TW200 Help

[bullfrog]

Trying to get my wife's 1990 tw200 running properly.

It starts, idles and runs ok but the throttle response is crap.

If I twist the throttle quickly, the engine stalls/hesitates until I back off on the throttle.

When I twist the throttle s-l-o-w-l-y all is well.

I am at 3600' elevation.

1400 miles on odometer.

Jetting is stock (#114main #40pilot)

Pilot screw turned out 2 turns (turning it out or in more does not help)

Cleaned out the carb and all rubber bits are OK.

Cleaned out the tank and filled with fresh fuel.

Intake manifold and airbox boot ok.

Air filter clean.

I tried to check for an exhaust obstruction, but the muffler cap is seized and not removable without major damage.

Intake and exhaust valve clearance within specs.

What else should I be looking for???

[XR650Rocketman]

What about the plug?

Steve

[Greasemonkey]

Make sure plenty of fuel is coming out the fuel line..Those thing sometimes have carb trouble so make sure the jets are clear"for sure".You've probably done both but just inputing.Try with the air filter off.Don't remember if it has the vaccum line to the fuel petcock.It can leak fuel into the manifold or not allow the petcock to work..Plus what he said.
Good luck!!!

[bullfrog]

New plug...forgot to mention.

No vacuum diaphram @petcock.

Same problem with air filter off.

New main jet and all other passages/orifices cleaned with carb cleaner and compressed air.

Yeah...it's got me stumped...

[TxSandman]

fuel tank vent clogged?

[thumper]

Originally Posted by bullfrog

New plug...forgot to mention.

No vacuum diaphram @petcock.

Same problem with air filter off.

New main jet and all other passages/orifices cleaned with carb cleaner and compressed air.

Yeah...it's got me stumped...

If it has it's power when you roll it on easy, then you've got good spark and you're CDI box isn't trashed. [That's good]

You've cleaned the carb,and you checked the intake for cracks or leaks?Are you sure there's not a leak. That's what it sounds like. Very common for that age bike that's been sitting up.

I'd fire it up, warmed up, and barely fog the air filter w/ ether. If it rolls right through then it's getting too much air. Diaphram torn, air leak, dirty jet?

[bullfrog]

Originally Posted by thumper

If it has it's power when you roll it on easy, then you've got good spark and you're CDI box isn't trashed. [That's good]

You've cleaned the carb,and you checked the intake for cracks or leaks?Are you sure there's not a leak. That's what it sounds like. Very common for that age bike that's been sitting up.

I'd fire it up, warmed up, and barely fog the air filter w/ ether. If it rolls right through then it's getting too much air. Diaphram torn, air leak, dirty jet?

Just checked intake boot.

At idle, hose down the boot on all sides w/ carb cleaner....nothin.

The only diaphram on the bike is a small decel enricher diaphram on the side of the carb.
http://www.ronayers.com/fiche/501_15...0&parent=28460

You think carb cleaner would do the same thing as ether with your fog the air filter trick??? (no ether in the garage...)

I am trying to upload a couple of videos right now so you can hear what's going on...

standby.

[thumper]

Originally Posted by bullfrog

Just checked intake boot.

At idle, hose down the boot on all sides w/ carb cleaner....nothin.

The only diaphram on the bike is a small decel enricher diaphram on the side of the carb.
http://www.ronayers.com/fiche/501_15...0&parent=28460

You think carb cleaner would do the same thing as ether with your fog the air filter trick??? (no ether in the garage...)

You could try it but nothing works better than ether. Also, I've seen people mist fuel right into the carb while rolling on the throttle. If it responds better then your getting to much air. I don't think fuel or spark is your problem. Otherwise it would bang out, pop, or just run out when you bring it up easy. Be careful w/ the fuel. Remember it'll melt through a spray bottle in a few minutes. Keep a wet towel around in case of a backfire!

[bullfrog]

Hey TIM!!!

you sure are on the ball with this stuff...

my videos are takin F O R E V E R to download on google video.

