Is this thumper near death?


19 replies to this topic
  • fearlu

Posted October 10, 2007 - 01:22 PM

#1

I have a '94 XR600R that is sounding pretty noisy. Sort of a clatter from inside the case it seems. I've been nervous about taking it on long trail rides since it sounds a little ill. My question is, if/when this trusty motor gives it up, what are the most-likely symptoms or signs? Any guesses about the noises?

I haven't taken it to the dealer to ask just yet, so your info is appreciated. Ever kill an XR600?

  • martinfan30

Posted October 10, 2007 - 01:52 PM

#2

I have a '94 XR600R that is sounding pretty noisy. Sort of a clatter from inside the case it seems. I've been nervous about taking it on long trail rides since it sounds a little ill. My question is, if/when this trusty motor gives it up, what are the most-likely symptoms or signs? Any guesses about the noises?

I haven't taken it to the dealer to ask just yet, so your info is appreciated. Ever kill an XR600?


can you pinpoint where it comes from? does it go along with rpms? is it a rattle or a knock?

  • jclaus98

Posted October 10, 2007 - 05:26 PM

#3

martinfan is onto something, if you can pinpoint where it is coming from, that'll make a big difference. If you can hear it while its at an idle and the frequency changes with the engine speed, it may just need the valve tolerances tightened up. Mine started making an aweful ringing noise that changed with the speed of the engine. Checked the valves and both exhaust valves had nearly an 1/16" clearance between the rocker and the valve head. NOT GOOD. The tolerances are suppose to be .006" and .005". If it is a noise that only occurs while your riding it at speed, it could be tranny related, in which case it'll probably need some tranny parts to fix that. But, don't fret, my XR600 is a '93 and all it ever needs is the valves checked a few times a year and a fresh oil change as often as possible and it starts first kick, every time, no problems ever.

  • jetfuel

Posted October 10, 2007 - 08:36 PM

#4

Yes a bit more info would be helpful .. Does it only do it at Idle? can you tell if it comes from the left or right side, top, bottom ect.? the more specific the better... does it change when you pull the clutch in? ...

  • fearlu

Posted October 13, 2007 - 06:50 AM

#5

Thanks for the info guys, I'm going to fire it up this weekend to see if I can get more specific about location/description of the clatter and whether it's RPM-dependent. It may be the valve adjustment mentioned above since my maintenance schedule has included, well, oil every 5 years or so...

  • fearlu

Posted October 13, 2007 - 08:58 AM

#6

Okay, just fired the thing up and roosted the neighborhood. It seems like the clackety noise originates at the base of the heads or near the top of the cases, pretty deep and hard to say for sure, but maybe more on the right side? It does seem to increase with RPM although with an unplugged XR and all the noise that implies, it's hard to say. It makes quite a bit of both low exhaust noise and the clacking I'm concerned about. Any likely scenarios you could reveal? It hasn't been to the dealer for many years so maybe there's something basic it needs. Like valve adjustment? Also, is there a cam-chain adjustment or something I should know about. You can probably tell, I'm no expert mechanic. Your collective experience is appreciated!

  • jclaus98

Posted October 13, 2007 - 06:13 PM

#7

If the noise raises and falls with the RPM, even at an idle, it is definitely valvetrain, or piston/cylinder related. That's good news, because as long as its had the oil changed when it was ridden, time is less of an issue. Meaning that, it won't matter if the guy that had it before you only changed the oil every five years if he only got on the thing once a year. If he rode it twice a month and only changed the oil every five years, thats a completely different story. It sounds like it definitely needs the valves checked and like you said, a cam chain adjustment. The XR's have spring loaded cam chain tensioners that are suppose to keep the slack out of the chain, but its possible that is worn down. I'd say if you aren't comfortable checking the valves, take it to a mechanic you trust, not the dealership, they'll undoubtedly listen to it and tell you it needs a complete rebuild. Checking the valves is very easy if you've got a manual and I'd say invest in one of those. The xr is an extremely easy bike to maintain yourself, but you'll need some guidance. I'd say your valves are the first thing you should check and go from there, you'll probably notice a huge change after that is done. And trust me, no matter how bad a shape it is in, it is worth repairing, because if it is fixed right and properly maintained, that thing will outlast you. Good luck.

