1992 350D Starting problems

[_Wilson_™ 6,567]

in the last video ... sounds to me like she's running Rich. at idol. and when you give it throttle your giving just the amount of air to allow the fuel air ratio equal out ie the engine revs. if it's a vacum leek, it should idol high most of the time. 

[shadetree 5,869]

and for the record ?, i went out to my '89 trx350D foreman 4x4, removed the flywheel center cap, put the tip of my finger on the flywheel bolt, slowly kicked her over..and just as i claimed , THE MOTOR ROTATES COUNTER CLOCKWISE !, i hate being right most of the time !..lol.

[TrxPipUK 169]

4 hours ago, oh400ex said:

 

Sounds like a vacuum leak.

Being that there is no throttle side diaphragm on this model (as we discussed earlier) the next primary suspect is the intake boot.

 

In the most simple terms... air is getting somewhere it shouldn't.

There are a few different possibilities that come to mind...

Leaky intake boot, improperly lapped/adjusted valves, carburetor/throttle adjustment and worn-out parts...

If the throttle is hard to push (at all) there may be resistance in the slide or cable causing this symptom.

Don't think it's that due to it revving up on its own though... hard to tell from video.

 

There are a few different checks that can be done to test for leaks around the intake boot.

The most common is to spray carb cleaner or starting fluid around the area to see if any is sucked in causing a noticeable difference in RPM.

That way is arguably dangerous due to the possibility of the flammable liquid combusting so is frowned upon by some.

My counter-point to that argument is that the amount needed for the test is so minimal that if it did catch fire would quickly burn away before causing further damage (assuming it didn't light something else in the process) (AKA use common sense!)

If you choose to do the test make sure you use very short bursts and give time for the product to evaporate before going further. 

 

Greasing the boot before installation (lightly) will sometimes make up for a slightly worn boot.

Some folks who run in deep water will use a large amount of grease around all sealing points as an attempt to prevent water from coming in.

 

 

Okay great thanks. I'll check for a vacuum leak.

Is there any chance the piston in the carb is sticking or something? 

[TrxPipUK 169]

4 hours ago, _Wilson_™ said:

in the last video ... sounds to me like she's running Rich. at idol. and when you give it throttle your giving just the amount of air to allow the fuel air ratio equal out ie the engine revs. if it's a vacum leek, it should idol high most of the time. 

Hmm okay... are there separate air and fuel screws? Or is it controlled by the screw on the bottom of the carb? 

 

Still haven't got my head around what screws do what lol.. I know what the idle does though haha

[shadetree 5,869]

6 minutes ago, TrxPipUK said:

Hmm okay... are there separate air and fuel screws? Or is it controlled by the screw on the bottom of the carb? 

 

Still haven't got my head around what screws do what lol.. I know what the idle does though haha

air fuel mixture jet/screw, bottom front of carb, this is where you set your air to fuel mixture.

[shadetree 5,869]

16 minutes ago, TrxPipUK said:

Okay great thanks. I'll check for a vacuum leak.

Is there any chance the piston in the carb is sticking or something? 

no..the piston ( most times ! ) never sticks...as it is not vacuum operated like newer carbs. it uses a lift cam arm to raise the slider as you push on the thumb throttle at the bars. 

[_Wilson_™ 6,567]

pull the plug and check for fluffy carbon build up, being this engine has not run long, there might not be much, you also might take your finger and rub the inside of the exhaust port, see how much carbon comes out on your finger, if it's black fluffy deposits she's running rich! but missing at idling in the video, I'd say running rich, in the other video she wasn't, so next question have you changed any adjustments on the air fuel mixture screw ? 

[shadetree 5,869]

6 minutes ago, _Wilson_™ said:

pull the plug and check for fluffy carbon build up, being this engine has not run long, there might not be much, you also might take your finger and rub the inside of the exhaust port, see how much carbon comes out on your finger, if it's black fluffy deposits she's running rich! but missing at idling in the video, I'd say running rich, in the other video she wasn't, so next question have you changed any adjustments on the air fuel mixture screw ? 

i just gotta ask !..rofl...why in the world would you tell him to use his finger in the exhaust port to check for soot/what not ??. now..mind ya..i've been doing atvs for 30 yrs now..and i've never used a finger in the exhaust port to see if an engine is running rich ?..NOT WHEN ALL YA HAVE TO DO IS LOOK AT THE EXHAUST COMING OUT THE MUFFLER !..LOL.

