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Pilot screws and their O-rings

the 900
the 900

Posts : 645
Location : Chester

Pilot screws and their O-rings

Post by jchesshyre on Sat 02 Aug 2014, 3:15 pm

Since I got my low-mileage CB a couple of months ago to replace my 150,000 mile-er I've been aware of a slight petrol leak from the left carb, coming from the pilot mixture screw. When I say slight, I mean nowhere near enough to form drips, just a kind of dirty petrol-y residue.

I knew that the previous owner had had the carbs apart to fit and subsequently remove a restrictor kit, so thought he might have damaged the pilot screw by screwing it in too far or missed out the o-ring or something.

So I finally got round to taking them out the other day. Sure enough, both were missing the tiny washers that go under the O-ring to protect it from being ripped by the top of the spring. I ordered two new full sets from Lings (I'm feeling flush at the moment, came to £40) and fitted them yesterday.

OMG! Ever since I got this second CB I've wondered why it feels as if there's play in the cush drive, or as if I can never get the chain tension right, because on and off throttle is glitchy. It turns out it's neither of these things, it was obviously a tiny air leak at one or both of the pilot screws that was enough to mess things up. It now, honestly, feels like a new bike around town. I'm not exaggerating at all. Can't believe the difference.

So check yours if you feel like your throttle response around town isn't smooth enough!

Posts : 1792
Location : Beccles, Suffolk

Re: Pilot screws and their O-rings

Post by badseeds on Sat 02 Aug 2014, 7:47 pm

This is very interesting. Thanks for posting.

    Current date/time is Sat 23 Jun 2018, 1:52 am