Manco 3.5 B/S Quits Under Load

[dale3in98]

kart info: Manco go kart with a 3.5 Briggs and Stratton Model #91212 with the air governor.


I had issues with the throttle springs/linkage and I think I finally have those correct, however, the kart won't remain running under a load.

The kart starts and runs fine, but after a few feet on a flat level surface... it quits. The kart will start back up but does the same thing after a few more feet.

Any suggestions?

 

[landuse]

kart info: Manco go kart with a 3.5 Briggs and Stratton Model #91212 with the air governor.


I had issues with the throttle springs/linkage and I think I finally have those correct, however, the kart won't remain running under a load.

The kart starts and runs fine, but after a few feet on a flat level surface... it quits. The kart will start back up but does the same thing after a few more feet.

Any suggestions?

What is your gearing? You might be geared too high for your 3.5HP. Post the tooth count of your sprockets. It might be too weak for what you are trying to ride. Post some pics of your karts as well

 

[dale3in98]

I purchased the go kart (Manco 703-01) used, but everything appears to be original to the kart. I will post the gear tooth count this evening.

 

[Doc Sprocket]

In addition to the above, you may well be due for a carb cleaning.

 

[landuse]

In addition to the above, you may well be due for a carb cleaning.

That is always a good idea.

You kart looks quite light, so it shouldn't have too much of a problem getting you going. Lets see what the tooth count is before we go further

 

[OzFab]

Welcome back

I have no idea of your level of expertise so, pardon me if the following questions offend

the kart won't remain running under a load.

Define "under load"? Have you tried revving it without any load?

I had issues with the throttle springs/linkage and I think I finally have those correct

You think you have it correct; can you post pics of the throttle setup on the carb?

 

[dale3in98]

Welcome back

I have no idea of your level of expertise so, pardon me if the following questions offend



Define "under load"? Have you tried revving it without any load?



You think you have it correct; can you post pics of the throttle setup on the carb?

I have some mechanical know how but am not experienced working on go karts or small engines.

By load...I mean me driving the kart on a level paved driveway. I put the kart up on a jack and gave it gas...runs fine from low to full throttle but won't run 20 feet when on the ground with a driver.

As far as the throttle set up, the previous owner rigged up a long spring to operate the throttle. The throttle would hang up and I didn't want my son on the kart until it worked correctly. I took the kart to two small engine repair shops trying to get the correct spring installed and the engine to run properly. Now, the engine runs and will rev up...just not with a driver.

Got to get this fixed...had it over a year and my son hasn't got to drive it yet.

 

[dale3in98]

kart

small top sprocket-12 teeth

larger bottom sprocket-72 teeth (appears to be correct according to the repair parts sheet)


Current throttle spring set up:

 

[philip metzner]

I would bet you have a carb problem or a air leak in the fuel system some place. Have you tried richening the mixture some?

 

[OzFab]

The combination of the weight of a driver, the kart itself & a low powered engine, I think your gearing is a bit steep, you may need to factor in a jackshaft. The other advantage there is it will slow it down so your boy can get used to it; how old is he?

My daughters kart runs fine on an old 3hp B&S but, it's geared at around 12:1; top speed is only about 15mph but there's no problem with acceleration...

 

[Poboy kartman]

Fabroman-
I didn't think any of those low hp (5 and under) Briggs had anything but a plug and play carb (idle speed adjustment only)? Correct?

 

[OzFab]

Later models maybe but, my daughters '77 model also has a mixture screw which, i'm sure, later models don't have...

 

[dale3in98]

kart

I haven't adjusted on the carb...emptied the tank, added new gas, new spark plug and a new air cleaner. Everything appears to be stock original.

I had someone try the kart out that weighed much less than me...does the same thing...starts up and runs but quits after pulling out a few feet.

My son will be 6 in a month...just growing into this kart. I am out of answers as what to do to fix this kart. I want to keep it original, but another motor may be the only way to fix this.