PM me your email address and i'll just mail 'em directly to you so you can give me your opinion.

-------

Just had a brainstorm...

17 year old bike w/ only 1400 miles.

Muffler cap/spark arrestor seized/rusted in place.

In other words, 17 years of VERY short rides = lots of moisture in the muffler didn't get cooked out.

Maybe the spark arrestor screen/mesh/whatever is scaled up and causing some restriction???

I can't get the cap off, but I ain't scared of removing the whole muffler and trying it out???

Worth a try or waste of time???

[bullfrog]

Nevermind on the email, Tim...here's the videos:

http://video.google.com/videoplay?do...17216236622332

http://video.google.com/videoplay?do...77494918252134

[thumper]

Originally Posted by bullfrog

Hey TIM!!!

you sure are on the ball with this stuff...

my videos are takin F O R E V E R to download on google video.

PM me your email address and i'll just mail 'em directly to you so you can give me your opinion.

-------

Just had a brainstorm...

17 year old bike w/ only 1400 miles.

Muffler cap/spark arrestor seized/rusted in place.

In other words, 17 years of VERY short rides = lots of moisture in the muffler didn't get cooked out.

Maybe the spark arrestor screen/mesh/whatever is scaled up and causing some restriction???

I can't get the cap off, but I ain't scared of removing the whole muffler and trying it out???

Worth a try or waste of time???

Definetly worth messing with! But I wouldn't go tearing things apart just yet. I watched the vids and either it's getting to much air or the pipe has a restriction.

I would ride, roll it on in 1st and let it decelerate a few times. If things don't improve, I'd ride it hard, hold it steady and see if it'll blow out. Otherwise if ether doesn't work then that theory is dead and I'd tear into the exshaust.You can pull the muffler, but don't run it w/o the pipe [you'll burn up the exshaust valve real quick.]

[bullfrog]

Originally Posted by thumper

Definetly worth messing with! But I wouldn't go tearing things apart just yet. I watched the vids and either it's getting to much air or the pipe has a restriction.

I would ride, roll it on in 1st and let it decelerate a few times. If things don't improve, I'd ride it hard, hold it steady and see if it'll blow out. Otherwise if ether doesn't work then that theory is dead and I'd tear into the exshaust.You can pull the muffler, but don't run it w/o the pipe [you'll burn up the exshaust valve real quick.]

Right on...I'll try it out in the morning.

I REALLY appreciate your insight and help.

Next time you go to Ruidoso to see your folks, give me a shout and I'll feed you a beer...

[thumper]

Originally Posted by bullfrog

Right on...I'll try it out in the morning.

I REALLY appreciate your insight and help.

Next time you go to Ruidoso to see your folks, give me a shout and I'll feed you a beer...

[bullfrog]

Had to go ahead and check the exhaust.

Spent about an hour with a deadblow hammer, brass punch, and a torch and finally wrestled the end cap/spark arrestor off of the muffler without any damage.

I took the muffler off the bike and tapped the end on the concrete.

A pile of WET coarse rust scale came out in a big pile.

Wet...with water.

All clumpy...

Looked like rusty saturated kitty litter.

Got about a Skoal can full out of there.

There is a 1/2" inlet hole in the muffler bottom and one in the top.

The bottom one was plugged up with the wet crap and the top one had a lot of dry scale.

I think I got it.

There is about a tablespoon of loose scale settled in a low bend toward the end of the headpipe that I will blow out in the a.m.

I'll put it all together and check it out.

But I think I got it.

Thanks for all the advice....

[Jack Giesecke]

Originally Posted by bullfrog

Trying to get my wife's 1990 tw200 running properly.

It starts, idles and runs ok but the throttle response is crap.

If I twist the throttle quickly, the engine stalls/hesitates until I back off on the throttle.

When I twist the throttle s-l-o-w-l-y all is well.

I am at 3600' elevation.

1400 miles on odometer.

