What are the symptoms of worn throttle shafts?

[TulsaFred]

I think the throttle shafts on my HS2 carbs are worn.
I know this is common.

What symptoms have folks seen with this problem?

thanks
Fred

 

[Guest]

What symptoms have folks seen with this problem?

thanks
Fred

Usually it starts with mild irritation and progress to all out tantrums and throwing carbs across the shop. :madder:

YMMV. :laugh:

 

[markberry]

What symptoms have folks seen with this problem?

thanks
Fred

Usually it starts with mild irritation and progress to all out tantrums and throwing carbs across the shop. :madder:

YMMV. :laugh:

well said!

 

[cdsmith]

Or in other words... They don't seem to want to sync up - thus the need to throw things across the room.
Seriously - poor/rough idle. At least that is what seems to be the case with my carbs.
A simple way to check is to spray some carb cleaner at the throttle shafts with engine at idle - worn shafts will result is drop in RPM's
cd

 

[PAUL161]

I agree with all of the above! The only cure is to replace the shafts. If you don't have the proper reamer, you can mess up the holes. Best thing is to have the carbs rebuilt, or take the bodies and new oversize shafts to a machine shop, have them fit the new shafts, then, if you have the ability, rebuild the rest of the carbs yourself. PJ

 

[TulsaFred]

I rebuilt an old 1275 I pulled from a barn where it sat for 20 years.

It idles very rough.

If I spray carb cleaner on the throttle shaft ends, the idle speeds up significantly.

I have little doubt the shafts need to be replaced. My understanding is that the HS2s have no bushing, and rarely need reaming since the brass shaft wears in preference to the hardened aluminum bodies.

Anyway, I'm just wondering if this is the only problem. The idle is very poor, and if I cover one of the carb venturis with my hand, the idle speeds way up and smooths out somewhat. That seems to indicate a big vacuum leak, but the only thing I can find is the throttle shafts.

Fred

 

[Rut]

Fred,
HS2s are pretty simple to replace the shafts if needed. When you take them apart and slide the shafts out it will give you a good idea of the wear. The shafts wear before the carb bodies do and it's rare to ever have to bush them. You should be able to feel the ridge on the shaft after you pull them out. Replace them one at a time so you'll keep the proper orientation of the discs.
Good luck, Rut

 

[JPSmit]

Just replaced the shafts on the Vauxhall's Stromberg carbs - you could see the wear. BTW you can also buy oversized shafts.

I had my SU rebuilt - am glad I did.

 

[TulsaFred]

Thanks guys.

Rut, the disc orientation is something I've been thinking could be a little tricky. Can you elaborate on how to get them in proper/equal orientation when there are removed/replaced?

Fred

 

[Rut]

Fred,
It's pretty simple, just take note of how they are located and mark the disc with a marking pen for reference. Make sure the throttle stop screws are backed out all the way. Unscrew the 2 screws that hold the disc to the shaft and pull the disc out, pull the shaft out the side and unscrew the linkage, replace the worn shaft with a new one, reinsert the disc and rotate the shaft until the disc is centered. You may have to wiggle it a little, but it will line up properly. Put the 2 screws back in,but don't tighten them all the way. Double check that the disc is centered and I look for light around the edges of the disc to help me. Once centered tighten the screws that hold it to the shaft. Doing one at a time gives you a reference.
Good luck, Rut