Honda TRX350 -- irregular running, stalls?

[Dry Rot]

I was out working with my Honda quad, went to restart it, and everything was dead.

Got it back home and it had intermittent electrical problems. Looked like a short. Started going through the electrics and decided it probably needed an overhaul anyway.

Checked the battery, fully charged and not old.

Starter wouldn't work when solenoid poles were shorted. Solenoid replaced. Now starting but running rough.

Battery voltage across the terminals was 13.6 at tick over. Manual says it ought to be 13.8 to 14.5.

Pulled the starter out and notice the braided copper wire to one of the brushes was frayed and could have been shorting out? New points fitted. Could this have caused the problem? No sign of scorch or burning.

The fuse to the fan was blown, now replaced. All fuses and diode since checked and OK.

Finally, got it running but tick over was intermittent and quad would finally stall. Smokey exhaust.

Carburetter stripped, soaked in carb cleaner, jets cleaned. No change, still running rough as above.

Carb stripped again and all seals and jets replaced. (OK, Chinese repair kit, so....! I hear they sometimes make the jets the wrong size?). No change and still running badly.

Pilot screw turned out to factory start up recommendations. (1 3/4 turns out). Without being a contorionist, it's not possible to adjust the pilot without special tools (which I now have - thanks China!). Same problem but exhaust less smokey.

All this time, the spark plug (changed for new) is sooty.

I am guessing, I have some how damaged the CDI unit or it is just (hopefully!) the pilot screw that needs adjusting? Anyone got any experience of the CDI going bad? Apparently, the best way to check them is to swap with a known good one, which I don't have. Of course, they are expensive.

 

[Mursal]

In our experience the CDi box will work or it wont no halfway, so its fine.
But worth pulling the connections to make sure they're not corroded dropping the voltage across the CDi box.

The low voltage you measured, will probably rise if you rev the engine up?

Did you try without the air filter?
Double check that the choke isn't sticking on as it seems to be running rich?
Petrol quality?
There is a breather pipe on some of those carbs that must be connected and must go above the fuel level in the tank to work correctly?
They are little feckers for bogging down if the carb isn't set spot on.
Can it pull itself if you keep it going?

Also worth considering if the battery isn't good (bad connection) it will run as you describe.
Check your earth strap from battery to chassis / engine for corrosion where you cant see the joint.

Edit (after a head scratch):
Try spraying WD40 or the like on the inlet manifold while the engine is running to see if the engine changes note? Might be sucking in air?
Double check the carb diaphragm for holes.

 

[Pheasant Surprise]

Fuelling too I reckon. Sooty plug = running rich on idle. How does it run when on the main jet?

Might be worth going up a heat range on the plug.

 

[Dry Rot]

In our experience the CDi box will work or it wont no halfway, so its fine.
But worth pilling the connections to make sure they're not corroded dropping the voltage across the CDi box.

The low voltage you measured, will probably rise if you rev the engine up?

Did you try without the air filter?
Double check that the choke isn't sticking on as it seems to be running rich?
Petrol quality?
There is a breather pipe on some of those carbs that must be connected and must go above the fuel level in the tank to work correctly?
They are little feckers for bogging down if the carb isn't set spot on.
Can it pull itself if you keep it going?

Also worth considering if the battery isn't good (bad connection) it will run as you describe.
Check your earth strap from battery to chassis / engine for corrosion where you cant see the joint.

Edit (after a head scratch):
Try spraying WD40 or the like on the inlet manifold while the engine is running to see if the engine changes note? Might be sucking in air?
Double check the carb diaphragm for holes.

Thank for that. I'll try what you suggest and report back. You've given me the confidence to struggle on which was lacking! I'd about given up, thinking it was the CDI unit, and booked it in with the main dealers in a couple of weeks time.

 

[Dry Rot]

Fuelling too I reckon. Sooty plug = running rich on idle. How does it run when on the main jet?

Might be worth going up a heat range on the plug.

I forgot to mention that it actually seems to run better with the choke out.

I changed the plug and it is the recommended one now set at the correct gap.

Oh for the days when you could repair an Austin 7 with a hair pin and a piece of binder twine!

 

[Dry Rot]

Well, the plot thickens!

To cut a long story short, it looks like I also have elecrical problems as restarting was difficult with some farting and back firing through the carb at one stage. I think there were blockages in the carb (it was flooding before I cleaned it) but also an electrical issue which has led to confusion!

BTW, the pilot screw has a couple of O rings on it. The repair kit comes with two types of these tiny O rings which look almost identical. They are not! I had the wrong one on, but that's now corrected. Very easy to do. It's the smaller one that's needed. Very easy to lose the little beggars, too!

I am going to start checking the ignition system in the morning.<sigh>

 

[Mursal]

It will do that after working on the carburetor.
Spluttering and farting without or without the air filter attached?
Try both ways to see if it improves .......

And try to dry it out before letting it stop, regardless of how bad its running.
Don't just stop it when its not running correctly, at least try to get it a little warm, if not up to running temperatures. Outside is best .........
This will allow it to start much better the next time, you go for a start. Very easy for it to get over fueled, then it need engine heat /running time to dry it out.

If you have good battery voltage (lights nice and bright when stopped) and all good connections between battery and CDi box, then I'd still think its fueling problem.

Absolutely certain you have a good correctly fitted diaphragm in the carburetor (8:30 10:30 and 11.04 minutes in on the video)? What is the fuel level like when you first take the float bowl off about half way up the bowl? If you think it might be flooding (bad float needle) dont turn the petrol on until just before you go for a start, see if that helps.

Cheap replacement carburetor, just to have it click

 

[Pheasant Surprise]

Cheap replacement carburetor, just to have it click

I don’t honestly know how they can sell them so cheap.

