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xr650rkyle

2001 650r Valves question

12 posts in this topic

Why are my valves always getting tighter?

I adjust them and then after 3 desert rides they are tight again.

What is failing ??

Valves? seats? Head?

Lwt me know what you think....Is it a common problem?

Thanks :lol:

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according to the factory manual valves need to be adjusted every 600 miles (interval). now a few questions:

1. what milage do you cover (approximately) over 3 desert rides?

2. what specific valve(s) are getting tight? intake/exaust, LH/RH...the reason for the this question is because there is one valve in particular that the auto decompressor is tied too.

3. to what tolerences are you adjusting the valves? .006 int, .008 exh...

4. I'm sure you are setting to TDC but are you checking the auto decompressor to make sure it is not engaged?

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Well as the valves and seats wear the clearance gets smaller. The only good news here is is it were rocker/cam wear then the clearnce would be getting bigger. My first guess is valves and the second is seats. As things go bad the rate of change will get faster and faster. The power loss from leaking valves is slow. It's hard to notice the slight reduction from ride to ride.

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Thanks fo the answers, I think the valves are going into the valve seats..

Probably need a complete valve job

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How many miles do you think are on your bike and what kind of riding do you do.

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The valves are probably "cupping" ( sometimes referred to as "tuliping"). As mentioned, the valves and seats wear and the valve heads actually become thin at the edges, the valve travels further into the seat and the clearance diminishes. This process can be aggravated by excessive engine heat, possibly from lack of sufficient coolant, high ambient temps, lean jetting or a combination of factors. If you are adjusting frequently with few miles/hours between, I would consider overhauling the head with new valves, guides and seals. If the valve(s) become heat weakened too much, a valve head can snap off with disasterous results.

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From past experience (1975-present)normal is:intakes get tight,exhaust get loose.Will usually hear exhaust "ticking",indicating valves (in-exh)need attention....also did ya know they are to be set COLD?

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In my experience, good air filtration is the best thing you can do to keep your intake valves alive. One big reason intakes tend to go tight is tiny bits of dirt imbeding themselves into the valve and valve seat faces. The XR650R's airbox sealing isn't especially good. Do what you can to keep the air filter in excellent condition and sealed within the airbox.

My intakes are usually .001" tight every 6-800 miles. My exhausts don't move much. I HAVE found a light dusting in my airbox before. I'd guess when the intakes are going a few thousands tight every 600 miles you should start planning on a valve job soon. It they ever go down to nearly zero clearance in 600 miles then the end is upon you. Check them frequently if you continue to ride until the valves are redone.

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