engine rpm isn't consistent ninja 250r

[Chaderotti]

When the bike is cold, I'll sit on 60 km/h at exactly 4k rpm. However after a bit of riding today in the heat, at 60 km/h engine rpm would fluctuated between 4.5k to 5k rpm, as in, I would accelerate from 40 km/h to 60 km/h in 6th gear and sit on 4k rpm, or I would reach 60 km/h and then shift up to 6th gear and sit on 4.5k-5k rpm. I'm using the recommended 10w-40 oil, and there is a couple mm of free play in the clutch lever. The bike has done 10,200 km and about 3 years old and had an oil change 200 km ago

Is my clutch slipping when the oil is up to temp? I highly doubt it would be because from the lights I still take off fairly quickly, though when I do give it the beans and shift into second the engine hovers at x rpm for a second and then starts increasing in rpm, kind of like the clutch is trying to grab.

ideas?

[duffman]

What oil did you use?

[Chaderotti]

Motul 3000 10w-40

[g0zer]

I highly doubt it would be because from the lights I still take off fairly quickly

when the clutch first starts going it usually slips in high gear not low, and when the oil is cold not hot.

[Stoneville]

I don't know, way to technical for me, I'm just curious as to why you are 6th at such a low speed?

[darkfibre]

Can you feel the revs fluctuate (seat of pants), or is it just the tacho fluctuating?

Bike tachos can be a bit variable.

[Dirty32]

... curious as to why you are 6th at such a low speed?

This^?

I realise you may only be doing this now for testing purposes and to see or find any flatspots, but your effectively labouring the engine if your in 6th at 4k rpm. I wouldnt make a habit of doing this too much...

If you need to roll on, drop it down a couple of gears. If there isnt any problem once you start getting into higher revs, then there isnt really an issue.

[Chaderotti]

Can you feel the revs fluctuate (seat of pants), or is it just the tacho fluctuating?

Bike tachos can be a bit variable.

I thought it was the tacho being a bit out, but I can definitely hear the engine working differently.

I cruise along at 60 km/h in 6th all the time

[Rogwick]

I cruise along at 60 km/h in 6th all the time

I used to cruise around in 6th @ 60kmph on the 250 all the time too. I wouldn't accelerate in 6th at 60 though. My ZZR revs used to fluctuate a bit on idle...until I had the carburetor cleaned, considered that. I Carbs should be done every 10-15,000kms no?

[Chaderotti]

I used to cruise around in 6th @ 60kmph on the 250 all the time too. I wouldn't accelerate in 6th at 60 though. My ZZR revs used to fluctuate a bit on idle...until I had the carburetor cleaned, considered that. I Carbs should be done every 10-15,000kms no?

It's at 10,000 km so I'll need to book in the carby's to be cleaned and all the jazz related to it.

I use 6th gear the most when riding

[Halo_2]

could try a fuel additive first like 'total fuel system cleaner', never needed to do it on my 250 though.

should be in 3 or 4th at 60kph

[Dirty32]

Sorry, i probably wasnt clear with my post.
The cruisings not the issue on 4k rpms at whatever speed in 6th.

More so the rolling on the throttle hard from low revs (eg 4k rpm in 6th on a 250), your labouring the engine and it will take a while to start moving. Your more than likely going to feel some flat spots and fluctuation / pulsing if your doing this.

[duffman]

I thought it was the tacho being a bit out, but I can definitely hear the engine working differently.

If it's not the tacho playing up, either your clutch is slipping, or your back tyre is breaking traction.

Id go with slipping clutch.

[Retro]

Some time ago I had a ute...just bought it 2nd, 3rd hand, whatever- it was the bee's knees. Installed a tachy in it one day and soon after saw it bouncing around a bit and heard the engine working different too at the same time. Within a week I cooked the motor; big end bearing was fried. Guess who never checked the oil level?

When the oil pump on my SRX250 failed in 2004 I had an erratic rpm level at times. Like a jump, a higher rev was heard and then it would settle. I paid no mind, the damn thing was born in 1984 so it was bound to have a few bugs and quirks right? Not long after I needed a new piston/barrel and oil pump.

Not saying that's the case but sometimes it pays to check the essentials too.

[polonY]

I may have missed it, but is the speed affected while the revs are fluctuating? If the engine speed is fluctuating and the road speed is constant, then you have clutch slip. If they are going up and down together, sounds more like an engine running issue.

[Chaderotti]

Another instance is, early on in a ride if I head to the freeway, in 6th gear at 100 km/h the engine is at 7k rpm, later on in the arvo when everything has warmed up, at 100 km/h in 6th gear the engine is spinning at 8k rpm and there is a difference in engine sound so it doesn't seem to be the tacho being out.

The engine rpm doesn't fluctuate constantly while cruising, it'll only pick up to a certain rpm depending on if the engine is cold. It's bloody hard to fully explain.

[out_in_front]

I am thinking the tacho pickup might be faulty... If there is no evidence of clutch slipping there is no reason for there to be a discrepancy mechanically... so I would guess its something to do with the electrickery.

[Chuck Steak]

when the clutch first starts going it usually slips in high gear not low, and when the oil is cold not hot.

In my experience clutches slip more when warm than when cold - for both dry and wet clutches

[filbert]

it's the battery

[g0zer]

In my experience clutches slip more when warm than when cold - for both dry and wet clutches

maybe it can go both ways

on my rz350 which is making a little bit more power than standard, it will always slip the clutch if you load it for the first 5 minutes into a ride.. once the gearbox oil is up to temp its fine so i figure thicker oil, higher viscosity more slip. i am not sure how thinner viscosity contributes to slip and a dry clutch oil temp is irrelevant?