TS185L Starts and runs, revs fine at idle, won't go over 30MPH
 

I have a 1974 Suzuki TS185, and I can't seem to get it to accelerate to more than 30MPH.

I have minor choke problems (it probably just needs to be cleaned again), but when I do get my bike started, it runs great. It idles, revs up quickly, runs well, and everything seems to work. In first gear, every thing is fine, it accelerates quickly and is very "peppy". But after second gear, it won't rev above about 3500-4500 RPM, and won't accelerate past 25-30 MPH.

I changed the spark plug, cleaned the fuel system from the fuel cock, to the carb. (and replaced the fuel line), I cleaned the exhaust baffle, and ran a compression test (120 PSI). Everything seemed to check out.

I haven't yet tried timing, but I'm not even sure if that could be it, being that it runs so well in neutral.

Any suggestions, comments, questions, or revelations would be much appreciated.

Ed:helpsmilie:

At a guess, tight valves, or perhaps a torn rubber vacuum diaphragm in the carb if you run that sort (Keihin style, CVKs).

Also check coils. If failing, perhaps can't cope with faster firing rate as revs rise...

It has the Mikuni vm24sh carb. My buddy Will, has the exact same carb on his bike, so I will swap them out and see if it fixes it.

I will also look into the coil, that could be it, but hopefully it's just fuel.

Thanks

Ed

The ignition timing is meant to be set in the center of three lines with the induction timing light, at 4,000 RMP. it's actually set at the bottom line, not the center, so it's about 2mm's off. is that enough to cause it to do that?

Hey EAnchak. I battled the exact same demon on my 82 ts. All the symptoms were exactly the same as yours. It was damn hard to start cold yet seemed fine once warmed up. I could rev it past redline in neutral but as soon as it was under load it had nothing. When I leaned out my carb jetting it ran better, but still not right. Turns out it was the ignition coil. It was producing a spark, but it wasn't hot enough. Leaner mixtures burn hotter which is why leaning out my jetting helped. If you can swap coils with a known good one you can be sure. Good luck :thumbup1: !

As for the timing, it's better to under advance than over advance. Ideally though, it would be set so that at the fully advanced position (4000rpm on the 71 model?) the middle mark lines up with the mark on the crankcase. To adjust the timing, make a note of the distance by which it is off, then rotate the stator plate that same distance in the direction required to advance or retard the timing.

Suzuki state that to ensure perfect timing, users should line up the mark on the stator plate retaining hole with the corresponding mark on the side of the crankcase. This doesn't work for me though. Magneto air gaps increase, wires corrode and increase in resistance etc, etc. I just use the 'trial and error' method listed above.

That was the conclusion I was drawing nearer to (and dreading).

Do you know how to get to the coil?

I can't seem to figure out how to get the magneto cover off. There appears to be only one large nut holding it on, in the center. But it spins freely with the magneto. How do I hold the cover still, while I loosen the nut, or am I just going about it all wrong?

Since my last post, I've de-carbonized the head and piston, and everything makes it sound better at idle, so hopefully, if I replace the coil, I'll have a damn fine bike.

Please let me know if you can help out, as far as knowing how to do the job.

Thanks very much

Ed

Just saw your second post, and I have the same question as to how I can get the magneto cover off.

Ed

Wait, now that I've replied 3 times in a row on my own thread, I have another question.

Are you talking about the coil in the magneto for ignition, or the coil for the spark plug for ignition?

Not to sound stupid, but don't those have the same name.

:helpsmilie:

Ed

In my case it was the ignition coil that the spark plug and HT lead connect to (bolted to the frame underneath the fuel tank). To remove the magneto you'll need to select 5th gear, then undo the retaining nut. After that you'll need a flywheel puller. Before getting behind the magneto though, I would suggest that you try Will's ignition coil as his bike appears to be running well.

Will do (first thing in the morning).

I'll let you know how it turns out,

Ed

Ok, so it isn't the ignition coil. I put wills coil on, and it didn't affect anything :censored:.

I already pretty much ruled out carb, because I tried swapping wills carb with no change. I've done the spark plug, coil, carb, pei wiring, all new oil in the oil tank, the oil injection works, timing is very close to the mark (about 1.5 MM off), Compression is 122, and it runs.

The only new thing I've found is that in neutral it will go to the higher RPMs, but what I didn't realize until today was, it will still bog down at WOT (Wide Open Throttle). If I hold the throttle wide open in neutral, it will bog down and sometimes continue to run at about 1 grand, but very poorly. Same thing while riding, if I hold WOT in second, It will putter along, sounding terrible, at about 1 grand.

It does this at any mixture setting, with 2 different mikuni vm24sh carbs,

Could it somehow be trans? :hammer:

I am at a loss

Ed

Aaarrgghhh!!!!!! The ts185 ghosts are back! This was one more symptom of mine - ran great on a small amount of throttle, died on full. When this happened we blew compressed air on the inlet side of the carb while WOT and the revs picked up again. So it needed more air. But the carb settings were stock so we thought 'that's not right'. I was pretty convinced it was the new coil that fixed the problem. But i did change both crankshaft seals at the same time - perhaps it was that. When the crankshaft seals go, the crankcase sucks in extra transmission oil from the gearbox which doesn't burn as easily as two stroke oil. If more air is added to the mixture (compressed air) then the mixture burns hotter and is able to burn off the extra oil. WOT will cause the greatest suction in the crankcase so that might be why it runs fine on 0-1/4 throttle, but dies at full throttle. In saying that, it could still be electrical if there is some damaged wiring in or around the stator plate...i think this is a problem for NigelMark :helpsmilie:

So what you are saying is that it is engine rebuild time???

That could be fun, I guess.

I took a small engines class, but that was a while ago, do you know where I can get a repair manual that would cover an engine rebuild?

Is there any reason that you can't reuse the original piston, because I have good compression, and I wouldn't know what size to order because I don't know if mine is already oversize or not? I'd just as soon leave it in there.

I will do what it takes to be :mchappy::clap::thumbup1::mchappy::mchappy::mchapp y:

Ed

Well, I just made the order of all the parts I need to do the rebuild, unless anyone else has a better Idea of what on earth is wrong with my bike.

I got the magneto flywheel nut off, but soon realized that I don't have any idea where my flywheel puller is or if I even still have it, so I tested the leads coming out of the stator to ground, and the Ohms we're about 50 to much, but because they we're both too high about the same amount, I assume it's just from my unorthodox test and they are fine.

I have quite a few tools, but other than a piston ring compressor, and flywheel pulley, what other specialty tools do you guys think I will need to do the rebuild?