Cracked liners?

[DEVO.RU]

Hi all.I whipped the engine out of my RU to drop if off to my local bike shop.i explained the poor running and said that I had measured the valve gaps and they were too tight .the mechanic said that it didn't sound like valve clearance trouble,more like a cracked liner.anyone have any experience of this? Searched google and couldn't come up with any info about it being a common Fzr problem as he said it was.

[Stig]

Never heard of that issue all the time I've been running the site and into Exups

What's the symptoms. Tight valves are usually associated with difficult to start once warmed up

[Teego]

What liner??
And why didn't you leave the motor in the bike?

[DEVO.RU]

Takes a lot to start the bike.eventually starts but won't pick up.only with a lot of feathering the throttle,it might make it up to 3k rpm.a lot of spluttering and backfiring.the headers start to glow.it went from running reasonably well to this.i have checked the valve clearance and a good few were very tight.the mechanic said they wouldn't have tightend up in just one run,mind you,I did drive the shite out of it

[Tipper2]

Sounds like timing or ignition problem to me.

Cracked liner is something I've come across before but never in bikes.
Dry liners (which is what bikes have) generally show a crack by a load of crankcase pressure so oil pissing out of the breathers.

Think he's talkng sh#te but quite happy to be corrected

[Tipper2]

Sounds like timing or ignition problem to me.

Cracked liner is something I've come across before but never in bikes.
Dry liners (which is what bikes have) generally show a crack by a load of crankcase pressure so oil pissing out of the breathers.

Think he's talkng sh#te but quite happy to be corrected

After reading this again it sounds quite possibly like tight exhaust valve clearances?

[Jay762]

Only come across cracked liners in early r6's - and given how robust the FZR liners are I dont know how it could happen as they are not put under a comparable strain to the much thinner r6 versions.

[Teego]

IMHO forget about liners.
Set correct vlave clearances. This accounts for the starting problem.
I'm 90% sure the other problems including flaming headers are down to bad fuelling.
Flaming headers seem to indicate it is running very lean.
Before you strip the motor check and clean the carbs and bring them back to best condition. Also make sure you check the emulsion tubes.
Then make sure you have good sparks.
There are plenty of carb experts around here who'll help you on your journey.
I think your mechanic has been drinking the black stuff with the little people.

[nugget]

I'll drink to that Teego. I think you're spot on with that diagnosis.

[DEVO.RU]

Thanks for all the advice.it used to run badly(no.3 cylinder wouldn't run under 3k rpm)sorted by removing the resisters in the plug caps.ive stripped and cleaned the carbs more times than I can remember.tubes look ok and it has a stage 3 dynojet kit fitted .i borrowed a cdi box,furs pump resister,and coils but made no diffence.the mechanic said I should whip the head off and check for a crack.how would the timing be off if its non adjustable?.i might just do the shims myself and see how it goes

[Teego]

Thanks for all the advice.it used to run badly(no.3 cylinder wouldn't run under 3k rpm)sorted by removing the resisters in the plug caps.ive stripped and cleaned the carbs more times than I can remember.tubes look ok and it has a stage 3 dynojet kit fitted .i borrowed a cdi box,furs pump resister,and coils but made no diffence.the mechanic said I should whip the head off and check for a crack.how would the timing be off if its non adjustable?.i might just do the shims myself and see how it goes

Good plan. Shim it up then you'll get a better idea about what to do next. My system has always been to start with the basic stuff first. Then proceed in logical order. Most times you find a solution without spending megabux or blowing the wife's hairdressing money at Bargain Booze in frustration.

If you ever get stuck, stop and take 5 mins with your favourite relaxant then come on here to discuss a way forward.

[DEVO.RU]

Thanks all.i forgot to mention,after I start it,if I shut off the choke,the bike cuts out and won't start or run without it.i changed some of the plug caps for Ngk ones as well as the standard ones were arcing off the head at the top of the orange seal.not sure if the new caps are any good.they were arcing slightly aswell

[krazyneil]

ive never heard of any liner problems on any exups , sounds more like tight valve to me ,set that then see how you go

[skelly]

Wowzers....
Absolutly no point whatsoever in cleaning carbs ect when you are not sure of the basics.
Allways allways allways ensure that the valve clearances are correct and you have compression on all 4 cylinders before contemplating anything else.
I know its a pain to do but it is worth it.
Its all about ticking boxes.

Hope you get sorted.

Skel.

[nismo]

Had a similar problem with the old Thunderace, which resulted in every single toy being thrown out my pram many many times. Multiple carb strip downs and cleanings before the culprit was eventually found... weak choke springs. Had many of the same problems you had, needed the choke to start, choke and a little throttle to tick over, running on 3 pots below 3k. Something that I obviously didn't think to check, only found it by running the engine without the airbox on and seeing liquid fuel running through the carbs. Replaced them, and she worked fine after that