GS 650E 650G head swap help

[Ricey650]

Hi all, I've done lots of reading here but first time poster.
So much great info on here, it's amazing!

Ok, so I recently acquired a 1981 GS650E.
The bike is in good nick but the cam chain is snapped and inlet and exhaust valves 1&4 bent.
Managed to track down a new head off a GS650G and purchased it last night, assuming it would bolt straight on (I know the bottom ends are different).
However, after stripping it down I noticed the markings on the cam sprockets are different from the GS650E sprockets.
GS650E cam sprockets show 450 on the intake and 470 on the exhaust.
GS650G shows 372 on intake and 373 on exhaust.

Now I'm worried the head from the G is not compatible with the E?
Wondering why the difference in numbers and will I still use be able to use the head and cams from the G
If you can shed some light on this it would be fantastic!

Also, can anyone tell me if the cam guides from the gs550 (78-81) will fit my 650E

Thanks in advance👍

[Guest]

The one thing I do know for sure is that the 81 650E has a different number of teeth on the cam sprockets than the 650G models. As for the rest of the head, I don't know. But as luck would have it, I have an extra set of 650G cams laying around. If you find out that you can use the rest of the head, I'll help you out with the cams.

Also, if you tell us where you live, there may be someone local to you that could help you out too.

[Ricey650]

Cheers super, appreciate your insight.
Thanks for the offer of cams, but I actually have 2 sets of cams now, one set off the E head and one set of the G head.
Cams, head and valves of the G are what I want to use as they're in good nick.
Could I just bolt the sprockets from my original cams onto the G cams and utilise everything else from the G head also?
ie would be a complete G head apart from E sprockets, bolted onto the 650e bottom end.

PS. I live in the Barossa Valley.... South Australia

[Guest]

I do believe that just bolting on the E cam sprockets to the G cams should work just fine. I have also heard that you don't want to mix the heads and cam holders. Keep the G head complete and just add the E sprockets to the G cams. HOWEVER... I'm no expert on this. I'm working off my memory so it might be better to PM blowerbike or rapidray. They are members here that know a whole lot more than me. But I think it will be just fine.

Hopefully someone else will jump in and add their knowledge too. Good luck with your bike.

[BigD_83]

Cheers super, appreciate your insight.
Thanks for the offer of cams, but I actually have 2 sets of cams now, one set off the E head and one set of the G head.
Cams, head and valves of the G are what I want to use as they're in good nick.
Could I just bolt the sprockets from my original cams onto the G cams and utilise everything else from the G head also?
ie would be a complete G head apart from E sprockets, bolted onto the 650e bottom end.

PS. I live in the Barossa Valley.... South Australia

Having some wine with your engine repair?

Nothing to add on the technical front, but I did want to acknowledge your area.

[Ricey650]

I do believe that just bolting on the E cam sprockets to the G cams should work just fine. I have also heard that you don't want to mix the heads and cam holders. Keep the G head complete and just add the E sprockets to the G cams. HOWEVER... I'm no expert on this. I'm working off my memory so it might be better to PM blowerbike or rapidray. They are members here that know a whole lot more than me. But I think it will be just fine.

Hopefully someone else will jump in and add their knowledge too. Good luck with your bike.

Cheers Super, will PM the boys and let you know how I get on.
Thanks for the info!

[Ricey650]

Having some wine with your engine repair?

Nothing to add on the technical front, but I did want to acknowledge your area.

Of course! You have wine with breakfast when you live in the Barossa!
Have you visited the region?

[BigD_83]

Of course! You have wine with breakfast when you live in the Barossa!
Have you visited the region?

I've never been, but I am a fan of the product coming out of the area, and it would definitely be on our hit list when we make it to Australia.

Trouble is, we have a girl heading off to uni next year, and she is going to soak up most of our travel fund for the next few years.

[Steve]

Back to the topic at hand, ...

If you are feeling industrious, move the sprockets on the cams, as long as the E sprockets stay with the E engine.

If you are feeling a bit lazy about it, just keep the sprockets where they are, but make sure the E cams stay with the E engine.

The cams are identical part numbers, the only difference would be any wear patterns in the bearing surfaces.

As mentioned, keep the cam caps (retainers) with the head they came on, as they are line-bored as a set.

.