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General Category => General Discussion => Topic started by: perter on May 24, 2018, 02:56:49 AM

Title: 2-1 throttle cable? Use of junction box or other ideas?
Post by: perter on May 24, 2018, 02:56:49 AM
I have PHF 36 carbs on my SP1000 without the "LM tops" so the cables exit the carbs in a swan neck. They run together under the tank up to my Tomaselli 2 cable throttle drum. I have a carb balancer and can balance the carbs but I find them very sensitive to small movements in the double cables so I was wondering if anyone has tried a 2-1 junction box setup to shorten the critical cable length?

Here's one I found on ebay. I remember there's another solution out for Guzzi with a bar pulling each carb cable but have forgotten the name?

Another idea I have is to run a kind of floating setup where the two carbs are connected with one cable and the throttle cable pulls from the middle of this cable through a flexible joint so the carb springs ensure an even pull, similar to break cable setup for tow trailers?

Any ideas welcome
(https://thumb.ibb.co/mvEkJ8/junction_box.jpg) (https://ibb.co/mvEkJ8)
Title: Re: 2-1 throttle cable? Use of junction box or other ideas?
Post by: rodekyll on May 24, 2018, 03:11:30 AM
How old is the throttle drum?  If the ramps are worn unevenly the cables will pull unevenly.
Title: Re: 2-1 throttle cable? Use of junction box or other ideas?
Post by: perter on May 24, 2018, 03:22:58 AM
Hi Rodekyll,
The throttle drum is 2 seasons old - little less than 10.000km and is a quality tomaselli drum.

I expect part of my problem could be the cables themself: When adding the swan neck I had to trim the outer cables and perhaps the trimmed end needs more care to be laying even on the adjuster screw. But even so, I was thinking there must be an advantage having shorter cables with less flex and a more smooth routing?
Title: Re: 2-1 throttle cable? Use of junction box or other ideas?
Post by: tris on May 24, 2018, 04:16:16 AM
My old 95 Cali had the same set up as you describe with the swan necks and 1-2 junction box. I  found it worked but wasn't the best/most stable solution

I seem to remember that one of the options if you had twin cables all the way, was that the cables crossed under the tank to provide the smoothest/straightest route to the carbs


Title: Re: 2-1 throttle cable? Use of junction box or other ideas?
Post by: perter on May 24, 2018, 04:01:28 PM
My old 95 Cali had the same set up as you describe with the swan necks and 1-2 junction box. I  found it worked but wasn't the best/most stable solution

I seem to remember that one of the options if you had twin cables all the way, was that the cables crossed under the tank to provide the smoothest/straightest route to the carbs

Yes, I have played with the cable routing, but still very sensitive I think. So the Cali had a 1-2 junction setup? Perhaps I should see if there's a standard solution available?
Title: Re: 2-1 throttle cable? Use of junction box or other ideas?
Post by: guzzista on May 24, 2018, 04:48:26 PM
I am using something similar to what you have in your pic on my Cali 1100 and running  PHM 40'S  with  regular round tops and elbow adjusters with the stock  single cable Cali 1100 throttle. Works like a charm , no balancing issues whatsoever.
http://www.mgcycle.com/index.php?main_page=product_info&products_id=1947