Anybody Identify this motor?

[Motovalet]

I've got hold of a 750 motor that came out of a GSX750F (1990) but it looks like a GSXR750 motor? The clutch actuating lever  (where the cable connects) is on the right hand side, like on the 750J and there's a a dimple in the clutch cover, I'll upload a picture when I've taken one but hopefully this engine number may identify it? It's R716-101635 or the last digit may also be a 3?

[Captain Chaos]

R716 is 750M engine (1991, the last oilcooled GSX-R750)

Edited January 10, 2016 by captain chaos
spelling misteak

[Motovalet]

Cool! That's great news, so better than a 750F motor then? The 750M's  are supposed to make 116BHP and I think the short stroke dot head 750F is around 106, not a lot in it but hopefully this motor will be quick enough. It's certainly better than the wheezy old 600F lump that it's replacing! I've never heard it run and took a chance on it, it turns over and all the cam lobes look good and the inlet tracts are clean as are the exhausts. When you look up the ports (either) the valve stems look very black and rough looking but hopefully just carbon build up?? I poured oil down the bores and squirted carb cleaner in the inlet and exhaust ports and it also looks like somebody drained the sump as it was empty, the oil that was left looked clean enough though. I'm optimistically hoping I can do a compression test, gap the valves, add new plugs and fresh oil and hope it fires! Is there anything glaringly obvious I ought to do before it goes in the frame that I may have missed? The only two negatives I've spotted are 1) the there's a sheared bolt right in the middle of the sprocket output shaft, I'm guessing it's some kind of retaining bolt although the shaft itself is threaded after the splines which suggest a fugging big nut goes on first? If so can I just leave the tiddly sheared bolt alone? 2) There was quite a lot of rust dust that fell into the bores when I extracted the stuck spark plugs and I'm hoping it'll just get blown out of the exhaust and not do any serious damage?

[Captain Chaos]

there should be a fugging big nut on the output shaft, with a locking tab which you fold over the flats on the nut.

On an unknown engine I always remove the sump pan, and clean the oil pick-up.

The valve clearances are adjusted with shims on the M engine as you may have noticed.

[fatblokeonbandit]

M's had a washer and bolt as well as the splines tab washer to retain the nut..

 

[Motovalet]

Yeah, shims, groan! Need a spring compressor as well as a compression tester now then! Here's my output shaft, you can see the small sheared bolt right in the middle of the shaft. So I need just the nut and a tab washer then?

[fatblokeonbandit]

Yes just a nut and washer

[Captain Chaos]

you don't need any special tools for changing the valve shims. The rockers can be pushed sideways.

[Motovalet]

Ok, thanks for that. Don't suppose you'd happen to know the correct inlet and exhaust valve gaps? :-)

 

[Captain Chaos]

intake 0,10 - 0,20mm

exhaust 0,15 - 0,25mm

Edited January 12, 2016 by captain chaos

[Motovalet]

Perfect! Many thanks :-)

 

[Motovalet]

On 11/01/2016 at 6:03 PM, captain chaos said:

The valve clearances are adjusted with shims on the M engine as you may have noticed.

Well, I decided to adjust the valves on my motor today and it definitely has not got shims? It has lock nuts just like on my 600F teapot motor, the engine number apparently says it's a 750M but if the adjusters are lock nut, it can't be right? Is it maybe an earlier motor from a slab side?? Thing is the clutch actuator is on the right and there's a dimple in the clutch cover, plus it's a 749cc motor so definitely not a short stroke J motor, any ideas and also are the valve adjustment gaps the same as quoted earlier? Thanks in advance :-)

[Captain Chaos]

750L motor is the same as M but with locknuts (and slightly different intake ports). Yours appears to be an L then.

Intake 0,10 - 0,15mm, exhaust 0,18 - 0,23mm.

[Motovalet]

Excellent! Many thanks, from what I've gleened from the internet the L model was considered the best, so I'm happy with that. Hopefully this motor will propel the lard arse 600 teapot a bit quicker than the outgoing 600F lump :-) Just got find somewhere to get those tiny springs that fit under the carb linkages and put it all together now! 

[Captain Chaos]

those springs are still available new from Suzuki.

[Motovalet]

1 hour ago, captain chaos said:

750L motor is the same as M but with locknuts (and slightly different intake ports). Yours appears to be an L then.

Intake 0,10 - 0,15mm, exhaust 0,18 - 0,23mm.

Stupid question, but is it better to set the gaps to the minimum setting or the maximum? Am I right in thinking if I set them to the minimum that the motor will run quieter but if I set them to the maximum setting it may sound more "tappety" but as the valves wear the gaps will get smaller and hence quieter? Also as an aside I've turned the motor backwards a few times when measuring the gaps, albeit slowly, am I likely to have caused any damage, as far as I can see the chain never skipped any teeth but I've read it's a big no, no to turn any motor backwards as it can cause damage??        

[Captain Chaos]

set the valves closer to the maximum clearances, they run better like this.