Topic: Drag bar conversion. idling at 4000 now?

[lendog]

For anybody who has switched to drag bars....are you using stock cables? I have 77' cb750f. I pulled the carbs and gave them a general cleaning with carb cleaner. the carbs were surprisingly pretty clean. I dropped the float bowls/accelerator pump only. I installed the carbs and fired her up without the air box. She's now idling at 4000 rpm when warmed up. I tried adjusting throttle stop (the big fat spring/screw..I'm assuming) but that didn't do anything. Is this beacause the air box is off? are my cables not adjusted poroperly? any advice would help ...thanks.
 

[cafe2be]

are the shutters on the carbs open? Did you remove the cables completely when installing the bars?

[Gordon]

Stock cables and brake line can be used with drag bars, but you have to get creative with the routing, especially with the throttle/clutch cables, because there can't be any sharp bends in the line.  It's much easier (and more expensive) to do it with new shorter cables, but quicker, because you don't have to wait for shipping, (and cheaper) to do it with existing cables.  

I recommend getting shorter cables and brake line, but I've done it both ways with success so can't make that decision for you.  

As for the idle speed issue:

Put the air box back on before deciding if there really is a problem or not.  If you're still having the same problem after that, then go looking for the solution.  

[lendog]

Yes shutters are slightly open. and yes I did completely removed cables.

[lendog]

Air box is off...and I am getting some sucking sounds.

[Gordon]

Air box is off...and I am getting some sucking sounds.

That would be your carbs sucking in air, and too much of it at that.  Put the air box with filter back on and see how it runs. 

[lendog]

Thanks for the advice. that'll be my next step.

[the technological J]

if u have the airbox off its a big differance much more air flow.... put it back on or whatever ur doing to restrict air flow and try it again

[cafe2be]

also check and make sure how you connected the cable to the carb body and that it is not too tight.

[BlackMax]

I had the same problem when I went to clubmans. 

Are you sure the throttle isn't simply opened?  There should be 1-2mm of "play" in the throttle, where you can twist it but it's just slack and doesn't operate the carb.  If that's not there, look at the metal tubes (90 degree bend) at the throttle.   It could be rotated in such a way that the throttle cable is being pulled thus setting your idle at 4000. 

[lendog]

Thanks for all the replies. I got home from work late. After checking this post I went in the garage for a few minutes. I loosened up the cables at the 90 deg. bends and started the bike up. It insantly dropped down to about 1500 or so. So it seems to be a cable/routing issue. I'm now going to mess arond with the routing. Does anybody know the best way to route using stock cables? Should I go with shorter cables? how much shorter should I go? ....thanks again. 

[eurban]

Your best bet with routing is to experiment and use your own judgement.  I have had good success with stock cables and various handlebar setups.  Play around with all the options and keep in mind that you can rotate the throttle housing and the hard pipe 90 degree bends that are mounted to the housing.  Cables in good condition with proper lubing is a must.  Remember that you want sweeping bends rather than tight ones.  You also want the cables to still operate OK even as the front end is turned fully to the left and right. Same rules apply to the clutch cable (in particular make sure that it doesn't exit the adjuster nut on the lever housing at an odd angle).  Good luck