Yerf Dog w/ Predator 6.5 struggling

[BMRbrnSNRbrd]

Hello all, I've tried to search and find an answer, but haven't come across anything that sounds like my issue.

Kart info:

Yerf Dog 3203
Rebuilt after a long life left outside with:
-Complete new rear axle assembly
-New torque converter
-New belt (just last week)
-New Predator 6.5

Basically the only thing now replaced were the wheels, tires, and steering. Oh, and of course, the frame itself.

Anyway, after finally putting a new belt on, this thing runs like mad! With myself (205 lbs) and my son (45 lbs) it was hitting about 35 mph according to GPS.

Recently, it has started to have an issue. At times, both before its completely warmed up or after a long ride and everywhere in between, it will seem to bog down. I mash the throttle and it won't even get up to ten. The engine sounds like its revved to the max but just won't go. Most of the time, after anywhere from 15 - 30 seconds, you can hear the engine finally get some relief, like the kart is finally going. At that time, we can easily hit full speed. I tried to get a video, but it was hard to drive while doing a video.

So, is this just a loose component? Something worse? I've even drained the fuel and re-filled it thinking that maybe it had bad fuel. Please help.

 

[OzFab]

I think we may need a vid for this one, I'm not fully understanding the problem; you say it bogs down but, the engine is revving out & it doesn't do it all the time

Raise the rear of the kart, run it & examine what is happening; be aware that you may not be able to recreate the problem because there's no load but, it's worth a try...

 

[KartFab]

Makes me wonder if you are holding your foot on the brakes and gas at the same time.

 

[mckutzy]

What is your gearing? Did you change that?

 

[BMRbrnSNRbrd]

Bogs down is the wrong way to explain it. I tried to get a video a few minutes ago and here is the best I could get.

http://www.youtube.com/watch?v=5d_9HV41CYk

This is about the best performance I've gotten out of it since the first day I installed the belt. You can hear it holding back (hey, there's the term!) at about the :39 mark and the cart finally takes off at about the :43 mark (about the time I run over the wood debris in the road.) At times, this takes as long as 30 seconds.

Also, it seemed to take a long time to get going at the beginning, but that may have been a slightly wet belt after a washing a while back. The belt has not been wet before.

Oh, and my feet are definitely not on the pedals at the same time and I replaced the gearing with what was on there already, but that was some time ago and I didn't have this issue last week.

 

[BMRbrnSNRbrd]

Oh, and my foot is flat on the floor when I start to accelerate again around the :36-:37 mark.

 

[KartFab]

Your torque converter should engage almost as soon as you stomp on the gas, it seems like it is lagging.... With that particular model of go kart your distance between the engine shaft center to Jackshaft center should be between 6 13/16ths and 6 and 7/8".....The belt number should be Comet Belt #203591A is also known as Yerf Dog Belt #Q43203W and Kartco Belt #7655.... Assuming you have a 7" diameter driven unit on your torque converter....

I'm guessing something is not right/aligned/sticking on your torque converter.


Take a few pics of the torque converter

 

[OzFab]

I'd put it down to a TC issue or a gearing issue. When it does get moving, it appears to be really moving; do a sprocket tooth count & report back...

 

[landuse]

Welcome. You could also give the tc a good clean just to rule that out

 

[itsid]

You sure guys?

to me it sounds like a clogged carb, or a governor kicking in 'slightly'.. maybe a loose throttle cable..
An engine problem, not a TC issue *shrugs*

'sid

 

[OzFab]

I did consider that while watching the vid but, the reason I ruled it out is because the engine is reacting ok but the kart doesn't move

 

[Oxymoron]

You sure guys?

to me it sounds like a clogged carb, or a governor kicking in 'slightly'.. maybe a loose throttle cable..
An engine problem, not a TC issue *shrugs*

'sid

I agree with this. It looks as though when he puts the pedal down, you don't even hear the engine rev up right away.... like the butterfly isn't opening on the carb.

Could the clamp on the governor arm where it attaches to the shaft of the governor gear be loose? Maybe it's slipping? That doesn't explain why it does suddenly start working though. Dirty carb maybe?

 

[BMRbrnSNRbrd]

I'll try to give as much information as possible now that my son and I did some extensive riding today. We covered about 9 miles today between riding to the park, a gas station for hot chocolate, and then surprising his mom at work.

I'd put it down to a TC issue or a gearing issue. When it does get moving, it appears to be really moving; do a sprocket tooth count & report back...

I am running 60T and 10T sprockets.

Welcome. You could also give the tc a good clean just to rule that out

Is there a how-to? I can't imagine it being too bad since it is practically brand new.

You sure guys?

to me it sounds like a clogged carb, or a governor kicking in 'slightly'.. maybe a loose throttle cable..
An engine problem, not a TC issue *shrugs*

'sid

I'm starting to think fuel ), they weren't nearly as often as when the temperature was in the 30s. I checked the air filter and although it was dirty, it wasn't horrendous.

I agree with this. It looks as though when he puts the pedal down, you don't even hear the engine rev up right away.... like the butterfly isn't opening on the carb.

Could the clamp on the governor arm where it attaches to the shaft of the governor gear be loose? Maybe it's slipping? That doesn't explain why it does suddenly start working though. Dirty carb maybe?

Is there a thorough how-to on cleaning the carb? Would removing the governor help at all or at least take that issue out of the picture?

Another issue I'm having is that sudden stops sometimes cause the engine to die. It is then a bear to get started again and sometimes requires the choke. Also, when this happens, it tends to lurch or even try to run away when I'm pulling the starter or get it started.

Thank you for all of the help and information.

 

[BMRbrnSNRbrd]

Oh, and I pulled the spark plug, everything looks great there.

 

[itsid]

Oh, and I pulled the spark plug, everything looks great there.

What do you mean great?

I hope you don't mean a white spark plug insulation,
otherwise that would mean you're running lean

'sid

 

[BMRbrnSNRbrd]

No, although I'm new to go karts and small engines, I'm not new to engines in general. The plug was a nice brown color.

 

[Oxymoron]

Is there a thorough how-to on cleaning the carb?

This is for a GX160, so the air filter is different, but the carb should be pretty close to the same.
http://www.youtube.com/watch?v=XYjpYcfyW7w

Would removing the governor help at all or at least take that issue out of the picture?

It would, but I wouldn't do that without first removing the governor gear from inside the crankcase. Temporarily overriding the governor for a few seconds is probably okay, but removing the linkage without the internals is a bad idea.

A simple adjustment could fix it, but...

Another issue I'm having is that sudden stops sometimes cause the engine to die. It is then a bear to get started again and sometimes requires the choke. Also, when this happens, it tends to lurch or even try to run away when I'm pulling the starter or get it started.

This sounds more like a TC issue, as stated by others... like maybe your driver pulley is getting stuck engaged. That would explain the kart trying to move when you pull the starter. Maybe it is just solely a TC issue. I'd check the driver out on it.

http://www.diygokarts.com/vb/showthread.php?t=7332

http://www.youtube.com/watch?v=C9yPHtfJO9w

Scroll to the bottom of this page...
http://www.gokartsupply.com/symapp.htm

I'd put it down to a TC issue or a gearing issue. When it does get moving, it appears to be really moving; do a sprocket tooth count & report back...

Yep, with the additional info from the OP... I think you're right! Plus, that would explain the engine not revving up too... if it were stuck in a higher gear, it wouldn't be able to rev up.