danfr
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Maybe someone can start a new thread on this.
Crankcase Compatability
- Thread starter danfr
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Combat increased power tune coupled that extra power being at high revs, resulting in piston tops departing and premature main bearing failure pre superblend.
SteveA
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You are indeed mistaken. The smaller plug you refer to was used without the large filter/oil pick up plug on 200,000 series cases. So '72 only.
And the answer to the OP is nope, whilst you could fit them, you should avoid 200,000 series ('72) cases, or you give yourself a range of other issues to solve including oil pick ups and breathers, and cam bushings!
'70/'71 as noted...fine.
As hinted at by L.A.B.
Totally agree the damage shown is a candidate for a weld repair.
SteveA
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No don't....trawl through the volumes of material on here it will have been covered, and at a guess many times....
SteveA
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200,000 series to be avoided.....if possible....
I bought a wrecked bike on Monday evening after blowing my race motor on the Sunday....built a motor t go racing the following Saturday, but.....I left the bottom end on the floor and used my own MKIII crank and cases...
Why? 200,000 series. That was something like '77. The issues were well known!
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OK Thanks.
Well at least i moved the pick up to the rear, machined the cases, sealed the front hole. fitted a HNW reed breather and fitted new cam bushing & thrusts
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77 sunset strip???
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Since this thread is already all over the place...
SteveA says to avoid the 1972 cases for a few reasons including cam bushings. News to me. And I have a 1972!
I am guessing this is because the tab on the thrust washer breaks off. It looks precarious.
I just looked at the Old Britts site and they have a nice comparison on the bushings and washers.
SteveA says to avoid the 1972 cases for a few reasons including cam bushings. News to me. And I have a 1972!
I am guessing this is because the tab on the thrust washer breaks off. It looks precarious.
I just looked at the Old Britts site and they have a nice comparison on the bushings and washers.
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Well I have a 72 too, but the thrust washers with the tabs are not being used, if the tabs break off they are the perfect size to enter the oil return gallery and jam in the unprotected oil pump return gears.
I also did this to add a mesh to reduce the size of any mess getting to the pump return.
72 crankcase mod to add sump filter
The 72 cases were a backward step, the removal of the sump filter was the worst part of this. The current recommended mods cure the issue with the forward sump pickup not working at high revs by changing the location to the back. The lack of a sump filter can be partially covered by drilling a...
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As long as it is a 20M3S stamped case, 70 & 71 cases should be interchangable.
A case stamped 20M3 would not be directly compatible, as it is a twin timing chain engine with the points mounted behind the cylinders and the tach drive on the end of the camshaft, bolted to the timing cover (like an Atlas)
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are you sure , if you miss the timing cover and the timing gear spindle ??
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You are correct, the timing cover and other components are different as well. I was focusing mainly on the cases themselves.
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