Flat spot in revs... Still!

[JackT]

First things first, the bike takes a while to start up, which i think might be related, posibly not. Once its got going she idles fine. Then the real problem kicks in. When i pull the trottle back she gets to around 5000rpm then wont rev any higher with a spluttery sound like shes running low on petrol.
1st gear pretty much doesnt exist when im setting off, and even in 5th i cant rev about 5000. (which usually results in about 30mph)
I've exhausted my knowledge in trying to sort this problem out and this is what i've done so far;
Cleaned carb inc main and pilot jet, made sure float isnt sticking and fuel line is clear,
Replaced air filter and airbox inc box - bard manifold,
Clean tank best i can, cleaned fuel filter in the tank, cleaned the tap out,
Replaced spark plug,
Replaced a broken exhaust gasket,
Replaced CDI unit (the actual unit not the coil).
Can anyone please give me some suggestions of possible problems and solutions as i really need her running for college.
Thanks
Jack

[P.addy]

Firstly....



what bike?

[JackT]

oh my bad, its a kinroad cyclone, coulda sworn i put tht lol. Musta deleted it haha

[P.addy]

Ok, what colour is the spark plug.
You say it splutters, do you have a spare key.. put it in the petrol cap and open it when it starts to struggle whilst moving. See if that cures it.

My old GS500 had/still has a petrol problem, it feels like its cutting out...it turned out to be the fuel tap! try using the alternative option on the tap?

Also... anything not connected at the carb end? Maybe an air pipe has come loose?

[JackT]

The plug i took out was black, and i tried the key in the cap, wasnt a vacuum problem. Not sure how to cute the black plug problem because i altered the air mix on the carb and that didnt help.

[P.addy]

sounds like its running WAYYY too rich, another symptom on the GS!!

Choke stuck on? Air filter clean? I think its either that or you need to adjust the carb to slow the amount of fuel being passed through.

[JackT]

When i cleaned the carb the choke plate seemed fine, movement wa free and no tight spots. And its a brand new air filter. What else would make her run rich?

[P.addy]

[tahrey]

Sounds just like what my CG does with the choke left on (and if there's a great remove between it and the kinroad...). It just won't go any higher because the choke is doing exactly what it says on the tin - restricting the air intake.

Unless it's something wierd like valves not opening enough or an obstruction/kink in the airway, it's probably carb adjustments time.

(Does fiddling the choke one way / the other make ANY noticable difference to how it runs, btw? IE if you get it nice and cold, is it harder to start with it off? Runs even worse with it full-on?)

[JackT]

choke seems to make no difference at all. Im not sure what ese i can adjust on the carb, done needle hight, idle, air mix. Is there any other adjustments you can suggest to do with air/fuel mix?

[Carvel]

[JackT]

So how would i sort tht, cos the choke plate moves freely when the carbs off the bike

[Carvel]

Check the cables moving freely.
____________________
2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[JackT]

cables recently new, pulls choke lever fine

[hmmmnz]

pull out the air filter and have a test with no air filter in the bike,
if it runs better then she's rich,

if thats the case we'll go from there
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[P.addy]

[JackT]

Just an update, pulled the filter out and disconnected the choke cable (with a combination of the 2) but she just sounded like she was gonne suck my leg in but the rev issue didnt change at all.

[Odie]

Ok simple question's:
Have you had done / had some-one else do any work on the bike prior to this problem happening.
When did it start happening and had anything happened to the bike (dropped it, cut out for no reason, a mate borrowed it, had some work done etc)?
The reason i ask these questions is 9 times out of 10 its some-thing has happened prior to the current problem that is the cause!
It dont matter that you think its inconsequential, it could of caused it because as i said it normally is!
____________________
You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[JackT]

No one else has worked on it, ive been doing it as a project so my hands only.
It just started one day a fair few months ago. (taken a while to do the stuff i know) i thought it was just low on fuel when it first happened lol. But never dropped or used by any one else (apart from previous user but it ran fine when i first got it)
As far as i can think back there wasnt anywork done on her in the period when i got her and the problem started, no crashed or drops or anything.

[Odie]

Long shot, its a problem on Honda CX500's, i know its not the same bike but the symptoms are very similar.
If the alternator on the CX500 is on its way out the bike will not rev past 5,000rpm, this is due to the ignitor sensors being part of the alternator and not letting the ignition advance under load.
Change the alternator and it solves the problem because the ignition sensors are changed at the same time as they are part of the alternator.
Another idea, my wife has a Gilera Cougar, some-one changed the rear under guard due to it breaking and didnt refit it correctly, this blocked the intake for the airbox, reducing the amount of air entering the engine, initially we went through everything because the bike would not pull above half throttle, checked cdi, carb, ignition, everything, even removed the air filter and cover, still no change, eventually found out about the flat covering the airbox inlet, put hand on the swinging arm, followed the inner guard up and found a rubber flap, pulled it out and haypresto, the bike was back to its usual self.
As i said these are idea's, it aint going to do any harm to check these out, hope you have a manual.
All the best
odie
____________________
You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[JackT]

I checked the clearance or the air intake when i first replaced the airbox. But yeah i'll check on the alternator idea. And as for manual's the genious who built this bike didnt make a manual to go with it.

[stirlinggaz]

chuck the carb in the bin & fit a mikuni,lol
& theres now a haynes (generic) manual available for these bikes.
cheers,
GAZ

[JackT]

mikuni are made for large engines. Mines only 125 unforunately

[stirlinggaz]

mikuni also make carbs for 50-125cc bikes & above. (including pit bikes)
the usual upgrade is the 29mm.
cheers,
GAZ