anyone know what these dodgy things are doing between the carby and intake. could it be the reason my bike won't rev past 10 000 rpm under load. why is the end is stopped with a screw? in neutral i can take it to red line and it sounds strong all the way but in any other gear the engine just starts running roughly and the revs actually drop as I increase the throttle past 10000. It pulls pretty good till about that. There could be air leaks after the carby, those black things are a bit cracked. I noticed that one of these things wasn't properly secured with the clamp. It was just hanging loose from the airbox. would that have an effect? Also, by the looks of it my exaust doesn't have exup. is it meant to? bike is approx 89 model it could be older, says 2kr on side of steering head.
That is where your vacuum gauges plug into for balancing. If it has no EXUP it can't really be sticking to prevent you from going up to high RPM so I'd be taking a look at the carbies. Can't really tell you much though as mine revs to rev limiter without a sweat <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s --> Those holes are however supposed to be stopped, and yes, with a screw.
thanks for clearing that up. I just thought it looked a bit strange. The thing about the bogging down at high revs is that it happens at the same spot all the time. Does the fzr have electronic ignition timing. could the engine be detonating causing the spark to be retarded? also, bike doesn't start from the starter when it's cold or if it does it can only burble in a low rev state no matter how much throttle i give it. it goes ok if i push start it and keep running until i get the speed up past around 4000 then the throttle responds and i can hold it there till it warms up. The starter motor and battery aren't the problem as I can hear it ticking the engine over. Anyone got an idea? thanks. One more thing, do you think this part needs to be replaced.
nah, it's the chain cover, it's not vital. Do your valve clearances - my intakes were shot and it was causing a lot of hassle around the 14k rpm range (used to bog down for 1 or 2 k rpm before picking up again). Also sounds like it's running rich - which is probably float heights. but I'd do valve clearances first, before attacking anything else. on a bike that old they're probably shot.
thanks for the info. I've got the bike pretty stripped down and taken the carbies off. I'll try and adjust the float levels and then I'll get onto the valve clearances.
personally I'd do it the other way around: start from the inside of the engine, and work your way out. 1) Valve clearances 2) Clean and tune carb 3) Balance carbs I think you'll find doing them in any other order will result in re-work.
thanks casso, i've been working on the valve clearances all day. i'm newb so it's taking a while. I think previous owner had the engine replaced with a low km one that never had clearance check because intake clearances are all less than 004 thou or ~ 0.1 mm. All exhaust clearances are within spec. One question about feeler gauges, if i can force a gauge in but it's really tight does that mean i am actually forcing the valve springs down or is the gap actually that size. Also is 0.1 mm resolution good enough. For example I could not fit my thinnest gauge (004 or ~ 0.1 mm) under any of the intake clearances. Would it be ok if I just got shims 0.1 mm thinner. I would know for sure that the clearance will be somewhere between 0.1 and 0.2 mm (the specified range). Anyone know where to get shims, would yamaha have them? Lastly should I get a different gauge set, I have: 004 0.1016 mm 006 0.1524 008 0.2032 010 0.254 thanks for the help people.
If you have to force it thru, it is less than that size feeler. If a 4thou goes thru easy or with slight resistance and the 5thou feels tight but goes thru then say its a 4thou gap. You need a better set of feelers, at least down to 2thou or 0.05mm - my set has a 1.5, 2, 3 thou, and so on feelers. Most bike shops should have shims to suit. If they swap for free or charge is the problem. Either way they probably won't take old shims with any visible surface damage.
Thanks for that bit of info, I was really wondering about how to use feelers properly. I'll probably ring the shop tomorrow, fix the clearances and then it's on to the carbs.
the way you've described your bike is exactly the same problems I am having.... to the T... the bogging, starting the bike and everything. I thought then I should try the valve clearances as well, but I have absolutly no idea how to do it. and there are no shops in my area that service japanese import bikes (the grey market ones). is it hard? any tutorials on the site?
