GSX400E hints and tips

[Anonymous]

Hello folks! Only found this site via Google before, so be gentle with me. ;o)

Anyway, my questions are as follows

Firstly, after 42,000 miles, the top end is getting rather noisy. The exhaust cam is showing definite signs of wear, less on the inlet. Plenty of oil coursing around in there, but lets be honest. Top end wear happens to us all. )
Now I believe the GSX400E, having 8 valves, is known for having a weak top-end anyway, so my idea is this.
Will a 4 valve head off a GS400 go on? If so, what will I need to look out for regards to valve timing etc. Same setup as a vanilla GS400? etc

Next, the carbs on this bike, although they are Mikuni 34 CVs, are unlike what I see in my 2 manuals (Haynes and Suzuki)
Differences being that on my carbs, the main/pilot jets live in the float bowl, as opposed to the carb body. It seems to run OK for this, apart from the left cylinder lagging behind. It does not fire at idle, although it will kick in happily above 2500 rpm or so. As you can imagine, this makes for a rather lumpy take off.
Both carbs appear to be identical in setup/jets/needles etc.

Any ideas as to what could be causing this mis-fire on the left hand side, also where I can find some info/settings for this particular set of carbs?
All the usual other settings have been taken into account. Valve timing is all OK, ignition timing ditto. Valve clearances and compression OK etc.

Finally, in case it helps, the bike is the twin cylinder UK spec, 1981.

Cheers in advance for all possible replies.

[Anonymous]

I really don't know whether the 2-valve head would fit but here is what I've come up with.

You would probably have to add or remove links from the cam chain assuming that both engines use the same type of chain

You may have to add an extra base gasket to raise the jugs if there is a chance of the valves/plugs hitting the piston, this can be done to lower compression if you find yourself in a part of the world with low octane fuel

You would have to see if the head bolts will line up, also check if the exhaust will fit

You should use the search command on the webpage. A lot of guys have wanted to do this on the big engines.

Also, I just ordered a bunch of o-rings for my bike and need to know what the float height and screw settings are. Would you happen to have these?

Cheers, Steve

[Anonymous]

Cheers for the reply Steve.
As for my thinking re: 2-valve head, its still DOHC, so I imagine the cam-chain would be same.
As for pistons hitting valves and so on, well it appears that the GS400 is the same bore/stroke, basically the same engine, minus 4 valves, so I was kinda hoping the head would be the same, minus those 4 valves. )

All this is theoretical, by the way. Until someone points out the errors in my thinking )

Anyway, float heights and settings for the GSX400E.

Float height 22.4 +-1.0 (Fuel level 5.0 +-0.5)
Main Jet #117.5 Main Air Jet 0.6 Jet needle 5D69-4
Pilot Jet #42.5 Bypass 0.9,0.8,0.8 Pilot Outlet 0.8
Valve Seat 2.0 Starter Jet #32.5
Pilot Screw 1 1/2 turns Pilot Air Jet #125

All taken from Suzukis own GSX400E/L/S Service manual.

Cheers

[Anonymous]

hey there !
Finally someone with the same bike as I have !
I have a GSX 400E 1981 , it has 68.000 kms on the clocks.. still runnung strong. Fires up imediately, and runs great.
I `ve only had it for about 4 motnhs, but I know that the cam chain has been changed, which is the only thing I know .

Shoot some pics of your bike !

this is an url to a part of my website, with pics of my GS, text is in norwegian ,but you can just click the different "links" in the text, and you will se different pics, before and after "restoration".
(three ofthe links, are links to MC dealers, where I got parts from, norwegian tho)

http://www.djmongoriders.com/minsusi.htm

Joakim