400 kohler 2 stroke vs 4 strokes

[andymaga]

I have a 1973 terra jet with a 400 kohler 2 stroke, its called a 27hp I believe. I am curious about swapping in a 4 stroke for a couple reasons, mainly to avoid mixing fuel, less noise and less sensitive to big temperature changes(im Canadian). So basically im wondering how big id have to go to match the performance of the 2 stroke, if its even possible to fit a big enough engine under the hood. I don't care much about speed as long as I can spin the tires in low range through mud im happy.

[thebuggyman1]

Comparing HP between 2 strokes and 4 stokes is tough....much the same as comparing gasoline motors to diesel. The RPM range and when the peak power occurs will be all different. I've never owned a Terra jet, so I'm guessing at weight and gear ratios, but I'd say if you went at least 16hp then you would be fine. Personally I'm a fan of HP, and it's usually only a little more to go up to 23HP, at least in a Briggs.

[Noel Woods]

I've driven a 2 stoke T.J., and it had a blown out muffler, I had to stuff some tissue in my ears to prevent ear damage. I think there is for sure room in the engine bay for the B&S 16-20 HP line. That should be more than adequate.

The 4 stroke will make the machine perform much better in the mud and deliver power when and where you need it and in a power band that will be very useful.

[ARGOJIM]

http://www.6x6world.com/gallery/data/892/Terra_Jet.jpg

This one worked great at Ledges with the Vanguard in it. I can't recall the drive on those machines but if anything like a Scrambler a smaller engine would work fine if the clutches are right.

[Tomo]

Hi
Providing clutches match the weight and power of the machine u should be fine .
The final drive ratio or the sprocket ratio should match the conditions u use the machine in .
EG a max iv that I am aware of [stock] spins its wheels on the hard pack beach sand 27hp Kawasaki ,the owner installed dual wheels and the spinning stopped .
Recommend 27hp minimum clutch and gear ratio to suit
29 efi Kawasaki ..........

tomo

[Adondo]

My Max II has a Vanguard 20, and it'll go straight up a sand dune. 4 strokes have low end torque that doesn't exist in the "ring ding ding" 2 strokes. They have to run full tilt Bozo RPM to get torque, which after an engine swap, you won't have to do anymore.

[andymaga]

i have been researching abunch of kohlers and briggs but itd likely all come down to whatll squeeze in there the best. from what I understand ill likely have to find a clutch off an argo or quad since the stock clutch will engage at too high of rpm compared to the what the 4 stroke will be turning at.

[thebuggyman1]

i have been researching abunch of kohlers and briggs but itd likely all come down to whatll squeeze in there the best. from what I understand ill likely have to find a clutch off an argo or quad since the stock clutch will engage at too high of rpm compared to the what the 4 stroke will be turning at.

Actually you will have to find a clutch that will fit the shaft on your new motor. The 2 strokes have a tapered shaft, and the 4 strokes will be a 1" or 1 1/8" straight shaft w/keyway.

[Tomo]

HI
both clutches will need to match a 4 stroke
Clutches are designed and installed as pairs
In the case of the comet/Salisbury 700 series
primary
1 or 1 1/8 shaft engagement speed 1400-1700 rpm set by weights and springs

secondary
3/4 7/8 1 shaft
select by required gear ratio 770 lowest first gear ratio lowest top speed
780 most popular factory on max
790 fastest top speed ,highest first gear
Ramps are available in 4 angles The higher the angle the quicker the acceleration and the slowest deaccel /change down .
The max uses a 28 degree ramp
Fine tuning is done with the coloured springs green stock ,preffered red

tomo

[andymaga]

great info so far, any suggestions on where to get clutches?