Engine RPM Question!

[STEALTH52]

We took the track bike apart today & done a full service on it, brake pads, brake fluid, spark plugs, oil, air/oil filter etc etc & it all works fine & runs much smoother, Only problem is the following...........

when you come off of the throttle whilst in gear the engine revs come down too slowly. If you rev it whilst stationary in neutral or with the clutch pulled in it comes down fine, it's only when in gear and riding when you shut the throttle it does it...

Any ideas???

It was doing this before we serviced it by the way....& it's a ZX6R Ninja 1998 G1 carbed by the way if it's any help...

Just want to get it sorted for Snetty in a couple of weeks

Cheers

[DoodleBug]

Do you mean whilst you are riding, or are you runnin gthough the gears on paddock stands?

I have no idea what is causing it other than an engine will run down slower on the road than stationary due to momentum.

[STEALTH52]

Whilst riding mate, Yeah i know it will come down slower but it should be comind down quicker than what it is.... Think i may get it checked out:grin2

[MICKTLS]

check all the throttle linkages are operating properly and one of them is not slightly sticking , also how much freeplay in the throttle cable is there ????????

[STEALTH52]

check all the throttle linkages are operating properly and one of them is not slightly sticking , also how much freeplay in the throttle cable is there ????????

It was quite tight so we loosened it off a touch to see if that helped but it didnt, Going to have another play next weekend to see if we can get it right...I'll give you a bell Monday Mick & have a chat with you about it & pick your brains!..... Off to bed now to get some shut-eye!!! :grin2

Cheers matey!

[stu600cc]

We took the track bike apart today & done a full service on it, brake pads, brake fluid, spark plugs, oil, air/oil filter etc etc & it all works fine & runs much smoother, Only problem is the following...........

when you come off of the throttle whilst in gear the engine revs come down too slowly. If you rev it whilst stationary in neutral or with the clutch pulled in it comes down fine, it's only when in gear and riding when you shut the throttle it does it...

Any ideas???

It was doing this before we serviced it by the way....& it's a ZX6R Ninja 1998 G1 carbed by the way if it's any help...

Just want to get it sorted for Snetty in a couple of weeks

Cheers

I balanced the carbs on mine and does the same thing

Answers would help me to

It hasnt been a problem though

I think it just the carbs i thought it was a air leak

But its all sealed

I think its just the carbs that are causing it

Do you have to rev it slowly to get to pick up but wen its above about 4 thou its ok???

Remember i have a G1

[STEALTH52]

Yeah the fella who i got it off off had the carbs balanced, I've been thinking today that maybe he had it set up like that being that its only been used on track??? It goes alright it's just annoying, i'll see how it goes at Snetty!

[STEALTH52]

Yep!!! if you open the throttle right open straight away it dont wanna go anywhere first off, once over 4000 it's takes off, maybe it's just the way they run then Stu!

[stu600cc]

It'll be fine

I think its just because the carbs are balanced and is getting a proper mixture

I've done a few track days and its been fine

I wouldn't worry geezer

You raise the rear up yet?

[STEALTH52]

Nop not done anything to it suspension wise etc, is that a good idea on the G1 then?, I know one thing though the backs got to be hardened right up, it's like a bouncy castle at the min, the pre loads wound half way down already, reckon it's going to be going a bit further yet

[stu600cc]

Make sure you set the static sag

And is it standard suspesion if so wind it up up up

Yeah its a bgood idea toi raise it up helps it turn quicker and hold a line

Its **** easy as it has 2 nuts 1 on top of the top mount and 1 underneath

Loosen the top one and turn the bottomn 1 till its about 20mm it feels so much better

I would advise in a replacement shock or at least a refurb on the old one

Get some Hagon progressive springs in the front

They are about 80 notes

[Lateshift]

its very likely that its the actual butteflies on the carbs that are causing this, no matter how much balancing you do it wont cure it, its a fairly common problem on older bikes due to the butterflies being a fraction too small in the throttle bodies (very likely due to wear and tear over the years).

If you hold a set of CV carbs up to the light you would expect to see no light through them at all when the butterflies are closed, however sadly its not the case on a lot of them and it can create this problem :)

I would have to question the need for progressive rate springs though, most race bikes use Linear ones (and on most Kawasaki bikes unless you are running with the top flight, the standard springs are more than up to the job ;) )

The whole idea of a progressive rate spring is to make it gradually stiffer the more load that it is put on it, the harder you corner then the stiffer the springs are going to get ;)


(again which is why 'most' racers will use a constant rate spring, with the correct valving, oil weight and air gap for their bodyweight :) )

[STEALTH52]

So in other words, just let it be i reckon then, to be honest i doubt i'll notice it on the track as i'll always have the engine high up in the revs anyway.

Cheers though latey.

[Lateshift]

If anything seeing as its just a track bike, i would probably raise the idle speed to around 2500rpm anyway, anything below your minimum rpm range on track is totally wasted, some race bikes have idle speeds around 4000rpm purely because they never use anything below that at all, and even then its only used for launching from the line :)

The only downside is that by raising the idle speed you lose some engine braking, but it isnt too bad on standard engine with a 2500rpm idle :)

[STEALTH52]

Cool ok lateshift, well i'll be tyring it out at snetty on the 6th so i'll see how it runs, main thing is it's all serviced & ready to go now.:grin2

[stu600cc]

The springs in th G1 are nearky 10 years old and as mine was bottoming out every corner and hard breaking manouver i have found that the hagon progrssive spring works really well and are not to expensive


Lateshift, you keep saying the standard springs and shocks should be fine

Yes on a newer bike but on a nearly 10 year old bike they get a bit knackered

Trust me changing the fluid doesnt really help

My advice from experience get some new springs and rear shock

Im not saying the originals are no good just that you can do much more to get a better feel and have a bit more adjustment than just winding the thing to full everything which is probaly wat is needed

The bit about the carbs sounds like the problem thanks

[Lateshift]

Stu, dont take this the wrong way but suspension is like tyre pressures its a personal thing where the feeling of the bike and the feedback you get cannot be related properly from one person to another :)

Thats why i say that standard springs pretty much do the job on most bikes until you start to hammer them into the ground, i agree totally with what you are saying about springs that are too old, but even then sometimes forks just need a good servicing to give a massive difference.

The only reason i queried the use of progressive forks is due to the fact that what works for you possibly wont work for him, bear in mind you tend to throw a bike into a corner extremely aggressively, progressive springs may work better because the sudden and increased force is slowed down more progressively (where doing it on constant rate springs would unsettle the bike too much), if he is a smoother rider then constant rate springs will work perfectly :)

Forks have an air gap in them that directly controls the damping in the fork, changing the oil weight and the air gap can have a dramatic effect too ;)

If anything changing springs is the perfect opportunity to get ones that are the correct weight for the rider :)

A rear shock is a must, even a revalved one which is sprung for the rider tends to be better than a standard shock anyway :)