GS750 head on a GS1100 motor?

[Guest]

While replacing cams and stuff I found that top end parts don't seem to fit this motor (when they should). Frame says it is 1980 GSX1100 (Australian for GS1100 4Valve head, chain drive). Crankase says its a GSX1100. But when I went to get a cylinder head cover gasket, the correct gasket didn't fit. I ended up getting an '83 cover gasket which did fit. So at that point I was thinking this must be an '89 GS1100 with an '83 GS1100 cylinderhead grafted onto it. I've now pulled down the carbs for cleaning and have found the new carb rubber intake pipes don't fit the carbs. So then I measure the carbs and they are 32mm. They look like BSS32's. Now there aren't any GS1100's or GSX1100's that were fitted with BSS32's sooooo.... now I'm thinking that maybe this is a 750 cylinder and carb set up grafted onto a GS1100. Does anybody know if that will fit? Just trying to figure out what I've got.

[hjfisk]

Or is it the PO stuck a 750 motor in the 1100 frame, The cams I believe will interchange. Someone with more knowledge then me will chime in if I'm wrong. What are the motor #'s ?

[78gs750e]

He put in his post the crankcase says 1100

[blowerbike]

also a 750 in 1100 frame requires cutting the bottom triangle frame bungs/ mounts from the frame and or engine.
an 1100 will fit the 750 as there is no interference between the engine and frame.

[chef1366]

Sounds like an 83 1100 head with the wrong carbs. I do not think a 750 head will fit on 1100 jugs.
What is the number on the front of the jugs? 1074 or 1075?
Did you have the head off? You could measure the valves. Intake 27mm and exhaust 24mm for an 1100.

[MiketheBike]

Just correcting what I said earlier, I meant to say that the cylinder head may be off a 759 (or maybe 850 - they both had BSS32 carbs). Chef, I can't find any numbers on the Jugs. I can Find "made in Japan" on the top fin of the jugs on the left hand side at the back, but no numbers. Can you tell me exactly where the numbers should be? The number stamped on the crankcase is GGS110X-114459. The story gets worse. I just got up to carb number 4 after stripping and rebuilding the other 3 (32mm carbs) and noticed it was jetted slightly differently and that it looked slightly different to the rest once I had it apart. Measured it up and it is 34mm. WTF? Who would gang up 3 32mm carbs and 1 34mm? I think I will need to have a few beers before I go back to the workshop again.

[chef1366]

The numbers on the jugs are on the front of the engine next to the crankcase on the outside cylinder.

[GregT]

Looks like you may have something built up out of what the builder had or could find...
I've seen stranger mixes - for running under speedway sidecar rules it was quite common to sleeve one cylinder of an 1100 to use a 750 piston to reduce engine capacity.

Pictures if you can would be of great assistance.

[m.qualls89]

I'm curious. What is the difference I'm the 1074 & 1075 jugs?

[chef1366]

I'm curious. What is the difference I'm the 1074 & 1075 jugs?

I have not seen any rhyme or reason for these two numbers. Same engine.

[m.qualls89]

I was just curious because I had a 1074 but I bored and put on a 1075 block... sorry to hi jack.

[MiketheBike]

Still couldn't find those cylinder numbers. I have posted some pics of the engine of where I thought the numbers should be.

[MiketheBike]

and this is at the front on the clutch side bottom of jugs... no number

[MiketheBike]

Just to try and verify which cylinder head I may have, the intake ports on this measure 32mm I.D. Does that sound right for an 1100 cylinder head?

[Homie]

It's on the lower left front of the cylinder. Where the cylinder joins the cases, there is a notch in the bottom fin. Inside that notch is a small rectangular pad with the numbers "1074cc" cast into it.