Suspension tuning tips

[Guest]

Hi I am currently building a 1978 gs5/650 with the intention of road racing. with that said, I need some suggestions regarding period-correct suspension setups. What forks were used by the guys who raced gs bikes back in the 80's? did they keep the stock ones and just change the springs? or swap them out entirely?

[GregT]

The smaller GS's were mainly raced in Production classes around the world as far as I know so vey little was allowed to be changed.
Nowadays the first move is to have a look at the rules of the organisation you'll be racing with and see what is allowed.
Go along to one of their race meetings and ask questions too....

[TheCafeKid]

+1. Have a look at te rules for whatever class you plan on/are allowed to be running in.
Most of these would have been run in production class, save for the factory works/factory backed privateer teams who had the cash to use/build custom one off bits.

Since it's likely you'll be in some sort of VinMoto or VRRA class, there likely won't be much you're allowed to change. But you probably CAN use the best of the vintage, and/or modern upgrades that relate to safety...

[Big T]

I don't think many racers changed their forks in the 80's

Some new springs from Progressive or Sonic, a fork brace and some emulators (if allowed) should be the hot set up

Plus, changing the fork seals and checking for slop

[ashdricky]

What is an Emulator? I have been considering progressive fork springs, but am not sure if they can be installed as the forks I have are from an 83 650GLX and have Schroeder valves on the top to adjust air pressure i assume.

Competition rules:
We are building this bike to be my entry in a contest between myself and a couple of others, the goal being to see who can build the "best" vintage sport bike. If all follow schedule we will debut our bikes at the local father's day auto show. Following visual inspections and voting from the crowd, we are then supposed to head up to Toronto the following day to do some track runs. I believe my main competition will be an late 70's cb750. with that said we have only come to the agreement to use period correct components, with the exception of, electronics and brakes (in case OEM parts are no longer available). This is really all the information I have as far as 'Rules' go.

[hampshirehog]

Ceriani were the forks to run in this part of the world back then. I doubt you'll find any now though.

[Tim Tom]

What is an Emulator? I have been considering progressive fork springs, but am not sure if they can be installed as the forks I have are from an 83 650GLX and have Schroeder valves on the top to adjust air pressure i assume.

Competition rules:
We are building this bike to be my entry in a contest between myself and a couple of others, the goal being to see who can build the "best" vintage sport bike. If all follow schedule we will debut our bikes at the local father's day auto show. Following visual inspections and voting from the crowd, we are then supposed to head up to Toronto the following day to do some track runs. I believe my main competition will be an late 70's cb750. with that said we have only come to the agreement to use period correct components, with the exception of, electronics and brakes (in case OEM parts are no longer available). This is really all the information I have as far as 'Rules' go.

Well since the rules seem to be fairly loose, I would rebuilt the forks with modern springs and cartridge emulators. It seems more like a bet for bragging rights than a sanctioned vintage race series.

http://www.racetech.com/HTML_FILES/EMULATORGV.HTML

I would give Racetech, or some another reputable suspension tuning company a call and work up something that works for what you need. IE: the outside appearance of a vintage bike. I would do the same for the rear, and get it dialed in to your size, weight, and style.

Also be sure to get some good modern rubber on there. There are a few favorite 'Road Racing' GS tires, I believe the Avon RoadRunners and Pirrelli Sport Demons get high reviews.

[wera racer]

I can't speak to the smaller GS, but I race a GS1000 in WERA and AHRMA. I installed Race Tech springs and emulators when I did my build. The springs were way too firm when I raced them for the first time at Barber in October, but Race Tech had a tent there and their great guys spent a half a day (for free!) dialing me in with lighter springs and adjusting the emulators.

I can highly recommend them based on their customer service and know-how.

I installed Ikon shocks on the rear and am happy with them, but if I had more $ I'd run Werks.

Good luck!

Here's mine at Barber...

[jaywelchy]

Great pic .. like to see guys running the dinosaur's

[trippivot]

looking good there!

[ashdricky]

WERA_RACER, judging from you photo your suspension set up must be working. I think emulator cartridges are the way to go, I checked out race tech's site and I'm not sure if I need special springs to use the emulators or not?

[gs58]

I know someone who put the whole GS1000 front end in a 550 race bike. I don't know if the 1000 has better specs than the 550 though. He just used it because he had it.

[gs58]

WERA RACER - whats the purpose of the shield between the headers and the engine? Heat reduction, or oil catcher?

[speedyandypandy]

I don't think many racers changed their forks in the 80's

Oh yes they did, just read books/articles/info about old racers, pro and amature, they changed what they could.

Ceriani were the forks to run in this part of the world back then. I doubt you'll find any now though.

They do pop up on evilbay, but not cheap

I know someone who put the whole GS1000 front end in a 550 race bike. I don't know if the 1000 has better specs than the 550 though. He just used it because he had it.

I think you will find the GS1000 stanchions have a bigger diameter, maybe a wider front wheel axle and better brakes(I'm just guessing, but it's like that on the hondas, big cc CB's have wider than small cc CB's and I excpect the GS's is the same), and that's a good thing.

Normaly a class will allow upgrade's that where allowed back in the day, and/or use stuff form the right period, even if the bike your replica is based on didn't have that spesfic part. You can use Brembo calipers, even if the original used AP Lookheed. It's also normal that brake parts are allowed to be upgraded beyond the era, because of safety reasons.

[ashdricky]

Thanks Speedy that is definitely useful,I got a used set of Ohlins last week and need to find a shop to rebuild them. they aren't the most cosmetically appealing.