Intake valves, XR650R


7 replies to this topic
  • iestrada

Posted September 18, 2006 - 08:41 PM

#1

I was checking the valve clearance as part of routine maintenance. Intake LH, I could not fit the gauge (.15mm) so i loosen it a little, set the clearance a thighten again. Now the RH intake, same deal but this time i loosen the adjusting screw all the way up and still can´t fit the gauge. I did the procedure 5 times just to make sure i was setting everything (TDC, gap, etc) ok.

Do you guys think the valve seat is worn out?

That would explain the explosions when I deccelerate letting go the throttle, and the tricky start when hot...

  • snaggleXR650

Posted September 19, 2006 - 06:05 AM

#2

Something is obviously wrong. You sound like you know how to do it all, but that just doesn't sound right at all. Tip; when you are at TDC, the rocker arms, intake AND exhaust, should both wiggle up/down some as they aren't on the cam. If you are at TDC on the wrong stroke, the rocker arms won't have any wiggle at all...

I would go back in, and try it again, if you come up with the same readings, take your bike to the shop. Good luck.

  • Old_Man_Time

Posted September 19, 2006 - 07:24 AM

#3

I was checking the valve clearance as part of routine maintenance. Intake LH, I could not fit the gauge (.15mm) so i loosen it a little, set the clearance a thighten again. Now the RH intake, same deal but this time i loosen the adjusting screw all the way up and still can´t fit the gauge. I did the procedure 5 times just to make sure i was setting everything (TDC, gap, etc) ok.

Do you guys think the valve seat is worn out?

That would explain the explosions when I deccelerate letting go the throttle, and the tricky start when hot...


You are either on the wrong stroke of the motor which means the cam lobe is in the wrong position or you have let the motor turn back wards as you were lining up top dead center on the compression stroke and the auto decompression engaged. Either one of these things will produce the problem you have.

This happens most often to the novice XR650R tuner because he lets the motor slip back and the decompresser engages. I had this happen to me several times when I first started tuning mine. Do you have the shop manual?

  • iestrada

Posted September 19, 2006 - 04:05 PM

#4

Yep, I have the shop manual.
I always remove the spark plug to check tht the piston is all the way up, and I have the hotcams stage 2, so no auto decomp.

I`ll do it again, just to be sure

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  • Old_Man_Time

Posted September 19, 2006 - 05:46 PM

#5

As your turning the motor over watch the intake valves. When both intake valves open together then keep turning till you hit top dead center. The way you have the valve adjusted now it should be way lose when you are on the right stroke. It does make a difference which direction your turning the motor when lining things up. So check your manual closely on direction of rotation. :thumbsup:

  • TEDDERTALKCRF450

Posted September 19, 2006 - 07:03 PM

#6

When All Else Fails Read The Service Book Ha. Ha .

  • iestrada

Posted September 24, 2006 - 01:28 PM

#7

OMT, I aklways remove the stator cover, i found it easier to turn the engine from the crankshaft nut, and there is an arrow indicatig the engine rotation.

I decided to check the head, so I took the bike to the shop, One of the intake valves was seriously worn, I was lucky the valve seat on the head was not damaged.

Valves, seals, gaskets and a ring kit (it is already disassembbled so i figure it it was worth it to refresh the engine) are already ordered. Can´t wait to ride with the new valves, I guess it will felt more powerful !!

  • Old_Man_Time

Posted September 24, 2006 - 04:10 PM

#8

Sorry to hear that. Something had to be wrong. I hoped it was your procedure but you sound very competent. Well at least you found it before it dropped through your piston.





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