Mikuni TMX part no. question

[pook809]

I am ordering a few tuning parts for my 03 cr250.  I have a question about a needle part number.  I was looking at the needle options and want a 74 needle, 1 leaner than the stock 73.  There are two options and I am not sure which I need.  The part numbers are as follows:

 

6BHY39-74

 

6BHY38-74

 

Can anyone tell me the difference in these two.  I know the stock is a 6BHY38-73.  Thanks

[greg-15]

On Mikuni carbs, It is important to change out the complete needle jet to really make a change with the mid range circuit. You can change the needle but from my experience not notice much change. A needle change is for very fine tuning on a Mikuni.

[pook809]

Fine tuning is what I am doing.  I got a S8 nozzle and just want to try a couple different needles.  Any idea the difference in these part numbers?  They are the honda numbers.

[bcislandrider]

TMX, fine tuned one day.

Waaaay off the next.

[RippinCR250]

Found this in my 07 manual.....it explains the needle differences although they are different than your 03 needles.

Have you got a manual for your 03?

[greg-15]

Fine tuning is what I am doing.  I got a S8 nozzle and just want to try a couple different needles.  Any idea the difference in these part numbers?  They are the honda numbers.

 

These are 2001 Honda Numbers and Numbers from the Sudco Mikuni Catalog.   Appears your on the right track and maybe confirm with this information.

 

[pook809]

thanks guys