GS550 Engines differences

[bill_face]

Hello everyone.

I've got a '79 GS550 with an engine that is in a bad way. I've put another thread up about my engine woes, but I am wondering about whether I can fit a later engine?

My brother-in-law just happens to have a spare engine in the 199xxx engine number range which i think makes it an '82. Firstly I'm wondering if its a straight swap?

Secondly I'm aware this later engine has electronic ignition whereas mine has points. I had bought a Dynatek ignition & coils for my '79, mainly for reliability reasons, but hadn't got round to installing them as yet. So i could possibly return them.

So I'm wondering if there are any advantages to a Dyna'ed '79 vs a stock '82 engine apart from the kick start?

Also will i need to re-register the bike?

[Guest]

Straight swap as far as engine mounts and exhaust are concerned. Different carbs.

[Guest]

Oh, and you won't need to re-register it, but you would need to inform DVLA of the engine number change.

[scratch]

You will need the matching carbs, air chamber, exhaust, the electronic ignition with the later model is pretty solid but you will also need the ignigtor and you will have to do some wiring. I have a Dyna S on a 78, points on a 77, and the ignigtor on an 80 (all 550s) the stock electronic system on the 80 is plenty tight with a clean harness & good battery... at least, I have had no issues.

[Nessism]

The early bikes use VM22 carbs which use different carb and airbox boots compared to the later CV carb engines. Some sort of work around will be needed to run VM's on the later engine.

[bill_face]

I think he has probably got a set of carbs as well.

I bought aset of K&N Filters for the VM carbs will they fit on the CV carbs?

[hampshirehog]

I think he has probably got a set of carbs as well.

I bought aset of K&N Filters for the VM carbs will they fit on the CV carbs?

No they won't - different diameter.

[hampshirehog]

You can swap cylinder heads - they bolt straight on. So you could run with VM carbs on a 79 head fitted to a 1980 bottom end.

[bill_face]

So, would all the valves and pistons be a match between a 1979 engine and a 1980 engine assuming neither of them have been rebored?

[Guest]

Yep, should all be ok.