2012 kx250f engine noise

[Crhenn23]

Hey guys, I traded my used 2017 ttr230 for a nice used 2012 kx250f. I stripped the kx250f down to the frame and rebuilt it. Took top end off and the piston and cylinder were in great shape. There is no play in the crank or connecting rod. I adjusted the cam chain and valves. It starts first kick and idles perfect. I took it out on the trail for 2 hours and it ran like a champ. 51.7 hours on the bike as it sits now. Here is a video of my bike idling on the stand.

I have never owned a Kawasaki, and was scared about the loud engine noise. Watched many YouTube videos and noticed the 2011-2016 make the same engine noise even when brand new. Here is another video of a brand new bike with 1.7 hours on it sounding almost the same. 

Can you guys confirm that this loud engine noise is just a kawasaki thing for my peace of mind haha.

[FaceDeAce]

Yes, generally.

 

[numroe]

On 11/14/2018 at 2:37 PM, Crhenn23 said:

the loud engine noise

What viscosity oil is in the motor? I'm thinking you could try a thicker oil.

How much cam valve clearance does it have?

[Crhenn23]

What viscosity oil is in the motor? I'm thinking you could try a thicker oil.
How much cam valve clearance does it have?

Synthetic 10w-40, exhaust valves .22mm and intake valves .15mm.

[numroe]

In my 2010 motor I've found the cam lobe bucket tapping noise is a lot less with the clearance on the tight side of the tolerance compared to a loose side setup. Power increase noticeable too.

But valve clearance won't change the piston knocking sound which yours has. I just listened to my 2010 and there is no bad knocking sound at idle. Just that normal mild mechanical clashing noise when I get my ear close.

Maybe the stock piston is different in your motor. More bore clearance. Did Kawi switch to a forged piston? I ask because maybe your fuel/air ratio at idle is rich and so your piston isn't fully up to operating temperature. I know from my 300 two stroke that idle fuel ratio (= piston temp and size) makes a big difference to piston slap with forged pistons.

Edited November 25, 2018 by numroe

[firefinch]

On 11/24/2018 at 2:48 PM, numroe said:

In my 2010 motor I've found the cam lobe bucket tapping noise is a lot less with the clearance on the tight side of the tolerance compared to a loose side setup. Power increase noticeable too.

But valve clearance won't change the piston knocking sound which yours has. I just listened to my 2010 and there is no bad knocking sound at idle. Just that normal mild mechanical clashing noise when I get my ear close.

Maybe the stock piston is different in your motor. More bore clearance. Did Kawi switch to a forged piston? I ask because maybe your fuel/air ratio at idle is rich and so your piston isn't fully up to operating temperature. I know from my 300 two stroke that idle fuel ratio (= piston temp and size) makes a big difference to piston slap with forged pistons.

Correct me if I'm wrong, but your 2010 isn't fuel injected.  The 2012 has 2 injectors.  It's a totally different engine as of 2011 (I believe) and maybe the switch from a carb to FI is the reason you aren't hearing anything.

To the OP, I had a '12 250F and it made a similar sound too from the day I took it home from the dealership.  You should be fine.

Edited November 28, 2018 by firefinch

[numroe]

Correct me if I'm wrong, but your 2010 isn't fuel injected.  The 2012 has 2 injectors.  It's a totally different engine as of 2011 (I believe) and maybe the switch from a carb to FI is the reason you aren't hearing anything.
To the OP, I had a '12 250F and it made a similar sound too from the day I took it home from the dealership.  You should be fine.

Yes sure. I guess that variation in the fuel air mix could cause a piston knocking sound.

[LSHD]

My 2011 doesn't have the banging/knocking sound at all, even at 85 hours on same top end. Valves were shimmed once, but really didn't need to be. I just did it for practice.

Personally I am not comfortable with that sound at all, but as I said, mine is a 2011 (single injector FI bike). What fuel are you running?

[Crhenn23]

My 2011 doesn't have the banging/knocking sound at all, even at 85 hours on same top end. Valves were shimmed once, but really didn't need to be. I just did it for practice.
Personally I am not comfortable with that sound at all, but as I said, mine is a 2011 (single injector FI bike). What fuel are you running?

91 octane pump gas. I’m located in Phoenix, so roughly 1000ft elevation. Ya, I know what you mean. It does sound concerning. It runs fine, it’s just loud. I’ll probably rebuild the engine after the season here around April. It has 54 hours on it now. It’s not losing any oil or coolant and it’s not smoking out the exhaust at all. It’s a mystery to me.

[numroe]

15 hours ago, firefinch said:

It's a totally different engine as of 2011 (I believe)

According to MXA articles I read ...  From the first engine in 2006 (all Kawi) until the 2010 a lot of mechanical improvements were made.  Ignoring EFI, the 2011 and 2012 is the same motor mechanically as the 2010.  In 2013 it got a new piston. New transmission parts in 2014.  Another different piston again in 2015. In 2017 the motor got another new piston design, a solid big end rod bearing and lighter weight cams.

[firefinch]

Here is a link to my '12 KXF before I sold it.  It has done this since the day I bought it brand new.  Never had a problem and it pulls harder than my friends 2012 CRF250R.  Bike is stock aside from a DRD spark arrestor.  The sound is more noticeable on video than in person.  Probably has 60-70 hours on the original top end and I haven't had them adjusted.