[_Wilson_™ 6,567]

 in the small shop that lJ had, in the winter time, that was favored over running a engine in an in closed shop, his call, the man that pays the money makes the call... lol. i found it odd myself... lol. 

[shadetree 5,869]

17 minutes ago, _Wilson_™ said:

 in the small shop that lJ had, in the winter time, that was favored over running a engine in an in closed shop, his call, the man that pays the money makes the call... lol. i found it odd myself... lol. 

who here thinks running an engine inside a closed building is a good idea ??..rofl.

[TrxPipUK 169]

46 minutes ago, shadetree said:

air fuel mixture jet/screw, bottom front of carb, this is where you set your air to fuel mixture.

Okay so that controls air and fuel mix? Am I right in thinking the more you screw it in the less fuel the engine gets? 

 

What about the screw on the side? I think it's near the idle adjustment. 

[TrxPipUK 169]

7 minutes ago, shadetree said:

who here thinks running an engine inside a closed building is a good idea ??..rofl.

Not a good idea lol😂

[shadetree 5,869]

8 minutes ago, TrxPipUK said:

Okay so that controls air and fuel mix? Am I right in thinking the more you screw it in the less fuel the engine gets? 

 

What about the screw on the side? I think it's near the idle adjustment. 

there is no screw on the side of carb near the idle screw, post a pic, so i can see it.

[shadetree 5,869]

9 minutes ago, TrxPipUK said:

Okay so that controls air and fuel mix? Am I right in thinking the more you screw it in the less fuel the engine gets? 

 

What about the screw on the side? I think it's near the idle adjustment. 

if you have the pilot screw installed right ?, read what the manual says from a lightly seated screw setting, back it out the correct turns. you do this by watching only ONE END of the slot in the screw, in other words, slot at top, 1/2 down, now at bottom where the slot was on other end. one full turn, slot makes a complete rotation , then back where it started.

[_Wilson_™ 6,567]

43 minutes ago, shadetree said:

who here thinks running an engine inside a closed building is a good idea ??..rofl.

 

oh i know that fact, i was always wanting to take them outside, or raise the shop door, lol, and you think people here squeak when they walk, ha, they have nothing on LJ .... he was always complaining about money going out... lol!, but i have say he's one great wrencher, young could probably relate this to how catfish is about parting out a honda.. lol! 

[TrxPipUK 169]

2 hours ago, shadetree said:

there is no screw on the side of carb near the idle screw, post a pic, so i can see it.

I will post a picture in the morning.. think there is one lol

[Goober 1,555]

when an engine rises and falls like that i think of variability in fuel flow (fuel Suction lines that don’t seal well, failing fuel pump) and incorrect carb synchronization.

Edited December 23, 2020 by Goober

[retro 4,048]

The screw on the side of the fuel bowl is a fuel drain, is that the one you are talking about? Just thinking outloud here.... is the small rubber plug in the right place (#2 in the manual page below) inside the fuel bowl? The choke plunger returning completely down when the choke is off? The small rubber hoses connecting to the carb all hooked up right? The pilot screw initial adjustment set at 1.5 turns out? Idle speed screw adjusted low enough for a 1500 rpm idle speed?

 

 

 

 

 

 

[TrxPipUK 169]

10 hours ago, Goober said:

when an engine rises and falls like that i think of variability in fuel flow (fuel Suction lines that don’t seal well, failing fuel pump) and incorrect carb synchronization.

Okay, so I need to make sure the fuel pipes are sealing properly.  I'm sure I synchronized it correctly, I opened up that piece on the throttle link so that there was no gap.

[TrxPipUK 169]

9 hours ago, retro said:

The screw on the side of the fuel bowl is a fuel drain, is that the one you are talking about?

Yes that's the one! Thanks 

 

9 hours ago, retro said:

is the small rubber plug in the right place (#2 in the manual page below) inside the fuel bowl?

Yes I'm sure it is. Maybe I'll take the carb off again and look through it.

 

9 hours ago, retro said:

The choke plunger returning completely down when the choke is off?

