Coleman BT200x Mini Bike (Puzzled, please help)

[pracydna]

Ok guys, here's a strange one I can't figure out for the life of me. My neighbor got a call today from Walmart saying his mini bike was in. It wasn't supposed to be here until Friday, so he was pretty happy about it coming early. We get there, they bring the bike out on a pallet, the box was in shambles. The guy "Bryce" noted the damaged box for us, carted it out to our jeep, helped us load it and we came back to my house. Took us all of about 30 minutes to put it together, pretty cut and dry. Filled it with oil and gas and took off. After about a half hour, we drove back to my garage to release the throttle screw some to give it a little more power. To our shock, the screw was tack-welded on. Little puzzled but not concerned, I grabbed my cordless dremel and off she came in about 10 seconds. Placed the air cover back on and started down our corn field trail across the street, when he all of a sudden passed me like I was standing still. Well, the bike literally wouldn't stop, he had to kill the engine.

Long story short, he ended up pushing it back to my house. So we took off both air filters to compare. Absolutely nothing was out of place. I have a Coleman CT200u-ex and between both of us, we're completely stumped here. Did we get a lemon, or did we do something wrong by removing the throttle screw? I removed mine the second I got it home (although it wasn't tac-welded either) but it ran just fine. Any help or advice would be greatly appreciated.

 

[EVOL Tweety Bird]

The tack weld seems to be something new they've started doing. I've seen a couple of posts about them.

As for the stuck throttle, throttle cable binding, weak/broken return spring, throttle plate binding, and so on.

If it was me, I'd remove the chain, then start with disconnecting the throttle cable, a manual check of the throttle plate to see if it moves freely, followed by the return spring snapping it back to the closed position. Then repeat with the engine running to see what is hanging up.

 

[pracydna]

The tack weld seems to be something new they've started doing. I've seen a couple of posts about them.

As for the stuck throttle, throttle cable binding, weak/broken return spring, throttle plate binding, and so on.

If it was me, I'd remove the chain, then start with disconnecting the throttle cable, a manual check of the throttle plate to see if it moves freely, followed by the return spring snapping it back to the closed position. Then repeat with the engine running to see what is hanging up.

We've narrowed it down to that governor arm that's coming off that adjustable part underneath the gas tank. (Sorry don't know the technical word for it). It's the bigger arm with the springs attached to it and it's attached to like an adjustable set screw. We still haven't figured it out but we did find a temp fix for it by stretching out the front spring and attaching it to one of the screws on the pull starter. Has a bit of top end on it but almost no torque. Can take pictures later today if anyone is interested in helping me diagnose this.

 

[ToXic U4ia]

I would post 'em. Lot of knowledgeable people on this site.

 

[EVOL Tweety Bird]

Yeah the return spring is known for being a little on the weak side. I removed the stock one and added a stronger one to mine.

Check the throttle pivot. Plate with the stud/nut securing it to the the rest of the throttle plate. If the nut is too tight it won't let the throttle return easily.

Here;s one of mine, with the governor deleted, but will give you an idea of what to look for.

 

[pracydna]

Yeah the return spring is known for being a little on the weak side. I removed the stock one and added a stronger one to mine.

Check the throttle pivot. Plate with the stud/nut securing it to the the rest of the throttle plate. If the nut is too tight it won't let the throttle return easily.

Here;s one of mine, with the governor deleted, but will give you an idea of what to look for.

View attachment 108266

Thanks Tweety, didn't realize that about the nut. Hopefully it stops raining here tomorrow so he'll come over and I'll grab a photo for you.

 

[TexMini]

Throttle was “sticking” on the new BT200 I got for my son. At first, I wondered if it was the linkage at the motor or the spring down there. When I manipulated them down there, they worked great. It was only when I used the grip throttle that things would hang up.

Throttle cable had no kinks, so figured it must be the grip throttle itself, binding up. Loosened the two screws holding it to the handlebar, and liberally applied powdered graphite to inside of throttle tube and on the handlebar. I also liberally applied it inside the throttle housing.

Put it back on, twisted the throttle a few times, and problem was immediately solved.

Also, make sure not to push the throttle on to the handle bar too hard. You want a couple millimeters of clearance between the end of the handlebar tube and the end of the grip, so that there is no friction there.