Rat motor mod question

[JohnsonM50]

The 437 cc John/Evinrude snowmobiles had a hop up kit where to added a new intake and a V-4 2 barrel carb. Could be a good solution, but, you might need to tweek the exhaust to get the full gain from more juice.

I had another thought taking from the A/AXS/J racing rule book...So you can't find a small bore two barrel.... Why not make your own choke collar
(restrictor plate) so if you need or have the lattitude for more juice, open up the plate for a very small cost or labor, and proceed.

I like the 1st idea, the motor in Q is opened up & is about 500cc. I ran it hard yesterday & its the fastest of my 31.8s so far. Im thinkin the next move will be to $pring for Boyesens since experiments have indicated they should work well. Do ya happen to know where I can look up the snowmobile kit?

[Skoontz]

You would need to find a snowmoblie junk yard, or, someone who has one on a shelf. The intake would be worthless to you, it is a 90° curved intake that was designed to biolt on a Johnson Rampage or Evinrude Bobcat snowmobile. The motor was a 180° opposed air cooled twin.

If I am not mistaken, the carb was off a 125HP V-4, I'm not sure of the bore.

[Mike Menter]

I have done numerous 2 cycle engine mods and have set many records. I have noticed that the 2cycles like the ports eyebrowed and raise the intake up a tad bit. Open the exhaust ports and you should see a diffrence

...The same applies to the sleds...however they like big exhaust numbers!!

[Sam La Banco]

Hey Johnson mod 50,

you need to check out the 31.8 cuber in the History section on Page 22.

[JohnsonM50]

Hey Johnson mod 50,

you need to check out the 31.8 cuber in the History section on Page 22.

10-4, Thanks

[OUTBOARDER]

heres an expeirment
.040" washer between reed stop and reed may require longer screw.
then try the 1.5"x1.25 venturi again.

The reed sop adjustment will help gulp down some more air and help acceleration.

[JohnsonM50]

10-4, Thanks

Sam, Ive been lookin at outboard history for awhile-p-22 What titles it under? Thanks.

[JohnsonM50]

heres an expeirment
.040" washer between reed stop and reed may require longer screw.
then try the 1.5"x1.25 venturi again.

The reed sop adjustment will help gulp down some more air and help acceleration.

I did alot of intake exp. work inc. bent reed dampers.That made the biggest difference since a gearfoot till a reed broke. Expensive mistake even tho it could-a done worse 1 set of Boyesens are pricey but still less.

[OUTBOARDER]

I did alot of intake exp. work inc. bent reed dampers.That made the biggest difference since a gearfoot till a reed broke. Expensive mistake even tho it could-a done worse 1 set of Boyesens are pricey but still less.

ouch!!! one reason why the O.E.s set the reed stops!


If you really want to get crazy try a leaf blower and a shot of Blue Thunder available at your favorit hobby shop. O ya just take the main jets out

[Mark75H]

Reed stop correct name = reed vibration reducer