Paging carb guru Eddie… please pick up a white courtesy telephone

Noob to TT, but been around the block. Just bought an '89 XT350. Searched the interweb high & low and all of the experts have different theories on how to make this beast run better. I'm so confused. I know this XT350 carb thing has been beaten to death, but I do not want to screw up these sacred carbs trying to alter something I know nothing about.

My bike specs;

1) All stock, well used XT350 with 4500 on the odometer (probably not accurate).

2) Unmolested factory airbox with new filter.

3) Stock exhuast with baffle removed? (hole big enough to shove a banana in :smirk:).

4) New battery.

5) Bike starts up easily.

6) Bike runs like a dream at 2500-3000 rpms.

7) Won't go over 55mph.

8) Won't idle, stalls at stop lights unless you feather/stay on throttle.

9) Only runs with choke fully on.

10) After riding it for a couple miles/extended period of time, leaks fuel. Looks to be half an ounce to a full ounce, then stops.

11) I live at 7100' in Southern Colorado and will do a majority of my riding at around 6500' to 7500'.

I want to get this bike back to it's original factory state of operation. Not trying to get yz450 performance, just solid reliability and idle. I've read all sorts of "tips" from drilling out the cap screw and backing out the mixture screw 2-4 turns, drilling out the main with a #77 bit, shimming the needle with washers made for an rc car, using XT600 jets, buying a new stator, etc. Why Tatsujin Yamaha had his ninjas build this carb set-up in the secret basement is beyonnd me, but I know that set up right it works flawlessly.

I am not a carb guy. I am moto-capable (as opposed to a motard? :smirk:). Your thoughts and insights would be appreciated! I had a banshee of the same year. The twin carbs where a constant battle to keep the Banshee even ridable. My solution was one of those 2 into 1 manifolds and a 34mm carb. It appears that the top end on the XT350 would be out of the same parts bin as the top end on the (350) Banshee. I will explore this option further as once I converted the Banshee, it had so much low end pull that it was a blast going up sand hills! Anybody have any thoughts or know of any research done on this?

I have heard of this mythical torque coming from the XT350, but I have not appeased the enduro gods enough to experience it. Since I want this bike to be a primarily around town & Jeep road fun bike, I want it to run like a new bike hence the effort.

Thanks for any and all help!

sounds to me as simple as the pilot jet is plugged up.

Thanks for the fast response. Stupid question, but how do I go about rectifying this? Where is it located? Main carb, remove the ____ to get to it? Clean it out with?

Thank you!

Edited by yzergod

Remove the pilot, replace it with a new one.

Check the adjustment of the secondary per the shop manual.

Ensure the slide diaphragms are sound and that there has not been any changes made to them (holes drilled) or needle shimmed.

Thanks Will. Now, what is this pilot and manual you speak of? :smirk:

Seriously, without a manual (looking at Amazon now), how to I get to and clean the pilot?

Ah, now that is a question!

To work on your bike, you really have to have a service manual. There may be copies on PDF floating about on the web. It will show you the location of the pilot and the proper setup on the secondary.

To get to the pilot, you have to remove the float bowl. I rec. removing the carb from the bike.

Remove the seat and fuel tank

Loosen the clamps from the carb to the manifold, and the carb to the air boots.

Pull the airboots off completely

Remove the throttle cables

Pull the carb assy.

Using an impact driver, loosen the float bowl screws on the left carb.

The jet in the center is the main, to the back is the starter jet, to the front is the pilot.

Buy a new pilot, do not bother to try to clean the old one.

OK, will search for this elusive pdf version. Anybody have a pic of just the carb diagram? Google was fruitless. EDIT: found it!

Also, assume that the local stealership can get the pilot or is there a better place you know of?

Also, any thoughts about the 2 into 1 manifold idea? Or am I wacky on the juice?

Edited by yzergod

Wow, checking out the SSW and Epic sites and now I wonder if I should fix and sell the XT and looks for a DZR400!

Eddie, if I brought it to the Springs, could your shop make it right?

On a sepperate note, was already looking into hitting the Pikes Peak Hill Climb at the end of the month. Now, I might have to make it a must do!

