Vintage Dirt Bike Q & A

Does anyone have experience putting a Mikuni on a 79 CR250? What is entailed? Is it bolt on? I know I can get a pre-jetted one from either Sudco or Vintage Iron. Vintage Iron claims it is a bolt on affair.

Please help me, I would like to make a good decision on this.

Kristi

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Kristi J
1979 CR250 with 43mm forks, Race Tech springs and Gold Valve emulators, Works Performance shocks

it is a bolt on as far as i know but the jetting in the replacement Mikuni is a good starting point if you get one pre jetted for a 1979 CR250.

you still may need to rejet and make adjustments here and there though due to the Altitude and temperature differences to get it spot on.

i plan to put a Mikuni on my 1979 CR250R sometime or i may go with a 38mm Kehin Air Striker possibly.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

Thanks Dave for the info!

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Kristi J
1979 CR250 with 43mm forks, Race Tech springs and Gold Valve emulators, Works Performance shocks

You may want to have some length machined off the bell side. It is longer than the Keihin and will be challenging to get into the air box boot without. Match them up and take them to a machine shop. This is my jetting from Southern California.

Pilot 35
Air screw 1.75 out
Slide 2.5
Needle Jet 159-P8
Needle 6FJ6
Clip #2
Main 360-380
Float height 19mm

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Thanks for the info Michael, I am moving to the Twin Air filter, the stock setup has to be the biggest pain I have ever seen for an air filter. If it is still to long, I can take it and have a little bit machined off on the bell side.

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Kristi J
1979 CR250 with 43mm forks, Race Tech springs and Gold Valve emulators, Works Performance shocks

When you remove all the OEM air filter cage, boot etc. to mount the Twin Air filter, let us know how you support the new filter in the air box.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

An Oetieker clamp on the inlet side from Aircraft Spruance. Works like a charm and no problems with a carb coming off.

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Kristi J
1979 CR250 with 43mm forks, Race Tech springs and Gold Valve emulators, Works Performance shocks

Photo?

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

i´m using the twinair filters for about 20 years now without any fixing and have no problems.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

I use Twin Air filters in all my bikes except the Elsinore where I am lucky to have a supply of OEM filters. My question was about mounting the filter in the air box and was a) simply curiosity and b) based on what I saw years back. So.. when you use the Twin Air it has an air boot attached and mounts direct to the carb, all the OEM cage / boot etc. is not needed. Given that the air boot on the Twin Air is smaller than the hole in the front of the air box, how is it supported? Or is this not an issue.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

I know a guy who loaned his CR480 to Chuck Sun with the stock hose clamp on the engine side of the carb and the Twin Air mounted, the carb came loose and came off, ending Chuck Sun's race. Since then he has run the Oetiker clamp with no issues at all. There are no problems with the Twin Air not supported. Since my bike is out of commission right now with an air leak somewhere, I have not gotten the chance to run the bike with the Twin Air yet.

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Kristi J
1979 CR250 with 43mm forks, Race Tech springs and Gold Valve emulators, Works Performance shocks

at first you have to cut the boot to the right length.



if not it looks like this shit.



sorry, i have no pic here where you can see inside the airbox. maybe later.



the twinair filter is very easy to change, no leaks are possible, best filter for a racer.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

It would seem that once the air boot is cut shorter, the size of the filter means it sits snug against the front of the air box and supports itself. Nice.

I am interested in your running a hydraulic clutch - which one? I have these on all my other bikes and love them.

Never seen anyone running the rubber sound-deadening blocks between the fins before. Shades of the Yamaha IT line...

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

yes, it supports itself


it´s a magura hymec for KTM LC4 models. the only extra thing you need is the small collar to fit it to the original cableholder.
i made this collar by myself on a lathe.


this bike was made by honda germany for Hans Werner Pohl for isdt races. to be road legal it had to be quiter, so they put the rubbers between the fins and addeted an suzuki rm250 silencer to the original muffler.
honda gave him two bikes, one for spare.
this is the second one, here without the rubbers, guess they got lost over the years or were removed when the cylinder was replated.
i got the first bike at 1989 and found the second one last november not far away where i live.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250