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Author Topic: mikuni jetting for 74 cr250  (Read 3059 times)

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Offline 35elsinore

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mikuni jetting for 74 cr250
« on: September 20, 2011, 01:47:46 am »
Wondering if anyone has any jetting specs for 38mm VM mikuni  for a 74 cr250m
Thanks for any help
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Offline Freakshow

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Re: mikuni jetting for 74 cr250
« Reply #1 on: September 20, 2011, 10:46:56 am »
38mm sounds a little big, i would have though a 36mm wouls have been more than enough.  guessing i would say start at #270 main and #50 pilot, the rest would be plug chops.
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Offline 35elsinore

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Re: mikuni jetting for 74 cr250
« Reply #2 on: September 20, 2011, 08:01:21 pm »
Fire breathing hondas love a big carby.
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Offline Freakshow

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Re: mikuni jetting for 74 cr250
« Reply #3 on: September 20, 2011, 08:05:18 pm »
really..... then why do they sell them with Keheins
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74 Yamaha YZ's - 75 Yamaha YZ's
74 Yamaha  flattracker's
70  Jawa 2 valve speedway's

For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff

Offline Freakshow

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Re: mikuni jetting for 74 cr250
« Reply #4 on: September 20, 2011, 08:06:15 pm »
Are you putting it on meth ? even then its seems too big for a piston port.
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74 Yamaha YZ's - 75 Yamaha YZ's
74 Yamaha  flattracker's
70  Jawa 2 valve speedway's

For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff

Offline jimg1au

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Re: mikuni jetting for 74 cr250
« Reply #5 on: September 20, 2011, 08:18:37 pm »
i have a 38mm on my methenol cr250 elsinore and a 38mm on my petrol (don jones) cr250 elsinore
both have reed valves.
i mate of mine also has a 38mm on his cr250 elsinore and his is quick he runs elf fuel
cheers
jim
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Offline GD66

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Re: mikuni jetting for 74 cr250
« Reply #6 on: September 20, 2011, 08:31:48 pm »
Braigasen chart has info for a '73 CR250 with a 38mm Mik...

http://www.braigasen.com/Mikuni_jetting_chart_two_stroke.htm

Should haul ass when you get it cleared up, buddy !  ;)

Regards GD
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Offline 35elsinore

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Re: mikuni jetting for 74 cr250
« Reply #7 on: September 21, 2011, 10:03:59 pm »
It currently runs a keihin 38mm but after many hours I cant quite get it just right. After fitting a new 34mm mik to my cr125 [taking off the 34mm keihin] it cleaned low and mid range up sweet. So now I love mikunis and thought the 250 needs a birthday to. Hoping the same could be achieved on the 250. Only running 98 ron on both bikes.
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