125-200cc Keihin vs. Mikuni for 150

It worked fine without grinding the knob, but I wanted a little extra clearence.... Jimi told me to do it.

They just emailed me with a very plausible explanation of the issue. They also sent me a new screw for free. I'll post a follow-up report with their explanation after I get the new screw and test it out.

You may want to try the next richest needle, then drop it down. My KTM guru said the NOZ needles are short and need to be run deep. When I asked for a smaller pilot, he said I needed to lower the needle as it was probably trying to pull off of the main jet at low rpm.
I am going to try lowering my NOZF then go up to a 40-45 pilot, but mine is a 125.
GP

Let me know how it works. I just ordered a NOZH needle. I believe that is one step richer than a NOZI. I will install in the #2 postiion. OH, ran a muddy / technical H/S this weekend and won my class by 1min29sec. LOVE THE BIKE. AND I got 19mpg.

Congrats Dwight!

Here is a video of the Cornerstone Ranch H/S this past weekend. Well done and captures the challenge of the event. http://vimeo.com/21616428

My bike is running really well so I should leave it alone but of course I am not.

Currently my TMXX is at RB Designs for the divider plate treatment. He is going to try to create a Mikuni mixture screw also.

I have Walts power valves which I am doing some final grinding on to get them .5mm from the piston. They look like they are going to seal up really well.

By next weekend I should be ready to test it all. I think it is really going to have a strong yank off the bottom.

Oh, I looked at my needle and it is the chy16-61. I think a chy 17 is half a clip richer, which would be good. But what about the "61" part? It is richer then a 62 but is that true across the entire throttle range or mainly at a certain place? With the Keihin I had the JD spreadsheet to figure this stuff out but I am lost on the Mikuni needles.

Mark,

The 61 is one step richer on the bottom(top section of the needle). I applaud you setting your pv gap to .5mm. I am not that brave and set my own set to .030" or .75mm and that is tight. As you lower them towards the cylinder it does lower the bottom edge a little so you might check the gap between the bottom and the top of the exhaust port. Set to 6.0 mm if you can.

NWRider if you don't mind let us/me know how the RB carb works out. I may send mine to him for my 144. Thanks, John

Walt - I am not an expert so I will be careful on the powervalve. I will probably get them to where my .75mm wire will rub everywhere, then I will make sure a .5mm one can clear all surfaces. So it will be .5 to .75 when I am done. RB told me .5 is fine but I do not really trust my measuring ability so I will probably not be that brave. I will keep an eye on the exhaust port height.

John - I will review the carb mods for sure.

BTW - I am also putting a fresh ring in just becuase it was cheap. Does anyone know the correct ring gap for the oem 144?

Thanks.

Mark,

Anything over .010" is good. Husky specs this at .017" and says to replace at .026". Seems like a lot to start with so I don't take them out that far. I think you could actually go as low as .009" but I have yet to have a 58mm ring show up with that tight an end gap. The first set of valves I ground, I gave the eyeball test for initial gap to test. Measured later and I had them at .018" and it scared me. I just don't have a feel for how much they are going to expand at 600 degrees F. If RB says .5mm is good then I believe him and .018" was ok, but I am just not that confident in my own measuring capabilities in that tight space on a curve.

Thanks Wally. I was trying to get some good valve measuring tips from RB. He does it by sight but my eyes are not nearly that well calibrated.

After 40+ how can you calibrate what you can't see without a magnifying glass.

True this!

I still have had my best luck by flattening a piece of solder on the end to the desired measurement. That way it is easy to bend and get in there. I set the solder to .035" and work from there. I just measured a set of new valves on a new OEM 144 cylinder and the gap is at .060".

Did you ever measure where the stock valves are in the stock cylinder when they hit the stops? It looks really tight to me but of couse they do not get close to the stops once assembled with the collars.

I'll try the solder.

You'll like the carb divider in the TMXX, Great low end response reminds me of the 36PWK pull.

So far the NOZH (#2 position) feels good. National Enduro in 2 weeks.
OH, I have an issue with my IMS 2.8gal tank. One of the shroud screw inserts is spinning in the tank and I can't remove the screw. Wonder what kind of warrenty they have ?