I just recently purchased a 2007 CO 150 UT (150 ST-H) ATV from an older gentleman that rarely used it. There are less than 40 hours total on the atv. When I got it home I hopped on to give it a test drive. Cranked up just fine and went into gear easy and smooth. As I was riding I noticed a strange popping noise that occurred only when I was riding uphill or on a slope. It almost feels like the atv is jumping when this is happening. It's weird because this doesn't happen when I'm rolling down a hill or on a flat surface riding. Is this a common problem with Cool Sports? Any help would be appreciated.
Thanks, Joseph.

 

Is this a GY6 engine? CVT belt drive transmission? Do you have a forward/neutral/reverse gear box on the output shaft of the engine (drives the forward (small) chain sprocket)?

On my quad (GY6 with all of the above) I had a lot of lurching/bucking under load going forward (especially uphill). It eventually started popping out of gear briefly, then popping back in (with some ominous noises). It turned out to be a simple adjustment of the FNR gear box. When it is in "forward" adjust it so that the linkage is a little *more* in forward. It solved my problem...

 

Indeed it is a gy6 engine with all of the above, I will adjust it first thing in the morning and reply with the results. I appreciate your information.

 

After closer inspection that was indeed the problem. A quick tweak was all it needed, it runs like brand new now. Thanks again for the info!

 

Im glad...

Just so you you know, I didn't discover this on my own. When I was going through this same issue (many years ago) I was leaning toward a problem with the CVT gearing up or down for some reason. A web search clued me in. Peter Ghruby (PGH) from www.buggynews.com deserves the credit.

 

After riding for about an hour I noticed the gear box was slipping into neutral as I was riding. Now I have to lodge a piece of wood in the gear box to keep it from going it to neutral. Is there a way I can fix this problem?

 

After extensive trial and effort, I finally got it to stop slipping from drive to neutral. Now the same problem is back with the lurching/bucking when going uphill, but it is not nearly as bad. Which part of the shifter cable should I Be adjusting to get the lurching to go away?

 

I'm confused. With the lurching and bucking you adjust the cable such that the shift lever is "more" into the forward position when you have the shifteer in "forward". That will put you further away from "neutral", yet you report it slipping back into neutral. This is backwards. Are you sure you are adjusting this in the right direction?

On mine I have a threaded turnbuckle type arrangement with a lock nut. If I run out of adjustment on the threaded adjustment rod then I have to remove the splined shift lever clamp from the gear box and reposition it.

The "block of wood" fix is forcing the shift lever which way? It seems that that is the direction you want to adjust the shift lever.

 

Below the gearbox is where my shifter cable is. It is threaded on both ends with a nut to lock as well on each thread. I'm awfully confused on how to get this right because this is my first atv. I can unlock the nuts and unscrew the cable completely. After I do this where should I have the threads adjusted on the rear and front for it to act normal? I'm so confused and quite frankly just aggravated because I know this is so easy yet I can't get it right. If you still don't understand what I'm talking about, I can snap some photos. Sorry for asking retarded questions by the way.

 

Actually after looking, mine is a linkage rather than a cable. No matter, the idea here is lengthen or shorten the drive path to adjust the position of the gear box shift lever at F, N and R.

You said you unscrewed the cable completely... This is not the right plan. You adjust the adjustable screws to lengthen or shorten the shift linkage and/or cable path - not to simply disassemble things. This adjustment is used to shift the gear box shift lever position fore or aft.