Vintage Dirt Bike Q & A

Can anybody tell me what mix 2 stroke mix I should be running?

The 73 manual say 20 : 1. A friend recommended 50 : 1 with modern 2 stroke oil.

Thanks in advance
Clive

I run 32:1 in my MR and it seems fine using Hondas 2 stroke oil. 50:1 no matter what oil you use does not seem to be worth taking a chance IMO.

I ran spectro at 32:1
I also ran a reed, radial head and grafted a CR125 ignition to mine.
Points wise 1.8~2.0 BTDC worked fairly well.

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1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.

Was that difficult to do, and did it work well? I assume a later CR250M CDI ignition wouldn't work? I've searched the Web many times but this is the first I've heard of anyone fitting a CDI ignition to an early CR250M motor.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

I was Midwest regional #1 and National # 4 on it.

All I had to do was match the taper on the rotor to that of the 250 crank, then make a base plate for the stator.

Mud races here in Ohio made me toss the points. Eventually my friend, the now late Dane Leimbach, set me up with a PVL which worked well.

I spent allot of time dialing in my 2fiddy and it worked well, just not well enough as say a mag 2fiddy or a hot penton. They didnt handle near as well as a hoosk and the down pipe just plain sucked. The foot pegs would break off, the frames and aluminum tank would break......

I ran a DG radial head, GEM reed, T&M swingarm, 125 steel tank, jemco pipe and not in the pic was works rear shock.

As soon as I could I built a mag 2fiddy......

Ill BET I still have the set up somewhere in my vast inventory.

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1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.

all my bikes get 1:50 without any problems for many years now.

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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

hahaha try 50:1 on an air cooled engine at Southwick..............

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1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.

that would be no problem.
we also have deep sand tracks here.

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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