Topic: Idle Screw Modification, is it necessary?

[ct_bobber]

I'm about ready to start tuning my carb.  I just put the new rebuild kit.  As I was searching and learning more about tuning, I ran into a page that talks about idle screw modification for 71/76 carb. http://www.hondachopper.com/garage/carb_info/idle_screw_mod/idle_screw_mod.html  Is is necessary?  It sounds valid.

My bike is '75 cb750.  It has open exhausts and pod filter (it came with the bike and can't change to the stock air box because the frame is bobber).  My air filter box looks like this




Do you think I need or should do this?

[dave500]

i solder them up,only takes a minute and its a proper job then,those ones with holes are so you cant enrichen too far for smog control,sometimes your lean and need less air,even when fully closed the bored ones pass air,even stock bikes can need less air.

jb weld is a bit amatuer?

[ct_bobber]

i solder them

Thanks for a quick reply.

This may be a dump question.  When you say "solder," does the wiring solder work or is it a different kind of solder?  Did you solder both side and tip holes?

thanks in advance.

[dave500]

a dump question?that stinks!wiring solder is fine,if the brass is cleaned properly the solder will fill the entire cavity,just sand down any excess.

[ct_bobber]

   Thanks

[Davez134]

I've never heard of this but makes sense. When I rebuilt my carbs, the kits i had came with "solid" idle screws with no holes. I just reused mine (with holes) cause they looked fine. After reading this, I just put those solid ones in, set at exactly 1 turn. Nice strong steady idle and no hesitation from a stop. I wanted to use the factory airbox, but it was long gone when I got the bike. Upon buying an air box, I found out the mounting tabs on the frame had been removed. I'm running K&N filters and MotoGP Werks 4-1 exhaust, and I couldn't believe how much this changes the idle and response from a stop!

[ct_bobber]

I've never heard of this but makes sense. When I rebuilt my carbs, the kits i had came with "solid" idle screws with no holes. I just reused mine (with holes) cause they looked fine. After reading this, I just put those solid ones in, set at exactly 1 turn. Nice strong steady idle and no hesitation from a stop. I wanted to use the factory airbox, but it was long gone when I got the bike. Upon buying an air box, I found out the mounting tabs on the frame had been removed. I'm running K&N filters and MotoGP Werks 4-1 exhaust, and I couldn't believe how much this changes the idle and response from a stop!

I finished soldering them, but haven't put them in yet.  Thanks for your response, I'm very glad to hear good thing from your experience.

[Nic]

My 750K2 has had a very slight hesitation off the line, off idle etc for the 6 months it's been back from the dead, I soldered up the screws yesterday and it now runs perfectly one turn out, stock air box, 4/4 K0 exhaust, 115 mains, 40 slow, unbelievable. It's a new bike now, in fact, as it is right now it couldn't run any better. Finally.

[dave500]

i always use solid screws,the holey ones are like idle mixture limiter caps on smog engined carburetted cars,you have to tamper with them to get what the engine needs.
the factory solids have a different taper than the holeys,you might need to fiddle with the turns and the book specs might not be what ends up working for you,always note down jetting/turns out etc for later on.