new engine noise HELP


3 replies to this topic
  • YZRider3087

Posted July 07, 2008 - 07:39 PM

#1

:thumbsup: i recently took a trip to the dunes on my 08 yz450. i purchased the bike back in april and took the time take the bike through its heat cycles, and give the engine plenty of time to break in before i started riding it like a dirtbike... i was told by the service tech and the dealership that it wasnt all that important to bring the bike in for a first service if i was willing and able to change the oil and filter and tighten the chain and lube everyting up. all that is a very simple task, however i am new to the 4stroke revolution and have always owned 2 strokes, so i asked him about the valves and he told me not to even worry about them till i have at least 50 hours on the bike. and i do now. while i was at the dunes i noticed that engine having to work way harder in the sand than on dirt and i slowly noticed the engine developing a tick mid to upper rpms... in my mind, the bike had always has a high speed tick that ive noticed out of all 4strokes, and i am assuming that the sounds is caused my the cam hitting the valve buckets... correct? and the sound that i am getting out of my bike is in tune with that same tick ive always heard, it just steadily got louder.... does this mean that it is time for a valve adjustment? and is the louder tick caused by the extra space between the cam lobe and valve bucket?..... i could have just been thinking about it too hard, but it seemed like the harder and longer i rode the worse it slowly got, and the bike seemed to loose a little bit of ummppff it the mid to top rpms... would out of wack valve rob the engine of some power as well!?... ANY help trying to understand this would be great!

  • KJ790

Posted July 07, 2008 - 07:47 PM

#2

Valves tighten as they wear, that is the space between your cam and your bucket gets smaller. 50 hours without ever checking the valves is way to much in my opinion. They are supposed to be checked every 10-15 hours. While it is rare for a Yamaha to need any valve adjustment before 50 hours (or even 100 hours in some cases), there are always the few that do require an adjustment before that. This is why they should be checked regularly as regular maintenance. I'd say it wouldn't hurt to check your valves, though I'm not sure if that is your problem. How often do you change your oil? Did you make sure you have the correct amount of oil in your bike?

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  • mkporn

Posted July 08, 2008 - 07:52 AM

#3

Valves tighten as they wear, that is the space between your cam and your bucket gets smaller. 50 hours without ever checking the valves is way to much in my opinion. They are supposed to be checked every 10-15 hours. While it is rare for a Yamaha to need any valve adjustment before 50 hours (or even 100 hours in some cases), there are always the few that do require an adjustment before that. This is why they should be checked regularly as regular maintenance. I'd say it wouldn't hurt to check your valves, though I'm not sure if that is your problem. How often do you change your oil? Did you make sure you have the correct amount of oil in your bike?


All good ideas..... My question is, how is you jetting? Pull the plug and take a gander at it. That ticking that you hear may actually be a little detonation going on if you are lean.

I have seen this seval times at the dunes, you are constantly WOT and if the main is small (like if you were jetted for 2500' and you went to the dunes at sea level) you slowly start burning it down.

As for the valves, most times they tighten up as the valve actually wears into the seat.

Good luck

  • YZRider3087

Posted July 09, 2008 - 09:54 PM

#4

i havent even messed with the factory jetting... and i usually ride around sea level to around 1500'. the bike seems to idle and run just fine and throttle response seems good... but im sure tweaking the jets would make a huge difference! im going to check the plug, and get in there and check the valves as well... i change my oil every other ride and always have to correct amout of oil...





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