From threads in different DRN forums, it appears that I need a 6BHY38-70 Mikuni needle (for tuning an 03 CR250.) I have looked through my local dealer's White Bros and Parts Unlimited catalogues and cannot seem to locate this part number. I have also looked at carbparts.com with no success. I understand, the 38-70 numbers (and the 6,) but I am not clear on what the BHY letters indicate. Any help would be appreciated.
Mikuni Part Numbers
- Thread starter GoesTo11
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NO HAND
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- Jun 21, 2000
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Only your honda dealer will have that part for the cr250. He will have to look in the microfiche for the 2003 cr250 in the section carb optional parts. I have found the 38-71 is better for me. I would get detonation sounds at 0 to 1/4 throttle with the 38-70.
- Thread starter
- #3
Thanks, No Hand. The detonation sound is exactly the problem that I am trying to address. When I jet the bike (with the stock needle) to where it runs okay, it sounds like it is going to come apart below 1/4 throttle. I tried the dealer and they had fiche for almost everyting except the 03 CR250. Likewise with Service Honda. I will try to find the fiche online.
- Thread starter
- #8
Thanks, No Hand. That is exactly what I need. Now, I can order it from Service Honda. The only place that I could find the microfiche for the 03 CR250 was on bikebandit.com. Unfortunately, it did not list the part number for the needle. (It has the diagram, identifies the needle, but does not list it in the parts list ???) Once again, thanks for your reply.
The numbering is a s follows.
6= Is the "series" (marque) of the Mikuni needle.
DYH +the needle has three different angle tapers, D=1 degree 0 minutes, Y=6deg. 15 mins, H=2 degrees.
The final number refers to the distance down the needle the first taper starts.
I claim no credit for any of this knowledge, it all can be found in an excellent book written by A.Graham Bell, called Two Stroke Performance tuning ISBN No. 0-85429-329-9.
If you think the tech articles on DRN get a bit scientific this book will scare the pants off you!, but there is also LOTS of good basic stuff as well.
6= Is the "series" (marque) of the Mikuni needle.
DYH +the needle has three different angle tapers, D=1 degree 0 minutes, Y=6deg. 15 mins, H=2 degrees.
The final number refers to the distance down the needle the first taper starts.
I claim no credit for any of this knowledge, it all can be found in an excellent book written by A.Graham Bell, called Two Stroke Performance tuning ISBN No. 0-85429-329-9.
If you think the tech articles on DRN get a bit scientific this book will scare the pants off you!, but there is also LOTS of good basic stuff as well.
oops, just noticed yours is BYH not DYH....well B=0 degs, 30 mins!...in case you wanted to know.
PS having looked online for Mikuni pars in the past there is a US calling itself Mikuni, but it is (seems) not related to the Mikuni Japan company...even though the US one deals in Carburettors. IMHO I would search broader and discount any US based companies.
PS having looked online for Mikuni pars in the past there is a US calling itself Mikuni, but it is (seems) not related to the Mikuni Japan company...even though the US one deals in Carburettors. IMHO I would search broader and discount any US based companies.
