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I inherited a GT235 with a Briggs and Stratton V-Twin in it from the former property owner here. After a couple of months it started intermittently losing power at full throttle and eventually refused to generate full power at all.

Starting the PTO causes a significant hesitation and the mower stalls if going uphill and mowing simultaneously. I broke the deck down and lubricated it and it is moving fine. I pulled all of the filters off and ran it without them, still low power. I checked the plugs - they are fine.

The tractor starts fine and runs fine. It used to have a staccato sound at high RPM, but now it is more throaty and growly.

Seems to be running a bit rich, but I can't seem to figure out how to lean it out. The little knob on the carb doesn't seem to do anything at all. Anyone have any suggestions, or resources for how to lean out the mixture?
 

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Thanks for making me feel welcome. One of the plugs was completely clean. The other had a bit of carbon on it.

I don't have the service manual, but I'm happy to check the clearances on the valves. Anything else I should look for?
 

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Glad to have you here.

Briggs V-Twin... which one exactly? Briggs & Stratton 350777 18 horse?

Any idea how many hours on it?
 

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Briggs & Stratton 350777 18 horse. No idea how many hours are on it. The prior owner wasn't much into maintenance ( none of the half dozen or so gas motors on the property worked when I got here in 2019 - including the 2004 Sierra 2500HD extended cab with 11,000 mile on it! )
 

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Maybe there's more to do, and the carb might need a rummage around in but. I'd start by checking the valves and then doing a compression test.

Fresh oil and stuff right? And even if the plugs look OK time can take its toll, throw a fresh set in.
 

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Alright, I'll get some new plugs, check the valves and do a compression test. I did change the oil and had to pull the carb and clean it out when I first restored it to running order. Probably take me a couple of days to get the parts and find the time. I'll check back here when I've tried these items.
 

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I would use an inline spark tester (or 2) to be sure both coils are working good.
Cannon
 

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The little knob on the carb you're talking about is likely the bowl drain. These carbs aren't really adjustable except idle speed. I forget if there's idle mixture adjustment but the main jet is definitely not adjustable. Did you have to clean the carb to get it running?

These engines are known for halfway blowing up due to lack of maintenance and then only running on one cylinder. Although, that usually results in a broken rod and a lot of vibration during running. If it lost a cylinder (spark, compression) but still has the entire rotating assembly, then it wouldn't vibrate as much.


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Hi oojoshua and
2449631
to My Tractor Forum...looks like you are getting some help....I know those carbs can me a bit of a pain to get in and out....but you might want to remove it and clean it out...possibly get a rebuild kit for it...also check the fuel filter and the fuel lines ...on both sides of the fuel pump.....are you noticing smoke indicating running rich?
 

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It sounds like one cylinder is only firing some times. I would try pulling the fouled plug when it is running to see if it makes a big difference in the engine speed. Also, one of the evil things about a carb is that it will sound good when not under load but then when a load is applied it bogs down. That is almost always one jet in the carb that is partially clogged up and when it needs more gas cannot get it. My bet is it's the carb.
 

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Start motor and put a infrared thermo on exhaust pipes and see if big diff. Can have fire but have a valve lift problem with no compression. Also you can spray water on pipes to see if same temp.
 

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It sounds like one cylinder is only firing some times. I would try pulling the fouled plug when it is running to see if it makes a big difference in the engine speed. Also, one of the evil things about a carb is that it will sound good when not under load but then when a load is applied it bogs down. That is almost always one jet in the carb that is partially clogged up and when it needs more gas cannot get it. My bet is it's the carb.
Only 1 high speed jet in this carb/motor.
 

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I bought the service manual for a gt245 here: JOHN DEERE GT225 GT235 GT235E GT245 LAWN GARDEN TRACTOR Service Repair Manual 鈥 SERVICE REPAIR MANUAL. I can't send it through email or this forum because the file is too big. It's only $15. I have no affiliation with the company and there may be others out there, but just the place I bought mine from.
You can find a Briggs service manual for the vanguard for free I'll try to post a link


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These motors have tendency of sticking a valve in the guide,it鈥檚 the exhaust that sticks.
 
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