 

[firefinch]

9 hours ago, numroe said:

According to MXA articles I read ...  From the first engine in 2006 (all Kawi) until the 2010 a lot of mechanical improvements were made.  Ignoring EFI, the 2011 and 2012 is the same motor mechanically as the 2010.  In 2013 it got a new piston. New transmission parts in 2014.  Another different piston again in 2015. In 2017 the motor got another new piston design, a solid big end rod bearing and lighter weight cams.

This description below doesn't sound like the same engine as a 2010. In addition to adding fuel injection (injectors make noise, my Corvette and Dodge V8s tick a lot), the changes were the following for 2011...

"they modified the valve timing, changed the cam profile (by increasing valve lift), strengthened the intake valve spring tension, raised the piston crown shape, raised the compression ratio (13.2:1 to 13.5:1), reduced the cylinder height, increased the crankshaft diameter at the taper mount and changed the crank web shape. "

For 2012

"The crankshaft, connecting rod, ACG stator and rotor have been revised. The crankshaft assembly features a balance factor of nearly 60 percent, which Kawasaki claims is on par with their factory race machines... The material on the crankshaft web and connecting rod has been thickened, and the crankshaft pin has been strengthened. For enhanced long-term durability, the cylinder walls and piston have a nickel-plate coating."

A considerable amount of internals were changed in addition to adding injectors and an ECU. My guess on the sound was always the injectors. I meant that since the 2010 doesn't have injectors, maybe that had something to do with the lack of noise?

Edited November 29, 2018 by firefinch

[Crhenn23]

Here is a link to my '12 KXF before I sold it.  It has done this since the day I bought it brand new.  Never had a problem and it pulls harder than my friends 2012 CRF250R.  Bike is stock aside from a DRD spark arrestor.  The sound is more noticeable on video than in person.  Probably has 60-70 hours on the original top end and I haven't had them adjusted.
 

Thanks for the reply, and the video! I did notice that the sound is more noticeable in my video than in person. I think it’s because I was in an underground parking garage and the acoustics really amplified it on my phone. From what I can tell from finding other fuel injected bikes idling on YouTube, the sound definitely started when the bikes became fuel injected. My friend here in the valley raced and was a mechanic for kawi, and came with me to pick it up. He mentioned his bikes all sounded that way from day one, so we went ahead and got it. I’ve put 4 pretty hard hours on it since that video and it runs perfect. I just thought it was crazy at first, and since it was used I was worried about it blowing up on me.

[numroe]

10 hours ago, firefinch said:

This description below doesn't sound like the same engine as a 2010. In addition to adding fuel injection (injectors make noise, my Corvette and Dodge V8s tick a lot), the changes were the following for 2011...

His noise does not sound like ticking.  More of a piston knock or rattle. Sounds very mechanical.  Like piston slap.

Seems my list of changes are wrong too.  If the changes are like you found, the compression (crown shape) and the valve timing, then for sure that could increasing the knocking sound.

In the 2011 I guess Kawi raised the comp and valve lift to try get back some lost power, because I've ridden a 2011 and it's very docile.  In the 2012 I guess Kawi tried to further balance the crank to compensate for the heavier high comp pistons being used.  Maybe the noise is that simple, just a heavy piston that rocks around more.  Maybe there is an aftermarket piston which is lighter.

In my 2010 I'll stick with the low 13.2 comp when I change it. The last carb fed motor's power is surprisingly strong and I don't notice any bad vibration. Has anyone weighed stock vs aftermarket pistons from Wiseco, CP, etc?

Edited November 30, 2018 by numroe

[firefinch]

On 11/29/2018 at 11:30 PM, numroe said:

His noise does not sound like ticking.  More of a piston knock or rattle. Sounds very mechanical.  Like piston slap.

Seems my list of changes are wrong too.  If the changes are like you found, the compression (crown shape) and the valve timing, then for sure that could increasing the knocking sound.

In the 2011 I guess Kawi raised the comp and valve lift to try get back some lost power, because I've ridden a 2011 and it's very docile.  In the 2012 I guess Kawi tried to further balance the crank to compensate for the heavier high comp pistons being used.  Maybe the noise is that simple, just a heavy piston that rocks around more.  Maybe there is an aftermarket piston which is lighter.

In my 2010 I'll stick with the low 13.2 comp when I change it. The last carb fed motor's power is surprisingly strong and I don't notice any bad vibration. Has anyone weighed stock vs aftermarket pistons from Wiseco, CP, etc?

I had great luck with the stock setup on that bike.  I had it for almost 6 years and never even had the valves adjusted.  Fired up every time right away and pulled hard, especially for a 250F.  I can't speak to everyone, but that bike as as close to bulletproof as a four stroke race bike could get.  I had an '05 Honda before...

[numroe]

12 hours ago, firefinch said:

I had great luck with the stock setup on that bike.

Do you mean the 2010 ?

[firefinch]

5 hours ago, numroe said:

Do you mean the 2010 ?

No, my 2012 I sold a few weeks ago

[Delfin]

Thanks a lot,very usefull all of tpur comments

 

[Blake18274184]

Hey guys Yh my does the same thing but I. Was like to my self it is what it is if it blows up then it blows up