Hesitant FZR 600 Genesis 1989 Bogging down (updated)

[satans_BIG_helper]

Hi, Just got one of these as a back to biking bike after a bit of a break, anyway its got a sort of odd problem i have my suspicions about it but before i start checking them out i want to see if anyone else has some experience or some info that might also help. IT starts first press of the button no problems and it rides ok most the time however at low revs particularly between 3 and 5K it seems to bog down then you open the throttle however if you pull the throttle back a bit more it picks up fine and takes off like a rocket ship it also sounds a bit rough when its bogging down as if a exhaust gasket is leaking, my thinking is the air box has come off or has a split in a rubber some where ? as if you keep it in high revs it rides like a dream, It has a carbon can co pipe and supposedly a K&N air filter and it has also supposedly been rejetted to suit the air filter not sure wether the pipe was taken into that equation. also the exhaust does not appear to leak anywhere i checked this earlier with the hand over the end can approach

[Kickstart]

Hi

The airbox can be difficult to get to sit properly, so I would agree with your first best guess. If it has been off for some time expect real fun trying to get it back on (possibly use boiling water to soften the rubbers).

While apart also check the carbs are balanced and that the diaphragms are in decent condition.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[TUG]

I'm hitting the same problem but thats due to my exup and poor carbs being 20 yrs old. If i was you I'd go here to this forum and ask them.
____________________
Haz ER-5, innit!

[satans_BIG_helper]

Well i guess thats all of tomorrow taken up then , better have it back in 1 bit by the end of the day for work on monday

Better get myself some lollypop sticks to balance them carbs

[satans_BIG_helper]

Well i stripped it down today and checked everything out, The air box seemed to be seated properly however i removed it and re fitted it to make sure and i noticed one of the rubbers has been pinched at some time, but i got it back on and it seems to seal properly,

Another thing i discovered is a massive leak in the exhaust system where the 4 down pipes meet with the collector box, i dont think this is the problem however does any one know if the middle section of the exhasut in the pictures i have put up is a standard FZR part or a aftermarket one of some kind so i can source a replacement

Me and a friend done a lot of ummm n ahhhing and we reckon its a flat spot due to the bike having a K&N air filter and the carbon can co end can fitted, the plugs were black when i took them out indicating it is running rich, the carbs seemed to be balanced close enough to each other i didnt remove them yet as i intend to give the bike a service next weekend and didnt want to risk not having the bike back together for work tomorrow. Does anybody know the standard jet sizes in FZR carbs and has any one had a FZR with a similar air filter and exhaust combination and remember what jets they were using to get the bike running right

[TUG]

[satans_BIG_helper]

i know the exhaust leaking can cause this problem but i have had bikes with far worse exhausts and not had this problem, im having hell at the moment trying to source a cheap replacement middle section for my exhaust i dont mind if its not in the best condition as i can get it sorted but this bike is now my everyday transport so i cant afford to take the current one off and wait to get it sorted out , The guide for the carbs would be helpfull i have done rejetting and swapping about before on 2 strokes in the past but they have been far easier to take the carbs out and swap the jets several times the FZR looks like a pig of a job if i have to change jets 3 or 4 times , so being able to get a close as match as possible with the jets in the 1st place would save me a lot of time and hassle

[TUG]

[Kickstart]

Hi

That doesn't look like the stock system on my FZR600 from memory (without going to the garage and checking). There are a couple of bracing tabs on the stock exhaust between the down pipes and they seem to rot around those.

D&K do replacement down pipes.

Might be worth checking the atomiser tubes. Normally these go oval on the larger engined fzrs, but might have happened on the 600.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Ichy]

I was going to suggest the same as Keith, check the emulsion tubes, doesn't take much wear to cause over fuelling.

Apart from that theres always my random way of checking stuff.
Warm the bike up, take the air filter out, go for a run and see if its any better or worse.

Rather than changing the jets straight away I think it might be worth dropping the needles a notch, if you can.