I got an old Moto-4 for my son, and realized it's not idling well and there's some popping seems like some blow back through the carb (I can feel it when I have my hand on it), so I'm wondering if anyone has experienced this with a Moto before. The wheeler does run, and has ridiculous grunt for a 225 I'm not a huge fourwheeler fan, I prefer old dual sport bikes but wow I like this wheeler. Anyway, I I'm wondering if I might have a vacuum leak, possibly need a good carb cleaning, or anyone think I might need to adjust the valves or timing? I'm looking for any suggestions from anyone with experience with these old wheelers.

 

At a guess, you either have the idle stop screw set a bit too low, or the carb needs cleaning. If things are different with a hot engine, you may need to clean the carb out as, if you adjust the idle stop to suit a cold engine, it can rev too fast at idle when hot. Also Yams are known for split rubber inlet manifolds, so check this when you have the carb off. Checking and adjusting valve clearances is never a bad idea either.

 

Thank you. I cleaned the carb and it indeed had a lot of gunk in the bowl, build up on the jets, and some crud in the bottom of the diaphram, and finally got it cleaned up. When my son and I started it back up it did the backfiring through the carb for a little while, but after riding around a bit, about 30 minutes later was purring like a nice thumper should.

Unfortunately, a bit later we toasted the solenoid, when we tried starting it back up it was just clicking and then, we saw an arc come off it and nothing. Don't even get clicking now. Starter wont turn, and very dim neutral light (battery has a good charge and fuse looks good), so I ordered a new solenoid from Amazon.

I guess that's what happens when one gets into these old machines, anyway, my son will have a good time with it. Again, thanks for the pointers, we'll also double check the valves now that we have some extra time.

 

Noid replaced, and it started up, ran smooth for awhile then started backfiring through the carb again, so after thinking about it and my son getting frustrated I thought maybe there's some crud coming from the fuel tank and since there was no fuel filter I put one in I had (not much space for a filter) and after about 10 minutes of running, wow running smoothly again. I guess one more thing to add to my to do list will be to clean the tank and petcock filter (assuming there's one in there) when I have some time. We also decided to order some brake pads front and rear since for intent and purpose the brakes don't work.

Due to not having any brakes, I thought I'd throw on the chains and plow that came with it and try my hand at plowing the driveway. Plows surprisingly well for a 2x4 and just my weight on the machine.