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Project "Got Milk" - Yamaha Cart

I wonder if it's like the hondas where you can get all kinds of soup up parts for them?
Unfortunately no on the original platform except for 1 option. There is 1 guy named Don Plowman who focuses on the OEM platform and claims to get over 15 HP our of these little 9 HP units. Its about $2k to do it, which exactly the cost of swapping in a Predator 670 vowing.

I think for now I am looking to get this running on the cheap and then swap out for a real Honda GX series V twin. We have a predator in the FIL's Club Car and it moves but is loud!! We like to go for long road rides haha.

Or drop something like this into it?

I have been looking at these closely! Only fear I have its still a splash type oiling ystem. If I was to swap i would really like a pressurized oiling system which is more prevalent in the v twins. Its also tough with these engines to get them quiet for camp site use. You can get them tolerable with small car exhausts but thats the best you could do.
 
There is guys here with those. Yeah the hondas beat up the yamahas. But you can mil the head 10 thou and bump compression- then that gapless ring helps hold up longer and keeps the oil out better. 3500-3700 rpm is normal but you can lighten the gears and back the Governor off to hit 4500 rpm safely- coating the gears with the friction modifier helps of course. You definitely want to inspect or replace the roller bearings if bumping up the power. One guy here sends in his little engine stuff for chryo along with his race engine parts because shipping and freezing an extra 100 lbs isn’t that much. Crank to piston and roller bearings.

yeah doing the oil pump instead of spalsh lube is pricey- idk if worth that. Here they run a lighter synthetic. Because of our heat they sandblast the aluminum with aluminum oxide to get rid of the surface aluminum oxide (ironic, right?). Then use radiator paint or the dipstick out at the racetrack who charges by the paint run to coat them with the heat rejection stuff. But since you are closer to Chris...

And the carburetor mods I am guessing you know.
but even all that - you are not gonna hit 15 hp.

The torque improves at a better percentage I think.

what you are really missing is a turbo! Maybe one of those electric turbos!

Or ya get tired of all that and find an old two stroke dirtbike like a cr80r ! Haha.

Ok, you have a yamaha but even back into the 80’s the honda was beating up the yamaha. I owned one more honda than yamaha- but liked them both. Hard pressed to find a yamaha that beat the equivalent honda, doesn’t matter power or long life. 5 hp to the biggest. If you soup up a yamaha to the max- it just tied the stock honda.
 
Got more done, but no pictures to prove it.

Cleaned out the rear pumpkin which all looked good. Scraped off the gobs of blue RTV on the cover and replaced with form-a-gasket. 85w-90 gear oil added and plugged. Also removed the 2 crank seals in preparation for new installs. The crank bearings seem to be in very good shape, nice and clean with no grinding or roughness throughout rotation.
 
Currently at a standstill waiting for parts. Hopefully this Project will get started back up the week after Christmas.

In the meantime we started cleaning up the 2pg out of the Marathon. The new jug, piston and rings came in the other day. We scraped the mud from the crank case and cleaned it out the best we could. Will try and throw some pictures in soon.
 
Well got the Rhox 6-inch lift started. Had some struggles and still do woth the angle of the rear track bar. From what I see on their how to its just a crank it down scenario. I don't really like that idea. Anyone have alternatives or did I do something wrong?
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The fronts need shimming of the kingpins vertically in the c-channel of the a-arms. Awaiting a drill bit to make it work with some smaller I.D. shims.
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So, I take it you got everything all shimmed and good to go? Can't wait to see that thing with the 11.50x15 BFG All-Terrains on it, LOL!
Yes. At first it was just too tight. Had to pull a washer out and grind a bit after I enlarged the I.D. its not "perfect" but with washers as shims I guess I am happy with how it turned out.

Not gonna lie, looking for more of a road pattern type tread. BFG mud terrain?
 
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Mud Terrain is big lugs with lots of void, very noisy on pavement. All-Terrain is civilized on the road, with very good off-road manners on dirt, in mud, snow and sand. A lot of the winners of the first ten or so DieselPower annual Diesel Challenges (which included sled pulling, drag racing, mpg competition, maneuvering with a trailer, etc) where competitors could only use one set of tires throughout all the competitions, were won on a set of BFG All-Terrains.
 
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