  • scalejockey

Posted October 14, 2007 - 06:11 AM

#8

noise...loose cam chain,"schaka schaka schaka" at idle. Bad rod.."clunk clunk"all the time. valves.."tick tick tick" too loose.Bad cam\rockers "rattle rattle rattle". The wife when she finds out how it will cost to fix it ......uh never mind..

  • fearlu

Posted October 14, 2007 - 07:10 AM

#9

Okay, valve adjustment it is. I happen to have the Clymer manual for XL/XR 500-650 singles, years 1979-1997, so I should be good. Sounds like the right-hand exhaust valve adjustment is critical due to the decompression system built into the camshaft?

In the manual it says that RFVC engines have no provision for cam-chain tensioning adjustment since it is maintained automatically. So I'm going with valve clearance assessment for now.

It may also be piston-slap? Is oil consumption the indicator for this? I think I'm burning more oil than I used to.

After a vigorous 100-miler to Carnegie yesterday, some pretty demanding hill-climbs there and a quick buzz with the supermoto guys on Morgan Territory Road I'm reminded that this thing really provides a LOT of fun/flexibility. Maybe I don't have to shell out 8-grand for a new bike afterall? (Now that's when the wife noise will be louder than the XR!)

I'm pleased to hear that the motor will outlast me...

  • fearlu

Posted October 14, 2007 - 09:45 AM

#10

Nevermind, couldn't even find the TDC indicator that the manual pictured...

Who's the best Bay Area Honda mechanic?

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  • XHMXR

Posted October 14, 2007 - 09:54 PM

#11

Nevermind, couldn't even find the TDC indicator that the manual pictured...

Who's the best Bay Area Honda mechanic?


In any 720 degree rotation of the engine, (One complete cycle) the piston velocity changes quite a bit. Particularly on a single cylinder engine. One research engine I was involved with at 1200 RPM, on the compression stroke the rotational velocity actually got (momentarily) down to about 800RPM equivalent velocity. That why large heavy flywheels are used to dampen out those variations. On a motorcycle where you are limited to smaller flywheels you typically will have a problem with clutch wear. The ears on the clutch discs that fit into the clutch basket become worn as well as the basket slots. When the engine Rpm varies it jerks the clutch ears back and forth in the basket and causes quite a racket in the lower end. As one poster suggested pull the clutch in and see if the noise varies at all. If the clutch is worn as I suspect it is, the noise will change a slight amount. To remedy this, change out the clutch discs or inspect them and see if they have a smooth surface or are notched. Check out the clutch basket (the mechanism that the discs slide into ) for notches where the load bearing surfaces of the discs fit. Sorry this is so drawn out but I dont know a better way to explain it.:crazy:

  • fearlu

Posted October 15, 2007 - 06:24 AM

#12

Thanks, I'll check that.

  • jetfuel

Posted October 15, 2007 - 07:21 AM

#13

In any 720 degree rotation of the engine, (One complete cycle) the piston velocity changes quite a bit. Particularly on a single cylinder engine. One research engine I was involved with at 1200 RPM, on the compression stroke the rotational velocity actually got (momentarily) down to about 800RPM equivalent velocity. That why large heavy flywheels are used to dampen out those variations. On a motorcycle where you are limited to smaller flywheels you typically will have a problem with clutch wear. The ears on the clutch discs that fit into the clutch basket become worn as well as the basket slots. When the engine Rpm varies it jerks the clutch ears back and forth in the basket and causes quite a racket in the lower end. As one poster suggested pull the clutch in and see if the noise varies at all. If the clutch is worn as I suspect it is, the noise will change a slight amount. To remedy this, change out the clutch discs or inspect them and see if they have a smooth surface or are notched. Check out the clutch basket (the mechanism that the discs slide into ) for notches where the load bearing surfaces of the discs fit. Sorry this is so drawn out but I dont know a better way to explain it.:applause:


Holy slide rulers Batman!!:D ... You get some gas for that effort :crazy: ... You certainly weren't vague in your explanation ... unlike ..just check the plates and basket for wear.

  • Kawabuggy

Posted October 15, 2007 - 08:37 AM

#14

One other noise generator on these bikes=the auto-decompressor. Several people on this site have complained about the spring loaded, cam driven auto decompressor making noise. This is just one more thing to check, and permanently eliminate!

