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New transmission gears, whirring sound (93 XR600)

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I took my engine apart because it desperately needed some new rings. Found that 2sd and 3rd gears were worn/pitted. Split the cases and replaced second and third gears on both the main shaft and the countershaft. Got my bike together Sunday morning and did a break in and test ride at Gorman Sunday afternoon. Everything went pretty much OK. At idle the engine is much quieter than it was before. Those new rings really helped the low RPM torque. :thumbsup: Wow!!

However, I noticed a new noise. It only happens in second gear when applying power to maintain speed or accelerating. If I hold in the clutch, or let off the gas it goes away. It's not too loud, so I can't hear it if I give it lots of gas. It's a whirring kind of sound. No sound like it in any other gear. Is this just the sound of some new straight cut gears? Should I be worried, or am I just being paranoid? If it's the new gears, why don't I hear in in third?

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Don't think so. It makes the sound even when just giving enough gas to maintain speed. It's not very loud, but it's definitely there.. If I really gas it, the exhaust drowns out the sound.

I was wondering about the clutch. Here's how I tested the clutch. On a paved road get going in 5th gear at about 1500 rpm. Apply full throttle. Hit the cultch for a moment so the engine gets to 7000 rpm. Release clutch handle. The clutch was always able to bring the engine back down to 1500 rpm in about 1/2 second. Seems like the clutch is OK.

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when you installed the rings, did you have to have the cylinder honed? how about the piston, did you replace it? the reason why I am asking is I just picked up a 93 XR 600 and was thinking that I should rebuild it and start out with a fresh engine. I am unfamiliar with the Xrs and not really sure on what should be done on a rebuild.

for your question, it sounds like you are breaking in new gears and perhaps a mismatch between the new gear and an old gear is causing the sound you hear. I would also guess that second gear was used allot more then third gear causing the sound in second but not third (more wear on the gear it meshes to).

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Well since you replaced both Drive and Driven gears the noise is not old

against new... could it be that there was / is slight wear on the shaft and

with the new gears on there .... could be causing it. Like Jon-D says 2nd

may have been used more and just bit more wear there.

Sorry I wish I could be more helpfull....

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Yes on the hone, and I did it myself. I have one of the three stone type. Generally,the ball type hones are considered better, but a ball hone would not have fixed the problem. There was some slight wear, about .001, at the top of the bore that the old rings made. I honed the bore that .001 to get make the rest of the bore even with those worn spots. I did this only after careful measurement that the resulting piston to bore clearance would be within spec. The piston measured like it was new so I didn't replace it.

There are other problem areas that you should check. Ususally the first thing to wear out is the valves and the cam chain tensioner. XR600's like to break 3rd gears. The usually make noise before they fail but not always. If you do take the cylinder off, you can look in the hole and see the transmission. That's what I did, and I saw wasted gear teeth. Another thing to look out for is the choke plate on the carb. Both the flapper and the rest of the plate on mine were about ready to break off and get sucked into the engine. I just removed it. If it proves impossible to start in the cold, there is an aftermarket plate available (for $25!!).

Then there's the standard list of things to do. Re grease all the linkage bearings, steering head bearings, new fluid in the forks, etc.

My experience with XRs is that the engine lasts a long time. I had an 81 XR500 that I picked up in 92. I rode it al least 50 times a year, and it finally failed in 2000 (when I got the 600). The camshaft bearing surface fried. I took the engine apart and the piston measured new. I was amazed. The rings were worn , much as I found with my XR600. The bore only had minimal wear. So unless it's giving you a reason to tear it apart, I'd say ride it.

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I just noticed a wirr on 2nd gear. Had the bike rebuilt 6 months ago. Never really noticed the noise before the rebuild or immediately afterwards (that doesnt mean it wasnt there, though...).

Bike has new clutch plates and steel plates. Tranny looked like new when I opened it up. Whirr only in 2nd gear. Goes away when I decel or clutch in or shift. When I ride next to a wall I hear more noise like the sound of a ducati dry clutch. Soudns like a rattling can of BB's.

