GS650GZ Katana Rebuild (Historical)

[KiwiAlfa156]

Finished the body work. Put on the Kat decals just to peez off Glen. Now the engine and there isn't much to do on that.








Got most of the crud off.

[KiwiAlfa156]

Head off.








Inlet ports matched to manifolds and tracts tidied up.





Casting lumps in the bowl and steps to valve seats removed





Attention to smoothing the roof of the port. Leaving. The floor rougher. Taking care not to take too much metal out or alter the cross section (guide boss profile not relieved excessively) as I don't want to drop port velocity.


A bit more work on the inlets. Exhaust ports I wont fettle with. Paint the engine and bolt her back in the rolling chassis.

[KiwiAlfa156]

Thanks Murray. I'm about 95% now.


Recently got back to the 650 project.











So all thats left is to drop the bottom end into the chassis, bolt the top end back on, pipe on, valve shims, carbs on and synched, and she's ready for a sneaky test ride...

[KiwiAlfa156]

Sludge from 1998... A very good vintage, and the last time this sucker rolled the streets.

[KiwiAlfa156]

Progress...

[KiwiAlfa156]

Ah nice Darryl, I like your installation method too! Nice and simple for one person.

Yep, can't rely on the in-house teenager being around when you need them. Rigged this to get it up on the bench. Did manage to dead lift the engine from the floor onto the bench by myself... once. But the last couple of inches were precarious to say the least. Thought better of it this time...

[KiwiAlfa156]

Getting there...

[KiwiAlfa156]

Thanks guys.


Well, apart from mirrors and re-registration (and repairing the seat pan at a later date) she's done. Valve shims took 4 days to turn up from Webike. Eight shims to start the set for NZD $10 each shipped. Local stealer wanted $23 each + freight... Set the valve lash correctly and bolted the cam cover on.





After a quick double check, the auxiliary gas tank was connected, full choke and she started almost immediately. After a warm up she settled into a relatively steady idle. An initial check revealed a fuel leak at the junction of carb 3 and 4. Out they came and the orings had been damaged by the PO when they reassembled the carbs and they had decided to let go. Appropriate replacement were on hand and the leak was fixed.


Set the ignition timing with the trusty timing light, balanced the carbs and then noticed oil drips on the headers. Initially it was a little puzzling where the source of the leak was. I had reused the cam box gasket which seemed to be in good nick, keeping the new one for the the post run in valve clearance check. It was leaking on the inside of the exhaust cam cover adjacent to spark plug 3 and running through an air passage onto the front engine mount and then onto the pipes. Clean oil meant tracing the oil was difficult. Put on the new gasket. Problem solved and another problem revealed.


I had put the tank back on the bike and when removing the tank to replace the gasket the disconnected fuel tap wouldn't shut off. I'd put a large rag down to catch spillage so no damage done. Luckily I had a spare tap on hand to replace the faulty unit.


Finally I set the fuel screws using the colortune. Engine is running really smoothly.  Happy as!


Weather is crapola so no sneaky test ride. Maneuvered the bike around the workshop so have 'ridden' about 2 meters to date.

[KiwiAlfa156]

The rain briefly relented and I got out for a sneaky 31 km test ride. On first blush it rides really well. She's very friendly. Runs straight hands off, didn't display any wiggles over mid-corner bumps. Steering is light, but seems reasonably accurate.





Kept the revs down and varied the throttle position as much as possible. I can sense that rolling on the throttle wide open at anything less than 6,000 rpm will have minimal effect on acceleration because I tried just that. But did let her run up to 6,500 briefly and you could feel it start to come on the cam. When it's run in a bit we'll see what the top end is like. Time to get the paperwork sorted and ride the G.

[1978GS750E]

Well......39 posts in one day! (Unless you added more while I was counting?) Gotta be a record!

[KiwiAlfa156]

Well......39 posts in one day! (Unless you added more while I was counting?) Gotta be a record!

Just something I prepared earlier....

[Eli69]

That's really nice. I'm always amazed by the talented people on the GSR.

[LeT]

Thanks for taking the trouble to post all these installments. I had a Japanese home market model 650G too. It was a great mile-munching bike, smooth and comfortable and yes really took off above 6500rpm.
It took me ages to sort out cold starting when I first got it. I didn't realise the cold start circuit (choke) actually runs through a passage in the carburettor float bowls. The little brass jets down in the float bowls were completely blocked. After I discovered them, the bike was a fantastic starter in all weathers.
The white wheels are a nightmare to keep clean. But easier than if it was a chain drive bike!

[craz1]

Nice job, that's the way I install my engines. I build a small bench that sits last a bit higher than the lower frame tube and then put my scissors jack in the middle at the same height as the small bench and slid it in. lower the engine in the mounts and done. Easy to do by yourself.