to crank hp) from the 250cc wouldn't be unrealistic with the unaltered stock cams. Same figure as Marc' got on dyno!

 

It would make sense that the cam retiming would shift the powerband lower in the rev range. Not give it 4 hp... Maybe an aftermarket cam with higher lift or longer duration. I have had posts disappear.... maybe this one too.

I think an earlier yr. model ignition would help make more hp.