Bike dying when hot

[keboh]

Hello everyone!

So this is my first 2 stroker, and I am used to EFI, so I could use some guidance from all of you!

I picked up a gt185 the other day, and it ran great the day I bought it... rode it about an hour home on country roads, no problem. Well, yesterday, as I was riding home from work, it started to cut out and misfire (about 20 minutes into my ride home). I noticed that it was the left bank that was cutting out. Shortly after that, it died completely. I let it sit for a few minutes (5-10) and I got it to start up again, and rode it about half a mile before it died again. I got pretty close to home, repeating this a couple times, before it just wouldn't start at all. I left it in a neighborhood, and my buddy picked me up to work on his car. When we finished that up an hour or two later, we went back to my bike, and it started right up. It ran until right before i got home, and then cut out again, but lasted longer than it had. I ended up just pushing it home.

I need some help, deciding what the issue is. Right now, I am thinking that the culprit is probably my ignition coil... does anyone have any input about what else it could be, or if I am on the right track?

Also, I'm not totally sure where to go about sourcing this part... there isn't a ton of support anymore for these bikes, so if anyone has a good website or store that has parts for these bikes, I would appreciate the help.

[Craig380]

Hi and welcome!

The fact it ran good for an hour after you bought it makes me think it's more likely to be an electrical problem, rather than a fuel blockage. I'm also assuming that there is a decent amount of fuel in the tank, and the 2-stroke oil tank has oil in it.

The ignition system relies on the battery -- if the battery is old and dying, or if the charging system isn't charging it properly, then it will give the symptoms you describe. The ignition system is NOT self-generating. It'll eventually die, then restart after a while because the battery will recover a little when the ignition is off.

So first, I'd remove the battery and see if there's any electrolyte in it, and put a voltmeter across it to see what state it's in. If it's less than 12V, the battery is probably dead. Good news is, the batteries for these bikes are pretty cheap.

If you can get the bike to fire up, put the voltmeter across the battery. If you see more than 13V, the charging system is working but the battery is a dud. If not, the charging system's faulty. But BEFORE tearing into anything, visually check the simple stuff like looking for a solid earth connection from the battery, bad connectors, loads of electrical tape on the wiring etc.

Let us know what you find and we can help with further troubleshooting.

[keboh]

Will do! that is a good point.... I should definitely start with the simple stuff first. When I'm off work, I'll tear Into it a bit and bust my voltometer out. I believe that it is a spark problem too, and not gas. There is gas in the tank and oil in the resivoir.

I should also mention the guy I bought it from had a shop rebuild the motor a while ago (year or two I think) and recently the carbs were cleaned and tuned.

Should be a good day... Pulling my xs650 apart, and chasing electrical problems in the gt.

[Vintageman]

Or, your gas cap vent hole is partially plugged.

I have a gt185 and there must be a venting scheme in the gas cap ... make sure it is free and clear.
else, it also can cause a similar problem to what you wrote.

[keboh]

Cool, I will check into that, too! Thanks for the advice

[yeadon_m]

+1 on the fuel cap as a possible, though I lean to the electrical more strongly.

You could pop the cap and see if it keeps going or does the same go / stop. If so, its not the cap.

Have fun! nice bike the 185.

Mike

[keboh]

I need to replace the plugs in it; I'm pretty sure at least one of them is fouled from one of my banks cutting out. I'm pretty sure the issue is not the gas cap though, tbh.

I bought a new battery, but it's raining out today, so I won't be able to test it until tomorrow. I am starting to lean more towards an issue with my stator, but for 40$, I figured I might as well start with the battery, so I know that won't be an issue, going forward.


Even if the bike is dead (ie. the battery doesn't have a charge), it should still be able to be started with the kick start, correct? and if it won't, then it's probably a stator issue, rather than battery? I am still trying to learn about these old bikes, forgive my ignorance

[Coyote]

Even if the bike is dead (ie. the battery doesn't have a charge), it should still be able to be started with the kick start, correct?

Wrong. These bikes don't have a magneto and need a good, fully charged battery to run. That's why they run worse as the battery weakens.

[jabcb]

The GT185 is different than the other models.

The T250/T350/GT250/T500/GT500 have a permanent magnet alternator & are kick start only.
Some will start & run without a battery while others will only run good if the battery has a decent charge.
They use the battery as a voltage regulator, so they'll quickly blow light bulbs if you don't have a battery.

The GT380/GT550/GT750 have an alternator with a field coil. The GT550/GT750 have electric start.
A battery is needed to power the field coil & get the bike running.

