StrayCats GSXR 750 Problem - Only VRF Forum Guys seem to be helpful

Discussion in '1st & 2nd Generation 1983-1989' started by straycat, Nov 20, 2021.

  1. sixdog

    sixdog Member

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    Follow the smoke Mike


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  2. straycat

    straycat Member

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    The 500's are bringing silly $ now. there is a coupe of (7 or 8 out of 10 condition ) bikes for sale in Ontario, they're looking for $25-30,000 each.

    I also sold my RZ500 2 yrs ago (it was immaculate too), again, not my finest example of decision making.

    Still have my NS400R, thats not going anywhere.
     
    Last edited: Dec 30, 2021
  3. Jim McCulloch

    Jim McCulloch New Member

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    Wow, I bow to your motorcycle experiences! I can only dream about 95% of the bikes you own or have owned!
     
  4. straycat

    straycat Member

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    img_3890-jpg.297120.jpeg

    Well, im not happy with the K&L carb kit that arrived for the GSXR, the Mains are all 112.5 and mine are 112.5 on 1&4 and 115 on 2 &3. on top of that the 112.5 from K&L are actually smaller orifice than the OEM (used pin gauge set to measure), Pilots should be 35's but are not marked and are also smaller.

    the emulsion tubes and needles are not visibly worn on the OEM (used pin gage and a light), and the K&L are narrower inside and out and have too much slop in the carb body.

    Choke plungers are also smaller OD by a thou or two on the K&L

    Ill use the new needle and seat's from K&L and keep the rest OEM as it looks/measures fine.

    Ill replace ALL the O-rings and Seals using the Litetek kit (which is top notch)

    I wasted $ on K&L it seems

    After the rebuild and cleaning, far so good. I didnt run it long yesterday as I ran out of time in the shop, other duties called. But...it fired up right away on choke and after some adjustment on the idle ( it rev'd to the moon when she first kicked off on choke) it was running fine for the few minutes I had it running. All 4 cyl headers were the same temperature on my laser gun, no popping in the pipe that I used to get (every time). So ill take that as a reasonable start.

    Ill pull it off the lift tomorrow afternoon, so I can back it up to the shop doors and run it longer without choking myself out, make sure all 4 cyls continue to run, set the idle etc.

    No Dyna Coils & wires on it yet, this was just a carb re&re.

    So what did I find with the carbs while I had it apart ?:

    1) Orings - most were dried out and likely shrunk, certainly the float assy Orings were not keeping that small plastic tube tightly seated in the carb body, and other Orings were not doing a good job either.
    2) Float height on cyl #1. probably at least 2mm too low, fixed that
    3) Choke bar that connects all the choke plungers - the left end connecting to cyl #1 was bent at 100-110 degrees at least, instead of 90. so... cyl. 1 would have been getting choke all the time (to some degree) when the choke was off, and Cyl 2, 3 and 4 were not getting full choke when #1 was. I bent it back to 90 degrees so all 4 plungers activate equally and all fully seat in the off position (may explain the initial high reving, on choke now that they're all functional)

    Of course its hard to know what other effect, if any, this second deep ultrasonic cleaning had, but it sure didnt hurt.

    Stay tuned for a report tomorrow when I run her for a longer time using the remote fuel tank....may get time to sync the carbs too. Depends if I get done digging out of this snow storm in time.
     
  5. NorcalBoy

    NorcalBoy Member

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    Always use jets and parts from the manufacturer whenever possible. Keyster seems to have some decent quality kits and Factory Pro.

    It's pretty common for the inner cylinders to be richer on the mains, due to the heat. I don't really know how much effect it has. Using the VFR400 & RVF400 as an example, the VFR had richer main jetting for the back cylinders from the factory, the RVF did not. I would have to talk to somebody that really understood these types of things to get an educated read on the subject. Something I will probably bring up the next time I'm shooting the shit with my guys.

    I do know that some race bikes have sensor bungs on each header pipe so that each indivdual cylinder can be tuned.
     
