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Hi All, i got this 98 220R as a basket case.
i checked the compression and it was showing about 80 PSI.(carb and pipe removed)
i checked the bore with a good gauge and was showing a little small if anything, and no scores or damage.
So took the top end off and replaced the piston with a wiseco , and rebuilt it.
i have had the reeds out and look ok and seem to lie nearly flat all over.
now retested and still only around the 80 mark.
am i missing some thing obvious .

i am going to do a leak down test next.

thanks mark

If it's low compression I would start by squirting some 30W oil in the top end and rechecking. Could be the cylinder is out of round not allowing the rings to seat well. Assume you checked the head for any cracks or anything when it was off. Also check for good seal between the head and cylinder to make sure you have no leaks there.

bufftester wrote: 03:20 pm Apr 10 2021 If it's low compression I would start by squirting some 30W oil in the top end and rechecking. Could be the cylinder is out of round not allowing the rings to seat well. Assume you checked the head for any cracks or anything when it was off. Also check for good seal between the head and cylinder to make sure you have no leaks there.

thanks for the pointers
will do ,
leak down test should tell more.
thanks mark

bearing in mind i got this as a basket case with unknown issues
well did the leakdown test and as fast as i pump it in its pissing out .
looks to me like the crank seals are toast.
should of done the leakdown test first (lesson learned)

cheers mark

Oh well. Good luck on the rebuild.

Well rebuilding now new crank bearings and all new seals all round.
still having issues with compression # and leak done testing .
on closer inspection i think the reeds may be toast too.
what do you think.
Worn out reeds by mark.dobson, on Flickr

as always thanks in advance.
Mark

Reeds are toast.

BURNT toast

Likely the source of your compression issue.

define nearly :-) :-)

"i have had the reeds out and look ok and seem to lie nearly flat all over.
now retested and still only around the 80 mark.
am i missing some thing obvious ."

Thanks to all ,
i have a set on order.
cheers mark

well new reeds are installed
but still cant get it to hold six pounds for a minute let alone 6.
again with the soapy water.
found a leak through the gear side of the kipps valve.
bollox.
must of damaged the seal on assembly.
top of again.
mark

That is a cheap and esy one to worry about compared to pulling it all apart again. You are almost there!