Jetting is stock (#114main #40pilot)

Pilot screw turned out 2 turns (turning it out or in more does not help)

Cleaned out the carb and all rubber bits are OK.

Cleaned out the tank and filled with fresh fuel.

Intake manifold and airbox boot ok.

Air filter clean.

I tried to check for an exhaust obstruction, but the muffler cap is seized and not removable without major damage.

Intake and exhaust valve clearance within specs.

What else should I be looking for???

Pull the main and pilot jets out and rod 'em out with a torch tip cleaner or small wire of some kind. Make sure they're completely clear of any varnishing from rotten gas. It's not enough to just shoot carb cleaner through 'em.

Is it a pumper carb, have an accelerator pump? Probably not, but if there's a pump on it, check the rubber in it, make sure it's pumping.

The jetting MAY be a little fat at 3600 feet, but normally jetting starts screwing an engine up at much higher altitudes, 6000-8000 feet and above. But, if the carb is clean, the jets are rodded and there are no obstructions, you might try a smaller main jet, see how it responds. You can also play with needle height, but that's a subtle effect.

My guess is you didn't get all the crud out of the jets, main and/or pilot, because it sounds like it's leaning out to me which would be the opposite of what would be happening at high altitude. However, it could be loading up, caused by fat jetting at higher altitude. Just 3600 feet, though, I'm thinking it's leaning from pluggage that wasn't removed from the jets.

If you don't get ALL the gum/varnish out of a jet, just a little layer in there will affect jetting, lean it out. Sounds like this is what's happening. I use a tip cleaner working up in size until I get the jet rodded out. Works great on small engines. Problem with small motorcycle engines, the jets, especially the pilot, is often so small it's hard to find a wire size that will fit it and rod it out. Sometimes you're better off just replacing the jet. Any amount of pluggage is too much, like I say. While the jet may LOOK clean, I've seen 'em with varnish around the jet leaning it out and it sure sounds like it's leaning by your description.

My $02 not being there to play with it.

Oh, an exhaust obstruction will choke the engine down at higher RPMs. It won't "lag" on throttle, it'll just choke down and not run well in upper RPMs. I have had to clean dirt daubers out of small exhausts before that have sat up in barns. One little 50cc Suzuki moped I soaked the pipe in water in a number 2 wash tub and ran a garden hose in it to get the nest out. This can definitely cause problems, though.

[Tracker]

took me two tries to get my carbs clean on my Speed. In the future, I'm getting out a magnifying glass and inspecting everything.

[bullfrog]

Alright, Jack Giesecke wins the prize...

I will need to feed you a beer next time I am in/around Port Lavaca.

After all the stuff that I did...(I am glad that I cleaned out the exhaust though)

Guess what the main culprit was???

The was some very slight varnish built up on the tip of the pilot screw....


Grrrrrr...

How frustrating....

Thanks a lot for the help guys.

[Jack Giesecke]

My pleasure. I didn't click on this thread until I was PMed by Tim (thumper) to check it out. Sorry I didn't get in on it quicker. I clean carbs for a living, buy gum out by the case. Seriously, EVERY FRIGGIN' SPRING the mowers, trimmers, bikes come in and smell up my shop with rotten gas. STABIL, PEOPLE, GREAT STUFF! I shouldn't gripe, it's easy money.

[bullfrog]

I guess I need to feed Tim 2 beers now.

I really appreciate you pointing me back to the pilot circuit and your logic behind using my tip cleaners in the jet.

When I shot carb cleaner through I noticed that there was a weak spray pattern coming out of the venturi side pilot hole with the pilot screw installed....I asked myself, "What Would Jack Do???"

Jack would find out why...

That's what I did...

Tah Dah!!!

[X1Glider]

At WalMart, you can buy a jewelry ultrasonic cleaner for about 10-15 bucks. Usually you would just add water. But these things work great for cleaning small bike parts. Just put the appropriate cleaner in it for carb parts or injector needles. Even valves. Hint: never use it again for jewelry after you add a caustic solution to it.