  6. straycat

    straycat Member

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    Yea, I used EGT's on my race snowmobiles for years. Mine weren't a bung, but a drilled hole in the header, a specific distance form the piston face. the Exhaust Gas Temperature Sensor probes were inserted into the holes and attached to the header pipe. Wires went up to a Digitron control unit on the handle bars to keep monitor on the 2T exhaust gasses. Good for tuning and for ensuring you didnt burn it down on a long drag run. I had one pro built & tuned sled that was tuned for 660ft and no more, it was on the ragged edge.

    Said sled is the green and black Arctic Cat EXT Special. 550 liquid, 2 stroke, tuned pipes, piston skirts cut, piston crowns shaved and chamfered, polished and ported, clutch work, and a blue printed chassis. It was scary fast, I did 91 mph in 660ft on ice, running 10-11,000 rpm feb08 047.jpg . The Yellow 76 Rv was mine too, the white ane red Yamaha's were my buddies sleds

    feb08 041.jpg feb08 040.jpg
     
  7. NorcalBoy

    NorcalBoy Member

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    I dig anything that has to do with tech, tuning, and engines. Doesn't matter what it is.
     
  8. straycat

    straycat Member

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    Well, yet again my joy and optimism was short lived. The GSXR shit the bed again today, this time on the second start since the carbs were done , like clockwork it dropped a cylinder, this time #3. Bike was popping in the exhaust again.

    #3 wasn't completely dead, just half dead. firing almost every other time it seemed half as hot as the others, not stone cold or anything

    last time #3 was the only cylinder left running properly (??hmmm)

    tomorrow im guessing #3 and one other will drop on me and ill be down to 2.

    Never Fails, starts off on all 4 running like a dream, then one by one they seem to go out on each successive Strat up.. perplexing

    still waiting on my crimping pliers to arrive so I can put on my new Dyna coils and new HT wires.

    Instead I decided to make myself feel better and finished off my decals IMG_3895 copy.JPG
     
    Last edited: Jan 19, 2022
  9. NorcalBoy

    NorcalBoy Member

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    Bummer, frustrating as all get out. Hoping the coils fixes the issue.
     
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  10. Jim McCulloch

    Jim McCulloch New Member

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    Holy Crap that is awesome! I would love to ride a sled someday. I missed out living in the South.
     
  11. Jim McCulloch

    Jim McCulloch New Member

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    Sorry, Boss...chin up, you will get it.
     
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  12. squirrelman

    squirrelman Member

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    hang in there buddy. the guy who sold you the bike knew it had that problem for sure. :confused:
     
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  13. RogueRC24

    RogueRC24 Member

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    I can just visualize Capt shoulder tapping for a bike sale with the VFR750RR sitting behind him, "so uh, I hear you gotta 2 stroke you don't need"?
    Stray, you GSXR looks awesome!! Well done. Sending some good vibes to get it running right.
    On bikes that we regret selling. I should have kept a few knowing what I know now. lol..miss my CB1 the most.....and my SuperHawk...and...
     
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  14. straycat

    straycat Member

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    Thanks Squirrel, yes I knew it had a problem too. bike wasn't even running when I got it, thats why it was so cheap LOL, no so cheap anymore I guess

    Like all the old bikes we resurrect we chuck too much $ at them sometimes.
     
  15. sixdog

    sixdog Member

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    Yea I agree but the satisfaction I get once I have it running and looking good offsets the cost … well at least for me.
    Today I finished my project CBR900RR and took it for a shake down ride… I was smiling all the way.
    You’ll get Cat …


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  16. Captain 80s

    Captain 80s Member

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    Wait... do we know about this? How dare you casually mention it and move on.

    If we are talking about GSXRs here, we can certainly handle a pic or two of a 900RR.
     
  17. sixdog

    sixdog Member

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    Jim McCulloch likes this.
  18. Captain 80s

    Captain 80s Member

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    "Sorry Cat don't want to highjack your thread......"

    You can blame me.

    Very cool. I like it.

    Early 900RR is on my list, but It will have to be the right "project". As in cheap, but good bones.
     
  19. Captain 80s

    Captain 80s Member

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    Did you source a genuine later headlight, or is that repro too?

    Require a later upper cowl / headlight bracket?
     
  20. sixdog

    sixdog Member

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    The headlight is stock 95 blade. I installed a "night rider" driving light above the headlights.
     
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