gearing wrong?

[crawdaddy]

Hi everyone. So my kids were riding around on the kart and it just got to the point where it would not move, the engine will go and rev but the kart won't move. I took apart the clutch (max torque cent. clutch), cleaned it up and put it back together. It moved me down the driveway but was slipping and I figured it was toast. This is a 10 tooth clutch and had a 54 tooth sprocket. I thought I had read a higher tooth count would give more bottom end and keep from burning up that slipping clutch so I ordered another clutch (max torque 4) and a 60 tooth sprocket. I put them on the kart today, fired it up and it would not move with anyone in the kart, slipping at least as bad as it was with the old clutch and sprocket. Shouldn't I be going to a lower tooth count on the rear sprocket to help the clutch and give it more bottom end?

 

[OzFab]

We need more info... & pics...

There's more to calculating gearing that just sprocket sizes:
How big is the kart?
What size are the rear tyres?

Being that it has a 54t axle sprocket, my guess is it used to have a torque converter which was removed by a PO. The best, simplest (but, not necessarily the cheapest) solution is to refit another one...

 

[crawdaddy]

ever get so caught up in stuff you forget to add important info? sorry
Engine is a OHH50, we know the clutch and sprockets I have, rear tires are 15X6-6. It is a two seater that I posted about a while back trying to figure out what it was. I'll get some pics tomorrow.
What I can't figure out is when I first got it and got it running it would spin gravel up and down my driveway but would bog down turning around in the grass. I figured I would just throw a different driven sprocket on there to give it more take off, that is when i started reading about going from the 54 to a higher teeth count. Now, with the old clutch and sprocket and the new clutch and sprocket it won't move. The key isn't sheared either.
Maybe the question should be 'why won't my kart move'.
I've been reading about jackshafts and the torque converters but sure don't want to spend that money right now.

 

[OzFab]

Ok then, elevate the rear end & turn the wheels to be sure the axle isn't binding, you may have a bad bearing...

Once you've made sure the axle moves freely, try running the engine with the rear still elevated...

 

[landuse]

If it used to burn rubber when taking off, and now doesn't even with a higher axle tooth count, then there is something wrong. Are you able to check the engine compression (after doing what Fabroman recommended)?

 

[crawdaddy]

thanks folks.....
I agree, something is wrong. I will check compression in just a moment. I do have an issue/question about the wheel but for purposes of this discussion the wheel spins freely and has new bearings (i put one in a short while back) A new chain came with the clutch and everything spins fine. I could hold up the back of the kart, give it gas and the wheel would spin. I could not stop the wheel by hand.
I was pretty frustrtated last night, didn't expect these new problems.
Just checked compression and it is 125, dry cylinder throttle shut
I notice it is running rich but don't see how that could deal with this issue.
Just a thought but could it be the engine is not revving enough to lock up the clutch? It ran before so I don't know

 

[landuse]

Have you checked all the throttle linkages from the pedal to the engine. You might think you are pushing the pedal in all the way, but at the engine you could only be opening it up half way. Have someone look at what happens to the linkages on the engine when the pedal is pressed.

 

[crawdaddy]

I just checked throttle, it opens all the way as far as amount of travel is concerned but we might be onto something with this throttle thing. I have always felt this engine is always 'lugging' has never opened up and I figured it was due to gearing and we didn't have enough room to let it 'wind all the way up'. even with the foot to the floor it has acted like the pedal is only half way. This is what I hoped gearing would cure. Now I wonder if this throttle is set up right. here are some pics if someone can take a look and save me some research? (if these images don't work or are too big I'll work on fixing them...i think photobucket has changed since i last visited)

 

[crawdaddy]

alright, i am officially out of ideas. I moved the linkage spring thing down to the #4 hole to the #2 hole, no change.
drive wheel off the ground it will rev and spin the wheel
I can put the drive wheel on the ground standing beside the kart, push the gas to the floor and it will rev enough to start to move forward but i can hold the kart still with one hand.
video hasn't been working too well for me on photobucket but I will try to capture what is going on somehow.

 

[Poboy kartman]

Something I noticed. ....your governor arm does not look properly adjusted.

Loosen the screw on the bottom. . ( making sure the shaft is totally free)....Open the carb throttle to wide open and make sure the governor arm is pushed left (counterclockwise) as far as it will go and retighten the screw...

BTW- forgot to mention. ....with engine not running. ....

 

[crawdaddy]

Darn it I was trying to adjust it while running but it was dragging me all over the place.... kidding but I had to
That could be a lot of the problem because with wheel in the air I can move governor arm by hand and get more revs than by full foot throttle. Not close to over revving but a lot more revs
I pulled up the service manual before taking a break. I also took a video but it hasn't uploaded yet. Ill update this when I get home. Much thanks again

 

[crawdaddy]

alright folks, still waiting on my video to show up on photobucket. I adjusted the governor linkage then it didn't want to start. I can hold the carburetor butterfly by hand and get it to start. Once started it didn't want to idle but I did a tap dance, kept the throttle going by hand then jumped into the seat to keep it going by foot (kids weren't home). It kept running fine, even took me down the driveway once then just wouldn't. Engine still running fine just wouldn't move me. I'm going to slow down, read thru that service manual again and start fresh. when the video shows up I will post it but just wanted to come back and say thanks - i'll update when i reach a new 'milestone'. I never leave a thread hanging.

