It's been many years since I messed with small engines. In fact, the last year for me was 1982 when I sold my 1981 Suzuki 750L motorcycle.

To compound matters and as a retired Chrysler Driveability Technician focused primarily on state-of-the-art electronics, fuel injection, and fuel management systems the last year I had to really focus on Carbureted engines was back in 1986.

So, while I may be a Chrysler genius, I am a bit of an ATV idiot [img]i/expressions/face-icon-small-smile.gif[/img] I have absolutely no doubt there are a number of young kids out there who know way more about this stuff than I do.

I purchased a 2006 350 Bruin and being a bit under-educated at the time, a 2006 400 Kodiak (instead of the much better 450). Both machines were making a noise; the Bruin a loud ticking sound and the Kodiak a lower knocking sound. I have finally come to accept that the Bruin sound is a normal sound for that motor. However, I'm still seeking feedback and guidance on the Kodiak sound.

The Kodiak makes a sound very similar to what someone rolling their knuckles around inside of a cast iron or aluminum box might make; a kind of low, hollow sound. It does it on acceleration only and the harder the acceleration, the louder the sound.

I've tried rejetting, I've tried 100 octane fuel, I've checked the valve adjustment, and I've replaced the engine oil and filter using a Yamaha brand filter and Yamaha brand 20w40 engine oil. I live in Florida and the average temp is in the 90's. Nothing has changed anything. However, I am now starting to wonder if the 20w40 is a bit too much? The machine only has a little over 200 miles on it and this was its first oil change from the factory oil. So, I'm thinking maybe I might have gone too heavy.

I can hear this same sound in the Bruin (in addition to the obnoxious ticking sound the Bruin makes), but not to the same degree. In fact, it's kind of hard to get the sound to come on in the Bruin. And, the Bruin also has that same Yamaha 20w40 engine oil in it but, maybe the Bruin being an air-cooled engine, runs a bit hotter than the water-cooled Kodiak?

The sound may prove to be a normal engine sound for the 400 Kodiak, but I would like to know that for sure so that I can relax about it - to be able to identify the sound. I was concerned about detonation a bit, but with the 100 octane fuel and no change in the sound, it is highly unlikely detonation.

So, anyone have any thoughts about all this? Any feedback at all will be most appreciated [img]i/expressions/face-icon-small-smile.gif[/img]

Vince

 

bruin could be valve lash the other is probly rod or cam chain slapp

 

You would be the first to report an engine failure in those quads.....you have nothing to worry about....my 450 is noisy as well

 

no strange sounds coming from my bruin....

 

Thank you all for the feedback. I'm a bit wore out this morning from my home and yard activities yesterday, trying to prepare for a both my birthday and Father's Day on Sunday. However, at some point today I am going to drain the engine oil out of the Kodiak and try the 10w30 in it. I will let you all know if that changes anything.

Vince