DR 650 project: It's now a Beast!

[DRjoe]

Thanks but that would mean 4 throttle cables going to the throttle, would be a bit cluttered.

I would rather keep the closing cables.

[Bambi]

Hey Joe,
I haven't had a look at my big if this could work:
In the eighties, a friend of mine decided the twin-cables and high-tension return-springs of the carbs of his big Guzzi being to hard to operate. So he mounted a rod on a small roller-bearing under the backbone of the frame in the middle of the two carbs. Then he put three discs with grooves to fix the cable-nipples and to run the cables in them on this rod. The disc in the middle was used for the cable coming down from the throttle. The two outer ones were set above the carbs and operated these via short cables. Thus enabled him to leave a lot of friction of the cables behind and throttle-/carb-operation (and tuning!) was much easier this way. Perhaps you can use parts of this idea for your set-up. This solution was also used on the Guzzis that were run in BotT-Races (Battle of the Twins) back in those days. Maybe, somebody here has got pics of one of those.
Kind regards, Bambi

[DRjoe]

I think I understand what your describing.
How did he keep the pull on the carbs even ?

[kellymac530]

Might be hard, even impossible to fit in the limited space on a bike, but maybe something like this:

Additional Photos Click for full-size image L & R arrow keys scroll through photos Standard Manifolds Race Manifolds 48 IDA Kit with Race Tube Style Linkage Tube Style Linkage Kit Weber Dual 48 IDA Kit Hexbar Linkage Kit 48 IDA

The small heim joints are readily available, mount a small shaft to the head or valve cover area above the carbs and 2 short shafts down to each carb linkage. Run the carbs without any springs on them, then 1 spring on the shaft that now connects them. you could adjust the tension on the spring till it is comfortable and safely closes the carbs...iit could still work with a basic 4 stroke dirt bike style 1 pull cable, 1 return cable throttle housing as a back up.

Just a possiblity....worth a look. If anyone could figure something like this to fit in there..you could.

[Bambi]

Hey Joe,
I have to admit that I don't remember how he did it. Having seen Kellymac's pic (thanks for this!) it might be possible that he used something like this. I'll ask my uncle, who was his neighbour at that time, if he does know where I can find him. I'd be surprised if he doesn't fiddle around with ole big Guzzis any more ... he's been very fond of them ...
... it just springs to mind that there is another Guzzi-fan in my wider neighbourhood (that means just some 10 kms in narrow and crowded Germany!) and as I said, things like that were a very common feature in these old days ...
Kind regards, Bambi ... nearly sure to find answers to these questions ...

[BeemerWolf]

Hey Joe and Bambi,

I believe that the answer is kinda like you are saying Bambi.

But in order to get a clearer picture, we all should just step back in time several years for the answer
......Back in the old days
before fuel injection was used everywhere, I am picturing a 4 cylinder Japanese bike that had 4 separate carbs.


From the throttle came 2 cables....1 pull on, and 1 to pull off. No springs here at all.


These cables went down into the inards in-between the line of 4 carbs and mounted up to 1 linkage.


Then this 1 linkage bar attached to each carb by way of an individual rod complete with adjusters on both ends
so you could at least get all carbs adjusted separately for idle speed and to make sure the slide opened fully.

There were adjusted on each end of this rod to allow those 2 actions to happen. And the return springs existed on each rod.
(the pic that kellymac posted displays this rod/adjuster concept)


HOW IT WORKS:
You simply set the slack for the cables first.
The main rod that goes crossways moved all of the individual rods the same distance. Any adjustment for individual carbs was accomplished separately. The bikes tuner simply just went down the line adjusting the rod/adjusters for each carb separately.
And you could set the spring resistance individually too.

And the pros would then put a tach meter on each sparkplug line and then fine-tune set the idle for each cylinder.

I don't have any 4 cylinder carbed bikes to show you, and my 86 guzzi Le Mans is all wrapped, packed, and covered
for the winter, so I cannot help with pics at all.

I am sure something like this could be built & tie the 2 carbs together and get what you are after.

Hope this helps
Thomas

[DRjoe]

hi beemerwolf i'm very familiar with the system you speak of and that is how I would like to join the two carbs but it is not very easy to do with the fcr-mx carbs.
The the original fcr carbs can be converted to run in banks of two or more and i'm keeping an eye out for a set that I can convert for use on the gs.


Thanks for all the ideas fellas, Once the engine is in the frame i'll be able to fit the carbs up and decide which way to go.

[BeemerWolf]

Joe,
difficult is just another word for challenge
......and I have seen you and your Aussie buddies beat back many a challenge over the years

here is a thought on joining those 2 carbs:
contact Jessie Kientz, owner of Kientech Engineering.
www.kientech.com
jesse@rvi.net

he has been wrenching and modding zukes for many, many years.

if has hasn't put together something like you are working, I would bet that
he certainly has a few ideas on how to pull it off.

him and his wife Janet are wonderful folks, and will always takes the time to help
out us riders and backshop engineers.

if you can call, give it a go. otherwise try an email.

Also, Eddie Sisneros might have something rattling around inside his head that would help you along.
www.sisnerosspeedworks.com

Thomas