PDA

View Full Version : ZZR250 idle mixture?



imthatguy
15th February 2015, 21:56
Hi Guys! Hope your all keeping well and enjoying the summer!

Ive got a question about jetting on my little ZZR250.

After a recent trip back from Auckland, I noticed It was dying without throttle input - aka it absolutely would not idle on it own.
I tried all the normal suggestions, checked and adjusted the throttle cable tension, adjusted the idle speed nob by the clutch peddle, flushed the fuel, checked fuel system for obstructions, blew out all the easily accessible parts of the carbs and carb cables. Eventually I came to the conclusion It was ether something off inside the carbs, or something engine related - since I had recently replaced the engine I figured it was more likely to be carbs.

So I set about pulling the carbs out, taking them apart, cleaning and reinstalled them. Those of you that know anything about carbs are probably shaking your heads here, as I started out with no idea what I was doing and fairly quickly realised I had opened pandoras box, as it were.

This evening I finally got it to the stage where everything is working perfectly again, including the idle which required me to pull, adjust, install and check the carbs more times then I care to admit.

My question relates to the mixtures screws located on the engine side of both carburettor bodies, to get the bike to idle correctly I had to turn them out almost 5 full turns which seems like an awful lot when the factor settings (I believe) are 2.5turns out. Anything tighter then that would cause the idle to stutter and die at anything below 3000rpm, and race over 3k. Is there any reason I shouldn't have them turned out so far? The bike seems to run perfectly now, starts instantly when warm, pulls smoothly and right throughout the rev range and don't bog when WOT from idle. I will pull the plugs after a run tomorrow and report back the condition, but it doesn't seem to smell rich (even though I would say the mixture is definitely on the rich side).

imthatguy
17th February 2015, 00:39
If anyones interested In the answer, it turns out that all my issues were being caused by a punctured deceleration enricher diaphragm - who would have know... :gob:

awayatc
17th February 2015, 04:43
Good job....