 

[Poboy kartman]

Ummmmmm......just to make sure. ..I probably should have been clearer on this. .....I meant the top of the governor arm. .... ( where it connects to the carb throttle with the little "S" link.......

Obviously. ....applying those instructions to the bottom of that arm would make everything backwards. ...and cause it to be off-idle...

There's also a set screw to adjust the idle speed.....which is another possibility. .....if you did adjust the governor properly.....the old adjustment may have been keeping the butterfly open at idle....and now it's closing too much. .....because the idle screw wasn't keeping the butterfly open before. ....the governor was......make sense? ??

 

[crawdaddy]

Yes, makes sense and just to clarify here is what I did. Loosen the screw on bottom of the governor linkage arm. Push top of the arm to the left, look inside carb to make sure throttle plate is fully open. Then I rotated the actual governor shaft fully left (counter clockwise) and tightened the screw on the shaft.
After doing this is when it would not start unless I manually worked the throttle plate. Now I can screw the idle adjust screw fully in and it still won't open the butterfly enough to let it idle.
That is where I took a step back figuring I was missing something, had too much in my head (in the middle of a motorcycle engine rebuild in the middle of all this).
I am posting my video on youtube (I think) so here is the link. http://youtu.be/zLtFtZTb4Uc
It is a short video with me holding the kart while working the throttle from idle to full throttle by foot. You can see the kart start to move and me holding it back easily. This was shot before messing with the gov. adjustment.

 

[Poboy kartman]

Ahhhhhh- Yes.......No.....That's wrong the shaft needs to sit in it's natural position... ( why I said it should be totally free. .)......

If you redo it that way. ...it should be right. ....

 

[crawdaddy]

that makes even more sense but what is its natural position? It freely rotates and will stay where left. I just went out, took the gov. arm completely off and the shaft will rotate and has no 'home' position.

 

[ML-TOYS]

May be stupid to ask but how does the kart react with the governor arm not connected.
Just curious to see if it moves better but not suggesting you eliminate it that way if it does happen to work.

 

[crawdaddy]

not stupid at all - heck, i welcome anything from anyone trying to help. So I went out and removed the gov. arm completely. The kart started right up and would idle with the idle screw. I had to work the throttle butterfly by hand of course but it sounded same as always, putter putter, no where near approaching any overspeed condition. That sure seems strange to me and a first first for any small engine I know. It still is running rich but rich enough to bog it like this I dunno.
Something else I felt was strange was as the engine was running both as full speed as i could get it to go as well as at idle - the governor shaft had no movement. I could rotate the shaft by hand a very small amount in either direction. Shouldn't the counterweights be moving that shaft or at least be felt thru that shaft, limiting the amount I am able to rotate it?
Wheels in the air, no governor attached, me holding the throttle wide open at the carburetor this thing should be screaming right?
As I sit here thinking more...I do need to address the running rich issue. There are 2 screws on this carb, bought new when i got the kart. One screw is the idle screw, the other I think is either low speed or idle mix adjust screw....maybe high speed adjust. There is no screw on the bowl jet / nut. I'm going to take the carb off and check the float height.

 

[crawdaddy]

RENAME POST TO:
Can running too rich cause a go kart not to move?

Talk about can't see the forrest for the trees. I work on ALOT of mowers but this being my first kart it never occured to me it was anything but clutch issues and that was the sound of a kart engine. I took the bowl off the carb and of course there is no adjustment to the float height. Plastic float. I made a shim out of an aluminum can to stick under the tab, over the needle end, in effect placing more pressure sooner on the needle for a given float height. The kart started running better. I started messing with that screw on the side of the carburetor and ended up screwing it out at least 5 or 6 turns. The kart runs the best it has since I brought it back to life. I still have alot of tuning to do but won't waste any of your time until I get a better handle on what is going on. I appreciate all the help and info!!

 

[Poboy kartman]

that makes even more sense but what is its natural position? It freely rotates and will stay where left. I just went out, took the gov. arm completely off and the shaft will rotate and has no 'home' position.

Well.....to explain it. ....the governor works off centrifugal force.....as the internal centrifugal mechanism moves in relation to rpms....the weights move outward....exerting force on the shaft that the governor arm is connected to. ....causing it to move the butterfly on the carb towards the closed position. ...

This is why I said the engine cannot be running. .....the internal governor mechanism will return to an "idle....non-interfering. ....un-engaged. ...or " natural position".....as long as you don't "F" with it.....AGAIN!!!!..Why I said it needs to be LOOSE on the arm......

IT WILL NATURALLY BE IN THE RIGHT POSITION with the engine not running. .....then you just put the linkingage in the correct positioning and tighten the screw down. ......gee wiz.....