You can't, especially with a small single like that. It's a waste of time. If your plug is the colour you say it is, and you did it correctly, you're probably substantially rich.


Correct.

I'll add that, if you already jetted it with a stock pipe, you probably don't need to again. On the other hand, adding a free flowing exhaust may very well cause it to run richer, and you may have to jet down a bit.

 

Q4 and Powerbomb...........Zero pop.

 

I really DO appreciate all the help...

It's hard for me to believe I'm running rich (not saying it's NOT rich, just saying it would be hard to believe). I'm setup with DJ116 main, needle clip on second notch, fuel screw 2 turns out. Compared to the normal setup instructions, I'm running a leaner jet, leaner needle setting, and a leaner fuel screw setting...

I noticed when riding today that I was getting a flat spot between 6000 and 7000 RPM that wasn't there with the stock pipe on it (all other things being the same).

 

Zomby: Can you elaborate? Usually I hear a free flowing exhaust will cause it to run lean (more air flow), not rich.

 

Increasing the airflow can increase the signal through the carb, causing it to draw more fuel. It doesn't always happen, but I have seen it first hand.

This is a funny story.
Many years ago, I built a 1.6 L Mitsubishi engine for circle track racing. It was a restricted class, so stock carb, and exh. manifold was required. I had the car running really well, and the car was fast. The carb was set up perfect. I made a jig and a cutter for the milling machine to get in to the exh. manifold, and open up the very small exit diameter. Once I did that, it went like stink, but started cutting out in the midrange, about 4-5000 RPM. I figured lean, so I pulled a plug. It was whiter than white, so I jetted rich, no change. I chased this problem for a week. Luckily I could test it down the road where I live. After pulling my hair out for a week, I finally followed my own advice. When faced with a problem you can't solve, do something drastic, and see what happens. I jetted it super rich. No difference. I jetted it super lean. Problem went away.
Why? What happened was, when I increased the flow (by freeing up the exhaust) through the carb, it started drawing a lot more fuel through. The RPM thing (which baffled me) was the secondaries opening up, and the plug was white, because the excess fuel was washing it clean, a problem that small singles are also prone to.

That's not the last time I'd seen that, but that was probably the worst case. A few years ago I built a pretty fast DRZ 125 for pit bike type racing. It had the big bore, carb, pipe, and Hotcams cam. When I put my own (much more aggressive) cam in it, it did exactly the same thing.

 

Thanks. That makes sense. And if I'm understanding this correctly, it also tends to support the aftermarket muffler guys saying that rejetting is not necessarily needed with their product, on it's own, without airbox mods.

 

How many of you with popping decel have removed the smog crap?

 

I get deceleration popping and have all my smog equipment still on.

 

Agree with 'ol guy^; check to see what your plug tells you. Sorry to (very respectfully) disagree, Zomby.

 

Well, have fun swapping jets... I installed the Dial A Jet in 1998 on a stock bike and have yet to do anything with the carb after every mod. Perfect plug reading and no popping except for that idle mix that I never adjusted, regardless of what I've changed - including a full tapered head pipe reverse cone megaphone exhaust. Maybe someone may be able to take advantage of knowing of this product before they go buy a bunch of brass.