TW200 Forum banner

1 - 20 of 46 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
Okay, I messed up very badly and left the tank on for months of sitting, yeah with ethanol fuel (although I did have a stabilizer in it). Eventually, the bike (2009 w/ 1500 miles) wouldn't even start. I pulled the carb and found all manner of crud in it: brass corrosion, tars/sludges, films all over everything. Most of the jets were completely blocked with green crusty corrosion.



I used spray Gumout and cleaned everything up as best I could, but it didn't faze the green stuff. So I (very carefully) used fine wires and even tiny drills to clean out the brass orifices. Only got green crud, never any brass shavings, so I'm pretty sure I didn't damage or enlarge any ports.



At first, the bike ran great but just wouldn't idle. Took it apart again and found that the pilot jet was clogged, and a small tube that projects down into the float bowl was also blocked. Cleaned those out carefully drill/wire.



Now, the thing is running super-rich like flooded all the time. Won't idle and barely runs, missing and 8-stroking. I've triple-checked the float level, while running, and it's fine, so I know the bowl isn't doing the flooding. I don't understand enough about how this carb works to figure out where the fuel is getting sucked through. I've screwed the pilot screw adjustment all the way closed without any discernible effect.



I'm just about ready to pop $400 for a new carb to get out of this mess. Any suggestions or ideas?
 

·
Registered
Joined
·
374 Posts
Okay, I messed up very badly and left the tank on for months of sitting, yeah with ethanol fuel (although I did have a stabilizer in it). Eventually, the bike (2009 w/ 1500 miles) wouldn't even start. I pulled the carb and found all manner of crud in it: brass corrosion, tars/sludges, films all over everything. Most of the jets were completely blocked with green crusty corrosion.



I'm just about ready to pop $400 for a new carb to get out of this mess. Any suggestions or ideas?


Ouch! Don't spend that much though. I found them for as low as $268 new http://www.2wheelpros.com/oem-parts/2012-yamaha-tw200bc1-carburetor-assembly.html?partnum=5FY-14301-00-00 and several in the $270 range. Afraid that might be what's going to be needed though. Sounds bad. Damn alcohol attracts water.



 

·
Registered
Joined
·
20 Posts
Discussion Starter #3
Hey thanks for the pointers. Right now, I'm in trouble for beginning a trip on time. Most places want a week to ship and a week in transit, ugh. Can't find anything local cheap, that's where the $400 comes from (dealer/tax/shipping gag).



I'm soaking the carb in Berryman's right now, but I don't expect any change; the carb body itself is not really that badly gummed up, it's mostly the brass fittings. And I don't expect the soak to get rid of any unseen corrosion, that stuff is like epoxy.



My worst element in all this is not knowing exactly how the carb sub-systems work. All those little passages are a bit mysterious as to how they are supposed to function. I can't find any way for extra gas to get into the engine, at idle, except for the "choke" (enrichment knob) and the coaster plunger/diaphragm. Both of them seem to be in great shape, but again, I don't know EXACTLY what kind of clearances etc. are needed for them to be working right.



Big hint: Originally after I cleaned the carb, the bike would not idle, just either race or die with no predictability. Took it apart the Nth time and found the pilot jet clogged. Then AFTER I cleaned the pilot jet is when it started to run super-rich. I'm thinking, even if I enlarged the jet slightly/unintentionally, it wouldn't account for HORRIBLE running, just maybe a tad on the rich side. So I'm still stumped, don't know for sure if the carb is still gunked up some secret place, or if I damaged something in my amateur cleaning efforts.
 

·
Registered
Joined
·
374 Posts
Hey thanks for the pointers. Right now, I'm in trouble for beginning a trip on time. Most places want a week to ship and a week in transit, ugh. Can't find anything local cheap, that's where the $400 comes from (dealer/tax/shipping gag).



I'm soaking the carb in Berryman's right now, but I don't expect any change; the carb body itself is not really that badly gummed up, it's mostly the brass fittings. And I don't expect the soak to get rid of any unseen corrosion, that stuff is like epoxy.



My worst element in all this is not knowing exactly how the carb sub-systems work. All those little passages are a bit mysterious as to how they are supposed to function. I can't find any way for extra gas to get into the engine, at idle, except for the "choke" (enrichment knob) and the coaster plunger/diaphragm. Both of them seem to be in great shape, but again, I don't know EXACTLY what kind of clearances etc. are needed for them to be working right.



Big hint: Originally after I cleaned the carb, the bike would not idle, just either race or die with no predictability. Took it apart the Nth time and found the pilot jet clogged. Then AFTER I cleaned the pilot jet is when it started to run super-rich. I'm thinking, even if I enlarged the jet slightly/unintentionally, it wouldn't account for HORRIBLE running, just maybe a tad on the rich side. So I'm still stumped, don't know for sure if the carb is still gunked up some secret place, or if I damaged something in my amateur cleaning efforts.
All that "green gunk" is transformed brass, therefore, there is some metal loss, albeit very small, simply due to the corrosion. Removing the gunk may alter the size/shape of the various orificia, thus altering the function of the carburetor in mysterious ways. If you can wait a day or so, you might be able to get a carb for $243 + overnight from http://www.boats.net/parts/search/Yamaha/Motorcycle/2009/TW200 (PURPLISH WHITE SOLID 1) - TW200Y/CARBURETOR/parts.html - worth a call since your dealer is talking shipping too. Best of luck, sorry I can be of little REAL help.
 

