I'm trying to tune a Keihin carb for my Ossa 250 Gripper. I don't have any experience with these modern carbs, so it's being complicated.

 

Can anybody give me a good starting point for its settings? If I'm not wrong, OKO jets are also valid for my Keihin.

 

Thanks in advance.

After installing Boyesen Reeds in my previous Beta Evos (both with Keihin 28PWK carbs) I have followed the instructions on this link, written for Miknui and Keihin carbs (on Lambretta scooters) and found this process easy to work with rather than doing the plug chop method in my suburban street!! So irrespective of age of bike and engine the principles should still be the same.

http://www.smellofde...ydy/jetting.htm

Note that the guide starts with the needle clip in the middle position and changes are then made around that starting position. So getting the pilot and needle correct without any influence from the main jet (or making me understand when the main jet circuit was coming into play) worked well for me. Having then set it up on the stand, then take it to your favourite practice ground and you can then test it on sections you are familiar with plus/minus doing plug chops through the various ranges. This helps refine the jet settings for the load and type of riding you do, but doing it first on the stand gets you a very good baseline to work with.

It's an interesting document, peterh. Thanks a lot!

 

But it would be even easier if somebody has tried a successful combinación for my bike.

Cant help with 250 but i have a sweet running 350 with the oko version fitted. Main is 112, pilot is 55, slide no3, needle JJH and clip in the middle.

Good luck.

Thanks, longlegscanbeuseful, that's what I was looking for.

 

I fact, the original Amal carb for both grippers is the same, so your settings should be a good starting point for my bike.

I've been testing my Keihin with Main 112 and pilot 52 (I had not an upper pilot jet in the toolbox), and it goes smoothly ... but sometimes it feels as if it's running low on fuel. I've ordered a 55 and a 58 pilots to continue trying.

 

Maybe a 24 mm carb would have been a more logical choice for my 250, but the one I had at hand was the 28. :-)

 

 

Thanks a lot for your help.

You're welcome Kingscorpion.

You might want to check the float height if you are having fuel starvation problems. It's quite easy to disturb the adjustment during dis-assembly and re-assembly.

Have a look at this website to help. It is for the OKO which is the copy of the Keihin.

http://www.mid-atlantictrials.com/Instal.html

 

Start with 3.0 slide for sure

Thanks again, friends. I won't be able to make any test in three weeks, but it's good to know the parts I have to find before opening the carb again.

 

I'll keep informing. :-)