change carbs to change throttle cables?

[Haalo]

I've tried searching all the threads I can, but I can't seem to find what i'm looking for.

I have a '74 tx650, apparently with BS38s and the dual throttle cable. I'd like to switch to a single throttle cable just cause it looks cleaner and it seems like there are more options to buy single throttle assemblies.

Can I replace my carbs, cable and throttle with a later model that uses a single throttle cable? ...and if so, what is a good carb and where is a good place to buy it?

Any helpful info is appreciated,
Thanks

 

[gggGary]

Yes you can swap to later carbs. Anything 76 and newer use single cable.
You will need a carb set, (overhauled) and the matching intake boots. Because the position of the carbs will change with the new intake boots you will have to go to aftermarket air filters. UNI foam filters have a good reputation.

It might be simpler to go to a Y cable if your carbs are sorted and run well now.

 

[XSLeo]

74 was the first year of the 447 engines and they used the angled carb holders. As long as you stay with BS38's you can still use the stock air boxes.
I like the 76-77 carb set. Others prefer the 78-79 carbs. The BS34's are a good carb but being longer you can't use your stock air boxes. They also use a different carb holder.
One thing to remember is that any carb tuning applies to the year of the carb, not the year of the bike. So if you use 78-79 carbs you use 78-79 tuning specs.
Using a cable with a splitter you will need to make the cable holders on the carbs adjustable. You will still need this adjustment to sync the carb.
Leo

 

[Haalo]

Right now, at idle, if i turn the bars all the way to the right it revs a little on its own. Seems like a throttle cable issue. Also, I plan on getting rid of the stock air boxes, the carbs would definately need a cleaning and the choke has to be held open by hand.

So..I figured changing the whole carbs, cables and throttle might solve all my issues in one go. If I went to a later model carb (or some aftermarket one), I could just go with a single throttle cable.

Does this make sense? I'm still very new to this stuff.

 

[5twins]

Yes, the newer carb sets are better anyway. They are bolted together as a "bank" and use a linkage between the two carbs. This makes setting the sync easier and it also holds that sync better and longer than the older separate carbs with individual cables.

 

[CDNTX650]

i run bs-34's on my 74. No airboxes though. Uni pods and 135 mains with mikes brit mufflers and a Pamco. Strong runner, those 34's are simple to deal with.

 

[XSLeo]

On the idle speed changing when the bars are full right is the cable adjustment, they are too tight. If you have the Clmer book start reading on page 20, Carburetor. It explains how to do the dead cylinder method of carb adjusting. as well as saying the cables need 1/4 freeplay.
Haynes manual page 77.
Leo

 

[Haalo]

Thanks everyone for the advice. I really appreciate it.

What's the deal with VM34s? If I change my carbs, should I get BS34s or VM34s? Where's a good place to order them? Do I need to be sure to get the pieces that would bolt them together as a bank?

 

[5twins]

Keep reading because you're still really "in the dark". VM34s are aftermarket high performance carbs. Very good in some situations like if you know what you're doing and are an ace carb tuner. Otherwise, if you can't tune your stock carbs, the VMs would be worse. The BS34s were the last stock carbs on the 650s. At one time they were considered the worst performance-wise because they were so E.P.A. strangled. That's just not true any more. There are parts offered now to "set them free". They may actually come to be known as the best stock carbs (with a few upgrades).

 

[XSLeo]

Also the BS38 carbs from 76 up and all the BS34 carbs were linked together and if you buy a set then should come with all the parts. The VM carbs are not linked. so you don't need parts like that for them.
Leo

 

[angus67]

Keep reading because you're still really "in the dark". VM34s are aftermarket high performance carbs. Very good in some situations like if you know what you're doing and are an ace carb tuner. Otherwise, if you can't tune your stock carbs, the VMs would be worse. The BS34s were the last stock carbs on the 650s. At one time they were considered the worst performance-wise because they were so E.P.A. strangled. That's just not true any more. There are parts offered now to "set them free". They may actually come to be known as the best stock carbs (with a few upgrades).

HAHA. when this site started, you couldnt give a set of 34's away, then xsjohn changed everything. I still have all the messages from needle install help back and forth between us, I read them sometimes.
They just need a good cleaning, and adjustable needles, and a good ear, and this excellent site.

 

[Haalo]

So i bought the VM34s from 650central. I managed to get the throttle cable hooked up, but I can't find anything online that helps with set-up. I have them mounted with my throttle cable running fine, but where do I put fuel line to? I suspect it is to the area pointed to in attached photo, but I don't want to do something stupid AND dangerous.

 

[tonyc]

Correct the fuel line goes there. I would run fuel filters with them and you mayhave to raise the rear of your tank a bit.

 

[Haalo]

Thank you. I will find some filters. Raise the tank? do the petcocks get in the way?

 

[tonyc]

Yes and sometimes you have to put 45 degree cable guides on the top of your carbs. I also connected the right petcock to the left carb and the left petcock to the right carb. It gave me lines that were not kinked.