78 GS550: 650e topend or complete engine swap?

[prichmon]

I have owned many GSs in my life; all but the recent crop are big bore 1000+cc. I currently own a GS650GT, GS1000GL, GS550 and a 650e parts bike. My current project GS is a 1978 GS550 wire wheels and all. Rather ratty but runs good and rides well. We have done all the standard maintenance items and upgrades to the chassis and electronics.
Dyna-s ignition, coils and wires,
Relay mod for coils
GS850 shocks
R/R upgrade
650E dual disc brakes and forks
Stainless lines
Performed valve clearance.
Caught up all mntc.

The only issue is the bike is weeping fuel from the carbs out the overflow/drain tubes. IDK if the plug is leaking or the fuel level is set too high. I have to pull them off to repair. Any thoughts???

I have recently heard the timing chain rattle on decel and combined with a wish to clean up the engine I am planning for a winter project to swap the 650e engine in or just the topend and associated parts.

I started this process from reading discussion on the 673cc install on the 550 but can't seem to find the "how to"s. I found a deal on a 650e which someone was butchering to be a cafe. I have the complete long block engine and most of the hard parts. The carbs are in pieces so I have no idea if the parts are all there.

I wish to get a little more go to match the whoa from the dual disc setup. I am not looking to race and am torn in the 6 speed vs 5 speed debate. I do want enough to beat a roll-on run with my son on a 500F. Bike and he weigh ~100#s less than me and the 550.

Are the VM22s adequate to feed the engine with proper jetting?
Is there another direct fit carb set which will work with stock air box and
Which cam should be run in the bike? I recall 650 intake 550 exhaust?
Are there an associated alterations which should be done during the install process?
I had read about degreeing the cams but have not found the page/article..???
Will the later 650e complete assembly fit in the frame and bolt up?
If I used a modern sealant in place of a base gaslet how much would the CR be affected?
I would prefer not to disassemble the complete engine to machine/open the case bore to fit.


Thanks for your opinion.

Rich

[Chuck78]

VM22 carbs will not work on the 650 head... And they are not big enough anyway.
You're best off restoring of the 650 carbs
you might be able to get a set of KZ1000 VM28 carbs and some particular year/model of KZ1000 or Z1R intake boots to work on that head, but you may need to have some special spacers machined to space the boots further off of the head, otherwise if I recall, the carb rack and linkage hits the cam chain tunnel on the head and the setup will not bolt on.

On a 650E, the cam sprockets are the same as 550. On a shaft drive 650G, the cam sprockets will absolutely not work at all with a 550 crankshaft. It will destroy the engine as soon as you try to start it, throwing it out of time on the second revolution.

I'm not sure if the 650E uses the same cams as the 650G, but if it does, it will give more mid-range performance, but the 550 cams will scream a lot harder at the top end of the tach with higher peak horsepower output.

Doing a 550 / 650 top end swap requires tearing the engine down and splitting the crankcase halves, and clearancing the upper half of the crankcase to accept the 650 cylinders. Then you need a custom thickness base gasket or head gasket. and you absolutely cannot use the shaft drive 650 camshaft sprockets, but you can use the 650 cams without the shaft drive 650G sprockets.
650 carbs are by far the best to use. and you can use some can in RC series air filters, I can't remember the exact #'2 (2382? 2873?), but I think they are the same as advertised for a GS550 1980-81 or 82.

Let me know if you need any more advice or assistance, as you noted in your message, you're only 45 minutes east of me.