Troubleshooting Tecumseh 6.5hp Motor

[MinibikeMike98]

Hey guys, Having issues with my minibike. Bought it, a Murray Track2, with an already installed 6.5hp Tecumseh engine. I was adjusting the carburetor on it one day and ended up breaking the float bowl. I then replaced the carburetor with a 6.5hp lawnmower carb, replaced the air filter, and replaced the spark plug. I re-adjusted the new carb and the bike idles fine. The issue I'm having is that once I pull the throttle, either the engine shuts off or if it doesn't do that, the engine sputters and I get short kicks of speed while riding. Anyone know anything about this matter? Been trying to figure it out for 4 months now. Thanks in advance, guys.
Regards,
Mike

P.S.:
I can attach pictures of the engine layout, the old carb, the new carb, the old spark plug, the new spark plug, the new air filter, and the bike itself; if that'd help you guys figure out the problem.

 

[buckeye]

Hey Mike, welcome to OldMiniBikes.

Sounds like ya might need high speed needle adjustment, if it has one. Thirsty!

 

[KB2ROCKET]

check for intake leaks and if it has a high speed adjustment open it up some it is also possible that this new carb is gummed up (it dosent take much) take it apart and clean it up and try again.
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if adjusting the carb never run the needle valves down tight they need to be open to work
have fun

 

[The Restore Kid]

Yeah your jetting is definitely wrong.. You need a bigger main jet..

if the carb has a primer bulb on it, it WILL NOT RUN withough a air filter screw in the primer bulb side of the carb

when you say you adjust the carburetor, what exactly are you adjusting?? Those 6.5 carburetors do NOT have any adjustment in them... That is your problem.. To adjust them ya have to get a different jet...

OPE and gummed up.. :laugh: YEAH the prejetted carbs are almost always gummed up, because the jet has like 4 tiny holes in it... THE VERY VERY VERY lowest point IN the ENTIRE CARB!! :doah:

SO, one DRIP of anything sitting in there, will glue all of the holes shut.. :doah:

The jet has two holes at the bottom in from the sides.. They allow fuel into the jet... drilled lengthwise, upwards from thos two holes, is the main jet.. the size of that particular holes, measures your fuel..

ABOVE that hole, the brass is drilled out like 4 times as big as the jet itself.. Thats where the jet meets up with the internal carb parts..

In that opened area, like RITE ABOVE the threads on the jet, there is (usually one on these) another SUPER TINY hole.. It is drilled from just above the threads, down into the jet at a 45 degree angle.. THAT little hole, is how fuel transfers OUT of the main jet into the circuit that feeds your idle...

You have to make sure to clean your jet out real well, and MAKE SURE that 45 degree angle hole is open.. It takes like one single strand of wire.. THIN wire..

Thats probably not the problem tough, because it idles.. If it idles the stuff must be working... just won't feed enough fuel to GO!!

So you have to find a bigger jet, make sure all 4 holes are clear, and try it.. :laugh:

 

[Rollin310z]

this happended to my 6hp power sport tecumseh it has no prime bul or any needles to adjust i showed it to my cousin and he spuyn in the idle srew all the way in the one that is on top of the carb connected to the govnor, before it bounced and it did not run good at full speed now it fires up good but try to screw in the screw all the way in.

 

[MinibikeMike98]

Thanks everyone. If there's anything else you could think of that might be the problem, please let me know. At the moment, I'm in school. I'll try to fix those issues when I get home. Thanks again, this is a better forum/website than I expected. Well exceeded my expectations. Thanks so much. :biggrin:
Regards,
Mike

 

[The Restore Kid]

No... it is the jetting %100 gaurantee... Don't speed the idle way up or the engine wil always be wide open... :laugh:

You just need to ad fuel..

If you take the chain off, so it's just the motor, and use your fingers dirrectly running the throttle ON THE CARB..

You SHOULD be able to slowwwwwwly increase the engines speed, and it will run good.. It just can't ACCELERATE hard, or make any power, because the fuel is lean..

SO... take out your jet, read the number on the bottom, ad about 8, and buy a new one.. :laugh:

If it just stalls out no matter what, ad about 20 and try it.. :laugh:
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.
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The engine being lean, is most likely caused by a lack of compression.. valves wear out, and you lose compression, causing a lack of vacuum, causes less fuel to be sucked..

You should check and adjust your valve lash (really easy on an OHV engine) That will not only tell EXACTLY where the fuel wants to be measured at.. But also might make the original jet run rite again..PLUS it will be easier to start and make more power..

If you are using the jet from the lawnmower carb, try putting the original OHH60 jet in it...

adjust the valves, put in the biggest jet you have (after making sure it's clean) then if it still does it, buy a few bigger jets to try..

 

[MinibikeMike98]

Thanks so much guys, got it running perfectly, better than when I got it. I sold my baby, had her for a little over a year. But she's in a good place now. Thanks again, so much.
Sincerely,
Mike