A tale of two options...

[jasonb]

Hi all,

This will dredge some oft trodden ground, however I have used the search function to the best of my ability the last few days and am ready for the abuse

A while back I bought a gs650gt... well, a v5 and a collection of bits that match up to it. Most of the bike is there but most of it needs overhaul. Now I only bought the bike as a cafe project and so I'm afraid there isn't much chance of the purists winning me over to restore it. However I'm at a slight fork as to what to do engine/drive wise.

The current gs650gt engine needs a proper going over and considering how tricky it seems to come across bits UK-side for them I was wondering about buying a good 550 engine (cheap and common) and building up a 550/650 hybrid as several have done on here. The draw to this is that with chain drive I would then be able to run whatever wheels I desire. (Be that spoked and classic looking for the occasional pottering about, or more modern, wider and grippy for being a bit of a hooligan if I so desire). Also, it offers another gear and the potential to drop some weight, but that is less of an issue. (I'm also a sucker for a kickstart... but that's another thing again...)

Of course the next thought that pops in is "if you're going to the trouble of swapping to chain drive then why not fit x,y,z sportsbike engine instead of an old GS lump". I'd quite like to keep the character of the GS so I'm less keen on this option. (I like the gs650 specifically because imho it is arguably the best gs engine)

So what I'm really after is:

a) How tricky is it to swap a gs650 frame to accept a 550 crankcase/mounts/chain drive i.e is it just a case of fitting a 550 swingarm? (I have searched everywhere and it is often brought up but always shot down in flames... I'm hoping for a decent answer here as I'm not butchering an already running bike...) I can weld, so little modifications aren't an issue.

or

b) Where do you buy gs650 engine parts for sensible prices in the UK?

or

c) Any other thoughts or good ideas?

Little more info: I was given the front end from a cbr600rr so I will be using the forks/brakes/bars/switch gear from that.

Thanks in advance for any help or input!
Jason

 

[tom203]

It would be a major PIA to swap a 550 engine into a 650 shafty frame- I think the frame was built around the narrow trans of the 650 shafty. You'd be better of scooping a 550 bike and adding the 650 head to it- many guys on here have done this or in process. then you get kick start, 6 speeds, chain drive ratio fiddling.

But if this 650 is currently running well, shame on you! Not to everyone's liking- obviously- but I find it perfect with nice manners and plenty of power

 

[jasonb]

Haha... it certainly isn't running! Literally everything needs going over (I bought it as a project and it was completely disassembled - the bike had done well over 70,000 miles before that too) and I wouldn't even trust turning the engine over by hand until I've taken it apart to look for bits of crap that have made their way down there.

This is mostly the reason for asking, as it is basically a blank canvas.

So the chain would foul the frame then... in which case that idea may be a bit of a non-starter. Hmm...

 

[UK-GT]

I have GS650GT, where are you located in the UK?

 

[jasonb]

I'm all the way down south in hampshire

 

[UK-GT]

Bugger!! It would have been nice to find someone a bit more local to help and learn etc. As much as I think this forum is fantastic, you still can not beat hands on experience. Half of the people I know do not know one end of a spanner from another and the other half are only interested in 2 wheeled missiles!!

 

[jasonb]

indeed! - Thankfully I'm pretty happy laying spanner to things, though this will be the first motorbike I've built from scratch (previously built a 106 rally car and am part way through a mk1 vauxhall cavalier)

My love is mostly for retro vehicles hence the cavalier and the gs

I'm so split on what to do with this project - still tempted by the chain drive conversion idea, but it depends on how much the frames actually differ really. I don't mind some chopping and welding, but there doesn't seem much point if it is drastic amounts of work.

 

[jasonb]

Right, a day out on the bandit cleared my thoughts nicely. Plan is to build a proper true to form shafty 650 cafe racer.

I'll basically be giving the engine a once-over and hopefully a re-ring/sleeve/bearings depending on what needs doing once torn down. Full carb rebuild with a dynojet kit. CBR600RR front end swap including brakes, bars, switchgear. Make my own custom wiring loom and fabricate some kind of exhaust using the bits I actually have...

I'll make a project thread if anyone would fancy it?