I have bandit number four running and idling nicely, but twisting the throttle it bogs from arounf 4 to 6 thou revs before going up to 16. cdi has been tested and is good. vacuum on the petrol tap seems good. plugs have been replaced and leads are in the right order. previous owner tested the coils and said they are ok. inspected the carb rubbers and they are in the right place. previous owner pulled the carbs apart and gave them a clean, not ultrasonically though. no compression test yet. cylinder two header not getting as hot as the others. recommendations?
Lots of possibles there, previous owners and carbs is often a potential red flag, small things get missed at times. Note, I don't have a Bandit, however I do know they use similar Mikuni CV carbs for the FZR250 as the slide rubbers are the same as well a a few other elements. Going for the simple things - fuel & air, compression and spark. So things you know: Spark: Plugs new - are there resistors in the plug caps, do they measure at spec? Trimming the plug leads on the FZR250 can help IF there is corrosion where the plug cap screws into the lead IF the plug caps are the same as the FZR250. Fuel: I don't know the fuel level of the Bandit, but using clear tube on the float bowl drain holes will allow you to do a visual check between the carbs for comparison. Suggesting this as #2 has issues which may be fuel related [too rich and running cooler]. It will also give you visual indication if there are issues with the needle valve seat leaking or not sealing fully. Carb: Is there a small o-ring beneath the cap like there is on the FZR250? - that small o-ring if missing will cause issues with the slide not lifting properly. Also is the carb slide rubber fitted properly, happens to the best of us... For a visual on this, you can look at the slides with engine running; Airbox lid removed, a 'lazy' carb slide will be obvious. Any indication as to why the previous owner cleaned the carbs and did the other things? What symptoms were they chasing?
Had similar issues on my '09 race Ninja 250. Bogs in mid-range then takes off! Turned out previous owner installed carb-needles from previous generation '94-07 Ninja 250. Wouldn't have any idea what was wrong until I went though carbs to verify each and every part was factory OEM. Turned out #2 pre-gen needle was installed instead of #3 new-gen. Caused super-rich spot in mid-range.
What Danno said. Who knows where you are these days with old carbs given that most owners will buy the cheapest parts they can lay their hands on. @ruckusman measured the Chinese emulsion tubes and they are wrong. By the time you add up all the possible wrong parts fitted it turns into a nightmare. Then you have the worst of the worst, people using "jet drills".
Yep, once you attack jets with a drill you really have no idea where you are. Drilling (usually done by hand, by the average backyarder) is such an imprecise method. No two holes will be the same and most likely will not be round. A method of absolute last resort in my opinion.
I have had feedback from another group to check the plug cap and lead. Since I have two carbs from the 45hp model and two more complete carbs of the 40hp, I am going to save up and get a set fully restored to brand new by a pro workshop. There is a business in Sydney who is a one stop restoration shop but I'm looking at around $1500 to $2000.
No need to spend that kind of money! Send your carbs to this outfit for expert restoration. I've sent over 10 sets to them. Anywhere from yearly refresh on my race bike to bikes recovered from decades under swamp! Bikes always ran like brand-new fresh off showroom floor! Expert workmanship, reasonable fees (u$200-250), fast turnaround. https://customcarbservices.com Testimonials, many with way worse issues than yours: https://www.ninjette.org/forums/showthread.php?t=369351 - ColoradoCal https://www.ninjette.org/forums/showthread.php?t=367339 - Detrailers <-- this guy is actually mechanic with moto-shop https://www.ninjette.org/forums/showthread.php?t=365823 - ChicagoBob https://www.ninjette.org/forums/showthread.php?t=354327 - clakmurrick https://www.ninjette.org/forums/showthread.php?t=352293 - notunderweight https://www.ninjette.org/forums/showthread.php?t=366273 - KurtF https://www.ninjette.org/forums/showthread.php?p=1225613#post1225613 - MakoMoto https://www.ninjette.org/forums/showpost.php?p=1040828&postcount=48 - aaronbtxnc https://www.ninjette.org/forums/showpost.php?p=1044779&postcount=56 - 22R88 https://www.ninjette.org/forums/showpost.php?p=1117646&postcount=100 - DevinWolfe https://www.ninjette.org/forums/showpost.php?p=1132954&postcount=102 - atomicrider266 https://www.ninjette.org/forums/showpost.php?p=1141467&postcount=107 - FSTASFCK https://www.ninjette.org/forums/showpost.php?p=1171943&postcount=132 - roundhouse https://www.ninjette.org/forums/showpost.php?p=1181224&postcount=134 - Ghostt https://www.ninjette.org/forums/showpost.php?p=1249223&postcount=150 - inconer Here's example of carbs I sent in, bike wouldn't even start! Came back in factory-fresh brand-new OEM condition!!! Bike ran perfectly!!
Something which just occurred to me. I recall reading the very well written blog of a race team called Army of Darkness... One of their issues with their race bike at one race was it wouldn't rev out properly, it spat and sputtered dangerously. The problem was a tiny piece of something black blocking the main air jet in a carb bellmouth. Essentially what that did was load up that cylinder with raw [un-emulsified - no air] fuel on that one cylinder and it didn't like it one bit. First task is that the carbs probably need to be cleaned and put back to OEM spec, BUT $1500 - $2000 is more than the cost of a whole bike IMO. You could just as easily and much more cost effectively purchase an ultrasonic cleaner, disassemble the carbs, clean them and put a kit through them for potential wear parts.
I DNF 1st race at 2019 season-opener at Buttonwillow because my bike wouldn't run right. Ran perfectly in pits, did warm-up lap just fine, then 1.5-laps into race, it just gradually slowed down, coughed couple times and died! Back in pits, I tore carbs apart to find this!!! Was able to get it all back together for race #2 & 3 later that day!
Dannoxyz, I'm in Australia so I am assuming postage to New York will outweigh getting them done here. That rough price included ultrasonic clean, new parts, vapour washing and a new coat of paint.
Yes, comprehensive service restores carbs to brand-new factory condition. All OEM parts, no non-compatible generic rebuild kits used. Unless carbs were painted originally, no painting done. I sent pile of parts to OZ recently, 2-kg only costed me about u$45. They've restored carbs for people world-wide.
The price is what I guesstimate from their Gumtree ad. I am going to take pics of my carbs and get an actual quote with what I want done (wrinkle paint on top caps, gloss coat on carb casing etc). I don't have the space, tools or confidence to do it myself.
Got in touch with the previous owner and he mentioned about repairing plug caps and leads, so I will re-read the how to do them in the tech section to eliminate that problem. The same issue has happend to a gj77a I just got when breaking it down. Plug cap came apart from the lead when I pulled it off.
For some closure on this thread. The issue was the HT lead on cylinder two, the previous repair job didn't seat the lead to the cap properly. The bike now revs freely under no load, and a quick ride around the court shows no bogging down.
Winning!...and a huge round of applause for reporting back on the solution, a multitude of forum threads taper off without the solution, which just leaves unanswered questions lingering...
Found another issue today. One of the rubbers from the airbox to the carb isn't seated properly. Time for the tank off for another once over.