Where the decompressor rides under the valve cover, right next to the chain housing would definitely resonate on the entire right side of the motor. This would be the first item I checked (if your bike still has it) before I tore the clutch apart.

Checking/replacing the clutch on a bike as old as yours is definitely smart. I recently had my bike torn all the way apart chasing what I thought was a 4th gear problem. I checked everything while I had it apart. For sure, I needed a new clutch basket as mine was beat to death. Someone had previously replaced the clutch, but left the tattered basket in place. I also measured the clutch springs and found them to be out of spec. I replaced basket, springs, and you will probably have to as well.

  • XR_RON

Posted October 15, 2007 - 08:51 AM

#15

Fearlu.dont try to kill it first,then repair it,fix it now,or you wont be riding for a while,and that would suck.

  • martinfan30

Posted October 15, 2007 - 08:59 AM

#16

One other noise generator on these bikes=the auto-decompressor. Several people on this site have complained about the spring loaded, cam driven auto decompressor making noise. This is just one more thing to check, and permanently eliminate!

Where the decompressor rides under the valve cover, right next to the chain housing would definitely resonate on the entire right side of the motor. This would be the first item I checked (if your bike still has it) before I tore the clutch apart.

Checking/replacing the clutch on a bike as old as yours is definitely smart. I recently had my bike torn all the way apart chasing what I thought was a 4th gear problem. I checked everything while I had it apart. For sure, I needed a new clutch basket as mine was beat to death. Someone had previously replaced the clutch, but left the tattered basket in place. I also measured the clutch springs and found them to be out of spec. I replaced basket, springs, and you will probably have to as well.



this happens on mine and have learned to live with it. until i decide to do a cam and piston.

  • TNathe

Posted October 15, 2007 - 10:36 AM

#17

hey man, just got done doing my valves last night, its easy...HERE:
1) Take off the top caps to the cylinder head cover to expose the valves
2) Remove both the large and small allen head bolts on the left engine case (the one in the middle of the case and the smaller one directly above it)
3) Get a socket and rotate the nut the the big allen head plug exposed until you see the "T" in through the hole the little allen headed plug exposed. This is Top Dead Center.
4) With the engine here try to wiggle BOTH the intake and exhaust rocker arms up and down, if they BOTH do not have some kinda play in them rotate the engine AGAIN to the "T" mark one revolution...do this till you can feel some slop in the rocker arms.

  • fearlu

Posted October 15, 2007 - 03:47 PM

#18

Thanks TNathe, that's exactly the procedure I followed until I realized that there is no letter "T" inscribed on mine. I would just have to guess about TDC and I know that can't be right. Also, I'm not that experienced so I don't want to make it worse!

But, I think it's possible that if I identify the place where all arms are showing slop/space/room that's TDC?

  • asf

Posted October 16, 2007 - 11:25 AM

#19

Take the plug out and put in a pencil or ong screwdriver into the jug (DONT PUT SOMETHING SHORT THAT WILL FALL IN). TDC is where the screwdriver is tallest

  • fearlu

Posted October 16, 2007 - 02:00 PM

#20

Found TDC, thanks. I was looking at the wrong radius/spot on the flywheel and once I realized that, I found the T (and an F). Valve adjustment was pretty simple but accessing the gap with the feeler was damn tight. Anyway, the valves were not maladjusted it seems and it runs just the same. Kinda' noisy.

It's not the clutch situation mentioned above, at least as measured by no change in noise when pulling the clutch in. I also inspected the compression release lever and it seems to be without a rattle source.

Another hilarious note: when I got frustrated and called the Honda dealer, the service guy had to check with someone else, while I was on hold, to see if they would even work on a bike this old. Finally he said they'd be willing. Amazing, you'd think they'd want the business at $90 an hour.

Anyway, thanks for all the input. I'm still puzzled though and am concerned about the noise and the oil consumption rate. Is it logical that it needs rings or something? Does that normally entail a re-bore and new piston on the XR? What about XRs Only "628" kit? Just run it and keep adding a lot of oil? One new symptom I noticed this weekend: when the throttle is backed off slightly it faulters/sputters a bit. At full throttle it seems to run without hesitation though.





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