Self adjusting pilot screws

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concours

concours

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I had hoped the new Premiers would have a clever fix added, but, still, the pilot screw will, over a few hundred miles, go from 1.5 turns out to 3 turns.... and not idle, backfire, etc.

Any shithouse remedies? fatter O-rings? Patch-lok? :idea:
 
Try a smear of RTV on just the threads as does not completely trap for turning but snugs up to stay put and easy to replace if needed. Same with other carb screws that must stay tight but can't be tightened enough on their own. Nice to read of idea base line 1.5 turns out air jets float level setting.
 
I would use a smeer of the RTV on the outside face of the screw head. less of a chance that it gets into the system and plugs the tiny holes. I've had them fall out before. :?
My 5 cents.
CNN
 
hobot said:
Try a smear of RTV on just the threads as does not completely trap for turning but snugs up to stay put and easy to replace if needed. Same with other carb screws that must stay tight but can't be tightened enough on their own. Nice to read of idea base line 1.5 turns out air jets float level setting.
Click to expand...

I've been using the Loctite 222 small screw threadlocker on bowl/cover screws with good results. You haven't gotten any RTV strings in your pilot jet? That sounds like it would be a bugger to clear... :shock:
 
concours said:
I had hoped the new Premiers would have a clever fix added, but, still, the pilot screw will, over a few hundred miles, go from 1.5 turns out to 3 turns.... and not idle, backfire, etc.

Any shithouse remedies? fatter O-rings? Patch-lok? :idea:
Click to expand...

Interesting. I've had plenty of issues caused by engine vibration, but never had this one. The o-rings even when badly worn could hold the mixture screws in place. Might be nice to have some custom screws made longer with extended knurled head with a spring between that and the carb body similar to idle screws on other carbs. These would make altitude adjustments easy as well.
 
I've not had the pilot screws loosen up just the all the other screws which RTV solved. You'd have to be accurate applying RTV and let it set up some to avoid the dreaded pilot blockage, so for sure no teflon tape trapping. Maybe my pilot screws got stepped on a bit so slight thread friction is sufficient. Its been so long since my Amals needed any service I don't know if one could jam an O-ring or fit a spring w/o more mods. As pilots once set don't need to move I'd consider a small drop of super glue on outside bottom of it too. The happy report of light loctite use here sounds like a no brainer as easy to reach square on screw to move again w/o frustrating removal and slot buggering as it sure can on other carb screws. I love it when farting with Commandos is the main stress to deal with.
 
Are you sure you don’t have some local spotty nosed kid moving your pilot screws when you are not looking :?: :shock:
 
I would just fit fresh new o-rings. Not ones from the local hardware bins but automotive type which are resistant to fuels swellings or cracking ups etc. R.T.V. silicones do run the danger of entering jet passages and ruining your day.
 
concours,

I am running Premieres and do not have that problem. I have about 3K on them as of right now. I would replace the "O" rings and see if that helps. If that doesn't work perhaps a dab of nail polish on the screw head/carb body would help. It should hold the screw in place and will be easy enough to chip off when you want to remove them. If you are careful nothing should get into the idle circuit. Gut feeling is new "o" ring should do it.

Pete
 
Torontonian said:
I would just fit fresh new o-rings. Not ones from the local hardware bins but automotive type which are resistant to fuels swellings or cracking ups etc. R.T.V. silicones do run the danger of entering jet passages and ruining your day.
Click to expand...
Buna-n or Viton are fuel resistant.
CNN
 
I

um

kinda

think

I

may

have

figured it out. :oops:

Ya know that tiny little oz. of Amsoil two stroke oil I dump in the gas? (oh wait, I hadn't told you guys) Guess where it dribbles down while tickling? My hypothesis is the lubed o-ring doesn't hold nearly as well as the DRY one...
 
Torontonian said:
Yeah every premium fillup I do the same to protect the valves etc.
Click to expand...

Do you use the gushing over tickling? Or stay dry externally with a 3 second count?
 
+10 here, never had low speed screws back off on any bike. Interesting problem.
 
needing said:
Re: "Buna-n or Viton are fuel resistant." Should read "petrol resistant" for Viton as it will swell when exposed to alcohol.
Click to expand...

Which alcohol?

Refer:
http://www2.dupont.com/Plastics/en_US/p ... 0Guide.pdf
Click to expand...

That datasheet says nothing about ethanol. And from my experience FKM (FPM) and FFKM work very well with ethanol-containing fuels as in "fuel resistant". NBR aka Nitrile rubber aka Buna-N is much more problematic in that respect.


Tim
 
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