92 cbr600f accelerating problem

[Dynamo_Delboy]

Looking for a wee bit of help here guys and girls.

Got a 92 cbr600f and recently when i accelerate hard in 2nd gear, around 6-7k rpm its like the bike bogs down a wee bit then feels like back wheel is jerking or losing traction then has full power and goes fine through all the gears.

It only happens in 2nd and only between 6-7k rpm.

[eastanglianbiker]

have you checked the basics like chain tension and sprocket condition?

[Dynamo_Delboy]

Sprocket looks ok mate.

Might try giving the chain a wee tighten up.

[eastanglianbiker]

check front and rear sprocket just in case and get hold of the chain in the 3oclock position on the rear sprocket and see if you can pull chain far enough away to see the tooth

[Dynamo_Delboy]

Just remembered i had posted this threat.

So chain and sprockets are fine.

The problem is still there,

If I accelerate hard through 1st, all is fine.

2nd gear, accelerate hard slightly bogs just before 6k rpm and seems to cough/splutter between 6-7k rpm then smooth again 8k rpm upwards.

3rd gear does same as 2nd.

4th, 5th & 6th gear all smooth.

Could this be a fuelling / carb issue?

Its really annoying me especially if i go to make an overtake.

Only happens in 2nd & 3rd gear.

Pulling my hair out with it.

[Mr Fro]

Could be the jets. Might also be the timing.

[Dynamo_Delboy]

Jets needing cleaned?

Is timing easy enough to check?

[Stu]

sounds to me like the fueling needs setting up

when you next go out stick a bit of choke on and see what happens when you accelerate

[Dynamo_Delboy]

How much choke would you say stu?

Quarter, half, less?

[Stu]

try all and if anything does make a difference make a mental note then come back to us

[Dynamo_Delboy]

Soon as the rain stops pissing down and wind lets up ill give it a try

[Stu]

I best explain why I'm telling you to do it

if the fueling needs sorting then sticking the choke on could help as if the fuel to air ratio is wrong by having the choke on you are altering it

if the bike runs better with choke its running lean if it dies a death then its probably too rich

[Dynamo_Delboy]

So today ive narrowed the problem down to the back wheel losing traction at said rpm.

Came off the main road, turned left on motorway sliproad and accelerated in 2nd gear.

Got up to 6k rpm then back wheel felt like it slipped to the side a bit.

Noticed my chain has a small kink in 1 of the links. I must've misses it when i checked last time.

Could this be problem

[Stu]

I can't see your wheel losing traction all the time at that RPM it may have been a coincidence

as for the link it shouldn't be causing the problem but you need to sort that out too

did you try the choke trick?

[Dynamo_Delboy]

I actually forgot all about it but ill do it tomorrow and post what difference it makes

[rob m]

Has the jetting changed or K&N air filter been fitted? If it was me, I'd grab my haynes manual and strip & clean the carbs. Sounds like a blockage to me, possibly jet related. While I was at it I would balance them using a carbtune or similar. I had a GSXR750 in the mid 90's with a similar problem and stripping the carbs fully, cleaning them and balancing had them spot on afterwards.

[Dynamo_Delboy]

Air filter is just a standard filter not K&N.

As far as im aware the bike is totally standard.

Jets have never been touched by me.

Ive had the bike around 18-19 months and the problem started a few months ago.

[Dynamo_Delboy]

Tried accelerating today with choke but made no difference.

Tried it at quarter, and half.

Still doing the same at the same revs

[Fozzie]

Always in 2nd?

Could it be hopping into another gear? A old aprilia of mine used to slip from 2nd to 3rd quickly due to nackered selectors. Could cause it to jump too and from!

That will be shite if it is, big strip down for that...

[Dynamo_Delboy]

2nd and 3rd mate aleays round about the same rev range.

Only when hard accelerating.

If running up the revs slowly it seems to be fine

[Fozzie]

Ah 2nd and 3rd... I wonder if it's a dodgy shift drum... Bouncing the gear up a gear under strain. You could get 5-6th gear issues on an old bike that did that.

Id need a video really to tell if it was fuelling or mechanical.

[Dynamo_Delboy]

When i accelerated today in 2nd gear it definitely feels like the back wheel is slipping and losing traction. Could feel it slipping out slightly at the rear end when going in a straight line then after the 7k rpm it grips fine again

[Stu]

I suggest going and getting the bike on a dyno

this way they will check your fuelling through this rev range and you can also keep an eye on things as its been run up

it will only cost about £30

tell the operator all your problems as they may refuse to do it but if they do then they know what they are looking out for too

It sounds a bit strange to me I dont think its gearbox and I find it really hard to believe the rear wheel is actually slipping!

although you could be suffering from a touch of clutch slip

[skiffer]

I was going to say clutch slip.. it sounds exactly what I had until I changed the friction plates. Only when I opened up. Certain gears will put more exertion on them, right?