1992 350D Starting problems

[TrxPipUK 169]

So just looking at the valves and the intake is a bit loose at just over 0.13mm, however the exhaust has no clearance at all and is too tight. 

The manual says the clearance for both intake and exhaust should be 0.08mm, so I'll set both to that. 

[oh400ex 629]

 

4 hours ago, TrxPipUK said:

Okay brilliant, thanks! 

So then at TDC use the feeler gauge between the top of the valve stem and tappet and adjust as necessary. Right?

Thanks once again for the help!

 

Yes exactly!

 

1 hour ago, TrxPipUK said:

So just looking at the valves and the intake is a bit loose at just over 0.13mm, however the exhaust has no clearance at all and is too tight. 

The manual says the clearance for both intake and exhaust should be 0.08mm, so I'll set both to that. 

 

Sounds great!

I have had mixed personal results using the feeler gauge method.

It is a very reliable method but for whatever reason I can not get them to sound perfect sometimes with gauges.

 

I use the gauges but rely more on "feeling" now

When you wiggle the rocker you can feel difference in the size of the gap based on the amount of impact 

(If the gap is wider the feeling and sound when wiggling will be different that when the gap is closed too much)

 

Also would recommend starting the bike and listening before full reassembly if possible.

Just a bit loose is not big deal but a bit too tight would potentially damage the valve seat

 

Thank you for sharing!

Edited December 13, 2020 by oh400ex

[_Wilson_™ 6,563]

5 hours ago, TrxPipUK said:

Yes I realised it wasn't on so I just removed that drive shaft along side the engine then put the boot on then put the shaft back on. It has one on now. Thanks 🙂

 

it just caught my eye is all, this is why we keep saying, pics are worth a thousand words ;) 

[TrxPipUK 169]

Earlier today I had a very exciting afternoon! After some fiddling and finding fuel wasn't being drawn from the tank, I put the fuel line to the pump straight into a can of petrol and she fired right up!!

I think the carb needs a little tuning as it needed to run with the choke half on. Apart from that though, the engine sounded great! No tapping or slapping noises or anything, I'll get a video of it running when I start her up again (need to charge the battery as I flattened it lol). 

 

But most importantly I wanted to say a HUGE thankyou to every single one of you on hear that has helped me and guided me along. I can't name you all but you know who you are! @shadetreethankyou ever so much for getting me the parts that I needed to get this old quad running. 

I can't thank everyone enough! Cheers guys 🙂

[retro 4,048]

Congrats Pip! Standing by for the rest of the story!

[shadetree 5,880]

outstanding pip !!!..glad i could help you :-). another old girl raised from the dead !!. 

[TrxPipUK 169]

Thanks guys! Yes I will keep you up to date and I'm sure there will be more questions lol..

Pics will follow as well as it comes together 🙂

Thanks, all the best

[Fishfiles 20,145]

Congratulations 'PIP' >>>> Been almost a year to the day from when you started on it 

[retro 4,048]

Paraphrasing a member on another forum.... you hung in there like a hair in a grilled cheese sandwich Pip! 🙂

 

[Goober 1,555]

Your fuel tank suction lines might have sediment in them. Use about a foot of string trimmer line or old brake cable to ream out those lines.

careful there’s an intake screen at the end of each suction line. Don’t punch through or get the steel cable hung up on the metal screen.

A clogged or bad petcock would also restrict fuel flow

also inspect the fuel hoses for extensive cracking which would cause suction loss.

 

 

[TrxPipUK 169]

15 hours ago, Goober said:

Your fuel tank suction lines might have sediment in them. Use about a foot of string trimmer line or old brake cable to ream out those lines.

careful there’s an intake screen at the end of each suction line. Don’t punch through or get the steel cable hung up on the metal screen.

A clogged or bad petcock would also restrict fuel flow

also inspect the fuel hoses for extensive cracking which would cause suction loss.

