Hi, I have recently bought Beta 270 rev3 2008 and tried to adjust idle speed with little success. The engine does not run smoothly and if I adjust it for less than 2000 rpm it dies (the manual says more than 1000rpm). When I fiddled with the knob on the cable extension from the air screw (it was either stuck or turning badly) to find out what position it was in the cable broke off. I am not an expert but I think there must be a reason for the cable, say if you operate the bike in extreme environment for example. 

Can somebody please advise me (before I take it out for a good look and find out I cannot do anything without the new part):

1, do I need a new cable with air screw or can it be re-attached? I could not find anyone who would sell extension cable with the screw. Any pointers?

2, do I need a cable at all? Can be an air screw reached and adjusted with hand/screwdriver?

3, I read there is a setting for air screw 1½ out which I am translating as fully in and that amount of turning anticlockwise out. Is it good for general condition or does it need to be adjusted according to weather, altitude etc.

Thank you in advance for any help

 The only thing you need is a good carb clean. The pilot jet is probably plugged.

Thanks Lineaway, it is an idea but I need to sort out the mixture first.

The mixture can't be fixed on the outside of a plugged carb.

The Keihin on your bike is notorious for plugging the pilot circuit because the passages are really small. As lineaway said, pull the carb, disassemble and blow it out with compressed air being careful to not force too much pressure through the body. There’s a couple of sealing rings in the Keihin that are damn near impossible to source if you damage them.

I find I have to do this routine about twice a year. 

Hi Dan you say "damn near impossible to source " can you tell where you were able to get them ??? I had heard that they were impossible to find , but damn near is a lot better Thanks geeman  

Dan, thank you for your suggestion. At the moment the engine is idling - not perfectly - providing it is set for no less than 2000 rpm; dying occasionally. I thought it would be a simple adjustment but I will do what you and Lineaway says since I have to take it out anyway. I found it quite satisfying to repair something on the bike and then go out and test it. Thank you  

Edited January 22, 20197 yr by Petr

8 hours ago, geeman said:

Hi Dan you say "damn near impossible to source " can you tell where you were able to get them ??? I had heard that they were impossible to find , but damn near is a lot better Thanks geeman  

 The oko`s fit and just a tad larger than originals so better. I did see some on a carb site awhile back, but did not save the page.

I remember seeing them years ago on the web but not for a while. When I do the disassemble and clean on my carbs I'm real careful. They may be impossible to source now.

6 hours ago, Petr said:

Dan, thank you for your suggestion. At the moment the engine is idling - not perfectly - providing it is set for no less than 2000 rpm; dying occasionally.

What happens when you turn the idle up is you are not running on the pilot circuit anymore so the mixture screw does practically nothing. I have used the extended cable air screw as well as the regular flat blade type air screw. I'm pretty much convinced it's better to just use the regular screw without the cable and make a couple of long thin flat blade screwdrivers for adjusting the mixture screw. The cable screws are just kind of a pain. If the carb is clean and jetted properly I'll adjust the screw at the start of the day for temperature and the bike will run fine all day. If the pilot circuit (not just the jet) is blocked I'm chasing the mixture all day and it never feels right until I clean the carb.

I made one after looking at my friends. I used the cable wire from an old clutch cable.

I drilled the head of the airscrew for a tight push fit then soldered the wire in place .

I routed it out the left side under the exhaust , it works fine. 

Thanks Dan and Lineaway I will look into the OKO option and I also am very very careful working on any part of my bike unless I have new spares in hand !! Thanks Geeman  

Dan, I re-fitted the carb back today and I found that no screwdriver would help. Obviously you have a better arrangement. My screw is hidden beyond the exhaust pipe. To do in the morning what you do means for me taking the rear fender off, put back air filter temporarily, start bike and adjust mixture with long nose pliers from the top (see the picture). Then re-fit it all and hope nothing is going to change  There is so little space that the screw hits the exhaust pipe with just couple of turns out. Now I know why the cable screw! Can you please confirm: is 1½ turn out good as a general setting for this bike? If I need to make a bigger adjustment, it is really best to take the carburettor out.

Eeeek! No, that won’t work. I’m sorry I didn’t realize you had one of the Jitsie accessory screws. I thought you had the original screw that came with the carb. I tried one of those on my 2013 EVO and ran into the same problem.

http://www.carbparts.com/keihin/pwk28parts.htm

parts 17 and 18

Edited January 28, 20197 yr by dan williams

Yea agree standard screw and a long slim screwdriver easy to adjust , I find having a flashlight helps to locate the slot !! Cheers Geeman