OK, will search for this elusive pdf version. Anybody have a pic of just the carb diagram? Google was fruitless. EDIT: found it!

Also, assume that the local stealership can get the pilot or is there a better place you know of?

Also, any thoughts about the 2 into 1 manifold idea? Or am I wacky on the juice?

No, that carb unfortunately is extremely unique and other than the dealer, parts are all but invisible.

Doing a 2-1 manifold creates its own problem due to the length needed to make the split and turns smooth.

im north of denver in longmont.

im north of denver in longmont.

Sorry Eddie, assumed that since your shop was doing the hill climb, you were in the springs.

I pulled the carbs out today and pulled the jets and cleaned everything with carb cleaner. I took the pilot and ran a staple into it to clear out all of the little holes. The one in the center of the jet was too small to run the staple through but I could see daylight through it. Better but still is too unstable at idle. It just doesnt want to stay smooth at about 1500 and will die if I don't either keep blipping the throttle or pull the choke out. The seals from the engine to the carbs look new. New filter as well.

Any tips what to check next? Thanks for all of the help so far!

what is the current fuel mixture screw setting?

Not sure. I was looking for a cap, but didn't see any on the bottom of the carb. The only one that might have been it is partially covered by the bracket that holds the primary & secondary together. But it has a brass button in it with a hole in the center.

You have to remove the cap to get to the screw. 3/16" drill bit, just pierce the cap. Coarse sheet meatal screw, in one or two turns. Yank with pliers and the cap is out. Close the screw gently, noting exatly how much you turn it (ie, 1.75 turns)

Thanks!!! I will pull the carbs off again when I get home from work today.

OK, after a long ass week of longer than normal shifts (11+ hours instead of the normal 10), I got home tonight and yanked the carb out again. Removed the brace, drilled out the cap, yanked the cap out. The air mixture screw (if that is what it is) was screwed ALL the way in!! I unscrewed it out 2 and a half turns. Better, but not great. Another 2 and a half turns out. Perfect! Then, after messing with the float/throttle set screw (positions the cable to set idle) it settled somewhere around 1300-1500 rpm. Thump, thump, thump, thump... music to my ears. I went out to restart it a couple hours later and it was hard to start (maybe I flooded it), but when I got it going, I took it up the road. Seams like it started to miss a bit at over 4200 rpm. I'm thinking either too much air at wot -or- since it's missing the spark arrestor end-cap on the muffler, it doesn't have enough back pressure. What do you guys think?

I replaced the oil filter cover with a factory new one from Bike Bandit as the one on the bike leaked. After examination, a po had busted it open and then "fixed" it with JB Weld and spray painted it. So, I replaced it as well as the o-ring. It still leaks around the cover and there seemed to be some coming out of the screw on the top. That screw is only about a quarter inch long, and seems like not the correct one from the factory. Not sure if that effects anything or not, but I want to stop the oil leak. Thoughts?

Last bit to fix will be the electrical gremlins. The turn signals I wired in (since a po yanked all of the originals) light up when I hit the switch, but do not blink. Additionally, the horn sounds like a sick chicken. I switched it with a horn from another bike with the same end result. Is there a relay or something I can swap out or upgrade? The tail light is also out, but I think it is just the bulb.

After all of the above, the plastic is chalky and needs spruced up. Having a Jeep, a trick we use is to take a heat gun to the plastic fender flares when they get chalky and that melts the plastic to a nice shiny sheen (google it). So, I don't think I have much to lose if I try that on the bike's plastics.

I do want to thank everybody for the help and info. It is nice to have this forum as a resource!

Five turns is way too much on the fuel screw. Either you need a new pilot jet or the one you have is too small. Screw shuld haveto be more than 3 turns.

Correct about the end cap, put it back and retest. If it is better, then to run with the cap off, you'll need a larger main jet though having the cap off only makes it lounder and not faster.

I bet your battery is no good.

Battery is brandy new. First thing I checked.

End cap is MIA. Searching fleabay for a replacement. shoved a half roll of paper towels in the giant hole and that seemed to be better, but a real unscientific testing.

I was thinking that 5 turns out was a lot, but remember that I reside at 7100 feet. Think that makes a difference?

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