Maintenance & Technical > KX500 Original

extreme loss of power

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Polar-Bus:

--- Quote from: Garrison on August 21, 2006, 01:00:44 PM ---Hello Everyone,
I'm brand new to the board and I'm looking for some help.
This is my situation:
I bought a 87 KX5 about two weeks ago, it had been sitting for a few years before that. I cleaned the carb, freshened up the gear oil and put fresh gas in her and she ran great, took her down the road and ran very strong and smooth thru all the gears.
 After about a week I noticed the gear oil looked milky so I replaced the water pump bearings and oil seal.
Shortly there after, but not immediately, I noticed a lack of power. The bike starts up with out a problem, but now as I run through the gears it seems to rev up high but have very little power.
I took the carb of again and looked it over, seems clean to me.
I messed with the fuel and air mixture and it didn't seem to make any difference at all.
I'm talking like 4 turns out just to see what it would do and no change.
I've done some searching on this forum and the only thing that seems to be a possibility is a power valve problem?
I'm not leaking oil out of any base or head gaskets, just around the gear shifter.
I took off the flywheel cover and it is bone dry so I don't think I'm sucking air at any bad seals.
I've tried explain this situation the best I can. Any help would really be appreciated.
Thanks,
Garrison

--- End quote ---

I am thinking you have a smoked clutch also. A quick way to confirm a bad clutch is to short shift right up to 4th (at a real slow speed), and then accelerate hard, if you hear the engine rev real quick, with no gain in speed your clutch is slipping. Clutches will slip worse when hot also). If you can do this test on pavement, it's easier to tell because the tire isn't loosing any traction. One caution, GET FAR FOREWARD ON THE SEAT!!! Be prepared for a wheelie! If your clutch is good, hang on tight!

Garrison:
Thanks so much for the replies guys,
I'll check and see if the power valve likage moves but it sounds like the clutch is the culprit.
I had it down a paved road earlier when troubleshooting and had it up to fourth gear. It was revving out but little increase in power. Fourth felt and sounded about the same as first.
And now that you guys mentioned the clutch, I can't get her into neutral with the clutch engaged and she'll stall when in first with the clutch engaged.
How many clutch plates are used total anyway? I'm just trying to figure out how much cash this will cost me for parts. I see that each plate runs a little over $8.00 a piece.
Thanks again for everyones help.
Garrison
Oh by the way, I used Belray Gear Saver 80 weight oil. Should I try something thicker?

gowen:
Garrison, that pretty much sums up the clutch. I found that the lighter the oil, the less my clutch slipped. My experience is, my clutch started to slip when I was using thick oil.

Take the clutch cover off and look at the plates and see if they look bad. If they do not look bad, a cheap way out is try replacing the springs, they are usally around $10 for the whole bunch.

hughes:
http://www.rockymountainatv.com/productDetail.do?prodFamilyId=3012&navTitle=Engine&webCatId=17&pageLinkUri=&vehicleType=&webTypeId=38&navType=type


This clutch says 89-04 but it's the same as our 87 500. I installed this same clutch this january and have got about 10-12 rides on it it works great no issues. Welcome to the site. You can check out my old 87 500 in the gallery.

Arigato:
Now that I've seen the other replies and thought about it some more, clutch makes more sense.  However, considering the age of the bike, an inspection of the top end and powervalves is still a good idea.

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