[Sarath Sivadas]

Hi, hope everyone doing good and safe. I am writing this to know much more about valve guide issues. Actually my bike has valve guide issue which is discovered by a mechanic while heard the sound. I just wanted to know what all are those effects which occur due to bad valve guides. I have some kind of vibrations after crossing 6 to 6.5 k rpm, buzzy noises coming from the head part when bike getting heated enough. I have done shim clearance work, replaced tensioner and timing chain. So these vibrations I mentioned above are because of bad valve guide or any other? Share your thoughts on this guys.

 

[DannoXYZ]

Hmmm, not sure you can conclude valve-guides have excessive clearance without removing valves from head and measuring guides.

Worn and loose valve-guides would cause sealing issues at all RPMs, not just at higher revs.

Have you done compression test?
Measured cam-chain wear and stretch amount?
Measured chain slipper wear?
Measured cam-timing?
Checked every single nut & bolt on and near engine and verified they are properly torqued to factory specs?

 

[Sarath Sivadas]

I think everything i have done. As you told buzzy sound is there in all rpm's, whether it is low or high. But I am talking about vibration from handle bar, seats, and foot pegs, only when crossing 6k rpm. If am continuously cruising on 110kmh - 115kmh i didn't faced these vibrations. It's coming up when revving the engine when we need sudden pick up. I think you got my point.. And it's a 2015 version CBR250r, I don't know whether there is any difference in refinement on various year models.

 

[Tamir]

I am writing this to know much more about valve guide issues. Actually my bike has valve guide issue which is discovered by a mechanic while heard the sound.

I like to give credit to professional mechanics.
I do not know how he came to the conclusion, because the valve springs is very strong and I think it is hard to feel free play when the valve is tense with that springs. But for this we go to professional mechanic, who sometimes just listens to the problem to give an accurate diagnosis.
Anyway I found you a nice video on YouTube (under the topic "motorcycle valve guide"):