Diagnosis help

[droyce]

Use a big screwdriver against your ear and place it against the left side cover and exhaust etc. to see if you can nail down the location of the rattle.

You might need a friend to rev it for you if it doesn't happen at idle.

Also, if it's the left plug running rich, someone on here just recently worked out a leaking fuel tap was causing his to run very rich, so have you verified your fuel tap is turning off correctly when the engine stops? Easy way to check is remove the fuel hose and vacuum hoses from the fuel tap and place a little container under there. See if there is any fuel in it after a while. There should be absolutely none.

Pete, I haven't noticed any fuel leaks anywhere. I work on the bike almost daily and never noticed any fuel, or even the smell of it. By "fuel tap" do you mean the petcock or the line between the carbs? Both are tight.

[droyce]

What is this brass nipple for?

[Gorminrider]

...possibly a fuel filter. That looks like an outboard motor fuel-line you have there, by the way. In any case, it looks haywire and I'd have it out to see. I don't mind haywire, if I did it, but to look at someone else's is an agony.

[droyce]

I'm talking about the nipple on the carb body, not the fuel filter. Directly behind the fuel filter in the picture.

[Thumper88]

That's the overflow drain, should be one right next to it on the other carb.

[Thumper88]

Is the vacuum hose connected from the petcock to the left carb?

[droyce]

Is the vacuum hose connected from the petcock to the left carb?

Nipple doesnt exist on the right carb


Vacuum hose from left carb to petcock


Is the nipple some sort of vacuum hose?

[Mekanix]

The noise is from that cylinder not contributing!

that plug looks dry, as if its not getting any gas at all.

that fuel filter is going to be a problem if it isn't already.

They never really help on these bikes and that one looks too small anyways.

Full tank of gas helps to push the fuel along as well.


Here's a quick test you can do to prove if its missing fuel or not.

Get some new plugs. Just to be sure they are not fouled.

Pour just a little bit of gas down the plug holes and start it up.

If that cylinder kicks in then you will know its not getting fuel from the carb and when it runs out of the extra fuel in the cylinder then it will die down again.

[barnbiketom]

What is this brass nipple for?

That nipple is the BOWL VENT. fuel will not properly enter the bowl unless there is a way for the air to escape and equalize the atmosphere inside.

the 'overflow' drains are on the bottom of the bowl. if the float sticks, the excess fuel escapes thru this route, thru a riser inside where if the level exceeds a certain point, it runs out the bottom instead of flooding the motor.. only on some carbs . some don't have this. others have the bottom nipple to aid in FUEL DRAINING for STORAGE by unscrewing a brass plug slightly.
the right carb probably has this vent nipple also.. but in the middle.. between the carbs. leave them alone or place SEPARATE short hoses on them.

As to the one side not firing.

SIMPLY spray starting fluid onto the bad side, onto the pod filter while running.

if it picks up and runs, there is a restriction inside the carb.

If it does not run, there is something amiss either spark/spark timing/ or engine mechanical.

I use starting fluid as a diagnostic tool. You should NEVER use it on a regular basis.

[pete]

By fuel tap, I'm referring to the petcock... I don't use the word petcock as over here that would mean a tame rooster

And there will definitely be an equivalent overflow nipple on the right carb, but it is *inside*, not outside. From the factory there were hoses on each that direct down the frame tube so overflow would drain on to the road like the battery overflow tube.

[koolaid_kid]

By fuel tap, I'm referring to the petcock... I don't use the word petcock as over here that would mean a tame rooster

And there will definitely be an equivalent overflow nipple on the right carb, but it is *inside*, not outside. From the factory there were hoses on each that direct down the frame tube so overflow would drain on to the road like the battery overflow tube.

It is the general consensus that when you go to pods you leave the hose off, just like in the picture. To be honest, I do not know the reason for this rationale. Perhaps one of our resident carb experts can chime in?
And I think the Suzuki parts fiche call it a fuel cock, which has very negative connotations here in the States.

[pete]

There have been reports that if you leave the hose on, it can cause turbulence and surging by negative air pressure sucking at the hose... or something like that. At least that's what I've read.

I've got the standard hoses on mine directed down the frame tube so they don't flap in the wind and I haven't noticed anything negative...

[droyce]

As to the one side not firing.

SIMPLY spray starting fluid onto the bad side, onto the pod filter while running.

if it picks up and runs, there is a restriction inside the carb.

If it does not run, there is something amiss either spark/spark timing/ or engine mechanical.

I use starting fluid as a diagnostic tool. You should NEVER use it on a regular basis.

Motor definitely quickens with the starter fluid sprayed onto the pod. Float bowl has fuel. Looks like I'm tearing the carb apart again.

[droyce]

Well, I think I've nailed down the problem. Notice the two float bowls below. I tried swapping them around, and now when spraying the right pod with starter fluid the engine speeds up. I'm assuming its because of the missing trench on the one bowl.



After swapping the bowls, the rattling on the left side is more consistent and I'm worried its piston slap. I'll try posting a video.

The last thing, should I be worried my needle valves don't have screens?

[cowboyup3371]

The screens act as another filter for your fuel flow. You'll want to find another set from someone who has spares.