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Discussion Starter #1
Hi to all,

I would like to ask what the recommended valve clearances for FMX 650 are. My net research gave me two outcomes: (1) 0.10 (intake) and 0.12 (exhaust) +-0.02 (like in XR650L, Dominator etc) , and (2) 0.10 +-0.02 for both intake and exhaust valves (see here https://www.bike-parts-honda.com/ca...-sheets/FMX650-honda-information-sheets/page1). I feel that the second outcome is a bit more reliable but a week ago when I adjusted valves (0.10 for both), the bike lost a bit of its torque at low rpm (but run significantly quieter). I readjusted however to 0.10 intake and 0.11 exhaust and bike regained torgue at low rpm. Anyway I am wondering what the recommended valve clearances are and if I should go for 0.12 (exhaust).

Thanks in advance.
 

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I adjust both the inlet and exhaust to 0.12mm i found it stalled a lot more when i adjusted the inlet to 0.10mm. better to be a little slack than a little tight. the correct adjustment is 0.12 for the exhaust and 0.10 for the inlet you should never go tighter on either. theres no + or - in the manual
 
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Discussion Starter #3
Dear 650 Fred,
thanks a lot for your comment. I'll follow your suggestion and adjust both to 0.12mm to see how it runs. My only concern is the noise of tapped valves, especially when motor warms up. I am commuting with it everyday (around 20 km per day) in traffic (Athens!) and the motor goes really warm and starts to run noisy... This is my first air-cooled bike and I am not getting familiar (even after one year of owning it) with those noisy motors...
 

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At those settings it wont be tappet noise you can hear, when the engine gets hot the tappets usually get quieter due to the gaps getting smaller with heat expansion that's why they should not be tighter than spec
 

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Discussion Starter #5
Hi 650 Fred,

I finally adjusted the valves to 0.12mm both. The machine runs wonderful but after getting hot the top-end noise coming out is worrying me. The noise is noticeable only at idle. Please take a look (exactly take a hear!) to the attached video to see what I am talking about. Sorry for the video being dark, but had no lights there.



After this noise, I am considering to try the inlet valve at 0.10mm

Giorgos


 

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Just sounds normal to me wait and see what others think
 

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Discussion Starter #7
Finally I decided to go to 0.10 inlet and 0.12 exhaust (actually a very tight 0.13mm - 0.005 inch). I feel that this setting gets the best out of this motor.

Now, however I am facing a different issue (and I think it is a bit serious) with my FMX and regards its smoking when the motor warms really up. I'll open a new thread on this in order to ask possible causes and possible fix options.
 
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