 

 

Thanks Goober! Have fixed the issue now. It was the petcock not sealing against the tank properly, replaced the o-rings and now it draws fuel fine 🙂

[TrxPipUK 169]

21 hours ago, Fishfiles said:

Congratulations 'PIP' >>>> Been almost a year to the day from when you started on it 

Thank you man! Appreciate all the help you have given 

[TrxPipUK 169]

I fixed the problem of not drawing fuel from the tank with a couple fresh o-rings in the petcock. 

Now I have had it started up (have to kick it because the battery is flat) I've noticed at idle the engine seems a little inconsistent? Not sure if it's normal or the carb needs tuning or what? Hopefully it's noticable in the video. Any help would be greatly appreciated once again.

Thanks 

 

 

[Goober 1,555]

I couldn’t really hear it.

do you have a muffler on it? I hear the wop wop wop like the can has a hole in it.

 

Carburetor synchronization off a little perhaps —what’s the setting of your pilot needle—1 and 5/8ths? 

[oh400ex 629]

Always tough to tell from a video but the motor sounds great!

 

Few things stand out to me...

Battery sooner than later... the stator is working overtime... "failure to discharge" was the term the forum came up with I believe. 

Idle seems low. More of a preference but too low can more easily show the instabilities.

There may be a vacuum leak somewhere... heard a bit of delay in increase and decrease of RPM.

Tiny holes in the throttle slide diaphragm would be my first suspect if something else doesn't stand out.

 

[TrxPipUK 169]

1 hour ago, Goober said:

I couldn’t really hear it.

do you have a muffler on it? I hear the wop wop wop like the can has a hole in it.

 

Carburetor synchronization off a little perhaps —what’s the setting of your pilot needle—1 and 5/8ths? 

Yes has a muffler on it, I welded up all the little holes I could find in it as well then painted it.

 

Yea could well be carburetor synchronisation as I don't know what that is haha... I'll have a look over the manual. Is that adjusted by one of the screws on the outside of the carb? I'm aware that there is an air/fuel mix screw somewhere as well. Is that worth looking at as well? 

 

Thanks Goober

[TrxPipUK 169]

14 minutes ago, oh400ex said:

Always tough to tell from a video but the motor sounds great!

 

Few things stand out to me...

Battery sooner than later... the stator is working overtime... "failure to discharge" was the term the forum came up with I believe. 

Idle seems low. More of a preference but too low can more easily show the instabilities.

There may be a vacuum leak somewhere... heard a bit of delay in increase and decrease of RPM.

Tiny holes in the throttle slide diaphragm would be my first suspect if something else doesn't stand out.

 

Okay great thanks! 

So I'll charge the battery up as soon as possible and I'll have a play with the idle speed, see what sounds best. 

 

When you say a vacuum leak, where might that be? In the engine? 

And lastly, what is the throttle slide diaphragm? I haven't come across it before.  

 

Thankyouuu 🙂

[Goober 1,555]

There’s no slide diaphragm on the carb for this model.

yes a flat battery can cause erratic firing especially on this model (spark is generated from the battery).
yes read up on carb synchronization—get that throttle slide and butterfly  synchronized to the linkage. Easier to do this with carb off.
 

Edited December 16, 2020 by Goober

[Goober 1,555]

Pilot screw adjustment first page 4-16

 

Page 4-13 4-14 

synchronize the throttle link to the piston valve. Be very careful not to over adjust the throttle link slot metal—if you break it you will be looking for a donor carb.

 

Afterward synchronize the butterfly with the throttle stop screw so you have the butterfly dead closed when installing the cable. Before I install the carb i make a mark on the throttle drum to more easily see the dead zero idle setting. 
here’s where i start

i advance the throttle stop screw just until the Throttle Drum starts moving and the butterfly starts to open. I back it off to zero and use an indelible marker and ruler to make a little mark on the carb body. See my little yellow mark in the picture?

When you install the throttle cable, you have to insert the cable end into the carb body—don’t attach to throttle drum yet! Screw the cable to the carb first but leave it loose. Adjust your handlebar cable adjuster so you can balance the cable slack.

