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Misfiring CBR600F when hot

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by norseman, Feb 9, 2006.

  1. Problem for your collective wisdom please:

    2000 model (carburettored) CBR 600FY (pre F4i) 18,000klms fully serviced and loved.

    Has been misfiring as I reach the CBD on the daily commute, but only as traffic slows up and the bike gets fully hot (it never overheats) about the time the thermo fan kicks in. So, I go to take off gently (e.g. to lanesplit a gap) using just a couple of thousand revs, and bup ba burr bur burp etc. With more throttle or an aggressive start, no problem at all.

    On the recent Melb lanesplit protest ride, sitting in choked freeway and hoddle street traffic for thirty minutes, the problem was much worse and the motor actually died at idle in the middle of hoddle street!! (p.s. thanks to the MRA marshall for protecting my back with his bike as a mobile roadblock). Worse, the battery was almost dead and I couldn't start! (Pushed to the side of the road, waited thirty minutes, jump started in second and kept the revs up to get home. Battery recharged just fine, and fine ever since.)

    Collective advice was the regulator/rectifier, which I have replaced with a brand newy.

    Now? Problem has returned in heated traffic, although slightly better post regulator replacement.

    Over to you guys - tell me what you think !

    Much obliged
  2. Did I tell you my fuel pump story? :grin: :grin: :LOL: :LOL:
  3. Lot's of carburetted Honda's between 1990-2000 suffered reg/rec problems, looks as though you have yours sorted, but it still may be to blame.

    Have a look at the state your reg/rec connector is in, including connector pins, wiring, etc, this may have suffered some damage when the old one was playing up. Often when they're on the way out they get so hot they'll fry the wiring which is hard to detect unless looking specifically for it.

    As to why it only happens when it's hot (sitting idling?), I'm not sure. If you hadn't already replaced the reg/rec, I would guess it was that. Best to get a multimeter and test it. While the bike is running, the battery charge should be 13.5-14.5 volts, check this. At idle, it may be at the lower end of that scale, but any lower will mean charging problems. Check out this site for useful electrical fault finding info:


    NOt sure if you're problem is electrical related, but incidentally, I'm on my 3rd reg/rec in two years!
  4. bahhh i was looking at the cbr600's as i thought honda made bulletproof bikes, damn nigly problems that all bikes seem to posess.. except my zzr which has never skipped a beat, yay! :)
  5. This hot mis-fire problem happened to Pink Angel's CBR, this definitely sounded a 'rich' mis-fire, maybe a kinked carburetor fuel bowl vent hose could have been the cause. I pull all carb vent hose off most bikes so that I never have the problem; just gotta be careful that fuel won't be dumped onto electrical stuff.

    I had a problem with a '95 CBR600 (same but different to 2000) that I used to race, at low speeds, sometimes there can be a mis-match in the airspeed going in the carb fuel bowl air intakes verses the the airbox air intakes; the pressure in the fuel bowls MUST be the same as the pressure in the airbox; that's why bikes with pressurized airbox's must have the fuel bowls vented to the airbox.

    To answer your question..... not sure, needs inspection.... sorry :grin:
  6. To Cammo and Johnny O, much obliged - am having the charging system load tested tomorrow so 'twil be interesting to see what that reveals.

    Will take along your experience to cover the bases. Thanks.

    To slyfox, despite this minor nuisance I am still very happy with the CBR and you will grow old looking for a bike model free of any mention in these types of technical help / maintenance forums - either through wear and tear; previous owner neglect or the by-product of increasingly sophisticated technology and finer tolerances of modern machinery. My humble view only of course - please don't inundate me with stories of uncle Dave's '56 Beemer that never needed new brakes or a change of oil !!!! :grin:

    Otherwise, keep 'em coming, folks!

  7. I'd be interested in hearing the result with your bike Norseman, so keep us posted please. :)
  8. :shock: Hey this problem of yours sounds very farmilar to me.

    About 5 years ago I bought a CBR600FY with 7k's on it and took it to Tassie for a two week tour the day I bought it. And guess what, in traffic it seemed to get very hot and would start to miss-fire, until... Until finally it would stall (while I was waiting in teh que for teh ferry to Tassie). I also only got about 200klms out of a tank on the freeway.

