Morning all after some advice please. I currently have a 2008 rev3 250 running the keihin carb. I had this stripped down for cleaning yesterday and took note of the jets. The pilot was 45 and main 110. Are these correct? What are the standard settings. 
 

the bike has always ran very sluggish with not much punch so wondered if this may be the cause. 
 

thanks Mike. 

Have a look at beta-uk 

https://www.beta-uk.com/index.php/all-bikes/previous-models/pre-trial/2008-models they have a link to keihin carb settings. A good place to start.

Happy New Year.

They never were the most powerful 250,the 270 had a lot more go.Is yours all good engine wise or does it need a freshen up?Do you know anyone with a similar bike you could compare yours to,could be you're expecting it to be something it's not

Engine wise is spot on had an entire engine rebuild when I purchased it a couple of years ago all bearings gaskets water pump new casing etc. it’s always been the same just fitted some boyseen reeds that have helped slightly. I also have a 2008 rev3 but in 200cc that the wife rides and that’s much snappier on the throttle but those do run the mikuni carb. 

The Keihin should should sharpen it up over the Mikuni,is the exhaust clear and the ignition timing right?

My thoughts exactly. The rear section is clear and recently repacked I did once try clean the mid section out but was unsure what chemical to use to break the carbon without eating the aluminum. Timing should be correct I had the stator rewound last year as that failed and reassembled as it was fitted. I’m not completely sure which notch it should be on. Cheers mike. 

clean the middle and header pipes then report back. Use a heat gun to get them self combusting, compressed air to help it along, middle section needs constant dousing with water (soaked rags) to control the aluminium temp. Don't heat the middle section carbon deposits to bright red as that's about the melting point of the fine steel wool inside. Cherry red is enough. Two people makes this job easier to control the temp..

And you might p*** the locals off with all the stenchy smoke in the process so keep what you're doing out of sight and do it at a mates place ?

 The 2008 with the Keihin was the best running Rev 3 of them all. I had a 2003 270 that I owned ran like a 125 and I came across a 2006 270 the same way. The 2006 I even changed carbs on, no matter what I did it never would run out right. They both seemed like the timing never advanced with the rpm.

bigger main than 110

What is recommended I am in the UK and at sea level 

Had a 2006 Rev 3 250.  Not really a fan of that one, but here is where I would start... 115 main, 52 pilot, needle 2nd from top, 1.5 to 2.5 turns out on mixture screw.  Good luck.