It’s hardly worth your time farting about fiddling with the existing one at that price.

 

[Dry Rot]

It will do that after working on the carburetor.
Spluttering and farting without or without the air filter attached?
Try both ways to see if it improves .......

Yes, tried both. The filter looks a bit dirty (discoloured) but I think it's fine.

I've watched that video several times. There is some good stuff on the Internet.

If you have good battery voltage (lights nice and bright when stopped) and all good connections between battery and CDi box, then I'd still think its fueling problem.

The battery is almost new and fully charged. Starter spins like a new one.

Going to check wiring this morning. The insulation was a bit chewed on one wire (mice!) next to the solenoid, but not so badly that I thought to replace it.

Absolutely certain you have a good correctly fitted diaphragm in the carburetor (8:30 10:30 and 11.04 minutes in on the video)?

Yes, that is fine. The slider is a bit dull on one side but works OK.

What is the fuel level like when you first take the float bowl off about half way up the bowl? If you think it might be flooding (bad float needle) dont turn the petrol on until just before you go for a start, see if that helps.

I'll check. I've changed the float needle. But I DO need to check the float needle seating as I have a nagging feeling I might have put that in upside down!!!

Yes, I got one of those cheap carbs listed "for TRX350". It actually has some sort of screw adjustment for the choke, not cable, so I reclaimed my money. It came from a UK address. The guy didn't like it but paid up and didn't ask for a return (I would happily send it back but he didn't give me an address or ask so I suspect it's probably direct from China anyway). Hadn't the heart to give the guy bad feedback, but I probably should! It did not occur to me to try the carb nonetheless! The one in your link to Ebay looks as if the choke is correct, so someone paid attention. The best alternative has to be the one to be imported from the USA at around £50 but has good reviews. I've bought a couple of carbs for B & S engines and they do work.

Thanks for all the help, guys. Much appreciated.

 

[Mursal]

I don’t honestly know how they can sell them so cheap.

It’s hardly worth your time farting about fiddling with the existing one at that price.

Even just to pop it on to see if the problems stay the same or change.
If you have no choke on the new one, I think that "pump" does the same job, give give it a few pumps?
Or a small bit (a fuel cap full) of petrol in the cylinder to get it up and running (outside with fire prevention to hand).

I'll check. I've changed the float needle. But I DO need to check the float needle seating as I have a nagging feeling I might have put that in upside down!!!

Good to keep a sense of humor, regardless of the little fecker not playing ball ...........

 

[Pheasant Surprise]

Even just to pop it on to see if the problems stay the same or change.

I was totally convinced I had a carburettor/fuelling problem on a GXV160 Honda - pulled the whole thing to pieces, cleaned jets, carb cleaner, ultrasonic cleaner, float bowl cleaned - everything.

Turns out the carb was perfect - I had simply put a smidge too much oil in, enough to let it run fine for 3 minutes, then mysteriously stutter out and die. Drain and refill with the correct volume of oil. Purrrrfect

I still blame the dodgy plastic dipstick, rather than the head dipstick!

 

[Mursal]

Yes it doesn't take much, good job you didn'd go stripping deeper ............

 

[Pheasant Surprise]

Yes it doesn't take much, good job you didn'd go stripping deeper ............

Luckily I stopped at draing the oil....hmmm bit more oil in this thing than I thought. Derrrrr

 

[Dry Rot]

Well, pulled the carb off again this morning. There does seem to be a lot of petrol about.

Yes, I am pretty patient and a sense of humour is the only way to go. Remember, I'm usually training dogs or horses and if things go wrong, I just smile, stop, then go behind the barn to have a good rant and rave, then calm down and back to work! I've tried bigger hammers on machines and they don't seem to work!

More later. Tempted to order a new (cheap) carb from the USA, but I hate to give up.

 

[startinghandle]

have you changed air filter?? or could there be blockage or restriction in air intake??
could there be problem with petrol quality??

 

[Sharpy]

My Dads Yamaha gave the symptoms you describe. The rubber hose from the carb to the head had a hole in it.

 

[Dry Rot]

Ha! I'm now overwhelmed with feelings of guilt!

Put the cheap nasty Chinese carb on (which doesn't have the choke cable attachment), and turned it over with the starter. Nothing! Told ya so!

Nice big fat spark so I poured a little petrol in the air intake side and opened up the idle adjustment and...started!

Runs perfectly with the cheap nasty Chinese carb! Didn't take it fo a run as I'd still like to get the old carb working and I have it all in bits.

Looking again at the non-functional carb (you were right, it's obviously that that's faulty), I am wondering if the float got warped somehow? There seems to be more 'travel'/up-and-down movement of the float in the Chinese one. Unfortunately, they don't appear to be interchangeable. Anyway, I'll order a new one -- that will probably cost as much here in the UK as a complete new Chinese carb!

Thanks again, you guys! The power of TFF strikes again!

 

[Dry Rot]

I'll check. I've changed the float needle. But I DO need to check the float needle seating as I have a nagging feeling I might have put that in upside down!!!

Not float needle, main needle seating. It was fine. The brain is going too.

 

[Mursal]

Great news .........................

I wouldn't stress to much about actually getting the original carb working again, the main dealer would just bin it and expect you to take the wrap. Honda's are nutritious for issues with float and float needles either sticking open or closed. So even if you do get it sorted, it will probably stick again unfortunately.

Take it for a spin on the cheap carb, it might keep you going until the postman comes?
Keep in mind the "American carb" might actually be "Chinese" .........

 

[Pheasant Surprise]

Keep in mind the "American carb" might actually be "Chinese" .........

Ssshhh!! Don’t tell the Donald.