Recent content by mjtursky

Thank you for the replies. I purchased a rebuild kit off E-bay awhile back and it did not function. I believe it was mislabeled for the fluid I required. The seals failed in a short amount of time. Fortunately I bought a used assembly and it has been working pretty well. Was hoping to find a...

Looking for options to replace the stock AJP clutch master cylinder assembly. Any suggestions for a direct bolt up? thanks in advance.

The reason Keihin went to plastic for the idle speed screw is to avoid breaking the tab on the slide. This occurred when people would let the throttle snap back when revving the engine. I found the screw used on Polaris snowmobile Keihin carbs to work better. Bigger knob and slightly longer. Be...

Still have the bike?

A quick trick is to shut the fuel off. Remove drain from carburetor and let drain. Watch or try to catch debris. Re-install drain and turn on fuel valve. Sometime the inrush of fuel will wash out any debris holding the vavle open. If this does not work you will have to dis-assemble the carb and...

yes, measure before the taper starts. Normally it is on the straight diameter before the slide opens and a period of lift. it varies by JN. That why I suggest measuring the length from top clip groove to start of taper. You can tell which JN is starting on taper sooner.

E-85 jetting Stay away from it. If you do run it, you will have to re-jet your carburetor to flow 30% more fuel.

Jet Needle It's tough working with a JN that you do not have the specs on. Do you have a micrometer that you can measure the straight diameter of the JN before the taper starts? That will tell you something from idle to 1/8. Is it visible to see where the taper starts in relation to the clip...

doughy bottom end There is always more than one way to approach the jetting. Some people here on the forum have attacked rich bottom ends with slides that have more cut-away (higher # on slide), I prefer to stick with 5~6 cut-away slides and focus on the JN. Usually the straight diameter will...

A little more In my prior post i forgot to detail that you can run 100:1 at idle or under light loads on a 2 stroke but heavy loading requires 40~50:1. I also have the luxury to buy gas at the airport which has high octane so I don't need to worry about oil influncing the octane. But I release...

Correct Oil ratio This is getting pretty deep into the science. My opinion on this is not to run higher than 50:1 oil ratios. You will give up engine life with mixtures higher than this. When testing outboards with variable injection, the engine can tolerate leaner oil mixtures (up to 100:1)...

To confirm, all Keihin measurements should be done when the needle has seated but not compressing the needle spring.

I personally would stay away from high cut-away slides. It maybe that you are masking a rich jet needle by using a 8 or #9 cut-away. I think you should be able to get a good idle with a #42 or #45 SJ and 1~2 turns out on the "air" screw. If this is too rich, try finding a leaner straight...

Machining notch Make sure to machine or file from the slide face (chrome) into the slide. This will prevent flaking of the plating or leaving burs. Might want to smooth edge slightly with emery cloth.

Notch on slide I'm currently using a notched slide in my 250EC and like it. The theory is it passes more air over the fuel circuits which increases the signal. It's easier to jet leaner than to deal with a lazy fuel delivery issue.