what do i have here??

Discussion in '1st & 2nd Generation 1983-1989' started by squirrelman, Dec 6, 2017.

  1. squirrelman

    squirrelman Well-Known Member

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    {#}

    recently bought a cheap, mystery '86 VFR750 engine + carbs from a known HawkGT forum member in the Boston area to replace the gen3 engine some dolt tried unsuccessfully to get working in an '87 frame only after that guy's original 700 mill done blowed up and bike came to me too cheap to refuse ! took me 3 days to figure out that it was the same white '87 i owned and sold in 1995 (to a cool-guy air force reserve pilot flying KC-135s from niagara falls, and who flew medivac choppers in vietnam), and it came back to me (with a gen3 engine. not running) after 2 other owners and 22 years !!! small town market. thought i was finished buying stuff, but no, not as long as i have room for one more. :(


    12-1-17 108.JPG

    the bike i owned in 1995, non-running now with gen 3 engine

    12-1-17 009.JPG



    View attachment 75218

    first concerns were sand-blasted covers and a hand-cut cardboard clutch cover gasket along with some suspicious clicks when turning the crank.

    compression test showed #1=120psi/#2=45/#3=90/#4=100, so i immediately wondered why i hadn't insisted that the seller do a compression test b4 he shipped it. my fault for trusting the seller.

    View attachment 75219

    tried again with oil, not much change, so i pulled the head and found 2 very leaky intake valve s on #2, maybe bent from bad assembly job after a rebuild ????? anyone tell me how to make a tool for removing valves from VFR ?? first time i needed one in years.

    the pistons i saw were surprisingly non-stock, so someone had been in the engine, not what i wanted but probably as a cheater race engine: high-compression, domed pistons with machined valve clearances. different material too , looks like CNC machined.



    looked more and found the heads had been ported and polished dec6 2017 015.JPG
    ,
    has radical, high-lift, longer duration cams and matching valve springs. what the hell ? reground cams are stamped on ends "NFI".

    dec6 2017 012.JPG
    STOCK cam at left.



    dec6 2017 017.JPG Stock at right

    :squid: how fuckin fast did this guy wanna go ?? :chicken::chicken:


    and who engraved "R.E.D. 12-98" on the heads ? any ex-racers know the guy ? he chose quality bits but messed up his math and measurements as the pistons contact the sparkplugs' side electrodes at TDC !!! a different style plug might work, more research needed. i don't believe the engine ran after its rebuild cuz combustion chambers and piston tops were totally clean. wouldn't have run well as sparkplug gaps were nearly closed by piston tops. :deadhorse: someone spent big money on this engine in 1998 and never started it or put it into a frame. unfinished project. definitely built for racing, either as a cheater in AMA or for a track rider like WERA or CCS . possibly a blowup sometime soon if anything critical is off only .002" can i trust the guy who bolted it all back together ?

    .
    i doubt this engine would ever be usable on a streetbike as cams are far too wild entirely, and it would require expensive race fuel. doesn't really match my tastes as i prefer slower, more reliable VFRs in my mature-er years, and my stock '86 700s are plenty fast enough already !

    .........another winter project among others stalled by bad weather.
     
    Last edited: Dec 13, 2017 at 2:30 PM
  2. squirrelman

    squirrelman Well-Known Member

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    dec6 2017 004.JPG

    wild cam at right
     
    Last edited: Dec 6, 2017
  3. Captain 80s

    Captain 80s Active Member

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    Far out!!!! Some attention to detail and you could have a real fire breather.

    You can get valves out without a special tool, but going back in is where you need the valve spring compressor. You can find the perfect deep socket (or something similar like a bearing spacer) that matchest the valve spring retainer diameter. With the chamber of the head down firmly against some rags on a bench, give it a pop with a heavy rubber mallet. The tiny split keepers will fall to the side and the valve springs will release.

    On larger engines with very stiff springs, your results may vary.
     
  4. squirrelman

    squirrelman Well-Known Member

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    12-1-17 189.JPG

    thanks, captain ! if anyone knew the trick, i imagined you'd be the one, and i'll try it !

    can i get a specially-made custom thicker head gasket to compensate for the intimate piston contact with the plugs ? you can see the spots on the piston crowns where they contacted the pkugs.

    special pistons, what make are they ?



    12-1-17 188.JPG
     
    Last edited: Dec 7, 2017
  5. TOE CUTTER

    TOE CUTTER Mullet Man

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    Somebody spent a ton of money on that engine. Stock bore? 750 crank?
     
  6. squirrelman

    squirrelman Well-Known Member

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    don't know about the crank, but it's an RC 24 engine #. i wasn't happy when i saw that the bores with new pistons hadn't been honed. :eek: hot intake cams have .020" more lift. :pass:

    12-1-17 108.JPG
     
    Last edited: Dec 7, 2017
  7. VFR4Lee

    VFR4Lee Active Member

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    You may have a highly modified engine that could be great with more work.
    Else, you have scrap metal. :Hat:
     
  8. squirrelman

    squirrelman Well-Known Member

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  9. Captain 80s

    Captain 80s Active Member

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    Get her apart and make sure the valves aren't bent. Then I would get in the NGK catalog and see if the is a slightly shorter alternative.

    Did the 700s have slightly shorter rods? I know the stroke is shorter but can't remember if it was the crank or a combo of the two. Might be the perfect fix to get the clearance needed and a compression ratio good for the street. And you could hone cylinders and make sure it's assembled properly.
     
