Hello All:
Forgive me for starting another topic that has been on the top of the hit list in the past but I have a couple of specific questions for some a specific members.

Background:
I have completed ALL of the basic mods, Carb rejet 124/40/2.5/ .032' Air box lid removed/ Smog circuit removed. Exhaust, stock head pipe, muffler modified to 1" outlet w/2nd baffle drilled also. 13T front sprocket.

Issue:
From what I read in the many excellet forums, my bike is still a bit weak as I can barely lift the front wheel in first but no way in 2nd.

What I would like to know is;

Does the exhaust make that much of a difference "after" the mods have been completed.
Many of you have recently installed muzzy's or big guns after all the other work and I'm just search for a little more ponys even though I did not want to originaly change the pipe.

Thank You for the feedback!

Don

 

Don,
take your muffler off and run it with only the head pipe on. That should give you a great testing base. Scat and I are running 14/48 and 14/49 gearing and that lightens the front end quite a bit.

 

With the mods that you have done I would think that you would feel more of a performance boost that you are describing. I too did all the mods that you have described and found a huge improvement in performance. I was waiting on the exhaust at the time so I too modified the stock pipe. When I changed from the modified stock pipe to the Big Gun I can't say that I felt a large improvement ...... It just sounded better so it must be, right? Mine will wheely at will in first gear, especially at 3500 rpm and above. The front will come up in second right after shifting or also at about 5500 rpm and above. The only difference is that I am running a 128 main jet, but I don't think that is that big of a deal. I'm also setting back on the bike and yanking up when I want it to wheely. (Didn't want you to think that it was happening all by itself)
So to answer your question...... I don't really know how much difference the exhaust makes over the modified stock one, but it sure sounds gutsy![sm=nxsmile.gif]

 

Don,

I am currently modifying my exhaust to the 1" pipe. Like you I want a more aggressive sound, but not to **** people off. I agree with you that the most restrictive piece of the KLX exhaust systew is the .5" outlet. I have 1985 Yamaha xt225 Serow that has the same .5" outlet as the KLX250s. The yamaha is a smaller 2-valve single overhead cam motor and it has the same size outlet as the KLX. That just doesn't seem right.

I am using the 1" pipe you describe, but I don't have access to a boring machine so I am leaving it with the factory 13/16" ID. You bored it to .9" (14.5/16"). I looked at your sound test file. Looks and sounds great. You mentioned at the time there wasn't any performance gain, but I sure with the snorkel and carb mods that larger outlet has helped in performance. Any advice before I go forward with your great custom mod?

I have a question about the carb slide vent. Do you have to drill it 7/64th with the basic carb mods? What happens if you do or don't?

As for your actual exhaust question. How heavy are you compared to some of the other guys? Also, a larger diameter head pipe can increase low end torgue for that pull up. I've had all sorts of two stroke bikes and even a few teeth more or less front or rear can make a big difference. I changed some sprockets once on my old 94 Yamaha Blaster (ATV). After that wheelies were possible in 1st to 3rd.


Thanks for the ideas, shaun.

 

Shaun:
If you looking for a better look along with a little more sound and nothing else, the mod I did works very nicley.
I am 5'9 / 170lbs so no more than whats recomended for the bike.
As for the vent hole in the slide, Drilling that one larger allows the slide to react with throttle position or go up/down fatser.
I may just throw a larger sprocket on the back as well.
I am starting to feel the cat is restrictive even though the "cat" guys I work with do not say that's the case.
Thanks for the feedback and let us know how it works.

 

Great info Don.

Sounds like drilling the slide vent is the way to go. I understand if you drill the slide vent to large bad throttle oscillations can occur. With so many guys already drilling the slide vent to 7/64th and no complaints I guess that's the sweet spot.

Well, I want more sound and a better look out of the stock exhaust. So even if the performance gain is negligibe I am going to still do your free mod. Eventually I will get some exhaust system, but when the price is right. The cat is an unsightly, heavy, and unfortunate addition to our bikes. Not much you can do there.

You know when I had my old tricked out Astro van I had a high flow exhaust system. The last thing I changed on that system was the catylitic convertor. I put on a high flow aftermarket cat and noticed nothing different in performance, however, my aircare readings in BC were better. I also lost 30lb-40lb off the stock cat. Maybe weight was the gain.

You and I are about the same size. I'm 5'9" and 185lb. Well see how my bike pulls when I'm finish the mods.

Again, thanks for the tips.

Shaun