Pilot screws - frozen??

[BigBear]

Yesterday, I went out to tweak the pilot screws after replacing the fuel pump.

 

Anyway...three of the four screws turned easily...the fourth...well...didnt turn at all (in or out). As luck would have it, one of the brass "slots" in the screw head appears to have fractured.

 

I sprayed liquid wrench on it to let it soak overnight, and will attempt to turn it this evening after work. Hopefully, I'll be able to use a flat blade to turn the screw.

 

So the question is...."Can I replace the pilot screw WITHOUT removing the carb rack from the bike"?

 

Anyone ever heard of the pilot screw seizing up? Is there a trick to prevent that from occurring? Maybe spray WD-40 on them?

[Peder_y2k]

I've heard of frozen pilot screws before, and seen some 'stiff' ones. They are made of brass and the carb body is white metal (pot metal) and the seizing is from corrosion of the white metal. Attempt to clean the access hole to the screw first, then use PB (Power Blaster) penetrating oil soaking overnight before attempting to unscrew it. It can easily be replaced without removing the carb unless the screw removal is botched.

Another instance of seizure is from turning the screw in tight, wher the needle tip jams into the orfice. Removing the screw breaks the tip off in the jet orfice. Then the carb must be removed to extract the tiny broken tip. That's why there are warnings to never turn the screw in tight at the 'bottom'.

I once got a '79 Yamaha XS1100 Special for $100 that the dealer could not diagnose the running problem, and it was a broken pilot screw tip. Once replaced, the bike ran well for many years till I sold it.

-Pete, in Tacoma WA USA

'83,88 Venture

[MiCarl]

Peder_y2k has nailed it.

 

I doubt it's from the screw being tightened too far. The tiny tip on these screws will snap off quite easily and wouldn't be a hindrance to removing the screw.

 

A screw extractor will often split the screw and then you'll never get it out. Screw extractor should be your final resort.

 

If the slot is broken your best start is to use a Dremmel tool to cut a new one - not fun. When you do have a good slot you need to use lots of penetrating oil and patience. If you're fortunate enough to get it to move you'll want to worry it back and forth to work it out.

 

There is a lot of danger here that you will ruin the carb body. Unless you have a very good reason to adjust it you might be better off to just let it be.

[BigBear]

LOL...is that a Beatles song?

 

Anyway...I know that the stuck screw is approx. 3.5 turns out...

 

As indicated earlier...I'll try to work the screw in/out later tonight...in a "perfect" world, I should just be able to turn the screw all the way to out to remove it, and replace it with a shiny new one...

 

Any ideas/suggestions on how to prevent this in the future?

 

Thanks for all of the valuable input!

 

This place ROCKS!!!!!

[Peder_y2k]

Prevention of pilot screw seizure can be accomplished by using a small amount of Anti-Seize compound on ONLY the threads of the screw itself. Be sure to mix the compound (stir) before application, and then using only a small amount just enough to color the screw threads with the silver color of the compound.

I use Anti-seize on just about any reassembly where aluminum or white metal (potmetal) are involved. Always on spark plugs, both new and reinstall.

-Pete, in Tacoma WA USA

'83,88 Venture

[BigBear]

Antisieze on the threads...excellent advice, Pete!!

 

Just to reiterate...I CAN take the pilot screws out (with the carbs installed on the bike) without loosing parts...correct?

[RedRider]

Yes, you can. However, it may be difficult to find all the pieces parts if they don't make it outside the engine V when removed.

 

Popping the carbs off isn't too difficult.

 

RR

[BigBear]

Popping the carbs off isn't too difficult.

 

Agreed!

 

There is NOT enough "grip" left on the pilot screw to take it out...gonna have to pull the carb rack anyway...

 

I'm just going to go ahead and order 4 new pilot screws and replace them all...and reinstall with antisieze on the threads.

 

Lesson learned!