What's done to de restrict it ? I've a fresh re built FZR 3LN & she does a lap & comes back in saying it won't go & little else feedback other than maybe it was seizing but it's not that, then it dawned on me it'll be restricted. I have other ECU's I can try but is it more than that or maybe it's just cut a wire that reads the ignition pulse of the RPM. Thought I read somewhere there was a link in the speedo related to a restriction. Busting to get her going & see what a fresh engine pulls like, we currently run another one that goes so well.
What year is yours ? Jap law changed in 1994 which restricted the power output to 40hp, Honda changed the cylinder head and cdi to reduce their power output, Kawasaki changes were in the cdi. Most restrictions were in the speed limiter so that you couldn’t go over 180kms per hour
The only restrictions besides the 180km/h speed restrictor in an FZR250 is the valve spring's and cams. You probably have carby issues
Make sure that you have the right CDI box for your bike. You could have one for the later lower revving version of the 3ln engine like the one in the Zeal
Thanks all, i'll check the box, now i'm wondering if the exhaust valve isn't opening. Carbies are perfect but anythings possible,
Raising the FZR speed restricton. https://www.2fiftycc.com/index.php?...3ln7-raising-the-speed-ignition-cutout.10275/ Have you checked all the carby jet's, needle's and float height's and put a new gasket set through it etc
That's a good link, i'm sure it's not that, also it's a 240 speedo. Carbies are perfect & better than new, i have 3 sets, tried em all. The more I think about it the more i'm thinking the exhaust valve, already had it apart but maybe a cable snapped or the servo's playing up or something sent to test me again. Be bloody beautiful if they just started making them again, i'd buy a new one tomorrow !
EXUP should be easy to diagnose, it cycles with the ignition, pull the left rear fairing off and watch the servo motor to see if it's working... should be able to pinch the free play out of the cables on both ends... check the exhaust side too. Disconnect the cables and manually operate the exhaust valve. It can also be removed for service and cleaning.
Doesn't the rev gauge double as a fault code reader ? e.g. 7,000rpm = bad fuel pump ? Or am I thinking of a different bike ?
Related: I was wondering just yesterday how the Across was restricted? It's a lower power output AFAIK, not a speed limit, but haven't seen anything around the intake during my work on the bike. Anybody know?
The across is a heavier bike and only has two twin-throated carbs. More touring oriented. All grey import jap bikes of this era will have a 180km/h speedo restrictor circuit. Later 40hp bikes are generally built to that power via heads and cams, sometimes ignition timing and carb jets. Really the 250's are built to 45hp and 40hp, to get more out of them you have to spend big and do a lot of work, then you start blowing clutches and transmissions without modifications... focus on finding and fixing the problem. If the EXUP is stuck or not fully open, that will be a problem at full tilt. If it has no power I would start with checking that it is getting adequate fuel... a blocked breather on the tank can do this, as can a blocked filter, or a kinked fuel line... work your way down the system you are diagnosing. The only real common issue on the FZR's is the emulsion tubes and needles wearing badly. They will run pig rich, bog, and consume 5L V8 amounts of fuel. Turning the fuel off temporarily can help to diagnose this. Generally with this problem they are OK at high revs and terrible everywhere else.
Yeah I don't need more out of the Across, was just curious if it was easy to get the restricted later models back up to 45.
FZR250's don't have a TPS, speed sensor (gearbox driven speedo) or tip over sensor. Those codes apply to some early fuel injected Yamahas, and some late carb Yamahas like my R6, which has a TPS on the carbs, a gearbox driven speedo, but no EXUP. Has a 4-2-1 exhaust instead. Each manufacturer will have a different built in diagnostic. Modern bikes are all OBD2 standard and can be read with a code reader and the right cable. It's not common for carbed bikes to have anything like that, generally the only electrics they have are ignition system and lights/instruments.
Keyster kits through the carbs? If so stay tuned whilst I find the relevant posts for you - I think I know what the problem may be
First post located https://www.2fiftycc.com/index.php?threads/the-second-fizzer.9044/page-15#post-108129 @my67xr - original discovery https://www.2fiftycc.com/index.php?threads/fzr250r-3ln3-bdst28-carburetors.9643/#post-105292 Second thread - note; if at some stage because you have several sets of carbs, different components - emulsion tubes N625 VS N638 etc need the corresponding air jets, main jets differ and so on - all 5CT7 needles with shims below centre carb pair of or a combination of 5CT7 - outer pair and 5CT9 - inner pair all on the same clip setting and no shims underneath any of the needles https://www.2fiftycc.com/index.php?...ne-behind-block-head.10478/page-4#post-123212 This thread covers the differences in the needle(s) - it's a PITA, but as @my67xr & @Joker discovered - minute differences/errors produce big consequences where the carbs are concerned https://www.2fiftycc.com/index.php?...8-26mm-carb-settings-specs-3ln-3yx-zeal.9787/ How much do we all love Fizzer carbs - let's have a show of hands shall we...
OOH Lah dee dah - Mr Fuel injection is showing off now - which makes me wish that if microsquirt units were a little cheaper I'd have a go at fuel injecting a fizzer, but alas they're not so I won't