Top end noise on R...


8 replies to this topic
  • Thumpmeister

Posted December 26, 2005 - 02:26 AM

#1

I have a 2000 XR650 R. Last summer I did a top-end on it because it was starting to get loud. Unon tearing apart the engine, I found out I had a loose cam chain, and some pretty bad piston slap, along with some valves that weren't seating right.
Anyway, I went through there and put in new piston/rings/pin etc, I sent the cylinder off to millenium technologies to have it re-plated, I got 4 new valves, and a new cam chain. I re-used the original springs, retainers, rockers, cam, and decompressor.
After I got everything back together, the noise had dropped, but I still have some noise. Whats weird, is that sometimes the noise seems to get louder after the bike is warm, or maybe its just cause I don't hear it when I'm riding. Anyway, it doesn't really go away after the bike is warm.
I was told by a tech that it might be my auto decomp system going out, but he didn't know. The noise sounds like a ticking noise coming from the top end, and it increases/decreases w/ engine speed.
Has anyone had this happen to them before? Anyone have any ideas? Also, can I take the auto decomp system off the stock cam, and will it still run just fine? I don't care about the starting; I use the manual decomp for that anyways. But, will the bike run fine w/ the auto decomp removed, and is it a chore to get that off? Thanks.

  • Xr650rhonda

Posted December 26, 2005 - 03:53 AM

#2

This last spring I would hear the auto decompresser " Click" every now and again, it would not always do it, but it would always be at idle. I would start the bike(it has to be cold) let the bike idle and listen with a stethescope and could hear it "click" right in the center of the rocker cover. I always felt it was the oiling plunger under the auto decompresser actuating and lubricating the auto decompresser, and it could have been, there was never any damage when pulling things apart.
There maybe a lot of people here that love the stock cam/auto decompresser set-up, I'm not one of them, and I'm putting in a Hot Cam stage I this Winter. The main thing I don't like about the stock set-up is you have to be very careful adjusting the valves, if you can't hold that flywheel steady at TDC, the auto decompresser engages and your adjustment is off.
Brad.

  • Thumpmeister

Posted December 26, 2005 - 05:08 PM

#3

Yeah, when I first got my bike a few years ago, I made that mistake w/ the valve adjustment.
I would like to do a hotcam stage 1, but I want to keep my Honda reliability. I don't have a lot of money, so I don't want to have to worry about my bike having troubles later on. I would like to get rid of the auto decomp to see if that makes the difference or not, and getting a stage one hotcam would give me the reason. But, like I said, I don't want my reliability to go down if I were to get one of those.
I had the exact same thing your talking about w/ that click you would hear every now and then at idle. I felt that it was the auto decomp kicking in at low idle. Now, either it stopped, or its doing it all the time. When I did the rebuild, I spec'ed all the parts for wear, and checked them as well. I replaced the ones that had wear on them, and re-used everything else.
So, does anyone know if the bike would run just fine w/ out the auto decomp? It really doesn't make any difference to me if I have it or not, because I use the manual one anyways. If anyone has any input, thats helpful. Thanks.

  • Thumpmeister

Posted December 27, 2005 - 07:59 PM

#4

Okay, I took the bike out today to listen to the noise again. It sounds more like a sharp knocking come from the top end. I don't really think it sounds like the auto-decomp, but it is coming from that side of the engine.
Anyone have any advice?
Also, does anyone know if I can run the stock cam w/o the auto decomp as well, w/o hurting anthing?

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  • BELL RACING ENGINES

Posted December 28, 2005 - 10:33 PM

#5

The noise could be comming from the counter balancer gear lash. Check it by placing a wooden dowel rod behind the front motor mount against the case. You will here the noise in this area. I have built some 650s that made this noise some did not. I put new gears in & the noise was still there. hope this helps you out. Greg Bell

  • Old_Man_Time

Posted December 29, 2005 - 12:27 AM

#6

Yeah, when I first got my bike a few years ago, I made that mistake w/ the valve adjustment.
I would like to do a hotcam stage 1, but I want to keep my Honda reliability. I don't have a lot of money, so I don't want to have to worry about my bike having troubles later on. I would like to get rid of the auto decomp to see if that makes the difference or not, and getting a stage one hotcam would give me the reason. But, like I said, I don't want my reliability to go down if I were to get one of those.
I had the exact same thing your talking about w/ that click you would hear every now and then at idle. I felt that it was the auto decomp kicking in at low idle. Now, either it stopped, or its doing it all the time. When I did the rebuild, I spec'ed all the parts for wear, and checked them as well. I replaced the ones that had wear on them, and re-used everything else.
So, does anyone know if the bike would run just fine w/ out the auto decomp? It really doesn't make any difference to me if I have it or not, because I use the manual one anyways. If anyone has any input, thats helpful. Thanks.


I ran the hotcam stage 1 in my 2000 XR650R. It had over 5000 miles on it when I decided I wanted a fresh set of plastic so I traded it in on a new XR650R. Before I traded it in I took the Stage 1 hotcam out and put the stock back in. I then installed the same Stage 1 hotcam in my 2002 XR650R (I purchased it new off the floor in 2004). It has now been almost 2 years and 2000 miles with no problems with reliability whatsoever. This is the second bike the same cam has been on and a total of about 4000 miles on the cam. :applause:

  • Thumpmeister

Posted December 29, 2005 - 12:55 AM

#7

I ran the hotcam stage 1 in my 2000 XR650R. It had over 5000 miles on it when I decided I wanted a fresh set of plastic so I traded it in on a new XR650R. Before I traded it in I took the Stage 1 hotcam out and put the stock back in. I then installed the same Stage 1 hotcam in my 2002 XR650R (I purchased it new off the floor in 2004). It has now been almost 2 years and 2000 miles with no problems with reliability whatsoever. This is the second bike the same cam has been on and a total of about 4000 miles on the cam. :applause:


I'm not worried about reliability on the cam, thats not that big of a deal. What I am worried about is the reliability on the rest of the valve train. I know HRC makes their race cam, but thats expensive, and the stg 1 hotcam is less aggressive then that one anyways.
Would there be that much accelerated wear on the valve train from running the hotcam? Also, am I able to run the stock cam w/o the auto-decomp system as well?

  • Mikie1

Posted December 29, 2005 - 09:31 AM

#8

Not sure about running the stock cam without the decompression. Never heard anyone do that. The Hotcams stage 1 is a very close copy (supposedly identical timing, lift and duration) of the HRC race cam. It won't cause accelerated wear on the rest of the valvetrain. I run the Stage II with OEM rockers, springs and valves, with no issues whatsoever.

  • wr450fyamaha

Posted December 29, 2005 - 10:07 AM

#9

my L's got a lil bit of a tick.....might look into it in another 10k miles.





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