Oil is golden spectro. Oil and screen are clean, also have a magnetic drain plug.

Bike pulls hard, tempted to just say screw it...only other trend is I hear it when rolling on throttle, but when I ride hard, no noise...

:excuseme:

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That's what I did, I rode it. It still making the noise just like it did in Feb 2006. Bike runs great. Usually starts on the first or second kick.

I am about to tear into it again. The engine is leaking all over. I'm going to replace all the seals and gaskets. I'll take a look at the trans and see if I can see anything. All that I can figure is those new gears are noisy.

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It almost sounds like a mismatched set of gears running together. Kind of unlikely. I would like to think Honda's quality control is better than that. They may get quieter as they get run in. Probably nothing to serious,I hope.

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It almost sounds like a mismatched set of gears running together. Kind of unlikely. I would like to think Honda's quality control is better than that. They may get quieter as they get run in. Probably nothing to serious,I hope.

If anything it has been getting louder. More reason to open her up and take a look see.

It can't be anything too serious as I have put about 4000 miles on the bike since Feb 2006.

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If anything it has been getting louder. More reason to open her up and take a look see.

It can't be anything too serious as I have put about 4000 miles on the bike since Feb 2006.

That sounds like a hell of a good idea. Makes me wonder if there's a bearing getting ready to take a powder,spun in the case maybe or just a misplaced shim, worn bushing, broken snapring or something. You think it would be making metal if it was real bad. I hate mystries.

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Being the novice that I am can you guys explain the issues of bearing pssinning in their case? Why is that major issue? I would have thought that a bearing spinning is fairly benign no?

Great topic - like to hear what you find CL, I always like you threads

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If the noise is only occurring in 2nd gear-as mentioned above it is probably a matter of those gears (main & counter shaft) wearing in. I would not worry too much about it. Keep an eye on your filter for metal specs, and MORE importantly check the oil strainer at the bottom of the frame for metal.

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If the noise is only occurring in 2nd gear-as mentioned above it is probably a matter of those gears (main & counter shaft) wearing in. I would not worry too much about it. Keep an eye on your filter for metal specs, and MORE importantly check the oil strainer at the bottom of the frame for metal.

That's what I figured too. Been keeping a close eye on the frame tube screen and filter. Very little metal.

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Being the novice that I am can you guys explain the issues of bearing pssinning in their case? Why is that major issue? I would have thought that a bearing spinning is fairly benign no?

Great topic - like to hear what you find CL, I always like you threads

a bearing spinning in the case is bad! if this happens it usually means the bearing itself got hot and seized.

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a bearing spinning in the case is bad! if this happens it usually means the bearing itself got hot and seized.

What he said. It will ruin a shaft or an engine case and cost cubic $$ to repair.

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a bearing spinning in the case is bad! if this happens it usually means the bearing itself got hot and seized.

Then there is the other issue that my engine has. When I had it apart in Feb 2006, the crank bearings were not interference fit. Quite to my surprise the crank just fell out of the cases. When I asked at the time most responses said don't worry about it. It's been worrying me ever since. It just didn't seem right. If those bearings are loose they will turn in the cases and get even looser. Just one more thing for me to check out when I take it apart.

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Then there is the other issue that my engine has. When I had it apart in Feb 2006, the crank bearings were not interference fit. Quite to my surprise the crank just fell out of the cases. When I asked at the time most responses said don't worry about it. It's been worrying me ever since. It just didn't seem right. If those bearings are loose they will turn in the cases and get even looser. Just one more thing for me to check out when I take it apart.

that is possible too. i have run across this problem with Radio control airplane engines. the bearing to case clearance is too much and though the bearing may be still good, the case is wasted from the still good bearing slopping around in its boss. must be the difference in metallurgy between the 2 metals.. hardened steel outer race of the bearing compared to the soft aluminum case. i dunno!

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i wouldnt be to worried about it if it only happens in 2nd gear its proably the new gears just wearing in im sure it will go away, when my rear end on my truck was regeared it had a slight hum like you are describing hear drove to the mountains and back by the time i was home the sound was gone.

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