[Whippet]

So I bought a 2004 TW about 4 months ago. It had about 800 miles on it when I bought it and now has 1500 miles. It seemed to run fine in the beginning and now idles poorly, hesitates on the top end, and leaks gas out of the carb hose. I ran a tank of carb cleaner. No real improvement. The air filter is clean. The air filter hose had some oil in it. From what I have read on forums and such I'm guessing the problem is a "stuck float"..not really sure what that means..or a petcock problem...you get the picture. I've heard these terms pointing me in this direction, but I don't know where to go from here. Should I run another tank of carb cleaner, "try" and disassemble and clean...will I know what to replace when I see it?, or take it to a mechanic? My experience with mechanics is that they "see me coming" and take me to the cleaners. I'd like to get to know the basics of service and repair but...



I know nothing when it comes to fixing stuff...I'm a master take-it-aparter, but then I just look at it and don't know what to look for. Putting it back together is always a challenge so I have not attempted with the TW.



Any suggestions or diagnoses? I'm in SLC, UT if anyone knows of an "honest" mechanic.



Thanks in advance for any help.

 

[vuldub]

Don't really know how to answer. If you're not sure you want to tackle the carb, then maybe you shouldn't. That said it's not the most difficult thing to remove and clean. Get a carb kit, follow the repair manual - there lots of useful info if you search for it. Putting it back together right is most important. Before you rip into the carb investigate some other possibilites first:



When you say it leaks gas out of the carb hose, which one and where - is it just a weak hose clamp?



Idling problem are not usually related to a stuck float - that usually manifests as a fuel dumping problem on acceleration or a lack of fuel acceleration (hesitation).



Take the spark plug out and look at it - is it nice tan brown like it should be? Or wet or sooty? That helps diagnose issues with the fuel input.



How about the lean/rich fuel mixture screw that is hidden behind a brass cap that Yamaha puts on to prevent us from messing it (emissions issues). Search the old forum for how to remove the plug and adjust the screw.



Did you try Seafoam in the gas tank? I have had good success with Seafoam on my older bikes.

 

[jbfla]

Wes has some good suggestions.



I'd try the Seafoam first (available at Walmart or most auto parts stores), and hope that works.



The usual amount of Seafoam to add is one ounce per gallon for preventive maintenance. For a clogged up carb, I use half a can (8 oz) per tank (1.7 gal).



It takes some time for Seafoam to do its work. Run the engine 5 min.,then let it sit for 20-30 min, then repeat. Or if the bike is running, go for a ride. Do the same thing for a couple days, and see if there is any improvement.



If not......... this is what you are up against:

I'm certainly no expert, but have taken apart and cleaned my carb more times than I care to. My bike sits for several months at a time, and when I forget to drain the carb before storage, it's time to take it apart again.



For me the culprit is the float valve needle, part 25, the bottom part in the above diagram. To get to it the float needs to be removed.... very carefully.



However, this may not be your carb's problem...For me carb work is a lot of trial and error.



If you are not comfortable doing that, call or go in to your Yamaha dealer, or independent, and ask how much it would cost to clean and adjust your carb. You can always say no.



Next time I clean my carb I will try to remember to take photos... although I hope it won't be too soon.



Good luck.



jb

 

[jbfla]

Here's a article about using Seafoam in a motorcycle:



Seafoam Article from WebBikeworld



You can tell it's an old article, the author bought a can of Seafoam for $2.99. These days it's closer to $9.



There are some naysayers about the Seafoam's effectiveness. My experience with it has been positive.



jb

 

[Whippet]

I put some Lucas in today and ran 1/2 tank. It seems to be doing much better performance wise. I think I'll run this tank out tomorrow then put in some Seafoam and see how that goes.



Thanks for the advice guys!

 

[Snake2715]

Let us know how it turns out.



I have a question and dont want to hijack, but that pic is great help.



Does anyone know if we have a sticky or thread that covers the basics on the carb?



In looking at two bikes I noticed that the older one my buddy is looking at, has a cap on the rubber boot between the carb and head... I am confused as to where that hose goes, as I can see it go under the gas tank on my bike.



Also I want to look into adjusting the possible lean ness of the bike as well due to the many people saying they come way too lean from the factory.

