[Rustler]

What are the reasons HD went to a push pull set up?

If I go to a single cable (cleaner look thinking of putting it inside the bars - I finally found the throttle control for this set up) what are the disadvantages?

Anyone put electrical cables AND the throttle cable inside a set of Chubbies? is there room enough?

Anyone got a source for chrome steel brake line and chrome 90 degree banjo fittings - to get the brake line to hug the bars is my thought.

TIA

 

[dxxxiii]

Push-Pull is just another attempt to copy ...

HONDA!

But seriously, a push-pull system is safer for a bike because when cables break they often leave splayed threads that jam in the barrel or housing. A push lets you release the throttle forcefully to come off the gas and even a second or two of full throttle while you figure out what happened can be dangerous with a bike's acceleration.

 

[Straydog]

dxxxiii, welcome to the forum.

I realize that all posts should be taken with a grain of salt, but your comment sounds logical to me. Interesting!

 

[Rustler]

Re: Push-Pull is just another attempt to copy ...

Originally posted by dxxxiii
But seriously, a push-pull system is safer for a bike because when cables break they often leave splayed threads that jam in the barrel or housing. Yea I thought of that but seriously with todays maufacturing, and assuming you keep them lubed what are the chances - in fact I can't remember hearing of that ever happening.

A push lets you release the throttle forcefully to come off the gas and even a second or two of full throttle while you figure out what happened can be dangerous with a bike's acceleration. Well see here is my problem, unless I'm getting things really mixed (very possible) the push cable is the idle cable - and if that is so then the push would be to give you throttle. The carb linkage is strongly spring loaded - and would return to idle if the throttle cable snapped - IMHO.

 

[dxxxiii]

I think we are saying same thing ...

The pull opens the throttle, so when you are sitting at idle and twist your wrist the top (pull) cable yanks against the carb/injector springs and is the cable that all bikes have. It would take a rigid linkage (not a cable) to have the push open the throttle. The (lower) push cable (idle as you said) returns the throttle and is assisted by the carb springs.

Many people convert as you are proposing and there are few failures. I have never heard of a failure causing damage but have had a pull cable snap. The throttle acted sticky for a few days before and I couldn't find problem until it broke. The strands were probably breaking one by one.

That was a time that I was in Ohio about 400 miles from home so in frustration I idled the bike up and got back on the interstate. In 5th gear I was about 25-30 mph and the cruise control kicked in. (That valk had some torque.) I made it home stopping only once more and stayed on cruise the whole way. Not the preferred way to ride but it worked.

 

[Rustler]

Re: I think we are saying same thing ...

Originally posted by dxxxiii
The pull opens the throttle, so when you are sitting at idle and twist your wrist the top (pull) cable yanks against the carb/injector springs and is the cable that all bikes have. It would take a rigid linkage (not a cable) to have the push open the throttle. The (lower) push cable (idle as you said) returns the throttle and is assisted by the carb springs.
Ok we are talking about the same thing - so back to my original question - what is the benefit to push pull? We agree that it is unlikely that the idle cable (push) would be able to overcome the carb linkage spring tension and push hard enough to give you throttle. The spring tension is more than enough to return the throttle to idle. So.... if the idle cable breaks - the carb linkage will still return to idle when the throttle is rolled off because of the carb linkage spring. If the throttle cable breaks - the carb linkage will return to idle just as if you had released the throttle.
oh wait a light is dawning the only purpose of the idle cable is to "push" the throttle back to its idle position when the carb linkage spring takes over.
Damn thanks for clearing that one up.

 

[HIPPO]

I believe the idle cable was put there for liability reasons. Mostly to cover up sloppy maintenance issues.

As far as it's function you can make an argument both ways, but it works much better in theory then in practice.

The pull cable opens the throttle against the force of the throttle spring, and on a single cable system the spring closes the throttle.

The two cable system works exactly the same way and the idle cable has no use (other then in Cruise Control bikes), except that if the throttle were to stick the idle cable would mechanically close the throttle by turning the grip with your hand, as opposed to snap back under spring pressure.

If the pull cable just breaks the throttle snaps shut by the force of the spring.
The idle cable is most useful if the throttle spring were to break. It is also useful in not properly maintained bikes where the grip itself does not move free so as to not allow the throttle to snap back on it's own. This is sadly very prevalent with Harley's as very few bother to optimize this sort of thing. It is also often the nature of the beast with aftermarket bars or grips not properly clearanced.

The downside of the two cable system is that it makes adjustment more critical, doubles the number of components that could cause a problem, and most importantly it has been my experience that in the typical failure mode where a cable comes apart internally the idle cable is usually not strong enough to return the system to idle and you would have been much better off to go for the kill switch to begin with then waste a second or so on something that does not work anyway. The idle cable could also develop an issue and then you would have nothing.



Internal throttles are quite finicky and mostly used on custom (show) bikes or TT bikes (tavern to tavern), not touring bikes. They are run inside the bars together with the electrical wiring, but these bikes have minimum wiring, much less wires then a touring bike.
It is a looks thing not a reliability or performance or function thing.
It can be done but you will have long term reliability issues, if you are thinking touring bike you are pi$$ing into the wind. The fairings hide most of this stuff anyway.

 

[Rustler]

Hippo - as always good points - food for thought - I was thinking of my glide but also the fatboy - have to think this one through some more I can see. Thanks

Oh as a side note the Magnacharger for the TC88 is shipping, looks nice but they don't seem to want to answer my question about clearance issues I think there will be on touring bikes and the highway bars (all they show is the charger on TT bikes)- all they say is "On some models the air cleaner may need to be angled" now what kind of response is that - sheeeez! I have pics. TC88 FI models will ship end of summer (remap included). I like the look much better than the aerocharger, and since all l I want is massive highway truck passing power I figured this is the way to keep a stock engine and attendant reliability and almost double the HP/torque. More thinking!

 

[HIPPO]

Well, you know how CRS goes, but it seems every one I have ever seen was not only on a TT bike, but they all had forward controls. Could be wrong though.

The Aerocharger is butt ugly, but packages relatively well even on touring bikes. On some TT bikes we have ceramic coated all the hardware in brushed silver color and fabricated minor parts of stainless, and they look quite good blending into a sea of chrome, but the guys running them do not blink at 5 figures approaching 6.