Rough running 9R

[Tenoq]

Got a problem with the new bike.

I find that the engine runs quite rough when pottering around at low speed, up to around 40-50km/h. This means the engine revs are around 4,000RPM and below. I've just had a full service done (carbs, valves, etc) expecting that to sort it out, and it hasn't.

So I guess the next question is, what's the cause? I'd really like to get this sorted... last night I nearly lost it taking off slowly in the wet, as the engine was jumping around and making the rear wheel spin.

Please help!

[Nanna10r]

Did they balance the carbies & does it have an after market filter or a slip on pipe ?. I'd Check the fuel tap mate & the filter sounds like a fuel drama from here. Check the choke is closing properly as well. I'm no mechanic But theres a few clever blokes in here with more info should be able to pin point the fault.
Cheers Brett

[Blackzxr]

I like it rough...





Hollywood

[SocialSecurity]

was the bike like that when you got it?

and did you mention the issue to the mechanic who serviced it? they might have some ideas...

also would like to know what the mechs did to the carbys... sounds like it could be in need of a balance, but if they only did one thing to the carbys it should have been balance them


if its not something obvious like a blocked fuel filter (tho that would probably effect top end not bottom end) or fuel tap then maybe its an issue with the float height, as that will affect the range up to about 4000rpm ...

does it do it with any throttle openings when in that rev range? or only if you give it full throttle? strange if little throttle openings cause it aswell..


does the bike run like a scalded cat in the top end and midrange still?

[Tenoq]

It wasn't like that when I got it, but developed the problem a few thousand k's after.

The issue was mentioned to the mech, and they did balance the carbs as part of the service (or so they said). Bike is 100% stock in engine bits... only aftermarkets are screen, oggies and rack. And it does happen at any throttle opening... I can't sit at 3000RPM smoothly, it just jumps around under me.

And yes, the bike goes NUTS once it's into the midrange and top-end.

Choke is a possibility... I was wondering if it was something like that.

[Tenoq]

The mechanics are going to have another look at it for me tomorrow, so hopefully they'll find out what it is. Failing that, any more hints would help!

Haven't mentioned who I've taken it to... not sure if that's allowed on this forum?

[mike-s]

read that link i put in the dynojet thread, see if you can figure out where its running rough according to their symptoms list.

[SocialSecurity]

does sound like a float level problem then....

try this guide:

http://66.47.68.116/tech/carbtune,CV,hi ... gines.html

[Tenoq]

Took it back to Brighton Kawasaki today, and the mechanic basically said: "That's a ZX9R for you." Reckoned there was nothing he could do tuning-wise that would make it better, without severely rooting the top-end. He seemed to think and aftermarket slip-on would help the situation immensely... I'm not really convinced.

Personally I would be more a danger to the bike than a help, so anyone else you recommend I take it to?

[SocialSecurity]

Hmmmm... its hard to find a mechanic actually interested in your problems see if you cant use that guide i posted to at least diagnose the fault... like does it get worse as the bike warms up, or does it get ever so slightly warmer?

[BladeBoy]

Took it back to Brighton Kawasaki today, and the mechanic basically said: "That's a ZX9R for you." Reckoned there was nothing he could do tuning-wise that would make it better, without severely rooting the top-end. He seemed to think and aftermarket slip-on would help the situation immensely... I'm not really convinced.

Personally I would be more a danger to the bike than a help, so anyone else you recommend I take it to?

One word answer BULLSHIT, you paid him/her to fix it, tell them to FIX it

[SocialSecurity]

yeah id be very displeased with that... id expect more from brighton kawasaki... sure the guy wasnt the apprentice? the guy obviously had NO idea about tuning bikes... and did he even test ride it? 9R's are not known for these problems...

the only way he could screw the top end would be by changing the main jets (which are currently fine) which wouldnt have the desired effect any way.

if its a problem down low, then its the float height that needs adjusting... assuming everything else is ok

i remember somebody on here had trouble with their coils causing similar problems

[Phil]

Took it back to Brighton Kawasaki today, and the mechanic basically said: "That's a ZX9R for you." Reckoned there was nothing he could do tuning-wise that would make it better, without severely rooting the top-end. He seemed to think and aftermarket slip-on would help the situation immensely... I'm not really convinced.

Personally I would be more a danger to the bike than a help, so anyone else you recommend I take it to?

does john kaiser (sp) still work on bikes down geelong way ....i went to him years ago when my zzr6 was playing up and it went like bat out of hell after he'd finished wih it.

HTH

[mike-s]

FYI i took the bike to work this morning, and all low end stuttering problems are GONE. what i did was, make sure all float valve springy bits (they compress when the float is over full) were compressing correctly, i replaced one that wasnt quite compressing correctly and adjusted another till it did.

I then made sure that all the floats were sitting 1mm higher (18mm not 17mm as before) when the float valves were "just seated".

Put it back together last night and aside from typical coughy coughy running at low revs when cold that i was half expecting (lasted all of 4-5 mins). It now runs perfectly. Definately a lot snappoer & less boggy than when i undertook my carby tweaking adventure.

Now to find out how fuel consumption goes tomorrow when i take it out for a spin

So yeah, that guide suggesting floats need to be raised (that is make the floats sit further AWAY from the carby body) by 1-1.5mm is spot on.

*grin*

[SocialSecurity]

crikey 17mm is damn lean! 18mm is rediculous... what model is your 9R??

stock height is 13mm ... im running 15.5mm and i think it might be a little too lean