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From: Adam on 28 May 2007 21:49
Last week, after a 20 year hiatus, I got back on a 2 wheeler; bought a 1983 Suzuki GS400E. Two days into ownership I noticed gas pouring from one of the carburetor breathing/overflow tubes (on the right) & the bike did not want to start. When it finally did (start), foam came from the the oil dipstick hole. I shut off the engine & discovered that the crankcase/gearbox was full of gasoline.
Drained everything and assumed that something made the carbs over-flow and drain into the crankase. (I am worried about a complex looking tank valve which seemed to be connected to the manifold, but I have been unable to get solid info on what this contraptopn does, how it does it do it, and could it be fixed?)
I have replaced the carb carb valves, but have been unable to get data on how to set (& to what value) the carb carb. Apparently the "E" model was not shipped to the US thus all the manuals (Clymer & Hayes) show a different carburator. I suspect mine are Mikuni Mikuni34SS carbs, but cannot tell for sure (does anyone know?) I also have difficulty in figuring out how the choke activating mechanism (& thotle throttle) fit together (should have taken a photo, but did not�)
If anyone knows how/where to find a schematic on the carb, carb hight (height where is it measured), information or suggeston on the strange gas tap, or ideas of what went wrong (& how to fix it beyond replacing float vales) I would greatly appreciate it.
From: Adam on 30 May 2007 15:59
Thanks for you very helpful responses. (I tried to reply earlier but I do not know if it was "sent" (I am a "newbie" to this group)
Had some difficulty in connecting to the URLs but eventually figured out most of it.
Float height on the SB35SS is 23mm or .905"
The choke problem was solved (I mis remembered how the throtle/choke bracket was mounted)
I have 2 further questions:
1 The main jet (the 1" brass tube with holes in the side, into which the needle in the middle of the slide fits into) is a VERY loose fit with the large needle which goes into it - hanging from the roud slide; is this this OK?
2 Trying to re-install the carbs into the manifold using WD40 and can't seem to make them slide in; (the carbs do line up) how much force should this take?
I aplogogize if this mail is a duplicate.

From: The Older Gentleman on 30 May 2007 17:00
Adam <Adam[at]profhorvath[dot]com> wrote:

> 2 Trying to re-install the carbs into the manifold using WD40 and can't
>seem to make them slide in; (the carbs do line up) how much force
should
>this take?


If the rubber sleeves are old, quite a lot. Tip: wrap rags round the
rubber manifolds, soak the rags in boiling water, and soften the rubber.
Makes the job easier.


--
BMW K1100LT 750SS CB400F CD250 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
From: Albrecht via MotorcycleKB.com on 30 May 2007 17:25
Adam wrote:

>1 The main jet (the 1" brass tube with holes in the side, into which the needle in the middle of the slide fits into) is a VERY loose fit with the large needle which goes into it - hanging from the roud slide; is this this OK?

The brass tube is NOT the main jet. It's the NEEDLE JET. The main jet screws
into the bottom of the
needle jet.

The manufacturers do not intend the engine to be running off fuel coming past
the variable needle jet/jet needle orifice when the engine is idling. They
intend the engine to run off fuel coming through the idle jets (AKA pilot
jets or slow jets)..

When the vacuum slide is all the way down, very little fuel is supposed to
pass through the tiny
gap between the taped jet needle and the needle jet. The difference in
diameters between the needle jet and the jet needle can be as small as 1/1000
of an inch.

As engine vacuum raises the vacuum slide, the tapered jet needle is pulled
further and further out of the needle jet, allowing more and more fuel to get
through the gap.

Nevertheless, most of the fuel used by your engine will come from the idle
jets, up to about 3/4's of the slide's total lift.

Since you seem to have access to some tuning information, maybe it has the
needle jet and jet needle's alphanumeric codes. You can figure out the
difference in diameter and determine exactly
how "loose" the needle should be if you look at the online Mikuni carburetor
tuning section at
Sudco International's website.

One thing for sure: the brass needle jet shouldn't have an egg-shaped hole
from having the harder aluminum jet needle rattling against it. If the hole
is egg-shaped, you'll need new parts.

>2 Trying to re-install the carbs into the manifold using WD40 and can't seem to make them slide in; (the carbs do line up) how much force should this take?

I installed a set of carbs on a Suzuki once that had such a tight fit I had
to force them into place with a 2 X 4.

It really shouldn't be that hard to install your carbs though. Just keep
rocking them up and down and pushing firmly.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200705/1

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