[TRX350D]

Hello All,

I had to rebuild my carb on one of my 1987 TRX350d's and when I did so, the Starter Jet screw totally stripped. Unfortunately, I had to drill it out since Easy-Out's didn't work. Now when I did this, it went all the way through and I felt my drill bit hit the inside wall on the other side (you can look through the top jet tubes and see it make contact, but I didn't obviously drill any further).

Now I don't believe this has anything to do with what is happening,but it's food for thought. Anyways, once I drilled it out, the rest of the screw collapsed inward and the threads remained intact without needing to be re-tapped.

So I rebuild the carb, machine starts right up - however it runs high on idle. Now, the previous owner had the pilot screw backed out 2 3/4 turns which I returned it to and I believe that to be the problem. I backed it down to 2 turns but it doesn't seem to be helping. Throttle is all the way to minimum.

Oddly the Oil Temp Light goes on and off too as this thing idles high ... I don't remember it idling this high before I did the rebuild, but then again it ran terrible before.

Any ideas?

 

[TRX350D]

Also - if you apply just a LITTLE choke to it, the idle goes back under control like it should sound... that should be a big hint for someone in the know!

 

[Goober]

Easiest to check the throttle cable tension.
During assembly, you can get the linkage adjustment just right, but then you have to hook up the throttle cable and maybe threading the carb onto the adjustment bolt you put extra tension on there.
You can readjust with it still installed just pull the cover off and run the throttle adjustment screw out until it’s just touching. Then retension the cable

Start there, otherwise your throttle linkage, pilot screw adjustments may also be out

 

[Goober]

Also - if you apply just a LITTLE choke to it, the idle goes back under control like it should sound... that should be a big hint for someone in the know!

That could be clogged jet passages

 

[TRX350D]

Also - if you apply just a LITTLE choke to it, the idle goes back under control like it should sound... that should be a big hint for someone in the know!

That could be clogged jet passages

Jet passages are for sure not clogged. They got power washed out, then carb cleaned, small wire brush, etc.

 

[TRX350D]

Easiest to check the throttle cable tension.
During assembly, you can get the linkage adjustment just right, but then you have to hook up the throttle cable and maybe threading the carb onto the adjustment bolt you put extra tension on there.
You can readjust with it still installed just pull the cover off and run the throttle adjustment screw out until it’s just touching. Then retension the cable

Start there, otherwise your throttle linkage, pilot screw adjustments may also be out

So I took it all apart again (begrudgingly) but the throttle cable wasn't seeing any additional tension. Nonetheless, I took it out, spun the carb around the insert threads until taught and in alignment with how the carb could insert back into the head, and then tightened the nut down (followed by installing the cable back inside of the carb). So that's all good ... however...

MY CHOKE CABLE THREADS ARE STRIPPED!

I noticed that my choke cable wouldn't go in at all. It just pops right out. The threads are totally stripped on the first three rungs and it won't seat at all.

So then I said - hmmm, maybe it was the culprit and it popped out? But that seemingly wouldn't make sense because the engine idles better when the choke applied (1/4-1/2) which means the cable is pulled more out ... Nonetheless, I put it all back together and just held the cable in taught by hand and started it up and literally no improvement - at all. When I'd apply the choke, it would still help out a bit, but only a bit.

So then I adjusted the pilot screw to 1 3/4 turns ... nope. Same status.

Thoughts anyone? @shadetree

 

[shadetree]

Easiest to check the throttle cable tension.
During assembly, you can get the linkage adjustment just right, but then you have to hook up the throttle cable and maybe threading the carb onto the adjustment bolt you put extra tension on there.
You can readjust with it still installed just pull the cover off and run the throttle adjustment screw out until it’s just touching. Then retension the cable

Start there, otherwise your throttle linkage, pilot screw adjustments may also be out

So I took it all apart again (begrudgingly) but the throttle cable wasn't seeing any additional tension. Nonetheless, I took it out, spun the carb around the insert threads until taught and in alignment with how the carb could insert back into the head, and then tightened the nut down (followed by installing the cable back inside of the carb). So that's all good ... however...

MY CHOKE CABLE THREADS ARE STRIPPED!

I noticed that my choke cable wouldn't go in at all. It just pops right out. The threads are totally stripped on the first three rungs and it won't seat at all.

So then I said - hmmm, maybe it was the culprit and it popped out? But that seemingly wouldn't make sense because the engine idles better when the choke applied (1/4-1/2) which means the cable is pulled more out ... Nonetheless, I put it all back together and just held the cable in taught by hand and started it up and literally no improvement - at all. When I'd apply the choke, it would still help out a bit, but only a bit.

