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Thread: New member. Nebraska 83 250R

  1. #1
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11

    New member. Nebraska 83 250R

    Long-time lurker first time poster. Greetings from Omaha.

    30 years ago I purchased my first R.. Someone convinced me to sell it years ago. I won't mention her name(wife). The only toy that I managed to hang on to over the last 20 years were my dirt late model's that I raced throughout the Midwest up until a few years ago.. Now they're all gone, and so is she!

    Recently I've been struggling with issues in going through my version of what has to be a midlife crisis. Not too long ago I purchased a ZX-14 to pound the pavement with. It's just not the same, most of you know what I mean... so a few days ago I literally stumbled on an 83R and had to bring it home. She's a 100% complete but the old gals been ridden to death, as in 50 lbs of compression. With nothing to do this past Easter weekend I decided to rip the top of her off.

    With The Jug off I measured the cylinder bore and it came out at a whopping 77.5 mm. Wtf was all I could think. Then I remembered back in the day Hondaline had a 300 Big Bore Kit. Then I thought yay!!! Until I realized it was on its last oversize and there were no more Pistons available

    I've literally spent the last two days searching the interwebs for a 78mm piston that from what I can gather no longer exists or was never made available. Which is odd, because there is still an extensive amount of meat left in the sleeve? Anyhow, all information I was able to obtain either belong to individuals that cannot be found, or companies that are now out of business. I've been out of the loop so long I have forgotten everything about all the mods we used to do to these 250R's back in the day.

    Can anyone out there and three wheeler land help me save this jug and point me to where I can find a 78 mm piston, or a combination of mods that will put this old girl back on the track?

    With regards, Jimmy

  2. #2
    Join Date
    Jan 2012
    Location
    Carthage NY 250r rules
    --
    2,345
    77.50 was the biggest over bore for the 300r. With some machining you can run the liquid r big bore pistons. The bottom of the cylinder would need to be machined down by about 4 mill. racerstoystore on ebay used to do this.
    Last edited by atc300r; 11-22-2019 at 09:03 AM.
    250r rules

  3. #3
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    I'm headed to the Machine Shop in the morning and we'll pass this info on to my Machinist. I appreciate your response, as I have found nothing but 78mm watercraft and snowmobile Pistons. Without knowing the pin height of these various Pistons I have nothing to go off of.

    I've been itching so bad to get on the horse again I hopped on Craigslist this morning to find another ride.

  4. #4
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    One thing I was extremely surprised to find was the stock compression ratio being 6-1. I don't see how it had any compression to begin with..with the Piston being Down in the Hole @ + .400 inch? I was under the impression that the hondaline 300 kits raised the compression and it would have a much tighter squeeze. I measured the stroke and it came out to stock. Incorrect piston with wrong PIN height Maybe?

  5. #5
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Did a quick search for Racerstoystore on eBay. Couldn't be found.

  6. #6
    Join Date
    Jan 2012
    Location
    Carthage NY 250r rules
    --
    2,345
    You could get a 250 jug,piston and head to use for now.The 300 topend has lots of potential with mods like porting and tighter compression,bigger carbs and aftermarket pipe.
    250r rules

  7. #7
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Update..

    Found a 78mm piston. Had my builder shave .100 off the bottom of the jug and just a fuzz of the head to bring the squeeze at or near 0 deck. With a .020 head gasket, compression should be greatly improved... The other main focus was on porting and Port timing.. 1, open her up. 2, correct the timing and casting flaws. 3, boost mid and top end. Everything's just about done just waiting for cometic to cut my 0.40 base gasket.

    Some additional Items I added while she was tore down was a PWK 38 quad vent Air striker, larger boot and billet spacer to go with the V Force4 Reed cage. The only pipe I could find to add to the combination was the DG National.

    This 83 still had the original chain and sprockets so I got them swapped out as well. Currently going through the brakes while I wait for the cylinder to return..


    Just wanted to take the opportunity to thank you guys for your help. Hopefully, with fingers crossed, should be up and running by this weekend!

  8. #8
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Click image for larger version. 

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    The problem child when it arrived at my shop

  9. #9
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Click image for larger version. 

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    As you view the pic the Piston is at TDC. It's over .400 in the hole. obviously somebody previously installed the wrong piston. Previous owner told me the compression was just a little weak! Ha

  10. #10
    Join Date
    Jan 2012
    Location
    Carthage NY 250r rules
    --
    2,345
    I wonder if that is the liquid R bigbore piston. If so these are the pistons everyone uses and they mill off the top or bottom to get the squish back. Another idea some of us 300r guys were talking about on AF.com was putting the 87-89 trx 250r rod on the aircooled crank to see if it would bring it back to stock 300r squish.
    250r rules

  11. #11
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    You are absolutely correct. It's an 86 or an 87 TRX Big Bore piston. I found it in 78mm, as well as. 78.5mm. it's a Wiseco piston, La sleeve had them.

  12. #12
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Quick update. Bottom of the jug was decked and ported. Head cc'd out @24cc's. Added V force 4 reeds, pwk 38 air quad vent striker, and a DG National to complete the upgrades. Everything should go back together this weekend providing the pipe shows up from being ceramic-coated. Just need to do some touch-up paint work on the frame maybe polish the silencer, tidy up some odds and ends and hopefully riding it.

    Thanks to those that contributed and pointed me in the right direction!
    Last edited by JPR95X; 05-22-2017 at 11:59 PM.

  13. #13
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    Then this little gem (82) popped up. Been stored in a basement the last 25 years. It's also a 300r on the original hondaline 300 bore. Plan on doing nothing to thisClick image for larger version. 

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ID:	243242 time capsule one other than putting the original plastic that came with the trike back on.

  14. #14
    Join Date
    Nov 2016
    Location
    Saskatchewan
    --
    23
    I'm pretty excited to get on my 300r should not be too long. What piston did u get to be able to only machine .100 tho off the bottom of they cyl? The ones I found needed like
    .375. the piston I got with my 300r ended up just being in spec so I just got some new rings.




    Sent from my iPhone using Tapatalk

  15. #15
    Join Date
    Apr 2017
    Location
    Omahe, Ne
    --
    11
    I will get the full details on the cylinder modifications this weekend along with the Piston part number used. The base of my cylinder was very rough and it appears that somebody has previously cut some off the bottom already. I will also include a total cylinder height as well.

    Jimmy

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