Flat spot in the rev range...

[zed9]

I’m leery of air filters that don’t get dirty.

[3alfa3]

Originally Posted by zed9

I’m leery of air filters that don’t get dirty.

Me too after what i saw today (throttle bodies), only OEM from now on. Had good experience with Hiflo on my 2 previous Z750. But, different bikes, different filters, different filter position.....

Z900 is good in regard to insect, not one in 51000km on air filters, but, dust needs some oil on filter apparently even, on paper filter, and OEM filter is slightly oiled.....

[zed9]

Originally Posted by 3alfa3

Me too after what i saw today (throttle bodies), only OEM from now on. Had good experience with Hiflo on my 2 previous Z750. But, different bikes, different filters, different filter position.....

Z900 is good in regard to insect, not one in 51000km on air filters, but, dust needs some oil on filter apparently even, on paper filter, and OEM filter is slightly oiled.....

👍

[3alfa3]

Originally Posted by 3alfa3

UPDATE:

51.000km, official Kawasaki service with excellent reputation for several decades.....
New spark plugs, new air filter, throttle body taken out and cleaned thoroughly and synchronized after reassembly (it was dirty, seen it with my own eyes, deposits ("sludge") everywhere, idle speed was 500rpm higher after cleaning - i had to correct idle speed twice in last 51.000km - it got to low twice so i bumped it up to 1100).....

I replaced air filter at 28000 km, it was dirty, but not much. This Hiflo air filter after 23000 km was clean almost as new. It is dry from the factory, OEM filter is oiled (very lightly, but oiled) and filters more efficiently, that's why throttle body was dirty. Not worth the savings given OEM filter is good for roughly 25.000kms.

Did not solved the Problem entirely, it is less pronounced, but still there.


Still, one thing that confuses me: 1st gear is smooth as it should be, but 2nd is not good between 2000-3000 rpm (god for 1900-2000rpms then bad in between 2000-3000 and good above that), so is the 3rd, 4th but much less pronounced than second gear.

Update2:
After 100km ride, no more flat spot, to be more precise, over 90% of flat spot is now gone, probably fuel used in 100km ride finished cleaning thrrottle bodies. Its a diferent bike now 😊

[RWH_900]

Originally Posted by 3alfa3

Update2:
After 100km ride, no more flat spot, to be more precise, over 90% of flat spot is now gone, probably fuel used in 100km ride finished cleaning thrrottle bodies. Its a diferent bike now 😊

Took my bike in to my dealer, who says there's no flat spot. I'm convinced I'm not imagining it, but I now think perhaps I'm being a little paranoid and it's not as bad as I think.

But just to clarify...

We've settled on cleaning the throttle body as a viable solution?

[3alfa3]

New spark plugs, air filter and cleaned throttle body made my Z900 to ride almost as when was new. Flat spot i had (it was bad, but only in the range 2000-3000rpm) disappeared almost completely.

[RWH_900]

Good to know... Cheers, I really appreciate all your advice! 

[3alfa3]

Update 3:

flat spot is still there today. Dont know why there was a day without it (or almost without it). Same outside temperature, same humidity.....
But, it happens only when riding on flat ground and downhills (engine "not loaded"), tried in 2nd gear today uphill for few secends and did not detect flat spot.

Dont know, some sensor out of tolerance, or valves out of tolerance, but, that was not present before (now at 51000 km, problem occurred roughly before 10-15 thousand kms)

[RWH_900]

Originally Posted by 3alfa3

Update 3:

Dont know, some sensor out of tolerance, or valves out of tolerance, but, that was not present before (now at 51000 km, problem occurred roughly before 10-15 thousand kms)

Mmm, sensor eh? Well, I don't know if it relevant, but...

I recently had an amber check engine light come up on the dash. It was only present for a day before it went on it's own and it hasn't returned. Dealer checked the error log and apparently it was an O2 sensor.

Warning light has not returned but the bike is starting to feel really off, noticed it first time today. Coming off the throttle, the bike sounds rough and I'm getting nasty vibrations through the right foot peg.

All this bs is starting to really wind me up and I don't know what to do for the best.