  10. squirrelman

    squirrelman Well-Known Member

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    plugs will be a problem and probably need to be colder than stock, shorter reach.

    i'll try to get a peek at the rods after i remove the oil pan, but i don't want do a full stripdown, please. don't wanna go there no way but will only if necessary to get running. if i find good oil pressure and no bad noises i'll just try running the engine on the road for minimal break-in and see if the compression gets any better. if not better, then sell as a project maybe. i'd like to send the 2 heads out to a top local guy for a proper valve job, which i don't think was done in this case, but don't have the money to spend. no money for any machine work either. found alot of valves set at 0.011", measured before disassembly. just a f-up or 'sposta to be that way with different cams ? where's Smokey ?


    with these radical cams, i think i'd need some expert advice (the guy who chose the tuning factors maybe) setting up timing and valve clearances. seems like research could be done to tune peak the powerband by setting cam time one tooth off for more overlap , changing lobe centers ? with so many teeth, degreeing in cams can be precise, and it's possible-- within engineering limits--to vary the valve timing, for fun or profit. might not be right to set modded cams exactly at OEM marks, don't know ? where's Isky ?

    then there's the jet-kitted carbs to tune, further complication.

    no more engine work for awhile as i'm trapped inside by foul weather, 22F. and far away from the shop for days.

    hoping setting up this mess might not require making playdough checks for clearances. PIA ! X1000% !! don't wanna hafta do it !
     
    Last edited: Dec 9, 2017
  11. squirrelman

    squirrelman Well-Known Member

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  12. fredsncoma

    fredsncoma Member

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    I have a set of piston that look just like those. They are Cosworths. When I put them in mine with the stock plugs the exact same thing happened at redline after break-in. pistons closed the gap on all the plugs. switched to non protective tip plugs(little shorter) and was fine. Rode it for a few thousand miles. Got some ported and polished heads like that too. all in parts out in the garage. Free to good home.

    [​IMG][​IMG][/URL][/IMG]
     
    Last edited: Dec 9, 2017
  13. fredsncoma

    fredsncoma Member

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    700s ran longer rods which made the displacement difference between the two engines. and the pin placement on the cosworth piston necessitates the longer 700 rods to maintain the 750 plus bore displacement.
     
  14. fredsncoma

    fredsncoma Member

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    Your biggest stumbling block will be bearings. I tore down my engine that had all these things you describe minus the cams and could not find any damn rod or main bearings to ever hope to get it back together. Good luck
     
  15. Captain 80s

    Captain 80s Active Member

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    Free to good home. I'll take em.
     
  16. squirrelman

    squirrelman Well-Known Member

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    thanks for the info :pipe: and thanks for the gaskets you sent me !!

    i think i saw bearing shells available from david silver spares. http://www.davidsilverspares.com/VFR750FG-1986/ they fit the european 1988 VFR750FG. would they work for us ????
     
    Last edited: Dec 9, 2017
  17. squirrelman

    squirrelman Well-Known Member

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    i doubt this builder constrained his wishes within any 750 displacement limit.
     
  18. VFR750F3

    VFR750F3 New Member

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    Squirrel-- Did you buy that motor from Ben?? I was interested in the whole pile of parts he had. You beat me to it by moments, for which I now forgive and thank you....

    Fred-- If the Cap'n comes to his senses and doesn't take your free parts, I will....
     
  19. squirrelman

    squirrelman Well-Known Member

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    well, yes, i did buy it from Ben. i had been in contact with him for about 8 months working out a deal. but when i got back my '87 white in July and needed a motor for that, i only hesitated paying $220 for shipping but went ahead. actually, i hoped someone on the hawk forum would buy it before i did.......so i wouldn't fuckin have to buy it ! :Noidea:

    my plan now is to replace the front head after i've fixed the 2 leaky valves and proceed to run it as-is, hoping the compression comes up with time and miles. if not, i'll do what's necessary--within the limits of my puny resource$. i suspect that, although the porting and polishing were good, the builder never did a proper 3-angle valve job or paid attention to seating.

    Ben promised he would send me the parts lot, but nothing yet. the carbs were damaged by rodent piss, one of the butterflies frozen up. :Help:

    IF i get this beast tuned and running right, i may try to sell it to someone who wants extra power, because at age 74, i don't need it or want it. :Nono:
     
    Last edited: Dec 17, 2017 at 4:26 PM
  20. Riding a 2000

    Riding a 2000 Insider

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    Regarding the plugs, and piston contact:
    Eh, I hope I don't stick my foot into the mouth here, as I sort of skimmed this thread and did not read every line.
    I run a shifter kart, and several of the motors I have used have been highly modified. Many of the combustion chambers in the heads were altered so that the plugs protruded too far. The standard solution was to use a custom-machined aluminum or copper washer under the plug's sealing ring. The normal thickness was 2mm for this application. Some setups worked well using just two of the normal plug gasket/ring pieces.

    Since the heads are off of the motor, a quick question: Do any of the threads. protrude beyond the surface of the combustion chamber? They should not. Only the ground electrode should.

    Now, if the compression is so high and the piston dome to combustion chamber roof so small that the electrode will be contacted, there are other plugs which can be used. Those have a shorter ground electrode, which approaches from the side instead of being over the tip of the firing electrode. I have one or two of those plugs. Right now can't recall the series. And of course the NGK website is frustrating, having been programmed by someone believing that "make, model, year" searches are the only valid ones......
     
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