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XR650R Valve clearance question

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Hello,

 

Quick question about valve clearance on my newly purchased '00 XRR. The previous owner uncorked it and put an XR's only competition exhaust on it but kept the stock header. As I was going over the basic maintenance on the bike I noticed the exhaust valves were way out of spec. This is my first bike with auto decompression, so I'm wondering if that has anything to do with it, or if uncorking/changing the exhaust caused the previous owner to alter the exhaust valves but not the intake???? or maybe its indicative of an engine problem that might require looking into.

 

According to the manual I got, the intake should be set at 0.006 ±0.001 inches, and the exhaust should be at 0.008 ±0.001 inches.

My intakes were set at a reasonable 0.005, but both exhaust valves were at 0.015, nearly double where they should be! In my limited experience, valves usually tighten up with use, not loosen up.

 

I'm hoping somebody could shed some light on why they might be set so high. I took multiple measurements multiple times to ensure I was TDC on compression stroke, and tried my best not to let the flywheel rotate backwards. I'm planning on setting the valves to within spec, but thought I would ask in case there is some bike specific reason why they are so far out.

 

Thanks guys,

Mike

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On 1/26/2020 at 10:21 PM, MikesBikes90 said:

Hello,

 

Quick question about valve clearance on my newly purchased '00 XRR. The previous owner uncorked it and put an XR's only competition exhaust on it but kept the stock header. As I was going over the basic maintenance on the bike I noticed the exhaust valves were way out of spec. This is my first bike with auto decompression, so I'm wondering if that has anything to do with it, or if uncorking/changing the exhaust caused the previous owner to alter the exhaust valves but not the intake???? or maybe its indicative of an engine problem that might require looking into.

 

According to the manual I got, the intake should be set at 0.006 ±0.001 inches, and the exhaust should be at 0.008 ±0.001 inches.

My intakes were set at a reasonable 0.005, but both exhaust valves were at 0.015, nearly double where they should be! In my limited experience, valves usually tighten up with use, not loosen up.

 

I'm hoping somebody could shed some light on why they might be set so high. I took multiple measurements multiple times to ensure I was TDC on compression stroke, and tried my best not to let the flywheel rotate backwards. I'm planning on setting the valves to within spec, but thought I would ask in case there is some bike specific reason why they are so far out.

 

Thanks guys,

Mike

There is no XR-R specific reason for overly spaced exhaust valves. I just can tell you from my experience, I had almost the same, bought an 02 XR-R, I noticed heavy clicking sounds when i kicked it at home, and measured correct clearances at first. When I dismounted the deco lever, clearances about three times maximum showed up. So the pre-owner messed something up big time. Your problem doesn't sound like its manual or auto deco related, anyways. Just wanted to say, I'd suspect the pre-owner not knowing exactly what he did in terms of paying respect to the deco system when setting valve clearance and/or using thumb rules for the valves. I wouldn't worry too much, sometimes it's unbelievable what pre-owners were (un)capable of doing to your vehicle. Did it tick/click beforehand btw? It should have been audible clearly at double the spec.

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If the previous owner installed an aftermarket cam,,like a HOTCAM ... the clearances would likely be larger,,are you SURE it`s the OE cam in there????

 

B

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Hey,

Thanks for the replies! As far as the previous owner mods, I have no idea what he did to it. A buddy of his was selling it because the owner moved to Nebraska, so I never got a chance to talk to him, but I got it for a good price haha! 

Before I readjusted the valves, I could hear them ticking and the bike used to hunt a bit on idle. As soon as I put the valves back to spec the hunting went away and the exhaust smoothed out considerably. 

I don't necessarily know how to tell if it still has the original cam in it without pulling off the top end... I might wait on that one for a while unless the bike starts acting up again. I am going to re-check the valves here in the next week or so, as it will have been almost a month and if there is any significant change in valve clearance over a month of riding I will look more into it.

Thanks again for the help guys,

Mike

IMG_2820.JPG

Edited by MikesBikes90

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The issue with not knowing which cam is in there......

If it`s a HOTCAM...  you have to run looser tolerances or you burn up the cam and rockers in short order..

If it`s a meagcycle or Webcam you`ll run into the same issues..

No aftermarket cam runs OE specs for valve clearances..

If it`s a HOTCAM it will NOT have auto decomp on the cam...so you can rule that out easily..

Megacam and Webcam use the OE decomp assembly....so just because it has decomp on the cam does not mean it`s a Honda OE cam in there..

 

If.....for sure,,,it has decomp on the cam... it is quite likely it`s the OE cam in there...you can assume then that OE tolerances are good..

But...  you know what ASSUME  translate into don`t you...lol

better to know for sure ...it tends to be the cheaper route,,eventually..

 

B

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16 hours ago, kwekuPaul said:

To my knowledge the Hotcam stage 1 runs the standard valve clearances ??? on XRR

Are you sure on that.....??????????  if not then it`ll be an issue..

B

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3 hours ago, brianhare said:

Are you sure on that.....??????????  if not then it`ll be an issue..

B

I will double check. I still have the spec sheet that came with the Hotcam stage 1. will post it up.

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