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Stacked gaskets on valve cap? & other questions...

By SHIFTY00,
in XR600R & XR650R/L

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SHIFTY00

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So as I said in my first post I am building a XR600R Yamda Warrior, Anyhow I am in the process of deciding how much work It needs to be reliable for the amount of time it takes to rip itself out of the warrior frame. I am thinking I got hosed on this deal because the more I look the more I find myself digging in my wallet...

So I already know I plan to bore it out .5mm, cylinder is gouged a little and there is zero cross hatching left. The largest numbers I pulled from the cylinder were 97.13mm and a 97.16mm (granted this was with china freight telescopic gauges and caliper) out of 14 measurements I averaged 97.046mm Is that enough meat to only go .5 over? The piston average was 96.753mm (but I measured it wrong and I forgot what I got for the 10mm above bottom measurement, I think it was within spec still). Can anyone tell if it is a coated cylinder from the pictures? The add claimed it was a 91 but the valve cap has a 93 etched (by hand) in it, and the serial number  backs this up. I am also looking for a trusted machine shop to do the work for a reasonable price, maybe one near PA? Also should I stick with oem C/R or bump it up to like 10:1? I do plan on running a sizable oil cooler, but I want reliability also. And maybe something that won't shatter my foot if I screw up a kick.

Now on to the head, It got smoked. 2 rockers were hammered, the middle bottom journal got chattered up, and one lobe on the cam was out of spec. The auto decompression cam pin/spring was already removed so maybe this had something to do with it? What I find odd is the bottom journal is rough but the top one looks fine. And when I pulled the cap there were 3, yes 3 steal gaskets on it. would this have been a fix to keep the cam from seizing on the middle journal? I was afraid the cap or head has been machined to make up for the nasty journal but it does not look like it has been. I am also wondering if this is what caused the head dammage? too much clearance at the journal and the left side of the cam got starved? I already ordered a new Hotcam stage 1 so I don't want to destroy it. Is the journal something I can clean up or do I need a sleeve installed. I planned on checking the clearance when I get the new cam with a plastigage. I don't know how to measure it otherwise. Thoughts on this?

And lastly, what the heck is the little oblong hole in the head between the two bolt holes beside the timing chain cut out? It was full of crud when I pulled the head.  I initially  thought it was an oil passage but there is no matching hole in the top of the jug.

As far as the bottom end it looks ok, no up/down play on the connecting rod (a little left right though), none of the gears that I can see from the cylinder hole look chewed up, shifts through all gears, no obvious oil leaks, clutch pack looks fine, and the oil filter inside the right case had no metal/crud stuck to it. Also the oil that drained out of it looked ok. 

So can you guys look over my pictures and give me your input?

Thanks for any help and sorry for the novel.

Oh and I ordered an OEM carb... Side note, anyone want to buy a no name 40mm CV pumper that needs rebuilt? haha

 

 

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Edited by SHIFTY00
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Grand Master

brianhare

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THE oblong hole is just a casting hole,,it actually goes up into the fin area,,,you can run water through it and it comes out by the sparkplug somewhere,,it`s all hollowed out in there for air flow..

 

the stavked valve cover deal isn`t good,,it spaces the cam,,but also holds the cam end bearings in place...the reason these always eat trhe lower cam journal and not the top valve cover is because there is a lot of clearance on top...the lower cam journal just supports the cam in the middle when rocker pressure push down on the cam and actually arcs it in the middle..it keeps the cyclic on/off pressure in the middle of the cam at a low amount or the cam can actually break there..

 

I`ve seen one cam that broke in the middle because the center journal was wrecked and could not support it anymore..

 

B

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SHIFTY00

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So what would cause this? Oil starvation? And a recent update, I got my hotcam in and the far left lobe doesn't clear the bearing journal! WTF? Is machining of the head necessary for a stage 1 hotcam? I can not see how even with the middle journal chattered up how this would have any effect on left right clearance. Both bearings feal ok with no slop but yet there is about a heavy 64th of material that rubs on the lobe. 

Anyone else have any input? I don't get why the p.o. used so many gaskets.. ugh...

Help 

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Grand Master

JoeRC51

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2 hours ago, SHIFTY00 said:

If you look right below the bearing and to the left  you can see a lip of the casting sticking out like 1 /16. It hits all the way around. Putting it becide the stock wont show you anyining. 

Then I guess you know the problem then. See ya.

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SHIFTY00

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Yes I do know the problem, the lobe is hitting the bearing journal. And as much as I like taking useless pictures I fail to see how a side by side will show you anything. overall they are the same length. The only thing that may be different is the width of the lobe itself. But again nothing that a picture is going to tell you because we are talking in decimals not eyeballing fractions... Now if you asked me for specific measurements I would be inclined to give them to you. But don't waste my time if you don't have any clue what the problem may be.

 

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Grand Master

brianhare

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So does the OE cam hit there too?????????? if not,,maybe the cam is not machined right or something...

 

So maybe if you posted pics of both cams beside each other we MAY be able to help...

 

you gotta help us help you....and I can`t help you if you don`t provide pics...

 

unless you wanna fly me over there and I can see it,,,and I can at least take trhe pics for ya...

 

 

 

B

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SHIFTY00

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On 3/31/2017 at 4:35 PM, JoeRC51 said:

One of us is clueless and it's not me.   ?

Good one. Yeah I am new to this engine and had some questions, so I must have no Idea what I am doing... But I am building something, what are you doing? ?

But just to indulge you, here are some side by sides. I am prepared to be dazzled by all of the knowledge hidden in these pixels... 

?

 

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Obviously not a waste of time. This is important stuff... 

Cams me oht side haw baht dat?!...

For the lolz

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Oh and B. hare, no the stocker does not hit but it only clears it by a blonde one.

 

 

Edited by SHIFTY00
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