R80 GST???????? Front forks

[Zed3]

I have a 1984 R80 that began life as an ST. A previous owner has swapped the front forks for some Suzuki DR650 forks and 21" front wheel in an attempt to convert it into a G/S lookylikey.

They did a pretty good job, but the swing arm was not extended and the gaiter on the mono swingarm now rubs a little on the underside of the frame, has split and leaks oil. I am also a little concerned that the swing arm might well be running at an unsuitable angle.

I have dropped the front forks through the yokes by about 1" but this hasn't completely cured the problem - so I am looking on thoughts as to how to proceed for the best

Obviously one option would be to try and find a ST front end, but I was wondering if there were any more modern forks (with better performance than BM originals and possibility of decent brakes!) that would be a straight swap and return it to original geometery?

Any thoughts o people of great wisdom?

 

[ianboydsnr]

I have a 1984 R80 that began life as an ST. A previous owner has swapped the front forks for some Suzuki DR650 forks and 21" front wheel in an attempt to convert it into a G/S lookylikey.

They did a pretty good job, but the swing arm was not extended and the gaiter on the mono swingarm now rubs a little on the underside of the frame, has split and leaks oil. I am also a little concerned that the swing arm might well be running at an unsuitable angle.

I have dropped the front forks through the yokes by about 1" but this hasn't completely cured the problem - so I am looking on thoughts as to how to proceed for the best

Obviously one option would be to try and find a ST front end, but I was wondering if there were any more modern forks (with better performance than BM originals and possibility of decent brakes!) that would be a straight swap and return it to original geometery?

Any thoughts o people of great wisdom?

I think it can be swapped, but it's not a simple matter, I think rob farmer has a set of ST forks, if you go down that line!

 

[Rob Farmer]

There's no difference in lengths of swinging arms on the St and g/s. If you extend the swinging arm the jacking action from the mono back end gets very pronounced.

The simplest solution is to fit a set of forks from an 81-84 bmw. These are identical to the g/s forks. You just need to drill mounting holes for the mudguard in the bottom of the bottom yoke and fit a small spcer under each spring. Front wheels for the St and g/s are hard to find. I've an St one in my stash that I'd be prepared to sell.

 

[cheb]

I've XR650 forks fitted to my paralever and to shorten them I added internal spacers that up the preload. I think I might even have posted a thread about it on here.

Time to see if I can post a pic or three.

 

[Dogbytes]

Modern forks

I went down the route of trying to find a modern straight swap for my ST project bike. If you want conventional forks you'll ave to look harder than I did - because I couldn't find one. Actually, I think I found a set of reproduction Cerianis but they cost more than the bike. If you're not bothered about it looking original then there are plenty upside down forks that'll go onto it.

 

[Zed3]

Thanks Rob.

When you say "fit a set of forks from an 81-84 bmw" - do you mean from any 81-84 BMW?

 

[Zed3]

I went down the route of trying to find a modern straight swap for my ST project bike. If you want conventional forks you'll ave to look harder than I did - because I couldn't find one. Actually, I think I found a set of reproduction Cerianis but they cost more than the bike. If you're not bothered about it looking original then there are plenty upside down forks that'll go onto it.

Not too bothered about it looking original as it has already been well messed about with. What are the sort of specs that I should be looking for in upside down forks? Any particular recommendations?

 

[Dogbytes]

Not really my area of expertise as I was looking for right way up ones. However, as I recall, in terms of correct overall length, Ducati Monster forks were perfect. There are usually plenty on eBay because they're (or were) non-adjustable. People used to upgrade to adjustable ones and sell the old ones for a couple of hundred quid. If you then have them set up for that bike with you on board they should be pretty decent - certainly better than the originals.

 

[Rob Farmer]

Thanks Rob.

When you say "fit a set of forks from an 81-84 bmw" - do you mean from any 81-84 BMW?

You can pretty much fit anything but the road forks would give you the g/s look. These forks

But the R65 forks are the same as the original ST forks and would probably be a lot cheaper to buy - a pair on ebay at the minute for £99 http://www.ebay.co.uk/itm/BMW-pair-...pt=UK_Motorcycle_Parts_13&hash=item23422b9726

 

[MickDB1]

I cant find the post but I am sure I have read you can straight swap a f650 dakar front end into the headstock
yerd get the wheel and brake all nice and still BMW HTHY a bit

 

[Beemerboff]

Just about every BMW fork , including the Ks and 650 singles have the same steering head bearings so just about any swap is possible.
And the All Balls site has a cross reference which will tell you which other forks will fit.

But as Rob F says the R 65 forks fit, work without the need to re spring / rework the damping, allow decent brakes and are available easily and cheaply so it would seem a no brainer to use them.

 

[Zed3]

Thanks for all the help, advice and info

I'll let you know how you get on!