    I lived with the problem for about a week (thuinking it was just the way the bike was), when a old guy on a '92 CBR100F that I just meet put some light on the subject.

    He suggested that I best change the air filter (bike may have been choking itself) and also the plugs as a caution while I was at it. And this seemed like a fairly cheap otion, took me a few hours but I did it.

    Problem was solved and it just went away. Turns out the air filter was very dirty, lot of dust and crap in it. Poor engine must have been choking itself at low chug speeds, cooking itself and then finally dying.

    I road it to 25k's (when I sold it) and it NEVER EVER missed a beat again.

    Which is kind of why I bought an F4i, after the F4 beening such a good experience.

    Hope this helps.... I suspect it's not you electrics :)
  9. :!: P.s.

    Dealer servicing varies and dealers may just check your air filter and decide not to replace it during servicing (Even if it's due). I would check you service reciepts to see if it's been replaced or not.

    :( Sorry about all the typo's in my prior post
  10. Thanks RedNinja. Very interesting.

    I have been thinking about an after market K&N or similar air cleaner but not as a fix for this. Maybe it's time!

    Curious - why's the 636 for sale...?

    Norseman :?:
  11. A dirty airfilter is a good call, although on non ram-air bikes, a dirty airfilter doesn't make a lot of difference until it gets substantially clogged, the CBR with seperate ducting for the fuel bowls, it could run excessively rich with a slight change in air flow through the aircleaner element.

    I'd be looking at that first.
  12. Hey there,

    ZX636 is for sale because I have too may bikes in my single garage (YZF Thundercat (Girlfriend's), CBR600F4i & the ZX6R) and only one butt.

    I like riding my F4i alot more, even tho the ZX is a nicer looking and more powerful bike. I guess I am just a Honda man and feel like it's a waste just having for the sake of having it.
  13. With thanks again to all concerned, the Honda dealer went through the electrics in diagnostic sequence and found the five-year-old OEM battery to be capable of only limited charge and vulnerable to flattening after only a dozen cranks. Other electrical wires and connections in line returned resistances within specified tolerances.

    For the sceptics, this lead to no charge for the labour by the dealer despite my protest, and I was offered the opportunity to ride away and shop for replacement bateries in my own time (which I will do, but give this Honda dealer first opportunity for the sale), and then fit myself. Can't ask for more than that! :)

    Of course, this means I probably have replaced the regulator for nothing, but the new one has a heat sink style construction and at least should be more durable than the original design.

  14. Let us all know if this fixes your problem, I am curious now. Goodluck
  15. ..and we all lived happily ever after with our CBR 600 F!

    For the record, I've now done over 50K with my Maria (I named her after Sharapova) and I'm still in love with her.
  16. Latest instalment folks.

    Had the electrical system load tested, and the five year old battery (original Honda-Yuasa from new) struggled to perform. Fair enough.

    Bought a new Yuasa (decided to maintain the quality for the extra price ($145 versus Chinese $65) and fitted it fine.

    Bad news - problem still exists. New rectifier/regulator, new battery, same problem. Grrrr... :mad:

    Am trying the fuel pump next (take note Godfather) - will let you know how I go. Should be able to build a second bike from the replaced spares in no time! :?

  17. Dude, I really suspect this is your air filter.

    Atleast take yours out, take it to a standard mechanic and have it blasted with compressed air, before you spend anymore money.

    Maybe try a near new second hand OEM one from a wreckers.
  18. Thanks RedNinja.

    Have already reviewed this option with the servicing manager as past of the 18,000 service last month.

    But thanks for the reminder. Will raise it again as a double check. Don't recall getting an answer on exactly whether it was replaced or blown or just 'checked'... :?:

  19. I think it's well worth checking. I also don't think they are due for replacement until later than 18k's, so it may only have been inspected, if they did even that.

    Have you noticed how many K's you are getting out of the tank? When I had this problem I was only just getting 200k's on the freeway before the fuel light came on.
  20. Funny you should mention that - used to get 250klms - but three tanks ago it was 210 and yesterday filled up after only 162 !!!

    Honda service manager was speechless - but no suggestion of the airfilter as the culprit!