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Diagnosis help

  • Thread starter Thread starter droyce
  • Start date Start date
Thumper88 said:
Is the vacuum hose connected from the petcock to the left carb?
Click to expand...

Nipple doesnt exist on the right carb
20130108_222853.jpg


Vacuum hose from left carb to petcock
20130108_190041.jpg


Is the nipple some sort of vacuum hose?
 
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.
 
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droyce said:
What is this brass nipple for?

20130108_195034.jpg
Click to expand...


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.
 
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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 :D

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.
 
pete said:
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 :D

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.
Click to expand...
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. :eek:
 
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...
 
barnbiketom said:
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.
Click to expand...

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

20130112_172923.jpg


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?
20130112_173313.jpg
 
The screens act as another filter for your fuel flow. You'll want to find another set from someone who has spares.
 
those two different bowls have me puzzled. maybe someone bought parts and they were different ones or the bowls aren't for that year or somethin or nother!!!##%^

maybe search/look on ebay and find a pic of a bowl and see whats going on???

i think the bowls for th 450 automatic are different because of the one side has an accelerator pump? maybe someone has done some bad parts replacing...
 
barnbiketom said:
i think the bowls for th 450 automatic are different because of the one side has an accelerator pump? maybe someone has done some bad parts replacing...
Click to expand...
True, there is an accelerator pump, but it is external to the bowl, and the carbs are completely different. :eek:

Yep, the carbs on the 450GA could be mistaken for carbs 1&4 on a GS1000.
They are 34mm carbs, but have what I call the "standard" configuration of float bowl and jets, not the arrangement shown there, with the jets in the bowl.

Those carbs are NOT from a 450GA.

.
 
barnbiketom said:
ok here a pic on EBAY auction for PRE 83 GS450 carbs and it looks like you have one of those float bowls instead of the correct, GS400 bowl!!!

There aren't currently any auctions for GS400s that i see but since yours runs on the one that has the channels, then you have the wrong other one...
Click to expand...

I also did some searching and came to the same conclusion. I think the GS425 bowls may be the same though. I'll have to do some more searching.

Anyone have a bowl for sale? :pray:
 
..doesn't mention that the other bowl is different and I can't see a picture that suits your other....
anyways, don't get confused with the GSX 400. The carbs are different.
 
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I have seen this on mine before.

I know too high oil level will do it.

If one cylinder is too rich or lean it will do that too.

Or if they are way out of synch.

I cured mine with a carb rebuild and swapping pistons left to right.

Can you do a video with a low idle ?

Srart spray will wash the cylinder of oil so use it sparingly.

Do you have any pics of the botton of your carbs?
 
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Gorminrider said:
from the Clymer manual...it says "they are all BS34 Mikuni"...
Click to expand...
They may all be "BS34 Mikuni", but they are not all BS34SS Mikuni. :o

The carbs on the '83-and-up GS450s (which included the 450GA) had the BS34SS carbs, which look more like the ones on the 1000G and 1100G.

.
 
Mekanix said:
I have seen this on mine before.

I know too high oil level will do it.

If one cylinder is too rich or lean it will do that too.

Or if they are way out of synch.

I cured mine with a carb rebuild and swapping pistons left to right.

Can you do a video with a low idle ?

Srart spray will wash the cylinder of oil so use it sparingly.

Do you have any pics of the botton of your carbs?
Click to expand...

I'm willing to bet if I can swap in the correct bowl, the rattling problem might disappear. Obviously the side with the wrong bowl isn't getting enough fuel and is causing an extreme lean condition. I try getting a video with lower idle.
 
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