Oil in cylinders

here is the instruction sheet.............Blame mikesXS it is always their problem.............back in 650 rider days Mike used to post and he was getting quite communicative about shipping times and when the next load was coming in and such..................he was trolled off the site.........

80MM piston ring gap 01 01.jpg
 
650Skull said:
here is the instruction sheet.............Blame mikesXS it is always their problem.............
Click to expand...
The "maximum compression ring end gap" in the instructions is wrong. Don't know about the rest of it.
 
Thanks again for all your help guys. I'm gonna take some measurements and record them here so I don't lose them and I have easy access to them. I'm not claiming to be a machinist nor do I have proper tools but I'm going to try to use the cheap micrometer that I have and see what I can come up with.
 
Top of left cylinder 79.64 mm
Bottom of left cylinder 80.04 mm
Top of right cylinder 79.60 mm
Bottom of right cylinder 79.92 mm
 
Not sure if I'm doing this correctly but I'm watching YouTube videos as I go.
IMG_4991.JPG
The feeler gauge doesn't fit here but it fits slightly here
IMG_4992.JPG
 
Well, I'm betting it was a gasket leak to begin with, New gasket Hone the cylinders and slap it back together is what I'd do
.....
Bob.........
 
I just checked the 2 new sets of rings I have and they're both in spec. So were the rings I pulled off one of the pistons.
 
I would take emery paper to those piston skirts and hone the cylinder and try your darndest to break in that very TIGHT MOTOR !
that means no high RPM and no lugging it and check how it's burning by a plug color check ...it looks like it got way too hot and the only thing that kept it from seizing was the burning oil ! I think you got real REAL lucky !!!!!!
I would hone that thing real, real, good ! to give it a bit more Room seams mighty tight to me !
but I don't know the 750s at all so Your on your own !
Good luck , and Please let us know how it works out !
....
Bob.......
 
^ clearance looks reasonable, not too tight, maybe not too loose. Does not look like 1/16" as in first pics. I want to know how it ends too. I predict something like eff it. Important question that was asked and ignored, was it bought new or used.
 
For all we know, could be anything. Could be cam timing. Could be none of the adjusters had nuts on them (where did that nut come from?) Could be crazy ignition or carburetion. Couuuuuld be a badly warped head. If I was that stumped I would take the cylinders and pistons and head to a machine shop and ask if there's anything there that explains why everything is so beat up. No shame in that.

I would not start to work on it not knowing what to do and why (especially if I might be due a refund).
 
so whats the ring cap supposed to be xj............if mikes has got it wrong help him out and share your knowledge. just might be the problem to the whole thing ..............Share
 
^Just to humor you, does a maximum that's 3x less than everybody else's minimum tell you anything? Plus the random spacing and capitalization there tells you nobody proofread it. "Mate".
 
What were the bore measurements done with?The reason I ask is the differences between top and bottom are quite large, 0.40mm and 0.36mm for left and right respectively. Compared to piston/cylinder clearances in the region of 0.06mm this seems unusual. If the bore measurements are correct then the piston/cylinder clearance is very big at the bottom of the cylinder, or are we saying the bore is badly worn?

Edit: If the clearance is correct as measured at the bottom of the cylinder then the clearance is super tight at the top.
 
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just humoring me????.......................i couldn't care less, you made a unconfirmed statement of fact.................just wanted to see if you could back up your statement with some actual information that would help the thread/OP............
 
xjwmx said:
The "maximum compression ring end gap" in the instructions is wrong. Don't know about the rest of it.
Click to expand...

Yeah, needs to be fixed.
Here's a corrected sheet.
XS-Performance-750kit-corrected_20170810.jpg


Stoop22kid said:
Top of left cylinder 79.64 mm
Bottom of left cylinder 80.04 mm
Top of right cylinder 79.60 mm
Bottom of right cylinder 79.92 mm
Click to expand...

If those numbers are to be believed, there's far too much taper in those bores, and that cylinder shouldn't be used. Also, cold pistons have a slightly oval shape, and "feeler gauge" piston-to-cylinder clearances are strictly measured between the center of the skirt and the bore. Piston skirt diameters are measured at 90° to the wristpin, about 1/2" from the bottom of the skirt.

For the inexperienced, piston and cylinder measurements are best done at a reputable machine shop, using quality, calibrated measuring tools. Otherwise, take numerous, repetitive measurements, crosschecking each, developing the 'deft touch', until measurements are reliably repeatable...

Edit: Illustration #1 of the installation sheet shows the 1st and 2nd ring gaps aligned with the centers of the skirt thrust lines. Myself, I prefer to NOT have the ring end gaps in those locations, but about 45° offset from there...
 
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