Engine swap...partly :-)

[earlfor]

I have a 79 750E 8 valve that I ride. I have a spare 1981 750E 16 valve engine. The old 79 has a kick starter, but the 81 does not. I am thinking I should be able to remove the cylinders, head and pistons from the 81 and install them to the 79 case with everything just bolting up. (I also have the CV carbs that fit the 81 and the exhaust system which is different than the 79 also)

Anyone done this?

Earl

[HiSPL]

Not gonna happen for you Earl. The 8 valve is a low pressure oiling system while the 16 valver is high pressure. It's the only GS that has high pressure oil, and plain bearings in the crank. Although I think there's a 400-450 engine somewhere that uses plain bearings too but I'm not sure. Just ditch the kicker and put the whole TSCC engine in there. 8)

[Hoomgar]

Well Earl I am sure beyond a doubt you know way more about it than I do

But I do remember reading something on here about the 16 valvers and the 8 valvers having either a different bolt pattern or it was the bottom wouldn't fit in right without some grinding. I was searching threads trying to find it quick as I can't remember what exactly it was but someone said they wont line up. I couldn't find the thread that talks about what I am referring to but it was here on the GSR in one of the forum areas. I myself would love to know

I have a tag on some GS1000 motors and a GS1100 in 16 valve and was thinking about the shaft-ability and 16 valve combo. I have loads of other parts as well as tanks and seats and so on and all I really would need to hunt down is a titled frame.

Please keep us updated if you do this

[Hoomgar]

Not gonna happen for you Earl. The 8 valve is a low pressure oiling system while the 16 valver is high pressure. It's the only GS that has high pressure oil, and plain bearings in the crank. Although I think there's a 400-450 engine somewhere that uses plain bearings too but I'm not sure. Just ditch the kicker and put the whole TSCC engine in there. 8)

Ahh! I posted late, there you go That may have been what I was remembering.

[earlfor]

Since I would be using the 79 ball bearing lower end, the original 79 oil pump would be fine for the crank. Since the camshafts dont rotate any faster on a 16 valve engine than they do on an 8 valve engine, I dont see why higher oil pressure would be required. what am I missing here? I only intend to "graft" the 81 cylinders and cylinder head onto the 79 case and crank.

Earl

Not gonna happen for you Earl. The 8 valve is a low pressure oiling system while the 16 valver is high pressure. It's the only GS that has high pressure oil, and plain bearings in the crank. Although I think there's a 400-450 engine somewhere that uses plain bearings too but I'm not sure. Just ditch the kicker and put the whole TSCC engine in there. 8)

[HiSPL]

I guess it could work if the barrels fit. Only one way to find out I suppose

[Anonymous]

swap

Just a guess but being that the base gasket is different part number, you may not get the oil galleys to line up at the case, and the head may have smaller oil passages or even on a few bikes I have worked on that where high pressure systems, have a restrictor between the head and cylinder, to force more oil to the bottom end, and may be a problem for the lower pressure system, starving the top end it would be nice if some people here could scan there manuels and send you the pics of the case and gasket and seals

[SqDancerLynn1]

Don't quote me I think it has something to do with the way the oil is routed up to the head thru the studs, they are spaced different . Like said put the whole engine in the bike LESS problems

[earlfor]

Re: swap

You and Lynn hit my concerns on the head, (no pun intended) :-). I looked up the part numbers for the cylinders for both and theyre different, but that didnt confirm anything either way. I could tear both engines down and look, but I could find myself tearing down two engines and then reassembling them just to get back to where I started. I dont think I'll do that. Its easier to swap a complete engine. I really liked my kickstarter. sniff sniff sniff :-)

Earl

Just a guess but being that the base gasket is different part number, you may not get the oil galleys to line up at the case, and the head may have smaller oil passages or even on a few bikes I have worked on that where high pressure systems, have a restrictor between the head and cylinder, to force more oil to the bottom end, and may be a problem for the lower pressure system, starving the top end it would be nice if some people here could scan there manuels and send you the pics of the case and gasket and seals

[shaftzuki]

Re: swap

I really liked my kickstarter. sniff sniff sniff :-)

Earl

Ah - the simple things in life .... 8)

[lhanscom]

Hey Earl, I have a 77 750 engine already apart, would pictures help?

As an aside, did the 750 bore/stroke dimensions ever change?

[focus frenzy]

Not gonna happen for you Earl. The 8 valve is a low pressure oiling system while the 16 valver is high pressure. It's the only GS that has high pressure oil, and plain bearings in the crank. Although I think there's a 400-450 engine somewhere that uses plain bearings too but I'm not sure. Just ditch the kicker and put the whole TSCC engine in there. 8)

the late 550 engine (83 up) uses plain bearings.

[earlfor]

Nah, I would want to measure everything between the two if I was going to be the first down this road. :-) I think the bore and stroke is the same between the 79 and 81. I vaguely remember though that the threaded crank end for the stator is different. I'll just take the chicken way out and swap the whole engine. :-)

Earl

Hey Earl, I have a 77 750 engine already apart, would pictures help?

As an aside, did the 750 bore/stroke dimensions ever change?