I would think so yes. Anyway I can check to make sure? 

 

9 hours ago, retro said:

The small rubber hoses connecting to the carb all hooked up right?

Again, I presume so as I never really took them off, so they have just been left as is. 

 

9 hours ago, retro said:

The pilot screw initial adjustment set at 1.5 turns out?

Yep it's set at that. I tried doing it as the manual says to by turning it clockwise until the engine stops and then screwing it out 2 turns, but the screw went in all the way to its seat and the engine was still running. 

 

9 hours ago, retro said:

Idle speed screw adjusted low enough for a 1500 rpm idle speed?

I don't have a tachometer so can't be sure of the rpm. Do I need to get one?

[retro 4,048]

7 hours ago, TrxPipUK said:

Yep it's set at that. I tried doing it as the manual says to by turning it clockwise until the engine stops and then screwing it out 2 turns, but the screw went in all the way to its seat and the engine was still running

 

Ok, there is the clue we need to diagnose this further. So its running too rich while idling.... 1st thing to check might be the choke plunger. Make sure that the plunger is returning to the bottom of its bore when the choke lever is released. You should be able to feel about 1.6 millimeters of cable slack by pulling and pushing on the choke cable where it connects to the plunger inside the rubber cable boot. Apply & release the choke lever on the handlebar while holding the cable just above the plunger, you should be able to feel cable slack while the lever is in the off position.

 

If there is sufficient cable slack, then the next thing to check is the condition of the choke plunger after removing it from its bore in the carb. There should be a small pointed needle on the end of that plunger. Make sure that it is not bent or broken. The end of the plunger has a rubber sealing ring surrounding the small needle which should appear in good condition with no cracks or other damage. Finally, check the condition of the rubber sealing ring that surrounds the plunger near the middle of its length. That rubber ring is a lipped seal.... the lip faces up (toward the cable connection) and must not be cut or damaged.

 

7 hours ago, TrxPipUK said:

I don't have a tachometer so can't be sure of the rpm. Do I need to get one?

 

Nope, you can tell when the idle speed is reasonable & close enough, no need for a tachometer.

 

Let us know what ya find out before we go any further.

 

 

[TrxPipUK 169]

1 hour ago, retro said:

 

Ok, there is the clue we need to diagnose this further. So its running too rich while idling.... 1st thing to check might be the choke plunger. Make sure that the plunger is returning to the bottom of its bore when the choke lever is released. You should be able to feel about 1.6 millimeters of cable slack by pulling and pushing on the choke cable where it connects to the plunger inside the rubber cable boot. Apply & release the choke lever on the handlebar while holding the cable just above the plunger, you should be able to feel cable slack while the lever is in the off position.

 

If there is sufficient cable slack, then the next thing to check is the condition of the choke plunger after removing it from its bore in the carb. There should be a small pointed needle on the end of that plunger. Make sure that it is not bent or broken. The end of the plunger has a rubber sealing ring surrounding the small needle which should appear in good condition with no cracks or other damage. Finally, check the condition of the rubber sealing ring that surrounds the plunger near the middle of its length. That rubber ring is a lipped seal.... the lip faces up (toward the cable connection) and must not be cut or damaged.

 

 

Nope, you can tell when the idle speed is reasonable & close enough, no need for a tachometer.

 

Let us know what ya find out before we go any further.

Okay perfect, that sounds like a good start. So when checking the cable slack I want the plunger out of the carb? 

 

I will remove the choke plunger from the carb and check it over. I did replace the lipped seal with a new one and it's the correct orientation. But I'll check the needle on the end and everyone else you mentioned. 

 

Thanks retro!

[Goober 1,555]

If you only replaced the seal on the choke valve and didn’t replace the whole choke valve assembly...well they don’t just sell the correct seal do they?

Where did you get the seal Pip?

[TrxPipUK 169]

3 hours ago, Goober said:

If you only replaced the seal on the choke valve and didn’t replace the whole choke valve assembly...well they don’t just sell the correct seal do they?

Where did you get the seal Pip?

I got the seal in the shindy carb kit I got

[shadetree 5,869]

2 hours ago, TrxPipUK said:

I got the seal in the shindy carb kit I got

the choke parts do not come in REAL shindy rebuild kits !.