·
Registered
Joined
·
374 Posts

·
Registered
Joined
·
2,409 Posts
The Berryman's should work fine. Let the carb body soak overnight.



Then rinse in clean fresh water. Use a compressor with an air hose to blow out all the passageways.



Be careful not to lose the rubber plug when you use the air hose.



If you weren't in a time crunch, you could overnight it to me and I could run it through the ultrasonic cleaner... That would be cheaper than a new carb.



Jb
 

·
Registered
Joined
·
20 Posts
Discussion Starter #7
UPDATE Sunday afternoon.



Thanks again for the leads/pointers. Yes I had seen the stickies, they're VERY useful.



Well, the Berryman's is truly awesome stuff, even got rid of green corrosion. Carb looks squeaky clean, and air flows through every hole I could find. I put fresh gas in the tank. BUT - - no change in the engine performance. It's running so rich it barely operates; plug turns solid black in about 10-15 seconds of operation. Pilot screw is fully turned in (OFF). Pulling the choke in/out has very little effect.



I don't believe I'm dealing with a plugged up passage now, I think I've got some pathway to fuel open that is normally not supposed to be. The only enrichening circuits I'm aware of are the choke plunger and the coaster plunger. Both of them are snug-but-not-tight fits in their respective bores. The coaster bore has some minor scratching/scuffing in it from when I removed the corroded plunger, maybe gas is getting past there? For troubleshooting purposes, is there a handy way to defeat the coaster circuit? I'm thinking of just taking it off for a trial rev. Maybe it's the culprit and pouring fuel past the plunger? For sure the engine is not making enough vacuum to overcome that spring.... I wonder what would happen if I just put some fuelseal on the plunger to prevent any bypass.....
 

·
Registered
Joined
·
1,619 Posts
I've had good luck with the spendy stuff. It will not attack plastic or rubber components. It's water based so you can fill a cheap ultrasonic cleaner with it and go to town. Or let it soak overnight.







if you are in a hurry to clean then try this recipe at your own risk with the cleaner pictured above



For really gummed up carbs, where they are going to have to come apart,

mix the carb cleaner 50/50 with water, put the carbs-or parts-in a can,

cover them with the mixture, and heat it to an “almost” boil – surface

should be barely rolling. Let them cook for approx. 15 minutes, then

rinse the parts in fresh running water, and blow dry with compressed

air. Check the bodies and bowls to make sure all the small passages are

clear, and soak them a bit longer if they aren’t.









I've read this warning about Berrymans...

Notice: You have to keep all rubber and paint well away from it (including rubber o-rings, diaphragms and seals). Hard plastic parts won't be affected.



The Berryman website warns "We do not recommend this product for cleaning of rubber or plastic parts. Any non-metal cleaning needs should be tested prior to actual cleaning to check for compatibility."







The Legendary original solvent based yamaha carb cleaner. This stuff is like gold if you can find it....



 

·
Registered
Joined
·
374 Posts
I've had good luck with the spendy stuff
I think he wants to add a bit of varnish to his plunger. Good luck brother, I sincerely feel for you, especially the rush to get on the road.



Everything in a carb is really tight and orifice size is critical. It doesn't take too much of a change in size of the wrong orifice or wear on a slide to get too much fuel to the combustion chamber. Bummer!
 

·
Registered
Joined
·
2,409 Posts
UPDATE...

I don't believe I'm dealing with a plugged up passage now, I think I've got some pathway to fuel open that is normally not supposed to be. The only enrichening circuits I'm aware of are the choke plunger and the coaster plunger. Both of them are snug-but-not-tight fits in their respective bores. The coaster bore has some minor scratching/scuffing in it from when I removed the corroded plunger, maybe gas is getting past there? For troubleshooting purposes, is there a handy way to defeat the coaster circuit? I'm thinking of just taking it off for a trial rev. Maybe it's the culprit and pouring fuel past the plunger? For sure the engine is not making enough vacuum to overcome that spring.... I wonder what would happen if I just put some fuelseal on the plunger to prevent any bypass.....
I agree. The carb is clean. I believe it's a mechanical problem... A missing part? A part improperly installed?



The only circuit that dumps a large amount of fuel is the choke/enricher circuit. I wouldn't mess with the coaster circuit.



jb



I sent you a pm.
 

·
Registered
Joined
·
2,516 Posts
This is a quick thought without reading all of the above......check the float,it is moving properly,set correctly?...hanging up?.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #13
UPDATE Sunday evening



In no particular order:

Float level has been checked multiple times, including while-running.

Missing parts? I've been over and over the exploded diagram, and everything there is accounted for.

