I have an old style HSR42 on my S1W and it seems to me that the throttle return spring is a little on the heavy side. After a 1/2 hour of riding I get a noticeable strain from holding the throttle open. I can live with it, but it's not as good as the CV carb on the Sportster as far as comfort goes.

I have looked on the Mikuni site and searched the forum to no avail to see if they make a lighter spring to make my riding experience a little more enjoyable. Does anyone know if you can replace the spring with something lighter or am I stuck with it.

Chris you might consider the different riding position causing that additional strain. Not related to throttle return spring.
If you're quite sure it's the spring, then take it off and stretch it. Try an 1/8" at a time. If you stretch it too far you can't go back without cutting some turns off the spring. (which is no big deal anyway)

I have a couple of those older Mikuni's with the stiff spring, too. The new ones are quite a bit lighter. The people to call would be Sudco, http://www.sudco.com/ , they're a Mikuni distributor.

Someone took my bike for a ride once and that was the first thing they mentioned: the tension of the throttle return spring. They were almost afraid to open it since it was so stiff. I guess I am just used to it. Let us know if Sudco comes up with anything, or if you solve it another way.

--Chris

The new ones are quite a bit lighter. If you tell Aaron that his old mikunis have too heavy of a spring he will just call you a "girly man" :)

That's what I called the dude who rode my bike.

nancy boy
sally
girly man would work too

--Chris

Thanks for the help guys, I'll call sudco tomorrow. I've got the number written down and I'll put it in my purse so I don't forget it. :o :o

Talked to sudco, no joy there. They said Mikuni builds the carbs to the specs of the manufacturer of the bike the carb is intended for ?????? Meaning the spring should act just like a stock spring as far as tension goes.

I thought they were a universal fit carb. Anyway I guess I'll just order one of these to solve my problem

http://cgi.ebay.com/Heavy-Grip-Strength-Training-Tool-hand-grippers-crush_W0QQitemZ150064811030QQihZ005QQcategoryZ1017 11QQrdZ1QQcmdZViewItem

:rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes:

Just like a stock CV spring? They're on crack if they think that's true.

--Chris

Just like a stock CV spring? They're on crack if they think that's true.

--Chris

I wholeheartedly agree with you there.:D

Hell, you think the spring is strong on a Mik 42?? Anyone other than me have experience with a Mik 40? Now that's a strong spring. I was pleasantly surprised when I put the 42 on.
Ted

I had an HS40 in about 1989 for a couple years, before they added the roller bearings (the R in HSR) so I know exactly what you mean there. The HSR42 is so much easier to open, although immediately after installing it you heard the slide knocking back and forth on the roller bearings at idle. One step forward - two steps back. Still wouldn't trade it for any other carb.

--Chris

I'll have one of the newer ones this week so I can see what the difference is between them. Thanks for the help guys, and the occasional chuckle.

Chris

Just turning it by hand the old one is like a bear trap compared to the new one. I'll definitely be looking closer at these two springs to see if they interchange.