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squirrelman

'86 VFR750 engine oddities

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posted  this @  http://vfrworld.com/threads/what-do-i-have-here.54567/#post-576927

 

 i hoped and expected to buy a stock, running 750 engine but instead got this shipped in, not runnable as-is and needing work.

 

5a2a18a183563_12-1-17108.thumb.JPG.af08fd162eb5e1743789a4c9a522038b.JPG

 

 

 first, a  major disappointment, as right front cylinder compression means big trouble:

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so i pulled the front head and found some surprises !

 

special (mystery) high compression domed pistons CNC machined vs.oem cast pistons, fancy stuff !

5a2a0e9c3f98d_12-1-17188.thumb.JPG.e10401f3ee1f6ae126b7bbc5e43e12f3.JPG

a spot where the top of the piston hits the plug electrode at TDC is visible, the next big disappointment.

 

 

stock piston for comparison: 

\8--1--17 040.JPG

 

 

hot reground cam at right, stock is left:

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hot reground cam is marked "NFF" or "NFI".  anyone know him ?  .020" more lift than stock.

 

porting and polishing by "R.E.D."  he has a website and alot of rich-guy, big-boat, fast-lane endorsers :

5a2a184ad4607_dec62017006.thumb.JPG.4b5e5a6db711a0066b784367f5c20515.JPG

 

5a2a13da9c0d6_dec62017007.thumb.JPG.d897be18885a7b8732a0e8eb2c7d0ab8.JPG

 

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nice work by a pro

 

i discovered  2 very leaky intake valves on the  right front cylinder, accounting for the low compression.  my current theory is that new rings aren't seated (cylinders were not honed or cross-hatched) so running  he engine for awhile might boost the compression up..........i hope.

^

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^^^^^^^^^^^^^^  from what little i  think i know about building engines and some experience, my best guess is that this one would be a troublesome beast in a street bike, needing expensive race fuel and prone to bad idle and overheating.  my challenge now is just to get it running, to test it out on the road a bit, then maybe sell it at some profit to a younger he-man multi-tattooed  bloke who needs to go fasta than i dare, or maybe an AMA or ARHMA vintage racer with deep pockets and 70+,  enjoying life in the elite atmosphere of the pits.

 

if it don't blow apart, that is.

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