Wear on a brass jet might cause it to be oversized, but not to this extent. However, the plungers are something else entirely.

I have some concern, difficult to quantify, for the brass-slug-in-aluminum bore situation. The brass parts were significantly corroded, and getting them out of their bores may have caused unacceptable scoring/scratching of the bores. Very hard to tell about this.



Another thing that haunts me is whether I made either the pilot jet, or the funny little tube the projects down into the float bowl, too large when I mechanically cleaned them out. I was diligent about looking for brass metal, and I found only green crud - - but who knows for sure. I do not see any bright brass in either part, they seem okay(?)



The last thing I tried by way of experiment was removing the coaster circuit, and then the choke plunger. No effect with the choke circuit.

The choke plunger opens up a huge 5mm hole directly downstream of the butterfly. Interestingly, with this enormous air lead, the engine ran fabulously well and at a high rev point. I found I could adjust the speed just be holding my finger NEAR the open choke mounting hole. The butterfly was completely closed (idle screw backed out), and the pilot screw was completely closed. This says there's just a HUGE amount of fuel getting to the downstream side of the butterfly (and leak enough air to compensate it and the engine runs fiercely). But from where and why is still a mystery. There are only three ports that open downstream from the butterfly: choke, idle bleed, and coaster enrichment. And the idle bleed is shut off tight via the adjustment screw. No other places that I can see for fuel to get through, given a closed butterfly.



>> Something else that has occurred to me a few times: the little rubber plug that closes a passage in the float chamber. The only thing in that passage is a pressed-in brass tube, and I don't know its function. The rubber plug is tired and loose but I don't have a replacement, so I gooped it with fuelseal and it seems to be snug. It's kept in place by a small protrusion from the bottom chamber, so I know it isn't coming loose. But maybe some fuel is being pulled past it? and to where? Again, very hard to tell.



Frankly, I don't have a big problem with popping for a new carb - - I just hate not understanding what's going on. Life-long engineer's attitude.
)



If I can think of anything else tomorrow (Labor Day), I'll try it. Otherwise, I'll order a new carb on Tuesday.
 

·
Registered
Joined
·
326 Posts
Aren't the new carbs cv? Diaphragms ok?



I would replace the jets and such before I went new carb on it.



Have you checked your airbox? Make sure a rat didnt make a nest or a gremlin or somethin'
 

·
Registered
Joined
·
2,409 Posts
Have you checked your airbox? Make sure a rat didnt make a nest or a gremlin or somethin'


I was thinking the same thing. A rich carb may not be caused by too much fuel, but by not having enough air.



jb
 

·
Registered
Joined
·
20 Posts
Discussion Starter #16
Long shot but I tried it - - airbox is clean, no effect (louder tho).

Unfortunately, my local shops don't stock the brass parts - - so I'm faced with waiting as long for parts as for a carb. Then if that doesn't work I wait for a carb too. I'm due to leave in 8 days, so this becomes the swing factor in decision-making.



Any and all thoughts are welcome, no matter the extreme. I've got another day (holiday no buying/shipping) to mess around and then it's game time.



Current thought: there's obviously substantial vacuum at the butterfly when the engine is running, typically 25 inches or so (around -11psi). So this is plenty of "suck" to pull fuel in. But with the butterfly closed (and upstream of the butterfly is the wide-open intake tract), there SEEMS to be only one place for fuel to get through, and that's the idle port (the one with the adjustment screw in it). I've pretty much ruled out the choke and coaster ports by previous experiments. BUT, dang, the idle port is closed off with the adjustment screw. So MAYBE the fuel is coming from just upstream of the butterfly, through those 4 tiny holes on the intake side. What are these for? Where do they connect? What passage/jet controls their flow?



When I air-tested all the passages, air would come out the idle port and the quad-port group at the same time. So they are in some way connected. Probably to the pilot jet, but I forget what I saw. Anybody familiar with this level of detail? So if fuel is being pulled in volume through the quad-port, then the pilot jet (which I drilled out) must have ended up with WAY too big a hole in it. But as I've said, I triple-checked to be sure I wasn't taking any metal out of it.



That's all I can think of for now.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #19
Well, my wife's pretty much up on things, seeing as how I've spent the last 2 days in the garage and driveway cussing like a longshoreman.







Anyway, she rides on the back while we are traveling, so she wants it running too. Otherwise we're stuck at camp with the RV -- not a disaster, but we're kinda spoiled.
 

·
Registered
Joined
·
7,051 Posts
My experience on the earlier model carb. that ran rich was with a jet that the hole had corroded making it larger.



The new #114 jet on the left, you can see the hole is smaller than the old #114 jet in the middle, but I didn't know that until I bought the new jet and compared them. On the right is the #116 jet that came in the POS ebay kit which I still have and never used. Point being if you don't have new, uncorroded parts to compare to the corroded parts you will never know how much things have changed.



I have posted this picture before but I think it is worth seeing again in light of your troubles. BTW, it runs GREAT with the new jet.



Where in Calif.. are you?



 
1 - 20 of 46 Posts
Top