LMIII + Dellorto flat tops: which throttle cables?

[KnowFear]

I would like to convert my LMIII to the flat carb tops. I tried making throttle cables this afternoon, but it was a failed attempt. If I'm going to buy some, which Guzzi model do I choose? I'm using a Tomaselli 2C throttle.

 

[Morizzi]

Failed attempt? :?

How can you fail at making cables? It is a simple soldering task. :roll:

The trick is to splay the wires out once it is through the nipple and before you solder it. It needs to be clean!

If you use the correct soldering flux and solder then it can be done with a decent soldering iron. High tin solder is best but I've used 60Pb/40Sn without issue. The cable wires wear through before the joint gives way.

Make sure the outer will get you to where you want to be. The outer/inner difference can then be calculated. Cables will stretch just a bit so make the outer just a bit short of the middle of the adjuster.

I could tell you which cable if you had the standard throttle but which Tomaselli? :roll:

Why flat tops? Why don't you just use the lighter internal spring to lessen the tension. There are 3 springs of differing tension to suit.

Hope you sort it but really? This is almost as silly as the "can't find lead washers for my bar end weights" topic. :roll:

I'm getting intolerant and cranky in my old age.

 

[KnowFear]

Failed attempt? :?

How can you fail at making cables? It is a simple soldering task. :roll:

The trick is to splay the wires out once it is through the nipple and before you solder it. It needs to be clean!

If you use the correct soldering flux and solder then it can be done with a decent soldering iron. High tin solder is best but I've used 60Pb/40Sn without issue. The cable wires wear through before the joint gives way.

Make sure the outer will get you to where you want to be. The outer/inner difference can then be calculated. Cables will stretch just a bit so make the outer just a bit short of the middle of the adjuster.

I could tell you which cable if you had the standard throttle but which Tomaselli? :roll:

Why flat tops? Why don't you just use the lighter internal spring to lessen the tension. There are 3 springs of differing tension to suit.

Hope you sort it but really? This is almost as silly as the "can't find lead washers for my bar end weights" topic. :roll:

I'm getting intolerant and cranky in my old age.

All good points. I was having a difficult time getting solder to stick to the cable. I took your admonishments to heart and tried again yesterday, with more success. I switched from flux-core to separate flux and solder. That seemed to help, but I could probably use a soldering tutorial. I completed the cables, but it wasn't elegantly done.

 

[KnowFear]

By the way, the cable pull with flat tops is smoother, and with noticeably less effort.

 

[Morizzi]

The parts need to be clean, clean, clean.

Degrease with water based degreaser if necessary, rinse, dry then use soldering fluid to clean the oxides off the metals. A clean wire brush can help too.

Clean the soldering iron tip regularly. The molten solder will want to follow the heat. Heat the nipple and allow the solder to flow in when it is hot enough. If it doesn't want to stick then the parts aren't clean. If the solder won't melt then tin the tip with some solder to help the heat transfer. If it still won't work the iron is too small.


Bell tops allow less throttle twist for rise of slide. You can also change the cable without pulling the carb apart. You can also get small solderless nipples that will fit in a OEM throttle and the side lever to get you home in an emergency.

I always carry a spare throttle and clutch cable that I have made.

Yes, I know lots and lots of Lemans owners have gone the flat top route. I just took a couple of harden up pills and got used to it.

 

[Chris R]

I switched from flux-core to separate flux and solder.

Well there's your problem! Don't use flux core - and the solder itself is likely to be largely lead and not the best choice.

I learned to make cables from 'Radco', the columnists for Classic Bike Magazine and teacher at my local adult learning course on motorbikes. So far I haven't had one break so he must of taught me something.
If you ever see Radco's book on fixing old motorcycles pick it up - it is endlessly fascinating if you want to do things like paint the barrels of a Scott two stroke with the original amber paint.

Here is what I learned:

First figure out if the cables you are using are stainless or high carbon steel. These days you can get very nice teflon lined stainless cables from the bicycle store.

Stainless requires its own flux.

For normal cables Radco swore by 'Bakers Fluid No. 3' for flux. This is only available in england so in NA Ruby Flux is the go. This is available at stain glass suppliers. I think in reality all this stuff is just zinc chloride.

The local welding supply store and or Heating and Cooling supply store is the other place to go.

The welding store will have the right flux for stainless. Then you want a tin-silver or tin-antimony solder. Lead is probably ok for throttle cables but not for brake and clutch.

The best way by far to cut cable and the cable outer is with a dremel 'mini-radiac' cutting disc.

Spread the end well using a punch.

You can 'pre-tin' the fitting but usually this is necessary only in hard case. Brass ends are obviously easier to solder than steel.

You should never solder the cable with an open flame. You either need a large soldering iron or, my favourite, just a small tin can. Put the tin can on the barbecue and heat it up. Put some solder in it, flux the assembly and dip it in so just the end touches the solder. Let the can cool with the solder in it and reuse ad infinitum. I have seen some people solder using just a metal plate on the barbecue. You don't want the solder to wick past the fitting as this will cause a stress raiser and cause the cable to fail early.

 

[KnowFear]

You should never solder the cable with an open flame. You either need a large soldering iron or, my favourite, just a small tin can. Put the tin can on the barbecue and heat it up. Put some solder in it, flux the assembly and dip it in so just the end touches the solder. Let the can cool with the solder in it and reuse ad infinitum. I have seen some people solder using just a metal plate on the barbecue. You don't want the solder to wick past the fitting as this will cause a stress raiser and cause the cable to fail early.

Chris - thanks! I love the tin can tip. I'm going to make up a set of spare cables so that I can try this.

 

[KnowFear]

Yes, I know lots and lots of Lemans owners have gone the flat top route. I just took a couple of harden up pills and got used to it.

I've ridden 70s and 80s Laverda triples for 20+ years. They have stiff throttle pulls, but the LeMans is borderline ridiculous with the bell tops. I understand the whole "agricultural" feel of heavy duty Italian bikes, but an overyly stiff throttle detracts from the experience, even for somebody used to a stiff throttle pull. Maybe I'm not man enough, but I'm not a pantywaist either!

 

[john zibell]

I'm riding my 1990 LeMans with the bell cranks. One of the first things I did was remove the external spring mechanism and went with internals. With the internals (from a V65), the throttle was no stiffer than the CAII I had at the time.

 

[Chris R]

I think around the time the lemans came out, some company was sued (triumph?) due to a sticking throttle and Guzzi's - or maybe Delllorto's - legal department went nuts. I agree the external spring is not required and the lightest spring. Never had a problem with sticking slides but check them at maximum vacuum before you hit the street - the vacuum pulls the slide into the carb possibly causing binding.

Same thing probably explains the 'auto-retract' feature on the side stand.

 

[KnowFear]

You should never solder the cable with an open flame. You either need a large soldering iron or, my favourite, just a small tin can. Put the tin can on the barbecue and heat it up. Put some solder in it, flux the assembly and dip it in so just the end touches the solder. Let the can cool with the solder in it and reuse ad infinitum. I have seen some people solder using just a metal plate on the barbecue. You don't want the solder to wick past the fitting as this will cause a stress raiser and cause the cable to fail early.

Chris - thanks! I love the tin can tip. I'm going to make up a set of spare cables so that I can try this.

Chris - do I need to heat the cable/fitting assembly before dipping it into the can of solder? I'm confused because I thought the assembly needed to be heated for the solder to stick.