640cc Engine Swap...

[1975 Argo 8x8 2-Stroker]

When you swapped out the Tillotson for the VM34, did you try to rejet the carburetor at all? It's unlikely that the Mikuni was jetted correctly for your engine. What did it come off of? A simple jet change out might have been required. Did the engine idle well, but just not produce top-end power? Your main jet might have been way to small, or way too large. It really is easy to do.

Oh heck, you're even running a CDI on that engine. It's probably a G44BSS, then. While your space is limited, you might have to just unbolt the elbow on the carb and put a thin phenolic spacer on it to get the Mikuni's carb body past the upper engine shrouud.

Yeah, exactally, it idled great, was perfect in low gear, but in high gear, was a complete slug. My dad had just said, that (when I switched the Tillotson I measured it), I should put the same size Mikuni on as the Tillitson, so a 34 Mikuni and a 42 Tillitson wern't very close, so I bought the 40mm Mikuni which is really close...

And I had to take the elbow off, you can't mount a Mikuni vertically, it has to be horizontal, using a rubber flange (that is bolted to the intake port) that the carb just fits into, and the rubber is tigtened around the carb with a hose clamp. See the photos, what I am getting at with all this, is that the carb is right close to the engine and might not clear the tranny. (I am sure you knew all this anyway! )

And it says on the side of the engine G44B... no SS so I'm not sure there...???

imagesCAEU46YY.jpgimagesCA0TIS3O.jpg

[shane]

Mine has the original 440 kohler, it has lot's of power, has a mikuni on it and run's real well. It's the fastest argo i've ever been in and i would not change it out for a four stroke as i love two stroke smoke and the simplicity of repairing them. Check your compression and if it's good get that mikuni jetted right and mounted on there. I believe my mikuni is a 34 or 36 with about a 300 jet if i remember correctly. Mine is a blast to drive and is very fast for a skid steer vehicle.

[1975 Argo 8x8 2-Stroker]

Hey, Thanks Shane!

Yeah, Mines pretty fast too (around 40 kms/h??), yes, you have it right there, the old 2-strokers are nice and simple!

And HydroMike... still waiting fro a reply... what do you think??!!

Thanks!

[1975 Argo 8x8 2-Stroker]

HYDROMIKE!!!??? Hahaha, come on, respond!

[micmac]

As far as jetting goes I've had good luck finding snowmobiles that ran the engine. Then once you figure that out then you can troll the vintage snowmobile boards for jetting that most are using. That should put you into the ballpark. Will you have enough room to put an airfilter on the Mikuni?

[hydromike]

Sorry dude! I think the VM40 is way too big for your engine. It's like the guys who put an 1150 dominator on a small V-8. The Tillotson 40 and Mikuni 40 will have drastically different flow characteristics since one is a butterfly style and one is a round-slide style. You can get away quite well with a VM34 on an otherwise unmodified G44B, I believe. The 34 will have a slightly small body, so you might be able to squeeze it in there easier than the big honkin' 40. I don't have any idea what jets I'm running on the G50B in my RIM, but it's running a VM32, and is basically flawless throughout the RPM range. It's unmodified, so I can't take any credit for it's good-running-ness. Don might have an idea of a good place to start on idle, pilot and main jets for a 32 or 34mm Mikuni. I just haven't had to tinker with mine....

[1975 Argo 8x8 2-Stroker]

Ahaha, np...

Oh, well, I can get the flange big enough to take the VM-40... so, I may as well try, I think the engine can handle it, I have a 640 Valmont (Same as an Ski-doo alpine, just shorter), and it was running a VM-34, I put a 40 on it, and it handled it like nothing, increased the engines power A LOT!

If the 40 in too big for the engine (or dosen't fit) I will just jet the 34... but here's hoping the VM-40 will work/fit!

And "micmac", I MAY be able to get an angled UNI filter on there, but I will probably have to built something instead, because it will likely hit the shifter...?