Any Carb tuning Experts... Assistance Needed!

[cmeripper26]

As of right now i am currently running the Novi Dual 42's in my 05' SXR. They are the Stock Mikuni 38's re-worked by Novi to the dual 42's. My engine setup is as follows, stock motor with JSU head 28cc domes, Factory Wet Pipe, Advent T3 programmable ignition, V-force reeds.

Now the internals on the carbs are as follows: 2.0 Needle and seats, Main Jet-155, Pilot Jet-77.5, Low Speed Adjustments- 1-1/2 out from closed, High Speed Adjustment- 1-1/2 out from closed, and im not sure the gram rating on the spring if anyone knows what Novi installs for the spring on the stock Mikuni 38's re-worked to 42's let me know. At this setup the motor runs great but i keep running into the problem of the needle valves becoming siezed up in the seats over and over again. I have a new pair of 2.3 needle and seats, my question is can i use the 2.3 needle and seats with the current setup listed above by tuning the adjustment screws. I currently don't have any other jet kits on hand. Any tuning experts let me know if the 2.3's are a possiblity, it's supposed to be a nice weekend and i don't wanna keep using the 2 sets of old 2.0's i have cuz the veins are all scored up and have all been locked up inside the seats before. Any help is greatly appreciated. thanks!

 

[Big Kahuna]

If you have 2.0's then that is what you need to run, you could try the 2.3's, but then you need to play with your popoff. I would run what NOVI spec'd.

I am not sure what carbs you actually have. These are not OEM Kawi spec'ed carbs.

 

[cmeripper26]

The carbs are the stock Mikuni dual 38's that come with the stock SXR 800, mine is an 05'. Novi was taking the stock 38's for a little while and re-working them to dual 42's. The internals i listed above minus the gram rating on the spring. Novi didn't spec these, i got em from JSU cuz i made an offer and got a good deal on them. They were brand new right from JSU. There haas to be a way to adjust the adjustment screws and run these 2.3's.

 

[Kennay]

38's? I thought they were stock 40 or 42

 

[cmeripper26]

The SXR's come stock with dual 38 mikuni's and i saw Novi was doing that with the Stock carbs so i did it, and i made an offer on another set and got them for real cheap but this problem sucks bro..... it happens all the time, and the only brand new set of needle and seats i have is the 2.3's. I'm just looking to see if it's possible by only using the adjustment screws to run these 2.3's.

 

[Kennay]

That is an odd problem.

What are you running for oil?

How quickly does it happen after installing a new set?

 

[Kennay]

And for what it's worth, I don't see why you couldn't clean up the inside of the seats with a dremel or some other rotary tool so long as you don't hit the sealing surface.

 

[Cliff]

38's? I thought they were stock 40 or 42

pretty sure they are supposed to have 40 s from the factory. neals ski which is gils old ski does.

 

[Big Kahuna]

The SXR's come stock with dual 38 mikuni's and i saw Novi was doing that with the Stock carbs so i did it, and i made an offer on another set and got them for real cheap but this problem sucks bro..... it happens all the time, and the only brand new set of needle and seats i have is the 2.3's. I'm just looking to see if it's possible by only using the adjustment screws to run these 2.3's.

Carburetion Twin BN40 Mikuni

straight from Kawi's website.

 

[cmeripper26]

Yup they are the BN40's..oops i haven't had the stock set since i built this one. Anyways any other takers on this weird ass problem. They usually sieze up after a few rides. I am currently running the Maxima Castor 927 oil.

 

[Kennay]

And for the record, you have started with an actual packaged pair consisting of the needle and the seat it came with from mikuni?

When you replace them, is their any binding that you can tell upon install?

And is their anyway you can post some pics of these seized needle and seats.. I'm having a hard time visualizing how one could seize together.

 

[cmeripper26]

This is a first for me too bro believe me. I have one set of 2.0's where i cannot even pull the needle out of the seat. I wonder if all the ethanol in the gas just eats at the dissimilar metals that make up the needle and seats. It's an easy problem to troubleshoot it's just hard to find the reason why it continues to happen. The ski i just finished the whole build and everything last summer and still runs great, this problem keeps popping up.......?