rx7171

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Jun 1, 2003
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thought I would try to move this. ok rx as jim has said it is an easy self do it job. an inexpinsive die grinder and metel burr tool will suffice. do the pickup mod as shown on freds site. as to the breather mod I used the origanil part from the rear and moved it to the timing chest so no need for pipe thread parts and it gives you a 90 deg fitting all in one :D just remember to gut it out. as I stated earler DO NOT forget the two piece cam thruster washer conversion to a flanged cam bushing. the tangs on the thrust washer wear known to break off and head to the oil pickup :x . if you dont already have one I would HIGHLY reccomend getting the INOA tech digest.

as for lowering the compression I would NOT run ANY kind of spacer plate. What I did ( have access to a mill ) is machine the tops of the pistons to drop the compression as there is plenty of material to do this mod. if you research this the plates is an oil leak waiting to happen and more trouble than its worth. if nothing else I would leave it as is and run a little octain booster as the added compression is good for extra torque :D .

one motor I have running was a combat with a change to standard cam and a single mic. and it has great lowend power with very little lose over 6000 RPM. my rider is a stock combat with .020 off the pistons and have 15000 on it and doin as much as 650 mile days with NO trouble so far.

windy
 
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Oct 12, 2007
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Bill,

How much did you mill off the tops of the pistons? More than one way to skin the same cat, eh?

I've run with and without the spacer. Never had a problem, no oil leaks with the spacer. No detonation without the spacer. I do lose some top end with the spacer, but it's a bit easier to kick over. As for kickover, it really depends on rider weight and technique. I'm six foot and weigh 255 and develope an attitude when it comes to starting my Combat. I'd probably gain back some of the topend speed if I lost 100 pounds. Fat chance! Now, if I use the metric system I'm down to 115.
 
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jim I milled .020 off but .040 is also doable if you want less compression. as for the spacer it will have one more joint to worry about. the later 850 did away with the base gasket due to leaks. it is to easy for the cyl base to walk around on the cases ( 850 through bolts to help ).
when I bought my first norton in 72 it was a combat and I was 135# soaking wet and still had NO trouble starting it :D so I guess it is all in how determind you are to ride but it does take the right tecnique.

I will be back in FL for the winter so maybe we can get tougather for a short ride? as were not that far apart.

windy
 
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Bill,

My Norton is scattered all over the garage, as of now. It had a piston failure (see post). It will be sometime before I'm on the road again. Thanks anyway. You're certainly welcome to stop by.
 
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