Best guesses on RGS "clutch" issue?

Paul LeClair

Paul LeClair

Administrator
Staff member
Location
Calgary, Alberta, Canada
Hi all

as I continue my medical recovery, I got the RGS out for its first ride of this year. Was riding with several guys on modern bikes, and spanking the wheels off the RGS. Hot day for us, around 30 ish C, rode a couple of hundred kms.

on the way home, still a ways out in the country outside the city, the bike "failed to proceed" and I had to have my spouse come and pick me up with my bike trailer. Long wait at the side of the road in the hot sun. Got the bike home and unloaded it, have not looked at it as yet.

was really pushing the bike hard for a couple of hours, lots of twisties, most of the time spent between 5,000 rpm and 8,000 rpm. At roughly 7,800 rpm in top gear, still accelerating hard in a corner, the engine suddenly revved hard to some ridiculous rpm and the bike lost all drive.

Coasted to the side of the road. Clutch pulls in and out like normal, feels normal. Lots of fluid in the master cylinder reservoir. No brake/clutch fluid apparent from the hydraulic clutch slave cover, looks nice and dry.

Would be nice if this failure to proceed does not necessitate an engine out crankcase split or something, I don't have the energy right now......

When I got the bike home, the engine fires right up, but moving the gear lever through the gears with the engine running gives clunks as the transmission enters each gear but does not produce any drive. The RGS is fitted with Kevlar clutch plates that have maybe 3,000 miles on them.

Anyway, anyone have any thoughts on what to look for when I start pulling the bike apart...??

Paul LeClair

ps - an RGS ridden by an experienced rider can still dramatically outrun less experienced riders on modern bikes in the twisties, at least to around 1** mph +
 

Attachments

  • rgs 1.jpg
    rgs 1.jpg
    107 KB · Views: 278
  • rgs 2.jpg
    rgs 2.jpg
    134.8 KB · Views: 279
  • rgs 3.jpg
    rgs 3.jpg
    138.8 KB · Views: 279
  • rgs 4.jpg
    rgs 4.jpg
    120 KB · Views: 284
Primary chain ok?
If the slave cylinder seal had gone you would see fluid dripping on to the frame under the sprocket cover.
 
Hello Paul,

Good to hear that your medical recovery is going well. Sound like a transmission shaft issue to me, but I may be wrong.

Regards Gerald
 
Whatever the issue may be, 7800 rpm in top gear and still accelerating well beyond 200 kph. That?s serious cornering for a patient! Hats off! 💪

Marnix
 
Ernesto said:
I've seen a mainshaft broken into 2 pieces before (on a 1200).

Ernesto
Click to expand...

So have I. And you could cycle through the box without drive just as you describe. Broken in the center of the bronze bush - which kept everything aligned.

Well done on the ride though. Part way through chemo myself and not up to that sort of thing without a transfusion.
 
physically I will pay the price of that ride for a few days, but important for morale and spiritual recovery.

mechanically, i was suspecting transmission mainshaft when I typed the first post in this thread, just hoping to hear something simpler, like clutch slave cylinder O ring.......

in the next week or so i will pull the primary cover and the clutch slave and have a look. If it is anything major like trans mainshaft it will have to wait a bit for my further physical recovery, I am not yet up to manhandling that lump of an engine around.

as Marty pointed out I do have other bikes to ride.... ;)

Paul LeClair
 
The ball bearing in the centre of the clutch pushrods can "spin weld" itself to the rods, then jam in the mainshaft tunnel and hold the plates open - had this once or twice. i take the small spring out from behind the slave piston to ensure it doesn't happen. - Could be that! - regards - Phil
 
Can't add anything to help with the fault diagnosis, Paul, but well done you for getting out and about.  And at speed, too, you old devil .. :D
 
Congratulations on having the where with all to get out and ring the neck of the ol' girl.  Having said that, I hope she doesn't extract too much pain from you in retribution! Good luck sorting the problem.  It's not often I envy you for the weather you have up there, Paul, but I certainly do now.  It's blazing hot down here; no fun at all getting out on a motorcycle. 
 
I reckon it's unlikely to be clutch hydraulics or a jammed pushrod if it let go under power without the clutch being pulled in. And you say that clutch operation feels normal.

I presume you had to rotate the back wheel to get it to cycle through the gears (unlikely that all dogs were in the right place to engage every gear). That tells you that there's still a drive connection between gearbox internals and the output sprocket. So it would appear to be a failure of the drive connection between engine and gearbox main shaft. You could do a quick check of the primary chain by screwing the adjuster in to see what happens. Although broken primary chains usually end up punching a hole through the cover or causing other carnage.

Could be some kind of internal failure in the clutch I suppose. I can think of ways that the clutch could fail (like the pegs in the cush drive rubbers snapping off) but they all seem a bit unlikely.

It's a mystery. I'm keen to know what you find out when you get into the primary case.
 
You had your well deserved fun thrashing it,  its now its time for a kinder gentler owner more befitting an "Executive". Since it's on the trailer anyway drop it in Winnipeg and I'll give you $2000 Cdn for it as is.
 
on the topic of a hard ridden vintage Laverda with an older experienced rider pitted against modern superbikes with inexperienced riders, it was a slightly surreal experience. I don't usually ride in groups, and this recent group I only knew two of the other riders who had organized the ride. The various superbike owners were sort of turning up their noses at the RGS before we set out, various jokes about whether it and I would be able to keep up and making sure I knew where they were headed so I could meet them there if they lost me......

not sure what the RGS top speed is, but 9,000 rpm in top gear is probably close to 130 mph? The top speed of the various superbikes I was with had to have at least 40 - 50 mph on the RGS. The riders were a different thing altogether. While they could blast past me on the straights where rider skill means nothing, they would tip toe around the corners while I blasted past them in the corners at likely twice + their cornering speed, where it counts. Some embarrassed faces at the first refreshment stop, and new respect for an older bike and older rider. At the first stop one fellow asked me if the brake light on the RGS worked, as the RGS brake light never came on into and around the corners ::)

also my first ride on the new Conti radials, quite impressive.

Today I am really feeling the energy exertion of the hard riding yesterday and it will likely take a few days for me to recover. It was worth every second of the riding, and I am planning to try and get out for a ride next weekend again, likely this time on the ZX14...... ;)

thanks for all the educated guesses on the RGS drive issue, I will get to partial disassembly and hopefully diagnosis this coming weekend, will report back with whatever I find.

Paul LeClair

ps  with the oversized 1200 high compression pistons etc. together with the petrified rubber engine mounts the bike has to be kept spinning above 4,000 rpm anyway to keep my hands from being buzzed to sleep, so it only makes sense to keep the revs up! Smooth as silk from 5,000 rpm up, seems to want to rev forever, no signs of distress at 9,000 rpm indicated. If the engine does have to come out, I will take the opportunity to install new engine mounts "while I am at it...."
 
You must log in or register to reply here.
Back
Top