U-Max G28A is slow and variable

[wwalkersd]

Hi, folks! First post here, and I thought I'd jump in with a problem.

The therapeutic riding center where I volunteer has a 2006 Yamaha U-Max G28A. This vehicle has recently lost most of its speed. But the speed is still highly variable, as though the governor is cutting in a very low speed.

The air filter is quite dirty, so replacing that is on the list (the cart is operated at a stable, a very dusty environment). The spark plug looks good, and the engine sounds like it's running fine. It's just not getting the revs up. It's crawling up hills that it used to tear up.

There looks to be a good 3/8" inch of slack in the throttle cable where it connects from the carb to the governor arm. I ran out of time today so I didn't get the air filter housing removed to see how the cable attaches at the carb end. Is this slack excessive, and if so, can I adjust it at the carb end?

What else should I check?

Thanks for helping a newbie. My own carts are electric.

[sabercat]

could you post a pic of the govener it sounds like it just needs to tighten the gov. idk what a g28 goveneror looks like.

[wwalkersd]

Originally Posted by sabercat

could you post a pic of the govener it sounds like it just needs to tighten the gov. idk what a g28 goveneror looks like.

Well, I didn't think to take one, and I won't be back up there until Wednesday. I think it looks just like this one that's posted in the governor bypass thread, except that that the two cables aren't connected to each other!

[sabercat]

right so i think the gov arm has loosened so that the gov. is kicking on at a very low speed. a pic would be able to tell us if it looks like it's just loose or it's somthing else.

[wwalkersd]

Originally Posted by sabercat

right so i think the gov arm has loosened so that the gov. is kicking on at a very low speed. a pic would be able to tell us if it looks like it's just loose or it's somthing else.

OK, thanks! I'll get a pic tomorrow and post it in the evening.

[wwalkersd]

OK, so I got some phone pix today, having forgotten my camera. I hope they're good enough (I've also got larger originals, but figured these were plenty big for posting).

Top view:


From the left side:


From the right side:



Having seen some mention of it here, I tried tightening the 10mm nut that's on the brass-looking threaded rod, and it did make some improvement. Also slapped in a new air filter. It's gotta be something with the governor, though, because it runs perfectly normally in reverse.

Thanks for your help, Sabercat!

[smallblock450sl]

Hate to sound like a know it all, Looks like 3 things. From the pictures, you need a "input shaft spacer", looks like the spring seat is riding close to the tranny case. Yes the cable #2 (from govenor to carb) is way loose. Looks like the bracket (that holds cable #2 may have been bent). Leave alittle slack, maybe 1/16 to a 1/4.

[wwalkersd]

Originally Posted by smallblock450sl

Hate to sound like a know it all, Looks like 3 things. From the pictures, you need a "input shaft spacer", looks like the spring seat is riding close to the tranny case. Yes the cable #2 (from govenor to carb) is way loose. Looks like the bracket (that holds cable #2 may have been bent). Leave alittle slack, maybe 1/16 to a 1/4.

Thanks. Yammie's online parts book shows me a blank page for the G28A (their problem, or a browser issue?), so I'm not clear on where the "input shaft spacer" would go. I can't even see which spring seat is too close to the tranny case. Could you please elaborate? Sorry to be such a newbie.

I'll check on the bent bracket. Is that the only means of adjustment for cable #2, or is there an adjustment available at the carb end of it? It looks like I'd have to remove the air filter housing to get at it, and that in turn looks like it's attached by 3 bolts from underneath surrounding the intake throat, plus one bolt at the rear. Correct?

One more question: if there's too much free play in cable #2, why do we seem to have plenty of throttle in reverse?

[smallblock450sl]

Originally Posted by wwalkersd

Thanks. Yammie's online parts book shows me a blank page for the G28A (their problem, or a browser issue?), so I'm not clear on where the "input shaft spacer" would go. I can't even see which spring seat is too close to the tranny case. Could you please elaborate? Sorry to be such a newbie. No worries, just looks like the "circlip" on the "input shaft" is gone and the best fix is a spacer. Your not a newbie, you just asked a question.

I'll check on the bent bracket. Is that the only means of adjustment for cable #2, or is there an adjustment available at the carb end of it? It looks like I'd have to remove the air filter housing to get at it, and that in turn looks like it's attached by 3 bolts from underneath surrounding the intake throat, plus one bolt at the rear. Correct? Nope , just the adjustment on cable #2 at the tranny bracket.

One more question: if there's too much free play in cable #2, why do we seem to have plenty of throttle in reverse?

Why are you going in reverse?

[wwalkersd]

LOL. Well, y'know, sometimes you run out of room and have to turn around, and the UMax doesn't have enough power to break the rear end loose and spin it around, so a 3-point turn becomes necessary. I suppose I could just work on adding horsepower. But since reverse works, maybe I should just go backwards everywhere.