130 miles in and sharp drop in performance

[maze810]

Buggy ran great for first 130 miles, has recently had a sharp loss in power. From top speeds in high 30's to now not breaking 18-20mph. This change happened in the middle of a tank of gas.

Everything is stock.

Cart has never sat for more than a couple days without being driven.

I drained and tried a new source of gas as well. All fuel has been non-ethanol.

Felt like the main jet of the carb was possibly clogged, Carb bowl is sealed and unable to be taken apart to clean without drilling out the metal plugs. So I ordered a brand new carb, existing carb says pd24j on it, so I ordered a replacement and once reinstalled, no change.

Therefore I am unsure of the issue, but do not feel it is carb or gas related. I don't think I should need a bigger main jet, since it was fine until all of a sudden, mid ride.

I checked the spark plug and it is a nice tan color. So I feel the air/fuel ratio should be good.

Buggy idles fine and forever, doesn't seem to search.

The engine revs fine in neutral, but when more than 50% throttle is given in forward or reverse it sputters and bogs down but never actually dies, just is very weak.

I put the rear up on jack stands and can give full throttle with no sign of weakness at full throttle in forward and reverse.

I am not sure what else could be wrong or what to troubleshoot next.

It feels to me like it can't get into a higher gear.

Here is a video.

Thanks in advance!

https://youtu.be/HfpvH0py-BE

[neo71665]

Pull the cvt cover and check your roller weights for any that might be stuck and/or flat spotted.

While it's down would be a good time to check the valve adjustment. These things to me seem like they get out of adjustment when the wind changes direction.

[OLDKID]

Ditto on what He said .... And a visual on the CVT under normal operation ( You can run it with the cover off to inspect ) . Is the variator closing all the way ? ... Belt to the outer diameter ? ... Is the Driven opening all the way ? ... Belt to the bottom ? ... And most importantly... The condition and width of the belt , any debris You find under the cover is more than likely what used to be your belt . As the belt gets " skinnier" Your buggy goes slower 10/4 ?

[maze810]

thank you both!

I got the cover off after a lot of hammering with a 2x4 to break the seal.

The belt looks ok, not really any debris inside the case.

I have an impact wrench ordered from amazon so I can get the nut off. I'll report back when I can inspect the rollers.

I'll try to do some homework on what each part is and run it without the cover to see what I see. I did try to squeeze the clutch spring ? with both hands like I'd seen on one video and was unable to budge it.

[neo71665]

If you are gonna check the ride of the belt the easiest way is to take a sharpie marker and draw a good thick line on both sides of the variator (front pulley)front he center to outside edge. Sit the rear end on blocks so you can rev it in place. The belt will wipe off the marker and you can tell how high it is riding on the pulley.

[maze810]

Drive belt looks to be in good shape to me.

When opening the case I didn't find any loose shredded pieces or anything like that. Spinning both front and rear pulleys by hand, I checked the length of the belt and found no abnormalities.

I attached a picture of the belt , which looks fine to me.

and here are a couple videos showing both pulleys under full throttle and idle

https://www.youtube.com/watch?v=adbIaa-m6OI

https://www.youtube.com/watch?v=UHcIlj9tO7k

to me it looks like the rear pulley moves the belt and closes together under full throttle

the front pulley looks like it moves the belt all the way to the outside under full throttle and back in when idle...I did the sharpie trick and everything is wiped clean except maybe the most outer half cm

So my take on this is everything appears to be functioning properly and I'll have to wait til tomorrow to check rollers and if that is ok then check the valves I guess

I can't tell you how much I appreciate everyone's help

[neo71665]

What did the roller weights look like? Any flat spots on them or have you already swapped them with sliders?

[maze810]

Got my impact today, took off the nuts and found the roller weights to look perfectly round with no flat spots. They were all sitting correctly, and able to spin freely. All three horseshoe shaped plastic pieces were intact and nothing else unusual by my inspection...

Then I went to the rear clutch / driven and am unable to get it off because the frame is in the way just by a cm or two. My question is do I need to figure out a way to take it off and inspect it further or can I leave it there...I spent an hour trying to figure out how I might get it off and couldn't come up with anything reasonable...I am barely able to squeeze it together and it will not stay together...Is that normal?

Here is a picture of the frame in the way of taking it off

I checked the 3 springs on the driven/clutch and they are all tight and I'm unable to move them so I believe that means they are working properly.

Anything else I should look at under the cover in the cvt area before I move on to the engine valves

Speaking of engine valves, it looks like I need to order some sizers to make sure they are all the proper distance?

[plee911]

You will need a set of feeler gauges to gap the valves correctly.
It can be tough to get them just right so don't be discouraged when you gap them tighten them and then check and the gap is wrong. Just back up and go again. It took me a couple of tries the first time I did it to get them to stay where I wanted them.

A trick I used was to use the 005 and tighten it down by hand against the feeler gauge. then when I finished tightening them up they were both spot on at 004.

You should only feel a little resistance on the gauge when you slide the right one in. If its hard or hangs they are too tight, If it slides free with no resistance try the next gauge up and see if it slides in if it does then your to loose.

There are others on here that im sure have better ways of doing it and know far more than me. That is just how I did mine.

check Youtube for GY6 valve adjustment. there are a lot of videos that will show you exactly how to do it

[SYCARMS]

Not sure what buggy you have, appears to be a 4 seater which I have never seen before. Kinda hard to be certain but it looks as if the top of clutch pulley was hanging up on the frame which I've also never seen. Assuming it gas a GY6 motor, on the back is your chain adjustment which when tightening chain moves the engine up and to loosen chain will move the engine down in it's cradle. Not sure how much downward movement there will be but if you loosen the rear adjuster the engine will drop hopefully enough to remove the clutch. However from the sound of engine in video it sounds electrical that is the ignition is breaking down. Make sure the 2 coil leads to back of coil are tight than get your volt ohm meter and start at the ign. switch making sure you have 12 volts to ign side of switch. I've seen switches go bad to where you have 12 volts coming in but much less to ign. side. If OK than using ohm meter check the coil for too much resistance. Not sure of your readings but google it and you will have all the info in front of you. If the coil also checks OK than it will be in the CDI. It could also be a fuel problem but I can't be sure from the video and if I remember correctly you have a new carb and fresh non ethanol gas. If true than I would not suspect it.

[maze810]

Thank you both for the reply, I was thinking the same thing… Ordered a new ignition coil spark plug and CDI. I'm going to put it all back together and swap those out and see what happens.

It's a dong fang 4 seater, gka200-4 or gkg200-4 depending on the site

Talk to y'all Sunday!

[maze810]

Put new variator and roller weights in even though I seen no issue with existing rollers/variator, (because I broke a piece when I removed it prior to getting an impact gun)
Kart was still acting wimpy

then CDI and ignition coil replaced, kart is back to normal

I tried putting old CDI and iginition coil back in one by one and it still works fine

so what the true culprit was I may never know...maybe a loose connection or intermittent electrical issue between CDI and spark plug or a nonfunctional piece of the variator I didn't notice.

Either way, I am happy it is back to normal... now on to air filter and main jet upgrades.

A big thanks to everyone who helped me troubleshoot!

[BuggyMaster]

And just a note...to get those screws out of the carb, use a Dremel to put slots in the screw heads. you will actually go into the body of the bowl of the carb slightly but you go in just enough to give you a bite on the screw heads. Make sure your carb is empty and no fuel around so sparks from the Dremel don't light anything on fire. Glad you are up and running.