Valve guide material?

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Petri

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My 2005 Euro FJR is having some exhaust valves replaced etc.

Now, the machine shop doing the work is suggesting not using the stock Yamaha replacement valve guides, but instead some after-market phosphorous bronze guides. They are quite a lot cheaper and easier to install.

The machine shop specializes in cylinder head work - that's all they do. So I guess they should know what they are suggesting.

But after googling (better safe than sorry), I became a little concerned, especially after reading this warning.

Thoughts? Experience? What are the FJR factory-installed valve guides made of?

I read elsewhere in this forum that Gen I FJRs apparently tend to wear out the exhaust valve stems and guides. The machine shop owner claimed it's been almost a "known issue" with a number of Yamahas through the years.

I wonder if a properly chosen (different) replacement valve guides could mitigate that...?

 
The FJR (Gen 1) valve guide problem was caused by valve guide seals that were too tight on some of those early FJR's. The guide material was not the problem.

 
I read elsewhere in this forum that Gen I FJRs apparently tend to wear out the exhaust valve stems and guides. The machine shop owner claimed it's been almost a "known issue" with a number of Yamahas through the years.
I wonder if a properly chosen (different) replacement valve guides could mitigate that...?
That was well-litigated here as well as the previous forum many here were at. That's why it's pinned as the very first issue on this forum. Short answer is that there was much speculation (including the bronze/other material issue including destructive testing by one of the forum admins), but I believe consensus in the end is that was valve guide seals. Not quite enough oil to lubricate and that then caused excessive valve guide wear.

It also tended to be less of a problem IIRC in later Gen bikes (i.e. 2005 and 2005.5)

I wouldn't imagine different guides would hurt...or necessarily help. I'd read the thread in its entirety and then make sure whatever valve guide seals you choose are up to the task.

 
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Tell to the machine shop to install new oem valves and valve guides and the newest valve guide seals and your head will be fine!
smile.png


 
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Is it a motorcycle specific machine shop, or a car machine shop doing a motorcycle head? Car biased shops tend to think in car needs. Yamaha spent the money on engineering design and analysis to develop guides that they can trust -- they have no desire to repair a head a second time, or lose customer base over internet reports of failing parts. Admittedly, those OEM guides are pricey -- what are the odds the cheaper ones are of similar quality?

If you do go aftermarket, the write up at https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwj_2_ni-9TUAhWHWCYKHbSWDooQFggxMAE&url=http%3A%2F%2Ffjrforum.com%2Fmisc%2FFJR1300_Cylinder_Head_overhaul.pdf&usg=AFQjCNFfCo1o8DCYqampQZ9m8BxoiY0czw&cad=rjt

is awfully educational.

 
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