 

[srs713]

In looking at two bikes I noticed that the older one my buddy is looking at, has a cap on the rubber boot between the carb and head... I am confused as to where that hose goes, as I can see it go under the gas tank on my bike.

I believe we found that the hose is called a "resonator" somewhere. It just goes up and terminates under the tank, not connected to anything.



A hose between the carb & cylinder would have vacuum. Maybe the engineers were originally thinking of using a vacuum shut-off on the fuel petcock. Like my '80 850 had.

 

[Whippet]

I had a friend take the carb out and clean it. He said I had a "really big main jet". I didn't get the number off it before he put it back together unfortunately. The carb itself looked very clean inside, but there was crud sticking in the float needle. It ran really well in the valley at 4000-5000 ft elevation. I took it up the canyon and it had issues (lack of power, stalling, hesitating) again at 7,000 ft and higher. Seemed to run better again in the valley. I commuted the other day and left the gas line very slightly past closed toward reserve and came back to a puddle of gas. I barely got it started and barely made it home. Stalling, etc. Let it sit a few days and took it for a spin today to run into the same issues down in the valley. I made it home, but now it sits again. I took out the spark plug...not sure why...just to "see". It's only about a 100 miles old and it was dry and black. Is that "normal" or is this is clue?



Have I narrowed down the problem? I willing to go to a mechanic now, but I'd still like to have a good idea of the potential problem.



Thanks again for the suggestions.

 

[migopod]

Dry black plugs indicate an overly rich mixture. Going from easy to not as easy, check your air filter. A dirty air filter reduces the airflow and leads to a mix too rich in fuel. Then check the carb main jet size against the stock part. You might wind up wanting to do that anyhow, since the puddle of gas suggests your float valve is crudded again or that your friend mis-set the float height when doing you carb before. Also if your float valve is re-crudded, you'll probably want to get an inline fuel filter to prevent it from happening again.

 

[qwerty]

The stock main jet on a 2004 is a 125 if a 49-state model or a 128 if a California "C" model. A 132 is also available. If you are riding at 5000 to 7000 feet or higher you'll want the 125 jet as altitude causes a richer mixture. You may find E10 works better than straight gasoline with your black plug at 7000 feet.



p.s.: If your carb is leaking while sitting it is messed up. The only times I turn Tdub's petcock off is when I'm removing the tank or hauling her somewhere. Otherwise, she never leaks a drop.

 

[Whippet]

Thanks for the advice. I'll have the carb and jet checked out.

 

[Whippet]

Qwerty...I got a question for you. I went looking for old posts related to lean/rich mixture and jetting and came across one of your posts.



"Centerline, why didn't you bring your TW over for a carb tune. I have both the genuine Yamaha jets for other TW models with the same carb and needle spacers. It only takes 15 minutes and it isn't necessary to remove the carb.



Have you done the pilot screw adjustment?



Everyone keep in mind that U. S. of A. bikes are intentionally jetted lean from the factory to appease the EPA treehuggers. This causes all sorts of nasty habits, like off-idle and midrange throttle response problems, high engine temperatures, surging at sustained cruise, etc. A good carb tune will find seat-of-the pants increases in low speed and mid range torque, throttle response, and smoother cruise operation. There will be a slight loss in fuel efficiency, though.



Beware any air intake mods that lower the air intake. If you want to dualsport with the rest of us DFWers sometime you'll need all the intake height you can get on some of the water crossings."



So my question is if I go back down to a 125 jet (assuming at this point I have something bigger...I think I have a California model) am I going to trade one set of problems for another. Other posts on the old thread discussed going to a 130 or higher to get more power. My problems at elevation seem to be jet or lean/rich issues.



If I understand your advice, my gas leak is likely unrelated to the lean/rich issues and possibly related to a bad gasket on the float bowl...possibly? The leak seems to be in that vacinity making my overflow hose shiny on the outside.



Sorry for all the questions. I'm a total noob, but this is helpful so at the very least I can use the right lingo and know what to ask the dealer to fix or check for.



Thanks again

 

[qwerty]

A bad float bowl setting can cause rich running and fuel leaking. So can a worn needle or seat, a stuck needle or float, and gunk beteen the needle and seat.



The first thing that needs to be done is to repair the carb. Tuning will do no good at all if the carb isn't to spec.

 

[Snake2715]

Thanks Srs

 

[qwerty]

de nada