650L top end failure, 2nd time!

11 replies to this topic
  • tntmo

Posted May 23, 2004 - 07:14 AM


For the second time in less than a year, the top end of my 93 650L is cooked. I bought it used so I have no idea what kind of maintenance it had before I purchased it. It started making noise and I found the cam and rockers were worn badly and the center bearing journal was scored. I replaced everything from the head gasket up and also changed out the oil pump, figuring that could be why the top end failed initially. The bike ran great for a few months and then started making noise again. Same story, cam, rockers and center journal. I might be crazy, but I still love this bike. I just can't trust it. Anyone have any words of wisdom, something I'm not doing right? I already ordered up a cam and rockers from Barnums, got the hard welded set. I'm ready to go for one more try. Like I said, crazy.

  • HCWHunter

Posted May 23, 2004 - 08:41 AM


Are you running a good full Synthetic oil? I have heard about top end failures on 650L's before as they run VERY hot, particularly when people start bumping up the power with mods. I run Mobil 1, 15w-50 in my XR's. Have you rejetted it properly? They are extremely LEAN (= heat) from the factory to meet emissions controls. Most people yank off the smog stuff although I don't know if that helps it run any cooler.

  • Dual_Dog

Posted May 23, 2004 - 10:13 AM


HCWHunter brings up a good point about lubrication. Check the oil line that goes from the right side case up to the cylinder head and make sure oil is flowing through it properly. In fact check all the oil lines, strainers & screens.

I'm not sure about how hot these beasts run, but too lean is not good as mentioned.

Are you doing the work yourself? If not, there are some reputable shops here in SD.

Good luck & hopefully you'll have better luck this time.

  • heliosstudios

Posted May 23, 2004 - 11:03 AM


Uggh, sorry about your luck. Well you know what they say, 3rd time's the charm. :thumbsup:

I've recently obtained a '94 650L... 6k miles, head appears to be fine (for now...) Anything I should look out for?

One strange thing, when I went to pick the bike up, the oil measured fine. When I got it home after 170 miles of trailering, I ran it for 5 mins and checked the oil and it didn't even register on the stick. Had to add 1/2 quart to get it just over minimum, and that's where it's stayed even after a 30-mile ride and repeated checking. Oil is black... bike behaves better with 1/2 quart part-synthetic added, can't wait to drain that and install Delvac-1 and maybe the SS mesh filter. (And of course the trick oil temp gauge.) :awww:

While at it, is there anything else us '94-ish 650L owner's should know? Clutch bushing OK? Any other issues? TY, and good luck TnT!

  • yooper_porkchop

Posted May 23, 2004 - 12:47 PM


I'll add this, use good synthetic oil, the air cooled bike runs hot so use a 15w 50 or 20w 50. I personally use Mobil 1 20w 50 for v twin engines in mine. Another point is make sure when you change the oil and filter that the filter goes in the right way, if you put it in backwards it will starve the top end of oil. When I worked at the local Honda shop every atv that came in with the top end cooked had a after market oil filter in backwards. The honda filters and some others are marked with this side towards the engine or this side towards cover, take a look at them, and make sure they go in the right way.

  • Dual_Dog

Posted May 23, 2004 - 02:40 PM


I'll add this, use good synthetic oil...

I read a lot about oils, posed questions in this forum and others, and researched the internet regarding the differences between petroleum based and synthetic oils. Synthetic seemed to be a better choice in every way. Next dilemma was deciding which one.

I chose Mobil 1 15W-50 "red cap." This is the "blood" for my beast. Not too expensive, available everywhere and its been around a long time. I'm convinced its better than dino oil. The motor doesn't work as hard due to less friction from the synthetic formulation. It runs better, shifts more smoothly, and it seems to run cooler, though I don't have any measured proof. And it doesn't burn oil like it did with the dinos.

Full-synthetic is the only oil for this Thumper, and I was a die-hard dino Castrol 20W-50 user for years prior to the XRL. Of course the most important aspect to remember is to maintain the proper level and change the oil & filter often.

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  • enduromaniac

Posted May 23, 2004 - 03:07 PM


tntmo..It really does sound like your top end has had some oil starvation. xr650L top ends usually go 30k or more without problems. And even then it's usually just the valve stem seals and inserts that go bad. Do you prime your oil pump when reassembling? This is a must. No type of oil would account for the problems you're having, only lack of oil. Personally, I like semi-synthetic, 10w40, but even the cheapest dino oil wouldn't cause the wear you've described.

  • tntmo

Posted May 23, 2004 - 04:13 PM


Well, I've always used Castrol GTX in all of my bikes, but it sounds like synthetic is the consesus, and Rob Barnum recommended it too, although he suggested Honda syn. I have to agree that it looks like oil starvation, but the oil pump was primed and I cracked the line to the head, it was pumping oil. Also, there was oil in the top end when I opened the valve cover. Wish I had an oil pressure gauge at times. Yeah, third time's a charm I hope. I'm gonna take some pics of the head, cam and rockers and post it up here in the next few days. Thanks for all the input, I'll let you all know how it goes.

  • jjjb

Posted May 24, 2004 - 02:46 AM


tntmo, been there done that (650L top end failures). One word of advice, if you haven't already, remove and check the screen in the frame. It takes two minutes to do. Its just in front of the engine pointing straight down, a 17mm wrench is needed if I remember right. You'll have to disconnect the oil return line from the frame to the pump. I'll bet you find that screen severely restricted with metal. If so, flush out the frame/oil tank as well.

  • tntmo

Posted May 24, 2004 - 05:17 AM


I cleaned the screen last time I went through this, and it was pretty dirty. What is recommended for flushing out the frame? I also pulled the screen in the motor, it was clean last time. I also have an oil cooler on this bike that I'll have to flush out. Joy!

  • MotoChris521

Posted May 26, 2004 - 03:31 AM


Check your oil hose at the bottom of the frame.It will twist and restrict oil flow if you tighten it with one wrench.Use two and hold the hose fitting with one and tighten the other.Also how long do you run your oil.Heat breaks down oil ,and these bikes run Hot! Use an oil temp gauge if if the oil exceeds 300 degrees.Let the bike cool. :thumbsup:

  • XR650L_Dave

Posted May 26, 2004 - 06:47 AM


When you guys pull the motor screen, are you guys priming the pump? I've heard that you can run one of these for awhile without the oil pump self-priming.
I've also heard of the flexible oil hoses getting kinked, and that causing a starvation problem.

I'd check for a crimp in the hard oil line running up to the head, and loosen the top bolt with the engine running to make sure there's flow up that line.

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