Overtight Keyster Airscrews!

[Andrew-S]

Well, after Nigel's (K2-K6) visit a few weeks ago we managed to get my K1 firing on all four pots, although No1 wasn’t firing consistently which turned out to be debris in the pilot jet. But after trying to wind out the Keyster air screws we found they were so tight (all but one wouldn’t budge) the heads just started to chew up and No3 snapped half its head off; they were turned out about one turn and hadn't been set by a gorilla either!  I know they are an interference fit, but..............

I'll be putting a micrometer on the threads and I'm pretty sure they'll be oversized.

Has anyone else come across this issue with Kester air screws?

Anyway, now I've got some free time (an oxymoron for a retiree I know! ), the carbs will come off again tomorrow to extract the screws and refit the originals.

Cheers,
Andrew

[McCabe-Thiele (Ted)]

I know the feeling about being a retiree - I can't figure out how I ever had time to go to work - plus my whole week will be messed up by a mid-week,   mid-day dental appointment.

One thing for sure you will be getting highly skilled in the carb removal process - sounds like you are getting there in sorting the issue.

[Moorey]

 Someone could have put a drop of Studfast on them in the past. When the carbs are stripped try some heat to break the bond.

[Andrew-S]

Ted,

Yes, I'm getting into the swing of taking these things off. In fact when I put them back on I'll fix them on with Velcro!

Moorey,

I've tried heat and shock but the brass is so soft the screwdriver just chews it up, so screw extractor time.

[Johnny4428]

Sometimes I’ll nip to the workshop even for half an hour simply because I’ve just about wasted every other hour that day! Note to self - sooner you get the mundane jobs done,the sooner you can get on to the exciting stuff!
That air screws look a right delight to work with Andrew!😡

[K2-K6]

Unfortunately it was my turning of the #3 screw that has brought the need of further work to the carburettor.

We had fettled through the various cables linkage etc to get a consistent and accurate closing and response to twistgrip control as it was giving Andrew concern with odd responses prior to that, this brought a more confident position that it would have correct control over engine speed.

Then looking at it's running it feels too rich with the throttle fully closed and needed input from throttle to keep idling as it would either quit when set at reasonable rpm or needed setting too high idle with the master tickover adjust to prevent that happening, hence then looking at the airscrew set point to consider fine adjustment and stable idle.

This is where the problem began with the keyster air screws, installed for Andrew by someone very familiar with working on carburettor they must have gone in easily (showed no signs of burring around the slot) but were very significantly tight to move at all. #4 came out although tight and we could compare to the original and see it had a slightly different profile.
#3 was very resistant to turn and so I used a straight and good fitting bit in a  1/4 inch drive socket with extension bar to get a very straight drive while holding the bit in full engagement.  This started to turn anticlockwise but then sheared one half of the drive slot from the screw as it wouldn't support the torque required to turn.
It just seems they should never be that tight and looks like they weren't when they went in , hence both of us being puzzled as to how that may have changed and was that specific to keyster materials? 

Conciuos that it's now caused more work in a one step forward then one backwards, but it's a really very nice original bike with low original miles, sounds very good mechanically along with the HM300 pipes having a particularly distinctive output too.  Very puzzling why the screws have ended up so tight when nothing appears to have been done wrong.

[Andrew-S]

It's just one of those things Nigel, it could just as have easily been me the screw broke for, and probably would have. I dropped the carbs off with Mark yesterday (they still are a black art to me!) and he was surprised at what had happened, particularly as the screws went in easily enough and internally were in great condition reinforcing its low mileage.

With everything else that's happened in the last 2 years, I'm losing a bit of love for the K1. So these photo are for me....

[Laverda Dave]

Stick with it Andrew, it will all come right in the end, a few days away from it will make the difference. In the words of Churchill when times were tough 'We shall never surrender' (maybe you can tell I'm a volunteer tour guide at the Battle of Britain Bunker in Uxbridge .

[Andrew-S]

Thanks Dave, I'm sure it will come right in the end somehow and the old girl will be on the road again.

You cant beat a Churchill quote in times of need or down a bunker in Uxbridge! 

[Andrew-S]

Phew! Mark managed to get the air screws out yesterday with a combination of heat, effort and an Easyout. He'll be giving the carbs another going over next week, after which I'll put them back on and fire the old girl up to see where I'm where I'm at.



 

[Sesman]

Feel your pain. I’m currently dealing with a very, very stubborn float bowl drain screw that shows no signs of yielding despite the use of heat, penetrating fluid and a custom screwdriver fashioned to fit the slot full depth and width. There has to be a way?

[K2-K6]

That's a relief Andrew, and phew  they all came out.

Thinking logically through it from running the other day it may be worth getting Mark to double check the idle circuit paths on number 1 carb as it was that cylinder running intermittently, it seemed to pick it up as throttle opening increased, and could be worth close inspection.

The other 3 seemed to be running fine and with the ability to set idle mixture I'm confident that there wouldn't be a barrier to clean running.

I think it's very close to being recommisioned effectively and shouldn't need much, just that ability to fine trim it as we couldn't last time.

Nigel.

[Laverdaroo]

Feel your pain. I’m currently dealing with a very, very stubborn float bowl drain screw that shows no signs of yielding despite the use of heat, penetrating fluid and a custom screwdriver fashioned to fit the slot full depth and width. There has to be a way?

Put your screwdriver on the screw apply pressure but don't gorilla it or it will just distort and knacker. With a small hammer or heavy 'ish' screwdriver, ( I have a 4oz machinists hammer). whilst providing said pressure just tap the end of the driver repeatedly, (not hard and ) and try to keep tapping for a couple of minutes. It'll come, if it doesn't just repeat.
Sometimes they give up easily, sometimes it may take a couple of goes but it worked a treat for me on pretty much every welded shut screw and bolt on mine.

Im not saying beat the granny out of it but a constant percussive force no matter how weak will dislodge it  in the end. 'Penetrating oil a go go' I hasten to add.............

[Andrew-S]

Yes, a big phew Nigel, I'm very pleased they came out.

Thanks for the advice, I'll chat to Mark.

Cheers,
Andrew

[Andrew-S]

My K1 carbs are now all sorted, Mark (MK Classics) not only managed to extract the snapped pilot jet see: http://www.sohc.co.uk/index.php/topic,25765.0.html but also the chewed Keyster air screws out which were slightly oversized (not the first time he's had problems with Keyster) and the originals are now reinstalled.

I refitted the carbs (for the third time) at the weekend and it's now idling which was the original problem.