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SUZUKI GT250 1973 only runs on right cylinder until engine starts to warm up..on left carb mixture screw as to be almost all way in to be able to tickover...carbs have been stripped and cleaned..

Compression on both cylinders is equal at around 100 psi cold after 5 or 6 kicks with throttle closed..when engine warmed up bike runs ok ...if I squirt some petrol down fuel tap suction pipe in to carb it starts on both cylinders and cuts back out after a few seconds when it as used up the fuel...fuel is present at carb drain plug.. Fuel flows freely to carb on prime position

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I haven't a carburator question in some time .
I had a 74 TM 125 it was a 2 stroke used to race it can't remember what carb was on it other then it was a 28 mm .
In any case yours is a 4 stroke engine a twin .If you have 1 carb then both cylinders should work the same if what your saying correct .
Look at the plugs is one white they should both be tan white means lean mixture witch means air leak after the carb maybe damaged boot or cylinder base gasket head gasket if the compression is the same cold it may not be hot although even compression is a vary good sign . Also check your pilot air screw and the passages in side the carb .
In a nut shell either its air leak or clog in carb or a draw problem like a bad valve or damaged ring .

Posted on Dec 02, 2016

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Be sure the ignition wire from the coil, the spark plug, and the plug boot are all in good working order and spark is present with the engine cold. Remove the carb that seems to be the problem. Make sure the fuel from the tank to the carb is not restricted at all, check any filters, screens, petcock valves, etc. Pull the float bowl from the bottom, remove the float ratainer pin, float assembly and shut off needle valve. Blow through the passage with compressed air to make sure it is clear of debris. Now remove the jets from the carburator body. Usually a small flat head screwdriver, and/or a 6mm-8mm wrench is needed. One is located directly under the needle jet, and the other will be close by the first. There may be 3 jets but without seeing the carb I cannot say for sure. If so, remove the third as well. Hold each jet to light to be sure it is clear of debris, used compressed air to clear the passages in the carb body. Assemble and install the carburator and run the engine. If the problem persists, find out if your engine has hydraulic lifters, if so the lifter may not function correctly until you oil warms up and is thin enough to pump through the lifter. This would keep the valve from opening or limit how far it opens, restricting the fuel from entering or exiting the cylinder correctly. Once it warms and the oil thins out the lifter would begin to work properly and the engine run normal. Some might suggest the timing but that isnt likely since the probpem isnt consistent after the engine is warmed up. This could be a sign of a failing gasket on the cylinder, since the engine cold may not pull enough from the intake to draw fuel in, then once the engine is warm, the cylinder expands closing the gap at the place where the gasket is failing, causing it to pull from the intake normally. A leak down test will answer that for you. That would be the last thing to check however. Hope this helps.

Posted on Dec 02, 2016

Testimonial: "it is a two stroke so no valves"

  • Doug Dec 03, 2016

    The reed valve in good condition? Is there a diaphram pump somewhere that could malfunction? vacuum hose cracked or not attatched? Some bikes have a vaccuum hose coming from the cylinder, to a diaphram, which connects to the carb. Yours may not but if it does thats a good place to check. The same holds true for the carb inspection and cleaning, try not to use wire if you can avoid it. Once a wire breaks off its a nightmare to get out if its even possible. Compressed air is your friend for clearing passagways in a carb body. Hard to know without seeing the bike in front of me but hope it helps.


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Hi, John sounds like a faulty spark plug or cable for more information about your question and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Sundial Moto Sports
Concours Owners GroupTM Sport touring at its finest SM
Suzuki GT250 workshop manual pdf
OEM parts for Suzuki
Suzuki GT250 owners manual 1973 eBay

Posted on Dec 02, 2016

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Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you

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