Position the carb in the boot and straighten up the cable—no twists or kinks. then connect the cable to the throttle drum. Then take out the slack—watch that little zero mark—you dont want to tighten the cable too much and unintentionally advance the throttle. Snug the cable lock nut and carb boot.

 

 

Edited December 16, 2020 by Goober

[Goober 1,555]

There’s a couple things i left out before you tighten the carb boot.

Connect the choke valve and install the cover while you can still rotate the carb in the boot.
now you’re at i initial setting ready to fine tune as presented in second paragraph on page 4-16

 

so you’re not surprised the engine won’t get any fuel or air with the throttle stop screw at zero. After the carb is secured you’ll have to advance the throttle stop screw a little to get it warmed up 

Edited December 16, 2020 by Goober

[shadetree 5,880]

1 hour ago, oh400ex said:

Always tough to tell from a video but the motor sounds great!

 

Few things stand out to me...

Battery sooner than later... the stator is working overtime... "failure to discharge" was the term the forum came up with I believe. 

Idle seems low. More of a preference but too low can more easily show the instabilities.

There may be a vacuum leak somewhere... heard a bit of delay in increase and decrease of RPM.

Tiny holes in the throttle slide diaphragm would be my first suspect if something else doesn't stand out.

 

these dont have that carb set up with the diaphragm..haven't we had this talk before ?..lol.

[_Wilson_™ 6,563]

besides that diaphragm issue, lol, i see in the video you have both keys on the ring ? I'd take one off, write down the 3 digits (you might need to remove the rubber weather cap) and put one key in a safe place, just in case you loose the other. 

[Goober 1,555]

This carb doesn’t have a rubber piston valve like the TRX300 but a metal piston. It doesn’t get holes init but it can bind so be gentle with it Pip.

But yeah same thing it’s all about tuning the air fuel ratio to the throttle control. If the butterfly is already open or opened before the piston rises then the main jet needle hasn’t started it’s upward travel. So the engine runs irregularly at idle and stumbles at throttle

[oh400ex 629]

5 hours ago, TrxPipUK said:

When you say a vacuum leak, where might that be? In the engine? 

And lastly, what is the throttle slide diaphragm? I haven't come across it before.  

 

Vacuum (in this context) is referring to the negative pressure generated by the intake of the engine.

It is used on some bikes to assist with throttle response and return. Can leak from the intake tube, carb, etc causing similar issues.

 

As Goober and Shade mentioned above the TRX300 (and most older racing models) have the rubber diaphragm style slide.

Many different slide styles... I was wrongly thinking you were working on the 300 style carb.

Great advice from Goober to get you fully straightened out above... you got it!

 

4 hours ago, shadetree said:

these dont have that carb set up with the diaphragm..haven't we had this talk before ?..lol.

 

I think so... 😂

Might have been discussing the 350x (which shares a ton of engine parts with this bike BTW Pip)

[TrxPipUK 169]

15 hours ago, Goober said:

Pilot screw adjustment first page 4-16

 

Page 4-13 4-14 

synchronize the throttle link to the piston valve. Be very careful not to over adjust the throttle link slot metal—if you break it you will be looking for a donor carb.

 

Afterward synchronize the butterfly with the throttle stop screw so you have the butterfly dead closed when installing the cable. Before I install the carb i make a mark on the throttle drum to more easily see the dead zero idle setting. 
here’s where i start

i advance the throttle stop screw just until the Throttle Drum starts moving and the butterfly starts to open. I back it off to zero and use an indelible marker and ruler to make a little mark on the carb body. See my little yellow mark in the picture?

When you install the throttle cable, you have to insert the cable end into the carb body—don’t attach to throttle drum yet! Screw the cable to the carb first but leave it loose. Adjust your handlebar cable adjuster so you can balance the cable slack.

Position the carb in the boot and straighten up the cable—no twists or kinks. then connect the cable to the throttle drum. Then take out the slack—watch that little zero mark—you dont want to tighten the cable too much and unintentionally advance the throttle. Snug the cable lock nut and carb boot.

 

 

Thankyou Goober. Plenty information for me to be getting on with. I'll go over the carb and sort it out. Thanks