RGS Head - Rebuild to Stock or to Corsa/SFC Spec?

[IAG]

I think that's a P1 grind, by all accounts not a great street cam - and Megacycle no longer show them as available.

Megacycle's 584-X9 cam is Jim's F1 repro cam w/ a bit more lift than stock F1 (9.9mm vs 9.5mm). The catalog hasn't been updated in a decade so a phone call would confirm availability. You're correct, the P1 grind would be shite on a street bike w/ 11.22mm of lift.

 

[Vince]

That's interesting, I thought they were only doing modified A11 cams to F1 grind. Metal spraying to build them up. So there full billet from scratch.

 

[Laverdalothar]

I cant say I was chasing power as such on my 79 Jota, but after buying an unused RGS head from the Slaters 120 show engine a few years ago, Richard and Clem doing the spannering, Keith Nairn recut the valve seats to 3 angle, some mild port work, cam wheels drilled( as was clutch, and balanced), billet cam blocks, sachse /red ignition, latterly full crank rebuild, an awful lot of shit in the near full slingers, new bespoke Arrow rods, barrels bored to 78mm, new pistons, RS36 Miks. New gearbox. It really is a delight, so much torque, then screams with the C4 cams.Now against all I have said before, and i guess because of the brakes on my Husky 701sm and Honda SP1, I am feeling the need for sharper front brakes.Anyway those mods strike a great balance, front forks re worked, wheels wearing Contis as Keith suggested, and now tubeless. Looks standard..but a long way from...divine

...and then soon you recognize that the front fork isn't built to cope with the bigger force of the brakes, which makes you invest there. Then the rear isn't corresponding well with the front and you go for better rear shocks. That done, you recognize, that even the new tires aren't enough in terms of handling and road holding and you invest into a set of wider and lighter GSX-R-Rims, which also - in combination with the way better and lighter GSX-R brake system - gives better braking on the rear, too. While you are at it, you enforce the headstock to support the stiffer front-end and build in a better swing-arm - just because you can... You mount also Brake and - if hydraulic - clutch masters on the front from the modern gold series to cope with the 4-pot calipers and give you lighter clutch actuation. And now you have a bike that, rides, performs and handles like a good one end of the 90's, like the Honda VFR 750 or similar. Oh - and with empty pockets, but you will still feel and tell your wife it was worth it!

Roughly that describes my journey over the past 30 years...

 

[Vince]

Me too.

 

[RGS1000RGS]

As a comparison, My 77,500 miles RGA Sprint came with dyno charts showing 83bhp at the rear wheel. It has a worked-on head ( no idea what stage), standard compression of 9:1, F1 cams, Mikuni RS36 carbs with sock filters, witt ignition and Jota 3-2 exhaust system.

 

[ksoholm]

Lothar sez: And now you have a bike that, rides, performs and handles like a good one end of the 90's, like the Honda VFR 750 -

Sorry to say, but no amount of mods to an RGS would make it remotely as good a motorcycle as a VFR750/800 - objectively speaking. I should know - I've had four VFRs . They're on another higher level of objective performance.

 

[Laverdalothar]

Hi Kristian,

my wive's brother owns a VFR 750 (RC34 I think? It's from 1990 or 1991) in white. I have ridden that one several times and believe it or not, with the setup I have, my 1000 SFC can keep up with it easily (and Uli is MUCH lighter than me and for sure not a bad rider...), on narrow roads and - with the upgraded engine - even on highways or straights. I agree though, that with the same components, the Jota feels much easier to ride and is even closer to the VFR than the 1000 SFC ever was.

Here is what I have done to both bikes:
1000 SFC: Wilbers rear suspension, re-worked front-fork with HH-Racing suspension upgrade (externally adjustable cartridge system), GSX-R-Rims and rear brake, front is Kawa discs with 4-pot calipers from a Zane; headstock upgraded to later factory specs (bracings, connector tube between the down-tubes)

Jota: 38mm Marzocchi front fork with progressive springs (WhitePower), pre-loaded to adjust for my weight, different oil viscosity, fork brace from telefix. rear shocks are from YSS, rebound adjustable. K&J box type swing arm with needle roller bearings, GSX-R-Rims with BT012SS. That one is a flicker really now, I like the way it rides and handles VERY much.

Standard RGx bikes though are not easy to ride I feel... some exception being the ones from Michael Stöcker or Andre g. on here, who I have both seen riding their bikes in anger. Impressive...

I also saw Andre on a VERY tiny race track in Croix en Ternois (france), where we were doing a track-training. Andre was in the fast group, chasing a Ducati 996 rider with his modified and lightened RGS/SFC.

I was in the middle quick group with my street legal Jota, chasing the Ducati rider's friend on a Triumph... big fun... in a brake, they were both talking in dutch about how damned quick these Laverdas are...

Not so much fun that I myself was chased by a girl on a R1, who defined it as a "relaxed touristic ride" afterwards, as she was doing the whole track in one gear only... embarassing...

 

[nick7]

Hi Kristian,

my wive's brother owns a VFR 750 (RC34 I think? It's from 1990 or 1991) in white. I have ridden that one several times and believe it or not, with the setup I have, my 1000 SFC can keep up with it easily (and Uli is MUCH lighter than me and for sure not a bad rider...), on narrow roads and - with the upgraded engine - even on highways or straights. I agree though, that with the same components, the Jota feels much easier to ride and is even closer to the VFR than the 1000 SFC ever was.

Here is what I have done to both bikes:
1000 SFC: Wilbers rear suspension, re-worked front-fork with HH-Racing suspension upgrade (externally adjustable cartridge system), GSX-R-Rims and rear brake, front is Kawa discs with 4-pot calipers from a Zane; headstock upgraded to later factory specs (bracings, connector tube between the down-tubes)

Jota: 38mm Marzocchi front fork with progressive springs (WhitePower), pre-loaded to adjust for my weight, different oil viscosity, fork brace from telefix. rear shocks are from YSS, rebound adjustable. K&J box type swing arm with needle roller bearings, GSX-R-Rims with BT012SS. That one is a flicker really now, I like the way it rides and handles VERY much.

Standard RGx bikes though are not easy to ride I feel... some exception being the ones from Michael Stöcker or Andre g. on here, who I have both seen riding their bikes in anger. Impressive...

I also saw Andre on a VERY tiny race track in Croix en Ternois (france), where we were doing a track-training. Andre was in the fast group, chasing a Ducati 996 rider with his modified and lightened RGS/SFC.

I was in the middle quick group with my street legal Jota, chasing the Ducati rider's friend on a Triumph... big fun... in a brake, they were both talking in dutch about how damned quick these Laverdas are...

Not so much fun that I myself was chased by a girl on a R1, who defined it as a "relaxed touristic ride" afterwards, as she was doing the whole track in one gear only... embarassing...

I dont plan anything further...the wheels and tyres are great the Wilburs too on the rear..and I had a hydraulic clutch conversion by Keith too. I too had a new VFR...now an SP1, same gear driven cams and maybe by same designer. There is no point in modding it..it is far better than me...my Jota is now a perfect blend of power handling, looks, noise. Always amazes me when shoving it out of the garage how it manages to lose the weight when rolling....

 

[Andy J]

I actually agree with you Nick. I better go and have a lie down.