Ran into another strange problem. Any ideas?

BKtje

I've already spoken to my mechanic and I think he understood what I mean't (I have a hard time explaining it in english let alone french!) but he didn't immediately have an cause.

Bike: Ninja 300, 6k km.
Problem: Accelerating in 4th gear near peak revs (at 11k rpm, 13k rpm redline).

I don't normally aggressively accelerate in 4th gear on the motorway but decided that I should try it once at least. Anyway what happened was that between 10k and 11k revs it felt like the chain started to "chug" or jarr. Sort of like when your in too high a gear at low speeds (but on the chain rather than the engine). The bike continued to accelerate but every half a second or perhaps second it felt like the chain was shuddering (for lack of a better word). Acceleration seemed to continue smoothly and engine noise didn't change. Shifting to 5th stopped the "problem".

This has only ever happened in 4th gear while at those revs (though never been at 11k revs in 3rd or lower). In 5th I don't have the problem and 6th I've never gone fast enough (6th gear at 10,000rpm I'd be doing around 155kph). I know I've probably explained it really badly but does anyone have any ideas? She's going for a full service soon and he said he'd look into it then but am curious.

I'll try to replicate the issue this weekend, had planned to try it sooner but actually forgot about it.

Thanks for any tid bits of info that may shine a light on the problem. I want to be fully confident and sort any issues before I bring her over the border to the german motorways for a proper top speed test.

gctest50

Problem: Accelerating in 4th gear near peak revs (at 11k rpm, 13k rpm redline).

What speed is it doing @11,000 in 4th ?

Why i ask :

Tiny chance this may be a "design feature" - for noise/pollution laws it may be tested in 4th @ around 11,000

Easy enough make the electronics lean out the fuel / change the timing a bit

EG:

some have a 186mph restriction in 6th gear

https://www.google.ie/#q=186+mph+sixth+gear+speed+restrictor

BKtje

Ah good question. To be honest I'm not sure what I was doing. Just joined the motorway but was overtaking others who had joined so possibly 100kph or maybe a little more. Will try it again this weekend or next week and will try to see and memorise all aspects.

Something I hadn't considered though I'd be surprised if it was that, it's a fairly quiet bike in general with stock parts.

KTRIC

Without seeing it I'd say you were hitting the Rev limiter or the back wheel was spinning or kicking out.

BKtje

When I finally get a chance to head out to try to recreate the issue I'll keep an eye on the rev counter to see if it hits a limit.

I'd be quite surprised if it was the back wheel spinning or kicking out as the bikes maximum torque is at around 10,000 rpm in 5th gear and I've never felt it in 5th but something else to consider. I imagine if that was the problem and I increased the weight on the rear wheel it would no longer occur?

Cheers for the replies

CJhaughey

It would want to be making serious HP to spin the wheel in 4th, Maybe a NW200 spec bike might but they are 200+bhp.
OP needs to try it in third to see if it does the same thing.

BKtje

Considering there is a total of 40hp available I doubt it's that so

Will try it in 3rd as well, cheers.

Fox Mulder

gctest50 wrote: »

Problem: Accelerating in 4th gear near peak revs (at 11k rpm, 13k rpm redline).

What speed is it doing @11,000 in 4th ?

Why i ask :

Tiny chance this may be a "design feature" - for noise/pollution laws it may be tested in 4th @ around 11,000

Easy enough make the electronics lean out the fuel / change the timing a bit

There is a common "defeat strategy" a lot of manufactures use to pass the EC CH.9 noise test. When the bike drives though the test area the rider is supposed to accelerate at wide open throttle at which point sound levels are recorded. Often the ECU is programmed to enter a special noise test mode when a precise rpm is held followed by the throttle being very aggressively opened(ie. something that would never happen in the real world). Usually the ignition is retarded to reduce power. Most of the noise at this point is just induction noise as your throttle bodies butterfly valves are wide open. This test is carried out in second and third gear so it wont have anything to do with your situation.

gctest50

The OP is apparently in

Location: Fribourg, Switzerland

- land of restricted engines - you'd even have 11hp sized utility engines only kicking out 6 or 7

BKtje

First I've heard that Switzerland is the land of restricted engines considering the amount of Porsches, Ferraris and Mazzeratis knocking about pumping out their sweet sweet sounds. Unless you mean restricted in the sense of keeping engine power down to fit in a different licence category then I can assure you I bought it new and unrestricted.

Why they'd restrict 4th gear only on a relatively small bike would also be a head scratcher. Anyway will confirm just to be sure. Thanks for the reply.

gctest50

They probably got sense - as an example i've seen something before like the attached photo with "CH" stamped on it

CJhaughey

A limited slide opening will affect the overall ability of the engine to rev, not just in 4th but every single gear.
OP can you fit a camera to the bike or yourself to show what the dials are doing?
If its safe to do so it would make diagnosis easier.

BKtje

No camera as yet, won't have one till June but if the problem persists till then then I'll take a video. I've gone to, or quite close, the red line in 5th so I guess it isn't that?

jameshayes

Did you try the usuals? Inspect the chain and sprockets - correct tension on the chain and all the teeth on the sprockets are ok?

BKtje

Yeah I did, one of the few things I can do. Checked all that when I gave it a good clean recently.

Got to try 11k+ revs in 3rd gear there today and had no issues so only 4th left to try.

BKtje

Tried to recreate the problem this evening without an luck. Guess I'll just forget about it.

Thanks all for the suggestions.