Light throttle kit

Hello to you all.
In an old issue of grumblemonger (2009) I came across a kit for a lighter throttle. This comprised of a stainless rod across the frame through the holes under the rear of the fuel tank supported on two small bearings. It had a pulley on each end each with a short wire to the left and right carburettor and a centre pulley with a cable to the twistgrip. The writer reported a light, easy action throttle. Have any of you any recollection of this or any information if this is still available? I have an 850T with the square slides and a stiff action even without the engine running. If this enquiry turns up nothing I intend fitting Venhill cables and trying lighter return springs. Thanks for any replies. Regards. Dave

I vaguely remember somesuch, only prob is the looong pull on the twistgrip, cos has to go around further, light throttle slide springs much simpler and don’t affect travel.

Before the redesign , try a crampbuster thottle grip attachment , cheap easy to fit / remove
various types available , wide / narrow .

I’ve seen one of those pully kits on a Le Mans, the pully sheeves were not that big so it wouldn’t make much difference to the length of the pull on the twistgrip.

square slides and a stiff action even without the engine running. If this enquiry turns up nothing I intend fitting Venhill cables and trying lighter return springs

Again, I sorted this by rerouting the cables for fewest and shallower bends, and light springs, on both the Spada and the 850. The pulley thing seems too much of a faff. But I guess it would help where it turns the direction of pull through 90 degrees, rather than by cable bends. My LM had the bell cranks on top of the carbs so cables just went forward from there. Still bluddy strong springs tho.

Could be new cables might help yes.

:smiley:

I’ve seen a photograph of one of these kits on a bike and as Chris says the pulleys look to be only small diameter. The writer also stressed how light and manageable the throttle control was with the kit fitted. If one was available I would probably try it but as the throttle cables on mine are shot anyway, I will renew them with Venhills and lighter springs. Thank you for your help. Regards. Dave

Dave, routing is the key, where the tank sits on the support rubbers on the frame my cables pass through short pieces of petrol pipe so they dont get pinched, they avoid the pinch and all tight bends. Before nylon linings I would oil my cables regularily, but I have heard that oil make the nylon swelll (can this really be true?)

I also have piggyback gadgets on top of my carbs but these put in another mechanical lever that adds weight. I tried flat tops on my carbs and they work very well but you have another 90 degree bend in the cable to deal with, I ended up running the cables on the wrong sides of the frame and crossing the back at the rear of the tank.

I have put the piggyback tops back on because they look cooler, and I have a tourer now so I will (if I ever get it back on the road) only use it on relatively short runs.

Best of luck with your investigations!

Lighter throttle springs are available for the square slide carbs. I had to buy mine from the States was all. I bought two sets and have one fitted on Blue my T3 and the other fitted to Jug the Loop. They do make quite a difference. They are light enough that you can almost imagine the throttle hanging if you are easing off the gas very gently. I also use what I think you are calling a ‘cramp buster’ – this just being a paddle that clips on the end of the twist grip. I have these fitted on Blue, and the Pearl - my V50. I find it can hinder very slightly the reach for the front brake. Not an issue on these two bikes as they run with linked brakes, but on the drum braked Jug where it needs all the help it can get to haul it down I have not fitted one.

Again, thank you both for your help. The petrol pipe idea sounds sensible. When I put the new cables on I’ll try that. I had thought about running the cables on the wrong side and then crossing them at the rear of the tank. There’s not much I can do about the 90 degree bend though. Eurocarb advertise medium and light springs so I’ll buy a pair of each and experiment.

I’ve just read a post and it seems that Eurocarb no longer have springs for vhb carbs. I’ll try the other fixes and if I think the throttle action is still too heavy then springs for phf carbs are available and, apparently, can be modified to fit vhb carbs. Good fun eh?

On my Cali’3, I fitted lighter springs, made a big difference.

I decided to fit barrel shaped grips, bigger diameter than the old ones, surprised me that it made the throttle even lighter.

Back in the day a fried had some BMW R100 Bing carbs fitted to his Cali3 to overcome a heavy throttle.

Here’s my cable routing photo of years ago, if it helps

carbcon2.jpg

Thank you all again for your suggestions. When I get new cables I’ll follow the routing as in your photo Mike H and if I can sort out lighter springs I’ll fit those as well. Regards. Dave

You also have to make sure tank is not pinching the cables, so after putting it on, try wiggling the cables to see if they’re free to move.

If memory serves, the right carb cable curved around and went under the top tube, then both exited forwards together under the right front of the tank, not far below the rubber mount buffer, then up to the twistgrip.

There’s a reason the Springs on Carbed Guzzis (big blocks anyway) are so ‘strong’, and that’s because with ‘lighter’ items, it’s possible for the Slides to stick open in some situations.
You may also have problems with a high idle.

I used light springs on the “square slide” VHB 30’s, the ones that people say stick open or “leak past” whatever if the springs are not strong enough, never ever happened in 30 odd years of using them like that. :smiley:

The sheathings on both cables are damaged where they pass under the tank but they’re free now and obviously I’ll be replacing them. They both exit at the front of the tank on the left hand side and this gives them a smooth sweep to the twist grip. I’ve had a break from Guzzis for about 5 years but like many others I’ve been drawn back. I’ve used a bsa single with a monobloc carb which obviously had a light throttle action. I don’t expect the same from my 850T but my previous Guzzi was a Le Mans and I can’t remember a heavy throttle on that. I think age plays a part in that though. Anyway, I’m confident that when I follow all of the above I can improve things to an acceptable level. Thanks again. Regards. Dave

As noted above I use a short bit of petrol pipe as a protective sleeve around each cable where the cables pass between tank and frame to stop the outer getting worn.

Yep. I’ll put all of the above together and I’m sure the results will be as good as it gets. Regards.
Dave