Strong Reverse, No Forward Power on Carbide 150

[jonstover]

I recently purchased an '08 Carbide 150. The motor is in great shape and runs and sounds good. However, I'm definitely losing whatever power I have between the engine and the tires due to some unidentifiable issue.

When the buggy is in reverse, it is completely responsive with a touch of the gas and you can feel the kart wanting to really take off. However, when you put the kart in drive, you have to push the gas to the floor for it to get moving and if you're on a flat or mild plane it will slowly get up to speed. And if you start mid way up a hill in forward, you can forget it. With gas to the floor it will just hold position and not climb at all. However, it would climb for sure in reverse. When stuck on a hill there does not seem to be any clutch slippage as the engine rpms hold steady as does the rest of the kart. It just never pulls or maxes out.

I do know this kart has the 20mph rev limiter on it, but given it's so strong in reverse and weak in forward gear I thought there must be a clutch or variator or potentially gear issue, but I'm not sure.

I'm fairly mechanical, but am new to the buggy world. Any thoughts or help on this is greatly appreciated! Thanks.

[bear]

Welcome to the forum! this is the place to get answers for sure! from what ur saying it sounds like u need to look at ur cvt, remove the cover and put a load on it to see how it reacts, just my guess, someone else might have another suggestion though. If all else fails contact Tom @ sycpowersports his header is at the top of our page he is all things buggy!

[jonstover]

Thanks Bear. Quick question, if I jack it up to monitor the CVT, what is the best way to put it under a load or stress it with the tires off the ground? Or is the better way to leave it on the ground and watch what happens on takeoff? Thanks.

[bear]

Start by putting it on jackstands to see if its working right, also check for glazing & belt wear while you have the cover off! if this all looks good then put it on the ground & see how it react on takeoff.

[xlint89]

Welcome to the site.

How many teeth are on the axle sprocket? And how many are on your reverse sprocket? How tall are your rear tires?

It sounds to me as if you're gearing is off.

Reverse has a very strong gear ratio which is why it is limited to only around 10 MPH or so. It's when going forward the ratio is reduced which allows you to go much faster, and not as strong.

[x-bird]

ditto the above, reverse is very "quick" on take off.

[jonstover]

I'll have to count the teeth on the sprocket and reply later. My tires are 22s. I believe stock was 21.

I did pull the cvt cover to watch what was happening. When on jacks and in gear everything seems to run fine. I put it on the ground and watched it on takeoff and the belt stays very low on the variator and doesn't seems to rise quickly. I didn't see it after moving over 5 miles/hr so maybe that's normal? This is where I'm ignorant to these machines. Not sure if you want the belt to quickly rise or not?

Otherwise the clutch engages well and doesn't seem to slip.

I'll post later about the sprocket. Thanks for your advice.

[jonstover]

Follow up on the sprocket. I have a 32 tooth sprocket on the axle. Not sure about the gear on the other end.

[jonstover]

Point of clarification on the tires....the kart drove the same even with the original factory tires on it as well.

[xlint89]

Hopefully someone else that knows more about the carbide will chime in.

But it sounds like the 32T sprocket MIGHT be an issue. And only compounded by the slighlty taller rear tires added.

I don't know what your internal gear ratio is, but on my Yerf, I needed to go bigger on the axle sprocket when I added reverse to it. Otherwise it would be gutless on the take off and hill climbing.

I have 16T on the engine sprocket and 36T (should be 37T to get me back to stock ratio) on mine now. It originally had a 31T axle sprocket and was recommended to install a 39T after I added reverse. (stock engine sprocket was 13T with a 31T axle. With the reverse, it was a 16T engine sprocket, that's why i had to increase the axle sprocket size)

Your slightly taller than stock rear tires also changed your gearing more for top speed than take off, that's why I say it compounded the problem.

Count your axle sprocket teeth and report back to us.

But i believe you just need a larger axle sprocket to get you where you want the kart to be.

[jonstover]

Thanks again guys for your feedback and thoughts. I was reminded that when I first got the kart home last week, that one time it did engage and pul up a hill very strongly, like I would expect it to. However, it's never done it since.

After watching the CVT work in motion, from what I can tell the variator seems to be working appropriately, although the belt doesn't go all the way to the top. Part of the reason might be because it doesn't appear that the belt on the opposite end slides down to the shaft between the clutch pressure plates (if that's what it's called). The belt on the clutch shaft stays in the same place for the most part, so my assumption is this essentially keeps the CVT locked in a single gear/ratio.

Any thoughts on what might keep the belt from moving appropriately on the rear shaft and if this might be causing my problem? Thanks as always!

[x-bird]

"rear" shaft is the clutch. if it's not riding up or down the pulley halves (sheaves) at all, there is likely an issue with it. It could be a broken or worn out main spring or worn-out belt (too narrow). likewise, since the belt is a fixed length, if the variator has an issue and is preventing the belt from moving all the way up or is getting stuck in one position, it will also only go so far up or down the clutch pulley. in the variator, it could be flat-spotted rollers or a roller that's out of place/turned in the ramp.

[jonstover]

Thanks for the help guys. Just based on what you've said and what I've seen, the variator seems to work correctly, so maybe there is an issue with the the clutch pressure spring (whatever it's called) and and/or the belt.

I looked online to try and find the standard size drive belt for a carbide 150 buggy, but there appear to be a couple different sizes. Do you guys know the standard size by chance? I've seen an 842-20-30 and a 835-20-30 and a 743-20-30. I'm sure there are other sizes too.

Regarding the spring, I think I read the stock spring is a 1500 rpm spring, is that correct? and it's red?

Thanks for your help.

[xlint89]

These karts use the "short" GY6 case, so the 743 20 30 belt is what you need.

Not sure what was stock spring on yours, but red is normally 2000 RPM, which is the strongest one they make. (most likely not stock)

[jonstover]

Thanks guys for your help. I'm going to take a look at the rollers and tension spring today. Will let you know what I find in case others run into a similar issue.