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daverbmxer 09-03-2012 07:20 PM

'78 Suzuki TS250 died on me
So the TS250 has sat for years, getting started and ran very briefly every couple years. It has sat for 5 or 6 years with basically no use, until today. So I added fresh gas, it starts quickly, and I drive it off.. around town a bit. It didn't run good in town.. low on power, sputtered under full throttle. I took it out on a gravel road out of town, power picked up to normal now that it had run 10 minutes or so. I was buzzing down the road at 40 mph and all of a sudden it starts to slow down pretty quick, giving it throttle it still slows down and quits.

I thought it may have overheated, although unlikely, so I let it sit for 5 minutes and try starting it. I got it to sputter for a second twice. This was with the choke pulled.. even though it would be hot enough to start without choke. Didn't sputter at all without choke. So I towed it back home and troubleshot it.

The sparkplug was somewhere between wet and dry.. dampish. Tons of fuel going to the carburetor, passing through petcock and filter fine. With a screwdriver grounding the spark plug lead, I saw and heard spark. Air filter had no rats nest in it, free flowing air. I dumped a pop bottle lid full of gas into the cylinder on the off chance it didn't get fuel through the carburetor.. would not start. I smelled fuel while kicking, but did not start. I took the carburetor off and apart. Idle jet was 90% plugged, so I cleaned it out and put it back in. Main jet was fine. Put carburetor back on and tried to start, nothing. Let it sit for a couple hours and tried to start, but no start. WTF! It has fuel, spark, air, and at least some compression! It was running awesome before it suddenly died! I doubt the engine would destroy itself that quickly. There was no weird noise when it quit, and compression seems the same now..

One thing that's been haunting me a bit is the transmission oil level. I have no idea how much it is supposed to have, never have known. I have always just used a coat hanger or stiff wire to gauge how much oil is in there. It wasn't as full as I would have liked, but was acceptable I thought.. maybe 2" of oil. So... does this transmission oil also lubricate the bottom end of the engine? I do not think so, but I'm not sure. Usually 2 strokes use the oil/gas mix in the crankcase before burning it don't they?

I originally wrote the above yesterday, I just could not post until now. So today I did some checking too, and I have a couple things to add that I forgot before. The spark plug throws a spark when grounded to the head. I also cleaned the spark plug up a bit, using fine sandpaper to clean up the gap.

I also removed the spark plug and kicked it over around 50 times to get rid of any excess fuel. Then I had my nephew push me down a hill as I popped it in gear. Once I got it to run for 10 seconds, very weakly, until petering out. I then suspected the fuel so I drained the tank and the fuel bowl, and put in different gas. Tried the pushing down a hill again, same thing but I couldn't get it to run for more than a second. It did backfire pretty nastily a few times. Seems like it might be getting way too much fuel...?

So what can I check to get this running? I'd really love to have this running tomorrow!

Kai Ju 09-03-2012 07:30 PM

Airhead that isn't......
Your Suzuki is in fact an Airhead, but you'll get better/more responses one forum over in the two smokes forum.

But just for grins, you mention gas but not two stroke oil. Is this an oil injected engine or premix ?
If it's oil injected make sure you have fresh oil in the injection tank and that it gets to the oil lines leading to the bottom end.
If it's premix, did you ?

From your description of the failure it sounds like you seized the top end. Stop kicking or trying to start it because if it seized you're only making it worse.

Good luck.

daverbmxer 09-03-2012 07:38 PM

Oh ok. I saw that the Airheads forum had a lot more posts, so since it fit in both categories/forums I would try there. Perhaps a moderator could move it that would be better?

The bike is premix only, or at least that's what I've been doing for 10 years! I had always mixed 25:1, but this time I had some weedeater gas which was at 32:1, so I used that. Close enough I figured. I did some reading a while back that the modern 2 stroke oils lubricate better. Some advertise 50:1 for any motor.. not sure if I would trust that though.

I would think that if the top end was seized, it wouldn't run for those 10 seconds would it?

hardwaregrrl 09-03-2012 07:47 PM

Actually this bike was originally oil injected, sounds like the system was removed. Doesn't sound like a seizure, even a soft one. Modern oils do not work well in our bikes....stick with the dino stuff. Yamalube is a good one. Go back to the old ratio as well. Disassemble carb and beg a local shop to let you toss the carb in there sonic cleaner for 1/2 hour, then reassemble. These motors are a bit more refined than your chainsaw, so be sure to use fresh gas. I have a TS185, and have been down this road....but I seized mine.:cry

daverbmxer 09-03-2012 07:51 PM

So you think it is probably carburetor related?

And just to show further ignorance, the transmission oil does not lubricate the bottom end does it?

