Hot start problem?

[aarron]

Hi all, I finally got my TC250 back together and took it for a maiden ride yesterday. This bike has been starting cold on 1 or 2 kicks. It was running good, went through the gears well etc. There were no issues to speak of. I got the bike back to the garage and parked it, took the dogs for a walk. When I got back I thought I go for another quick ride. It simply wouldn't fire. I have spark and fuel, battery is 3 months old and is always on a battery tender. It wouldn't even pop, and this bike ALWAYS starts. It also wouldn't start this morning after it sat all night. Any quick ideas of what I'm missing? Thanks in advance for your help!

[karl pa]

Sorry I dont have the answer,my t250 scrambler has the same issue,alway's starts 1 or 2 kicks unless it's hot,it seems to be an issue with the mufflers being so close to carbs,and trapping heat in.If I stop for gas or any short period,the only way to start is to open throttle while kicking,acting like its flooded.

[pearljam724]

Just because a battery is new, always been on a tender, etc. doesn't mean it's any good. You have to properly test a battery with a multimeter before installation, with ignition and accessories turned on, when the motor is cranking via a starter, at idle and finally at higher Rpms. 3-5k Rpms for example. You have to test a battery under all of those circumstances. A battery straight off a store shelf can have a dead cell, a battery can develope one in a very short time frame. Many people are fooled into believing a battery is good just because it holds a charge. They only test a battery to see if it's holding a charge close to 12volts. That's not how you test a battery properly. However, if the problem only exists when the motor is warm that would point to an ignition coil. There's an easy way to test the ohms of any given coil with a multimeter as well. You have to know the ohm rating for your given coil to see if a coil needs replaced by the coil being in an exceptable ohm reading range when testing one. A majority of mid to high cc bikes run on 4.5 ohm rated ignition coils. A reading between 3 - 4.5 ohms would be acceptable. A smaller cc bike likely uses a lower rated coil. You have to find what ohms your specific coils are rated for before testing. You test the coil with the battery disconnected.

[aarron]

Thanks a lot for the replies! I'll try and get back out there this week and check the battery & coils.

[pearljam724]

If you have original coils, it would be in your best interest just to replace them. There are very affordable coils listed all over EBay. You don't need an original factory coil. All you need is the same ohm rating, same spacing for mounting holes. Coils come in two types single tower or twin tower. Twin towers are one coil that has 2 leads to feed 2 cylinders. Most bikes have a single coil that feeds spark to each cylinder separately. I've used other non factory or other model coils and they work just as well. As long as mounting and ohms is the same. You'll most likely need to change the electric connection adapters if using one from a different make or model. Which is a piece of cake, by swapping your old adapters onto the new. Some coils have the ohm rating etched onto the coil. Some don't. If not, its usually listed in a manual. If not in manual, you test a known good coil that is consistently firing under any circumstance on your bike. Or find out what ohms the coils are that people are selling for your specific bike. Many ways to find your coils ohm rating.

[aarron]

the only way to start is to open throttle while kicking,acting like its flooded.

I went out to the barn on a whim, tried to kick normally, got a sputter. Opened full throttle and kicked a couple of times and it fired right up. Reved it few times to clean it out, let it warm up and went for another nice ride. Came back, shut it off and it started 1st kick. But I didn't let it get cold. I still haven't checked the coils & battery yet. Any ideas?

[pearljam724]

If you had to open full throttle to start, it would be flooding. Most likely your fuel petcock is leaking and bypassing fuel to the carbs at all times. Pull the fuel line off and see if the petcock dribbles fuel when the bike sits. Your needle valves in your carbs may need changed, also could have rust particles clogging them due to rust particles in tank. Has it ever been sealed ? Do you have an inline filter ? Have carbs recently been cleaned and rebuilt ?

[karl pa]

On mine ,I was wondering if the float level might be a bit high,when it is shut off hot,the high pipes next to the carbs expands the gas in the bowls, to raise the fuel level even higher.If it sets for a few hours the level goes back down and there's no problem.The warmer the weather the worse the problem gets.

[pearljam724]

That could be. Today's gas also evaporates a lot faster. You shut a motor off, the heat from the pipes makes it evaporate while it sits. Today's gas evaporates quickly without heat. Imagine if temperature is added to the equation.