Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Older ZXR250 warm up

Discussion in 'Technical and Troubleshooting Torque' started by Rogues84, Jun 5, 2012.

  1. Hello all,
    My old 91 ZXR250A is temperamental when it comes to idling when cold. It won't idle without choke for 3-5 minutes, minimum, when it's cold. Also, whenever the choke is on, even a little bit, it dies whenever the throttle is touched (probably floods).

    While the weather isn't good for riding I'd like to sort this out, because waiting for 5-10 minutes for the bike to warm up before riding to work 10 minutes away takes any fun out of it... especially when I have to repeat the process 12 hours later to come home.

    Would it be worth a strip down of the top end, good clean up, clearance check and carby adjustment or is there something else this could be? Anyone similar experiences?

  2. Sounds like a fueling problem, striping the top end out would be a waste of time and money.

    I would give the carby a good clean out, maybe get new seals (there cheap), make sure your pilot screw is adjusted to the standard setting in the manual and adjust it from there.
    Usually you set it, rev the bike, if the revs drop suddenly and then rise back to idle you turn it one way (directions change depending on brand of carby), if the revs "float" before returning to idle you turn it the other way, untill you can get it to rev and the drop straight back down to idle.

    The choke circuit could be gummed up too or not functioning properly.

    Other then that it could be many other things, whats the state of your spark plugs? is the air cleaner old?

    Also my bike takes a while to sort its self out when cold, but it does stall or cut out. Some bikes need a lot of choke some don't, but i don't have any experience with zxr250s so i couldn't tell you.
  3. thanks for the suggestion. I think I'll start with just the carbies and the idle screw (tried before without much luck). I've experienced the effects you've said about dropping and floating, which tells me the screw at least works.

    It has a brand new air cleaner, might replace the plugs though when I clean the carbies.

    There is a bit of engine noise (high rattle) so might need to strip top end anyway... really don't want to.

    Open for anyone else with suggestions too. Really want this thing riding like new.
  4. Not a clue about most of it... But I could say that my GPX250 - also carbed takes a while to warm up. I usually ride tame with the choke on until she's warm-ish then take it off.

    Sorry I can't offer much... Mechanical advice. I just thought you might like to know that some of those bikes do take a while to warm up to idle.
  5. my friend's 97 import zr250 (balius) will start and idle without choke from cold 90% of the time, if its extremely cold needs choke for about 1 min before idling without.

    just thought i'd throw that in =]
  6. Had a ZXR250, needed about 1/2 choke to start from cold for about 30-40 seconds before it could idle on it's own. Rev'd fine with the choke on so yeah something is wrong with your bike.
  7. No way it should take 10 mins to warm up. Try a tune up and see how much that improves things.
  8. Been sitting for a bit, started it up today. Took about 1 minute to idle without the choke, but was very sluggish on the throttle. Played with the idle control screw a little, but still think a carby clean and check is in order. Basically not as big a problem as I initially thought. :) thanks
  9. How's it run when it has warmed up?
  10. Once warm it runs fine, perhaps not as quick on throttle response as it should be, which could be a good indicator towards carby cleaning