So then I adjusted the pilot screw to 1 3/4 turns ... nope. Same status.

Thoughts anyone? @shadetree

pm me your phone number, so I can get the facts here. ( only if your not in Canada ! ).

 

[TRX350D]

pm me your phone number, so I can get the facts here. ( only if your not in Canada ! ).

Sent! I'm available for a call.

 

[shadetree]

welp, after spending a few on the phone, seems to be a issue that forced trx350D to send the carb to me, I will fix him up, send it back like a new carb, and have him up and running in no time, will post in the '' pay it forward '' section, as this is shipping to and back only ( least I can do for the guy ) .

 

[TRX350D]

We tried a bunch of everything. But so people can understand what we think is happening ... There's the big needle jet that's attached to the bottom of the piston that moves up and down through the carb. The piston is connected to an arm that mates to a shaft which originates from the side where the throttle cable ends up going.

At any rate, this shaft + piston arm mating is where we have the (apparent) problem. When mated together (using the screw), the mated pair will be pressured to push the piston down to the bottom of the carb due to the recoil spring located on the other side of the shaft (it's in the same compartment as where the throttle cable goes). Unfortunately in my setup, I can push the piston arm/shaft mated combo up all the way and it does not automatically snap back down as it should. @shadetree believes this is what's leaving the throttle body open, not the actual throttle cable (which remains relaxed), but because the piston doesn't glide freely and snap back down into the bottom position (which is where the throttle body would be fully closed).

So we tried a bunch of stuff to fix it including:

• Winding the return spring one additional time to increase the downward force
• Using 1500grit sandpaper to lightly sand the sides of the piston to make sure it wasn't fouled and could glide easily (which it could if it wasn't mated to the shaft)
• Use a wire brush to clean off of the shaft to make sure it wasn't burred
• Countless other tweaks and tidbits including eliminating or shifting the washer

Nothing worked and after seemingly endless utterances of profanity, we agreed to ship it on down to @shadetree for his expert analysis.

We'll keep you all posted on how it goes!

 

[shadetree]

We tried a bunch of everything. But so people can understand what we think is happening ... There's the big needle jet that's attached to the bottom of the piston that moves up and down through the carb. The piston is connected to an arm that mates to a shaft which originates from the side where the throttle cable ends up going.

At any rate, this shaft + piston arm mating is where we have the (apparent) problem. When mated together (using the screw), the mated pair will be pressured to push the piston down to the bottom of the carb due to the recoil spring located on the other side of the shaft (it's in the same compartment as where the throttle cable goes). Unfortunately in my setup, I can push the piston arm/shaft mated combo up all the way and it does not automatically snap back down as it should. @shadetree believes this is what's leaving the throttle body open, not the actual throttle cable (which remains relaxed), but because the piston doesn't glide freely and snap back down into the bottom position (which is where the throttle body would be fully closed).

So we tried a bunch of stuff to fix it including:

• Winding the return spring one additional time to increase the downward force
• Using 1500grit sandpaper to lightly sand the sides of the piston to make sure it wasn't fouled and could glide easily (which it could if it wasn't mated to the shaft)
• Use a wire brush to clean off of the shaft to make sure it wasn't burred
• Countless other tweaks and tidbits including eliminating or shifting the washer

Nothing worked and after seemingly endless utterances of profanity, we agreed to ship it on down to @shadetree for his expert analysis.

We'll keep you all posted on how it goes!

yep, i'll get it, go through it, and take a few pics along the way, and post them up here.

 

[TRX350D]

Hello All,
@shadetree received my carb and it turns out that someone likely put a TRX250 carb in my 350 machine! What gives?! At any rate - like the nice guy that he is, he happened to have a spare 350 carb laying around and transferred all of my new jets that I put into the other carb and shipped me back his spare and it worked like a 'beaut ... well, after I got done fighting with the throttle cable and choke cable issues I was having - but the carb was fine!

After another 2 days of hard work - the restoration is complete. Without further ado - I give you - the completed 1987 Blue - TRX350D.

 

[shadetree]

well done !. glad I could help ya. when I get a chance, i'll text ya that drawing we spoke about .

 

[Goober]

Great job @shadetree! Thanks for making that trade with him–these quads don’t like modifications at all do they��

@TRX350D that’s a great looking quad. What’s next on your list?