Sound coming from valves

[posada85]

So I did a post last year asking if anyone knew where a sound was coming from Previous post. Everybody saying that (naggy tone) "the ST is a nosy bike", "the chain tensioner had to be changed" etc. It was not that at all.

My bike is a 2013 with 67,000 km. and the problem was the following and I would like to know if anybody else has had this problem.

The Decompression CAM pin was making an excessive force on the Valve Lifter and it got carved.

this is the valve carved, you can see the others smooth.

The pin´s point should be like a ball bearing, perfectly smooth and rounded, and this is what it looked like.


The other end of the camshaft had a weird color shift to a bronze color


So my questions are: Has anyone had to replace this part in a 67.000 S10? can this be a problem from Yamaha? because in any forum I have found this problem. Can I have a recall for this kind of failure?

Thanks.

 

[StefanOnHisS10]

Wow, haven’t heard that before. I see more “wear” than I would expect with that mileage. Gut feeling says wrong lubrication. No proof off course.

 

[WJBertrand]

Looks like the cam pin was improperly machined or the material was substandard and it wore that way.


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[~TABASCO~]

The color on the end of the cam shaft all "looks" normal (to me). I would check the centrifugal force springs. Make sure that all snaps back properly. I have had one spring stick before and when talking to high up Yamaha techs they said they have seen the springs break before in other models. I dont know if that pin is replaceable? If it is, I would probably replace the pin and the bucket and head down the road... (OF COURSE this is only judging by the photos and the info provided)

On your second picture of the cam, that looks like excessive wear on that right side. I don't recall ever seeing it polished like that. Your intake cam looks normal and correct. The wear on the exhaust leads me to think about how that could happen. I wonder if that could possibly happen if someone over torqued those cam caps. How does the rest of the exhaust cam look? What about wear on the inside of the exhaust cam caps? That right side looks worn to me, it being worn might have something to do with that pin being out of tolerance and "possibly" too close to the bucket....... (Im just thinking out loud and spit-balling..... Just an idea...... Ive seen a lot of these motors over 10-11 years)


By the way, looks like the whole motor has been pulled out of the bike? Thats a 'fun' job I've done before... LOL

 

[Jlq1969]

If the spring were to break, it would not depress, the spring keeps the pin out and the counterweights (by inertia) and their offset cam insert the pin inwards. If the pin were “locked”, the force of the counterweight will always be greater than that of the spring, therefore it would remain locked “inside”. it is impossible to assemble it wrong, the decompressor shaft would not fit….most likely it is that the decompressor shaft cam “is not” or is worn

 

[Fordf350]

Thanks for the education, I continue to learn more and more about this bike I love. Many smart people on this site.

 

[Jlq1969]

My ST has a rattle sound

Hello guys, I´ve been looking for this in other forums and videos with no luck. I've been having this problem with my ST it has a metallic rattle sound and has a higher pitch as you can hear in the video when I'm going down hill with no throttle, or when I brake with the engine. My ST started...

yamahasupertenere.com

I no longer see as before, but at least my ears are not failing me yet

 

[Jlq1969]

if there is no one to hold the bolt, this by inertia of the rotation of the cam, it would tend to be always outside…..I don't know if it would be ejected….apparently it didn't come out