XR600 valve clearance question???


9 replies to this topic
  • TEETBOYSDAD

Posted June 22, 2007 - 05:55 PM

#1

I replaced my camshaft and rocker levers, redid the top end, set the valves acording to spec .004 (int) .005 (exh) ran the bike about 100 miles, engine was running fine but I thought I would reset the valves and to no real surprise the settings were a little loose about .008-.010 I figure new parts breaking in,so I reset them to spec .004 and .005 and took the bike for a ride and had a noticeable power loss slower acceleration. So I reset them again and increased the clearance back to .008 and .009 took the bike for a ride again and power is back much quicker acceleration. Has anyone had any experience in this? or have any ideas?. There are no performance mods done to this bkie except for Super trap exhaust, I'm not sure what the stacking is in the silencer I bought the bike with it on.

  • cleonard

Posted June 22, 2007 - 07:08 PM

#2

That sounds strange. I'm not sure about after a rebuild, but in my experience with cars and bikes, the clearance decreases as the parts wear. The valves and valve seats slowly wear and this reduces clearance. Increasing clearance is due to rocker arm or cam wear.

Did you check the clearance when it was totally cold. I only check valve clearance after the bike has cooled for hours. Doing it first thing in the morning is best. Since the aluminum head casting expands more than steel, the valve clearance increases with temperature.

  • TEETBOYSDAD

Posted June 23, 2007 - 10:13 AM

#3

I'll see once in the next 100 miles what the clearance is. I'm under the assumption that installing a new camshaft and rockers with a light coating of assembly grease probably acounts for the seating or wearing in of the rocker assembly. what seems odd to me is that the extra clearance makes it run better.

  • cleonard

Posted June 23, 2007 - 10:49 AM

#4

My understanding is that valve timing is a compromise. The valve timing requirements are different at low and high revs. With extra clearance the timing changes. Particularly, the intake closes sooner. This helps to make a little more torque at low rpms. You lose a little at high revs though. Maybe that is what you experienced.

  • beezerjoe

Posted June 23, 2007 - 02:41 PM

#5

Depending on which cam is installed sometimes the manufactures will specify certain clearances for a particular cam in order to achieve what is to be considered by them proper timing and lift to get optimum performance out of thier cam.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • kellismechanic

Posted July 26, 2007 - 10:25 AM

#6

That sounds strange. I'm not sure about after a rebuild, but in my experience with cars and bikes, the clearance decreases as the parts wear. The valves and valve seats slowly wear and this reduces clearance. Increasing clearance is due to rocker arm or cam wear.

Did you check the clearance when it was totally cold. I only check valve clearance after the bike has cooled for hours. Doing it first thing in the morning is best. Since the aluminum head casting expands more than steel, the valve clearance increases with temperature.


As parts wear, the clearance INCREASES:prof: , as the wear, things get looser, but this still sounds strange. Oh, and if the valve seats wear, you have a big problem, they just don't wear, they will burn or crack, but not just wear out.

  • cleonard

Posted July 26, 2007 - 11:05 AM

#7

As parts wear, the clearance INCREASES:prof: , as the wear, things get looser, but this still sounds strange. Oh, and if the valve seats wear, you have a big problem, they just don't wear, they will burn or crack, but not just wear out.


I guess that has just been my experience. I have never had cam/rocker arm wear. So I have never seen the clearances increasing. I have had a lot of valve and valve seat wear. Yes, that included replacing a few of the valves and valve seats on my 600. As far as I can tell cam and rocker arm wear are symptoms of poor lubrication and I call that abnormal wear. I call normal wear the slow recession of the valve/valve seats. For me it is a very slow processs. I would say around .001 per 3000 to 5000 miles. When my seat fried it jumped massively. On the last ride before the head rebuild, I had to adjust the clearance during the ride, because it went to zero and the engine would no longer run.

I did have the clearances increase once. That happened when my XR500 cam decided to eat the bearing surface on the head. It was the end of that bike.

  • HawkGT

Posted July 26, 2007 - 11:46 AM

#8

As parts wear, the clearance INCREASES:prof: , as the wear, things get looser, but this still sounds strange. Oh, and if the valve seats wear, you have a big problem, they just don't wear, they will burn or crack, but not just wear out.


I'm with cleonard.

The parts that always seem to wear the most for me over time are the valve sealing surfaces--the valve seats and valve faces--especially on intake valves. As these places wear the valve lash clearances DECREASE, not increase. If the valve starts seating deeper into the valve seat the clearance between the top of the valve stem and the rocker will go down.

  • creeky

Posted July 26, 2007 - 12:03 PM

#9

I've had the same experience as cleonard and HawkGT.

  • Kawabuggy

Posted July 27, 2007 - 05:55 AM

#10

+3 on the DECREASING clearances due to valve seat wear





Related Content

Wiki
Want to add a kickstart to your XR650L?  Here's how - last post by clc3251

Want to add a kickstart to your XR650L? Here's how


Articles
  • 0 replies
Reviews

Honda XR650L 2017 by Chris.GVS


Honda XR650L 2017
  • - - - - -
  • 0 reviews
Forums
Photo

ignitech programmable XR650L CDI by brianhare


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  60 replies
Forums
Photo

2015 XR650L Squeaking noise by Crayjay


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 3 replies
Forums
Photo

Fell Off Trailer by usafxr


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  43 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.