Any suggestions on how to say for sure if it is carb., governor or gearing?

 

[philip metzner]

Here is the problem with the gear or weight theory. If that was the problem the engine should keep chugging and chugging all day until it over heats, burns up the clutch, or runs out of gas. It should not just quit running. Something is wrong with the engine. It takes more fuel to pull the kart than it does to rev up with the wheels off the ground. I dont know what carb he has, but I do know that there are some briggs that have a carb with a diaphragm between the carb and tank instead of on the side, and a jet hanging down in the tank. Some of them have the tank full of some kind of foam stuff. Those carbs can be troublesome.

 

[landuse]

I would say it is gearing. If you have had it up on stands and it goes from idle to full throttle OK, then it has to be gearing.

You have 6:1 at the moment. With a 3.5HP engine, I definately think that is too high. I would get a jackshaft and gear down further to 10:1 at least. Like Fabroman says, his daughters kart is at 12:1 with his 3.5HP engine

I know this is not what you want to hear, and it means some fabrication work, but I think it is what you need. Either that or get a 6.5HP Predator engine for $100 - $125. You should then not have to regear

 

[lude]

I would say it is gearing. If you have had it up on stands and it goes from idle to full throttle OK, then it has to be gearing.

You have 6:1 at the moment. With a 3.5HP engine, I definately think that is too high. I would get a jackshaft and gear down further to 10:1 at least. Like Fabroman says, his daughters kart is at 12:1 with his 3.5HP engine

I know this is not what you want to hear, and it means some fabrication work, but I think it is what you need. Either that or get a 6.5HP Predator engine for $100 - $125. You should then not have to regear

so you guys think instead of fixing it the way it came, and obliviously worked or these carts would of all been recalled. you should start adding things to it?. thats medicating the symptoms not treating the illness, when that still wont fix the issue, its not getting enough fuel, clean the carb and i will bet it works better, 3.5 hp should be be enough to slip the clutch if its not geared right to pull you, clean the carb. play with the settings, all else fails, go buy a honda clone and put the stock engine on a shelf somewhere so you can put it back if you ever want to.

 

[landuse]

so you guys think instead of fixing it the way it came, and obliviously worked or these carts would of all been recalled. you should start adding things to it?. thats medicating the symptoms not treating the illness, when that still wont fix the issue, its not getting enough fuel, clean the carb and i will bet it works better, 3.5 hp should be be enough to slip the clutch if its not geared right to pull you, clean the carb. play with the settings, all else fails, go buy a honda clone and put the stock engine on a shelf somewhere so you can put it back if you ever want to.

If you read the thread through again, we have been asking the OP to clean the carb, as well as post pics of the linkages. We are not just telling him to change things.

How do you know that this kart even came standard with the 3.5HP? Karts generally get sold with at least a 5HP engine nowadays, not a 3.5HP. The reason being that 3.5HP is just not what people want. They want power and speed.

The OP himself said that he is not averse to getting a new engine

 

[dale3in98]

kart

First, thanks to all that have replied with suggestions/help. I do have the operator's manual and repair parts sheet for this kart and all indications indicate that these karts came with a 3.5 Briggs and Stratton motors.

I will give cleaning the carb a try as several have suggested. Any tips...do's/don'ts, etc. that I should know before doing this?

 

[landuse]

First, thanks to all that have replied with suggestions/help. I do have the operator's manual and repair parts sheet for this kart and all indications indicate that these karts came with a 3.5 Briggs and Stratton motors.

I will give cleaning the carb a try as several have suggested. Any tips...do's/don'ts, etc. that I should know before doing this?

Those carbs are really easy to clean. Have a look at this link for step by step instructions on the cleaning

http://outdoorpowerinfo.com/repairs/briggs_pulsa-jet_horiz_adj.asp
http://outdoorpowerinfo.com/repairs/briggs_pulsa-jet_horiz_fixed.asp