skyefarmer Posted August 2 Report Share Posted August 2 A 1978 TY250 was left in a stable of a house I bought. After 20yrs of looking at it, I thought I'd get it going. The job was nearly done, but I fear I've just messed it up. The last step was installing a new carb, after which it started fine (multiple times) and sounded decent but did not have enough revs to tick over when the throttle was released. I was adjusting the Idle Adjust Screw, turning it clockwise, and starting to observe an increase in idle revs, when I realised I'd left the choke on. I turned the choke off, and the engine died. Since then I have not been able to start the bike. Not even close. Suspecting that after many failed starting attempts I had flooded it, I drained the carb and removed the plug. Neither the plug nor the cylinder was wet with fuel. Good spark observed outside the bike. Checked there was fuel to carb. Refilled fuel tank. If anyone has any suggestions I'd love to hear them. Thanks. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted August 3 Report Share Posted August 3 On 8/3/2025 at 1:49 AM, skyefarmer said: A 1978 TY250 was left in a stable of a house I bought. After 20yrs of looking at it, I thought I'd get it going. The job was nearly done, but I fear I've just messed it up. The last step was installing a new carb, after which it started fine (multiple times) and sounded decent but did not have enough revs to tick over when the throttle was released. I was adjusting the Idle Adjust Screw, turning it clockwise, and starting to observe an increase in idle revs, when I realised I'd left the choke on. I turned the choke off, and the engine died. Since then I have not been able to start the bike. Not even close. Suspecting that after many failed starting attempts I had flooded it, I drained the carb and removed the plug. Neither the plug nor the cylinder was wet with fuel. Good spark observed outside the bike. Checked there was fuel to carb. Refilled fuel tank. If anyone has any suggestions I'd love to hear them. Thanks. There's a few possibilities here. Most likely is because you have wound in the idle speed screw, the slide might be too high for the start device to function. If it's a modern carb, the starting device is not a choke. Modern starting devices use the pressure difference across the slide to draw fuel through the cold start circuit and if the slide is too high, not enough pressure difference will be generated while kicking, to draw fuel through. If winding the idle speed screw back out again doesn't solve the problem, narrow the range of possibilities by putting a couple of drops of fuel into the cylinder via the plug hole, then see if it fires. 1 Quote Link to comment Share on other sites More sharing options...
skyefarmer Posted August 4 Author Report Share Posted August 4 Thanks @feetupfun, I didn't know that, and it sounds promising because it explains dry cylinder and plug. I shall try and undo my actions, and will report back. The new carb is a VM26-8074 from Motocarb. Quote Link to comment Share on other sites More sharing options...
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