Engine bogs down

[Darian1m]

Hey everyone, this website is awesome love reading the posts and responses. I've been able to really get some good advice here. Hope I get some on this as well.

So I have an OHM120 224618A (Tecumseh Powersport 12hp) on a Manco 800 series cart. I believe its the 812 model (I assume the 12 in 812 means 12hp)

This thing has been sitting collecting dust for over 4 years. I decided to pull it out and get it running again.

The old carburetor was shot and I threw a new one on there. Got it running. However, the engine is doing some weird stuff.


1. Sometimes it will pop and a flame comes out of the exhaust.

2. When I am doing donuts in one direction it’s great when I try the other direction the engine feels like it bogs down and looses power for a second or two and the power is back.

3. Riding full throttle in a straight line is fine for the first 5 seconds then it bogs down loses power and goes back up and bogs down. I thought this could be the governor, but it happens at low speed and during donuts too.

The linkages on this thing are complicated and seem very touchy, not sure I have it “tuned” correctly.

Has anyone else experienced anything like this? Any good resources for setting up all the linkages and governor?

I suspect it’s the brand-new carburetor. All the posts I have read about these engines say they are touchy.

Any pointers would be appreciated.

 

[Brianator]

If this problem wasn't apparent in the past and the carbs are the same I personally would clean/install the old jet(s) and set the float height identical to the old carb as a test. Worst case you've eliminated those as possible causes.

 

[Darian1m]

Unfortunately, the old carb stopped working and I messed with it quite a bit to get it going so the float height is not where it was at. I did not open the new carb to see if the float was set correctly I do have the float measurement tool, and I did run it before cleaning out the fuel tank so it may have gotten dirty.

Thanks for the advice I will open it up and check the settings and give it a quick cleaning.

 

[Brianator]

Good luck! Hopefully a good clean out and adjustment does the trick!

 

[pearl111]

Maybe dirty gas tank?

 

[Darian1m]

I am going to give this a shot on Saturday and will keep you posted on the results.

 

[Darian1m]

Very annoying. Now this thing barely runs. I put a fuel filter in cleaned out the carburetor. Adjusted the float. Now I can't get high enough RPMs to even engage the belt. This thing is going like 10 miles an hour. The linkages on this thing are complicated. I'm at the point where I'm pulling out the governor. So I don't have to mess with all the linkages. If that doesn't fix it I don't know what's up.

 

[Darian1m]

Ok so after being discouraged last night with the go-kart I took another look at it today in the sunlight. I found that the speed screw on the throttle plate was out way too much. I screwed it in all the way gave it another shot and the RPMs were high enough to engage the belt. I hit about 29mph governed and no engine bogging!

This is what I did to fix it.

1. cleaned the carburetor
2. Installed a fuel filter on the fuel line
3. Adjusted the float it was really high
4. adjusted the speed screw

TFunny thing is that a welch plug was missing from the carburetor I left it off and it does not seem to affect performance.

I took the kart down the road no bogging. Did some donuts, no bogging, did some donuts the other direction no bogging. This thing is running like a beast!


My daughter got on the go-kart hit the gas and the ran over the some roots. For some reason the chain popped right off and the master link is missing. Any thoughts on what could cause the chain to break like that? It was a little loose on the sprockets. Go-Kart supply store says 1/4" to 3/8" chain flex. I had more like 1/2" to 3/4". I would have expexted the chain to just fall off.

Can a chain break from engine torque? I am using a 420 chain

 

[landuse]

Glad you got it running well

So did the chain actually break, or did the master link just come off and the chain then fell off. Master links do sometimes fail. Make sure that the closed end of the masterlink clip is pointing in the direction of chain travel. This stops the clip potentially catching something and come off

 

[Darian1m]

Thanks, the master link came off. Doesn't look like the chain broke. I put a new master link on in the direction you recommend and hope it stays on this time

 

[Bo-Kart]

Ok so after being discouraged last night with the go-kart I took another look at it today in the sunlight. I found that the speed screw on the throttle plate was out way too much. I screwed it in all the way gave it another shot and the RPMs were high enough to engage the belt. I hit about 29mph governed and no engine bogging!

This is what I did to fix it.

1. cleaned the carburetor
2. Installed a fuel filter on the fuel line
3. Adjusted the float it was really high
4. adjusted the speed screw

TFunny thing is that a welch plug was missing from the carburetor I left it off and it does not seem to affect performance.

I took the kart down the road no bogging. Did some donuts, no bogging, did some donuts the other direction no bogging. This thing is running like a beast!


My daughter got on the go-kart hit the gas and the ran over the some roots. For some reason the chain popped right off and the master link is missing. Any thoughts on what could cause the chain to break like that? It was a little loose on the sprockets. Go-Kart supply store says 1/4" to 3/8" chain flex. I had more like 1/2" to 3/4". I would have expexted the chain to just fall off.

Can a chain break from engine torque? I am using a 420 chain

Hi there, I have the same Engine as you and seem to be having the same problem and really need HELP!
Are you able to attach a pic of the speed screw that you adjusted and what exactly did you do to the float?
Thank You.