The GT185 is quite small & has electric start.
To keep size & weight down, the bike has a combined starter / generator.
The generator produces DC output & the bike does not have a rectifier.
A battery is needed to power the generator & get the bike running.

Generators typically have poor output at low rpm, so your GT185 needs a battery with a good charge to run good.

GT185 wiring diagram:

[Craig380]

I bought a new battery, but it's raining out today, so I won't be able to test it until tomorrow. I am starting to lean more towards an issue with my stator, but for 40$, I figured I might as well start with the battery, so I know that won't be an issue, going forward.

Don't forget to charge the battery for 3 or 4 hours before fitting it - even from new. They last MUCH longer if you charge them fully before putting any kind of load on them.

With a fresh, fully charged battery, you'll get a good couple of hours running before needing to recharge the battery, even if the generator is giving zero output.

[keboh]

Yeah I had the batt on a trickle all night. I am going to see if she will start up with the current plugs when I get back home, I'll probably go grab some new ones regardless though. Wish me luck guys.. Ha.

[Vintageman]

Hmmm, If the battery was acting like an open (not connected behavior). If you push start the bike you may get the self excited DC gen to spin fast enough to create enough power to start the little bugger

maybe some day I'll find a big hill and try this ... Myth Buster.. nah

As always, interesting stuff on these posts

[pearljam724]

Your symptoms could be one of a few issues. If the bike runs fine at times and easily starts I'd rule out the coils and a few additional electrical parts. In your case, I would start at the battery. Then move on to timing, address the points and condensers. If the timing is not correct. It can run fine until the bike warms or you need more power. Once the bike cools off or is allowed to idle for a few minutes it will run ok thereafter. Those symptoms will cycle. I just went through this over a long period of time. Thinking it was possibly other things, because in my mind I was sure the timing was correct when it wasn't. Once the timing was in fact correct. It ran perfect. If the points are not clean or gapped properly you can have the same symptoms as well. As the points wear, it changes the timing. It's important that the crank lobe is clean and continues to be cleaned by the felt or the point bridges wear very quickly. Changing the timing during that occurrence.

[keboh]

So I get a new battery for the bike, charged it up, and put it in, as well as new spark plugs. Boom, kicked right over and started right up. I rode it around the block a few times, it idled correctly, didn't die, etc.

However, I noticed that one of my cylinders was pushing out a lot of smoke... more than it should. The other one was pushing out possibly less smoke than it should. It still ran fine though, regardless of this. (possible crank case gasket?)

Later that night, I rode it to the gym, which is pretty close to my house. It did fine on the way there, and started right up on the way back, but once I got in my neighborhood, I could feel it starting to bog a bit, and then right before I got home (good timing, little guy) it died about 40 feet from my driveway and wouldn't crank back over. The lights and everything seemed to be working fine, as in they weren't dim or anything), so I am wondering if this isn't a charging system issue? I really don't want to spend the 200$ on a used stator, unless I am certain that is the problem. Same with the coils.

It ran for significantly less time than it did when I first bought the bike, after replacing the battery.

Supposedly this bike had gotten a tune up very recently before I bought it... does this sound like a timing issue, though? I really know absolutely nothing about points/timing, so I am not sure what symptoms would be if they were off.

[pearljam724]

If you rode the bike a considerable distance and it had no problem making enough power to climb hills, the timing would be ok. But, if it has a hard time climbing hills. It can also be the battery. If the battery is not up to par. The lights will still turn on. You CAN NOT test a battery by only charging it and checking it's charge. You have to run a few test with a multimeter. One at charge, 2 as the motor is cranking over, 3 at idle, 4 with light turned on and idling and lastly with lights turned on and increasing the rpm to about 3 or 4 K and holding steady. Don't take for granted that a battery bought in the past several months is good. They often can be bought with a dead cell, right off the store's shelf. That's why it's critical to run those several test phases. Sounds like you have a crap battery or something is not allowing the battery to keep it's charge. That's why it's important to run the test. It will tell you, if it's one or the other. The deal with the smoke. Don't drive yourself nuts over that. Nearly every 2 stroke I've seen smokes a little less on one side compared to the other. It could need crank seals. But, if the bike run's fine and the plugs are reading in a safe range. I wouldn't worry about that either. You also have to remember your bike has not been running for a whole lot lately. It may also just be a build up of oil somewhere. Your carb's air screws are likely in need of adjusting causing also.