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Discussion Starter #21 (Edited)
Personally I have never seen oil come out of that location on the XCR 800, I've checked quite a few I have owned several and still have 2, seems to me it's more of an oil return line even though it's Tee'd together..I do NOT believe that is your problem..the other same crankcase triples do not have that line at all, exception is the 99 XCR 700 which has it. All of my big bores do not use that line and they are all made from the 800 XCR crankcases.
Ok, well I still need to see if oil is getting to the PTO (edit) cyl. The fact that it doesn't flow to the crank bearing line makes me want to check.

Also, I got no difference in exhaust temps which tells me that there isn't a mixture or timing issue going on. Yes, hoping for an easy solution, but not scared to tackle a crank issue if need be.
 

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Update: no intake or seal leaks detected using ether, brake cleaner and wd40. Made it cleaner though.
However, I pulled the oil line off the PTO crank bearing oil feed check valve, and got ZERO oil out of it. Not even a drop even when running at idle or 3000 rpm for 30 seconds. That line is fed by a tee that comes from the PTO intake oil line, so I think I have found the problem.

I'm thinking I should have had some evidence of oil coming from that line. Not a drop. I will pull the carbs off tomorrow and see what's up with the line or the pump.

Again, any thoughts appreciated and thanks to all for weighing in. Great site for experience and help.

Brent.
Pretty sure that line is for back/forth recirculation from the PTO cylinder bearing which happens when the pressure builds inside the case on each stroke.

I own a 2000 XCR and I've checked the flow to be minimal in that line. As I recall, there is no check valve in that fitting.

I believe you have another reason for your PTO cylinder seizures.

One place to check is the choke plunger in that carb. I've seen the stem break off to that plunger. Then, the plunger flies out. This causes a huge air leak.

Another is worn slide slots in the carbs.

What needles and clip slot setting? Fuel screw turns?
Paj size used?

What cutaway black slides did you install? Are the small white washers under each needle?Not on top of clip.

Are all slides synched to the center slide?
 

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Discussion Starter #23
Pretty sure that line is for back/forth recirculation from the PTO cylinder bearing which happens when the pressure builds inside the case on each stroke.

I own a 2000 XCR and I've checked the flow to be minimal in that line. As I recall, there is no check valve in that fitting.

I believe you have another reason for your PTO cylinder seizures.

One place to check is the choke plunger in that carb. I've seen the stem break off to that plunger. Then, the plunger flies out. This causes a huge air leak.

Another is worn slide slots in the carbs.

What needles and clip slot setting? Fuel screw turns?
Paj size used?

What cutaway black slides did you install? Are the small white washers under each needle?Not on top of clip.

Are all slides synched to the center slide?
Ok thanks, that is another vote for the oil line not being an issue. I used stock sized 2.0 slides to replace the green ones. Needle clips are all in the middle. Had one occasion of the same type of quick seizure with the green slides. Definitely kept track of the white washers, all went back together properly. Pilots are all stock size, pilot screws are all 1.5 turns out.

I will check the choke plungers now, but didn't notice anything amiss on reassembly. So frustrating!

Thanks again, will update.

Brent.
 

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Discussion Starter #24
So, update from last year: finally took pto cylinder off. Delays from work, kids, wife, house. Before disassembly, I fired it up and it is running on all 3 which is after the last light seizure I had at the end of last season. New high quality compression guage shows bad cyl is down 10 lbs from the others which are at 130.

Upon removal of the cyl, I found the piston and cyl to be decidedly dry of oil. Having been a long time 650 owner (4 since 1988) I have a great deal of experience with engine disassembly, and always found a decent amount of oil on the assembly. This one is dry. The other cylinders have the usual black/wet look to the exhaust flange, the pto cylinder does not.

The piston pin was pretty tight in the piston, some heat and a c clamp pressed it out fairly easily.
No sign of lean melting out the exhaust, or any detonation. Piston crown is intact and healthy, top ring is not stuck or melted in. There is signs of seizure on the intake and exhaust sides of piston and cyl, aluminum transfer on cyl, but no visible scoring or cyl damage. Cross-hatch is still visible, and I imagine it will clean up well.

So, doesn't look like a mixture, timing or phasing issue. Looks like lack of oil to that cyl.

My questions to you guys:
Is the oil pump something that fails? I've never seen it, except for return spring or cable issues.
Can I still get rebuild parts if needed? Other cylinders seem fine, but maybe the PTO cyl is the first victim of a failing triple pump? I don't know. I will check and replace the lines, but I know I got no flow from the pto crank bearing line while running.

I see I can't buy a complete pump any longer.

Thanks for any help!!

Brent.
 

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I may have several pumps, I don't use pumps on the Big bores so may have some here..you could pre-mix too.

What rebuild parts are you asking about?
 

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Discussion Starter #26 (Edited)
Yes. Premixing would be a perfect diagnostic step to eliminate or confirm the pump issue. Would like to keep oil injection in the long run, but great suggestion for diagnosis.

I don't know where you are, but I'm in Ontario, Canada. I would happily pay for a pump and shipping if you have a good used one.

Honestly, I've never had a pump apart, but I imagine there is a shaft and gear to drive it, and a variety of washers, gaskets and tolerance measurements that make it function properly. I will take mine apart to see if there are any glaring issues.

Edit: I see you are in Wisconsin. And, I was looking for a basic rebuild "kit" from OEM or winderosa. My mad internet skills can't find such a beast.
 

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Discussion Starter #28
Super! Thanks, looking it up now.

Any opinion or experience on my diagnosis or findings? I'm open to hearing any opinion, even if it is me being an idiot on the situation.
 

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Pre-mix some fuel, disconnect the oil lines, run engine, catch the oil from the lines in cups or?? See if they all produce the same amount between them.
 

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Discussion Starter #31
Ok good, thanks. I'm on it.

And I realize a lack of oil probably was not great for the crank either, but I see no glaring evidence of crank issues at this point, and I'm going to bang it back together with a good used piston and rings, new carb boots (because I have them), and see how it goes for a few hundred miles with mixed fuel.

At least then I can feel confident doing a complete rebuild at some point and not having the same crap happen all over again.

Great suggestion to measure oil flow while running on mixed fuel. Thanks.
 
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