Navin 09-03-2012 08:02 PM

No, trans oil is seperate, premix lubes the crank. Stop push starting it. It is still broken if it will not kick start normally. Try a new plug first. That failing, tear the carb apart and clean it + add a fuel filter inline from the tank. Could be alot of gunk in there, flushing it is a good idea too.

Still no? Crank seals of that age are suspect, leak down test time. bad crank seals can cause a lean seizure by pulling in air to the crank, or oil fouling the plug by drawing in trans oil. Neither is good but most are easy to replace. The question is what was damaged if this is the problem. usually the top end at least needs a rebuild.

Hope it is the first thing or two I suggest checking. I had one of these years ago, fun bikes.

daverbmxer 09-03-2012 08:15 PM

I did have the carburetor apart, just the bowl off. The idle jet was 90% plugged, but other than that the carburetor looked quite clean. What specifically in the carburetor could be malfunctioning?

hardwaregrrl 09-03-2012 08:25 PM


Originally Posted by daverbmxer (Post 19513207)
I did have the carburetor apart, just the bowl off. The idle jet was 90% plugged, but other than that the carburetor looked quite clean. What specifically in the carburetor could be malfunctioning?

Remove it from the bike and remove the jets. Drop it in a sonic bath and then reassemble. You say this bike has been sitting on and off for 6 years? Carbs cannot sit that long with fuel in it without clogging passages. It's not difficult...if you want specific assistance ask here. you'll need to remove the airbox, and oil tank if it's still attached, then unscrew the clamps and the top of the carb. Pull the top off and the spring/slide will dangle from the throttle cable and the carb top. Pull the rear of the carb towards you exiting the left side of the bike. You may also want to replace the two rubber boots that hold the carb on. Air leaks are very bad for 2 stroke motors. It ran before, bet a clean carb and some fresh gas/oil that sucker will kick right over.! gl

Navin 09-04-2012 09:43 AM

It also may have sucked up more crap and clogged again! The entire fuel system is probably full off fluff/debris.

daverbmxer 09-05-2012 12:58 PM

Well I just called all around our little town of 50,000 and no one has a sonic washer. One place said they have a gallon thingy of some sort that they drop the carburetors into that removes all the dirt in an hour, but it still needs to be blown out after with air. And for that they charge $79.. if it's just dunked in, already dissembled and cleaned, then $30. Not going to happen..

I have a spray can of carb cleaner and I'll see if I can work some speaker wire down the small orifices to clean them out.

Oh and the rubber boot that connects the rear of the carburetor to the air filter had a gap where it didn't meet up flush on the carb. It's old and hardened. Perhaps going that fast on a gravel road kicked up some dust which the carburetor sucked in and got plugged up.

Sniper X 09-05-2012 01:47 PM

Do you have an Auto parts store in town? If so, they carry that gallon can of carb cleaner for like 20 bucks.

daverbmxer 09-05-2012 05:34 PM

Yeah, have lots of auto parts stores, just don't feel the need to buy a gallon of that stuff. A bit under pressure with a straw should work. Not sure when I'm going to tackle this, and won't be able to try it on the bike for another week or 2, when I go home. So if there are any other ideas let me know!

daverbmxer 09-08-2012 06:51 PM

Ok so I took the carburetor completely apart, soaked everything in carburetor cleaner, sprayed it down passages, etc. All passages seem clear. I was kind of wrong before, my dad didn't actually make a lead enrichener valve, but rather it looks like he soldered a nut on the end of a fitting over the valve. The valve is the factory brass one and didn't break apart. Everything, including the enrichener valve area seemed clean.

So I put the carburetor back on the bike, and it wouldn't start. I put a bit of gas in the cylinder and it started on the 2nd kick and ran great until I tried to let it idle, then it died. Repeat 4 or 5 times. I could even drive around with lots of power, but the second I got out of the throttle it would lose power and die. To me this seems like it would be a plugged idle jet but I have confirmed twice that it is clear if debris! What else could do that?

There is either something wrong with the idle "system" OR else there's something wrong with the venting of the carburetor. I say this because I have a new fuel filter and hose and have confirmed that there is a ton of gas able to flow to the carburetor. Everything is free. But with the fuel hose attached to the carburetor the fuel filter seems to only get 1/3 full. This is the case even with an empty fuel bowl, petcock off, then turning the petcock on. Fuel doesn't rush in like I would expect it to (like the fuel line gushes with it not hooked up). So perhaps there is an air lock in there now allowing fuel to enter or something??

Any thoughts at all? It pisses me off so bad, it runs great with throttle, but won't idle, and won't start like it used to.

DirtDabber 09-08-2012 07:12 PM

Have you checked compression?

daverbmxer 09-08-2012 07:36 PM

Not yet.

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