FZR Help!

[mark247]

Ok, so i was checking out the EXUP system on my FZR. Thought it would be easier if i took the exhaust off and put it on the bench so i did. While the exhaust was off i thought i would turn the bike over just for the hell of it to see what it sounded like, so i did and it went pop pop pop but never started, so i just shrugged and continued looking at the EXUP stuff. Now this morning i put the exhaust back on how it was and i cant get the damn bike started! Hardly firing at all ( exhaust isnt getting warm ) and it backfired a few times. Engine started hasnt helped, WHAT DID I DO WRONG???

I hope I havent burnt a valve, i cant really see how i did that because it didnt even properly start with no exhaust... any positive input is appreciated..

[Paul in NZ]

Hard to say but it could have not started with the ex off for the same reason it wont start now.... Why were you looking at the EXUP??

FZR400's apparently get harder to start as the valves get worn....

Cheers

[avgas]

sure u havent flooded the carbs?

[mark247]

Hard to say but it could have not started with the ex off for the same reason it wont start now.... Why were you looking at the EXUP??

FZR400's apparently get harder to start as the valves get worn....

Cheers

I was looking at the exup because it was disconnected. But the entire valve has been gutted, so yeah, i just put it back together and left it how it was without any exup. I dont know why, but i got the fzr going after a while, after turning it over again and again. Engine start didnt help. But enventually it started. I think it was just a mixture of the fact it was probably flooded, nearly froozen, and the battery was not fully charged.

[Paul in NZ]

Keep an eye on it. They are difficult to start (apparently) but its an early sign of trouble to come... Probably flooded it...

[mark247]

Keep an eye on it. They are difficult to start (apparently) but its an early sign of trouble to come... Probably flooded it...

Trouble to come? You mean valve troubles?

[Paul in NZ]

Trouble to come? You mean valve troubles?

Its an FZR400 so yes - valve trouble! (eventually)

[mark247]

Its an FZR400 so yes - valve trouble! (eventually)

What type of valve trouble? Burnt valves? Reshimming? Valve grinds?

[mark247]

Hi, I used to have an '89 FZR400. The EXUP mechanism can be a real pain in the ass when it misbehaves and you forget to check whether it is seized and instead send it to the mechanics who spend hours trying to diagnose the problem...

Anyway, I would guess that you may have left the EXUP in the fully closed position, effectively closing the exhaust flow. My old bike had a broken bush, which kept the valve from opening.

So basically, grab a pair of pliers and try to turn the EXUP shaft so that the valve is open and try starting it again - it should start if the problem was the closed EXUP valve.

BTW, if the EXUP mechanism is working, it would be best to keep it connected.

PS: I have a couple of brand-new EXUP bushes lying around in the garage (ordered too many). PM me if you want them.

The thing is i dont really know what the exup is ment to look like. I took the exhaust off and where the cables are ment to hook onto the actual valve, all there was was a bolt. So i think its been gutted. Would i be correct in saying so? I took the cover off so i could see into the exhaust and there was nothing in there.....

[Paul in NZ]

The thing is i dont really know what the exup is ment to look like. I took the exhaust off and where the cables are ment to hook onto the actual valve, all there was was a bolt. So i think its been gutted. Would i be correct in saying so? I took the cover off so i could see into the exhaust and there was nothing in there.....

Check my fzr400 exup thread for pictures of the valve.....

Yeah - FZR400's seem to need frequent attention to the valves... Burnt, shimmed, cleaned etc...

[slob]

I was looking at the exup because it was disconnected. But the entire valve has been gutted, so yeah, i just put it back together and left it how it was without any exup.

I had a '89 FZR400 which developed a problem where it wouldn't idle - I would have to hold the throttle open and it would just "idle" roughly, only to stall as soon as I let go of the throttle.

So turns out the problem was the EXUP valve being stuck due to a shattered bush. I removed all the EXUP bits, decoked and polished them, replaced the broken bush (got a couple of extras bushes if anyone wants them), and then it ran sweet as.

If your bike isn't smoking like a steam engine, then the valves are probably ok (at least the exhaust ones). Are you sure that all the EXUP internals have been removed? Sounds similar to my problem, but if there's no restriction in the EXUP, then I don't know..

[mark247]

I had a '89 FZR400 which developed a problem where it wouldn't idle - I would have to hold the throttle open and it would just "idle" roughly, only to stall as soon as I let go of the throttle.

So turns out the problem was the EXUP valve being stuck due to a shattered bush. I removed all the EXUP bits, decoked and polished them, replaced the broken bush (got a couple of extras bushes if anyone wants them), and then it ran sweet as.

If your bike isn't smoking like a steam engine, then the valves are probably ok (at least the exhaust ones). Are you sure that all the EXUP internals have been removed? Sounds similar to my problem, but if there's no restriction in the EXUP, then I don't know..

I just looked at the pics from the other fzr400 exup thread and my exup valve is totally not there. I read on some fzr site that a lot of racers ( im not racing mine, but anyway ) remove the exup anyway because its all just added weight. I also read on that site at its not the exhaust valves and shag themselves, its the intake valves.

The site i am talking of is here http://www.fzrarchives.com/fzr400/FZ...Questions.html

"The EXUP valve is a servo motor controlled exhaust valve that increases back pressure to your motor under certain circumstances, increasing torque while reducing emissions. This option was only present on the California model FZR400's, and was promptly tossed at the race track."

"Yamaha apparently made the intake valves out of a very soft metal (kind of a good thing as replacing the valve seats is incredibly expensive). After a couple of seasons of pounding the seats at 14+K, the valves tend to "cup" meaning the edges get worn, then the valve becomes shaped like a tulip."

"The most tell-tale sign that your valves are out of adjustment is hard starting."

[slob]

The thing is i dont really know what the exup is ment to look like. I took the exhaust off and where the cables are ment to hook onto the actual valve, all there was was a bolt. So i think its been gutted. Would i be correct in saying so? I took the cover off so i could see into the exhaust and there was nothing in there.....

Whoa, you read that post before I edited it!

Ok, the EXUP valve is a wedge-shaped object (see attachment) that is connected to the cable. If all you saw was a bolt, then yeah, sounds like someone's removed the EXUP valve and left the bolt so the cables would still be connected to something..

[mark247]

left the bolt so the cables would still be connected to something..

nah the cables arent connected to anything. I think the bolt is just there so i dont get an exhaust leak out of where the valve should be.

[slob]

"The most tell-tale sign that your valves are out of adjustment is hard starting."

Sounds like the most probable cause, but why would it suddenly stop running just after you took the exhaust off? If the valves were cupped, then wouldn't you have had the problem prior to removing the exhaust?