BW80 aka “The Witch”

Discussion in 'Some Assembly Required' started by greasyfatman, Dec 3, 2020.

  1. Nathan_66

    Nathan_66 Been here awhile

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    prev owner did a great job with this, note pipe angle is parallel to swingarm arm angle

    IMG_0230_rsz.jpg

    Happy New Year!
    #21
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  2. greasyfatman

    greasyfatman Long timer

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    Started it up today got a heat cycle in. Kicker went limp. Kicker keeps popping off the spring return. Will have to lay it open again tomorrow.
    #22
  3. greasyfatman

    greasyfatman Long timer

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    8FD38029-BBA7-4CF7-9E40-A6FD50FD8D8D.jpeg 4F67F1CD-D120-46F4-86A4-ADA9B640DCD8.jpeg B3B4ECB3-7250-4DC7-AAA9-5215A0EA97AE.jpeg

    Failure of the blue bike “Hansle” Chinese casting. Also the failure of the red bike Grettle blue failed with lateral contact and the other failed with exhaust port contact. Casting are so bad they can’t stay round, at temp or lean conditions. I might need to find OEM pw BW castings any one have some?
    #23
  4. greasyfatman

    greasyfatman Long timer

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    743DA233-D66E-4123-9073-90F8C792C70F.jpeg
    heated and ground. Think my fix is better than theirs...... yup Chinese shit don’t stay round with heat. Need to find a casting with the same bolt spacing as the thie two stroke scooter racers.
    #24
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  5. VX Rider

    VX Rider Long timer

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    would pressing a steel sleeve help that?
    #25
  6. greasyfatman

    greasyfatman Long timer

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    Not sure how sleeves work on air cooled bikes. Lots I don’t know about sleeves. Would that be the same ring material?

    probably best to find OEM real Yamaha castings. Going to start gobbling them up from ebay.
    #26
  7. greasyfatman

    greasyfatman Long timer

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    1B471C4E-46B5-486F-A522-F8B0CEDB8745.jpeg

    Errr ummm I might see a hot spot problem some amount of shelf, gasket shelf.


    @OnOff other than my stuff being totally unclean at the moment. Can we talk about air cooled head shaping?
    #27
  8. Pezz_gs

    Pezz_gs Cant ride for crap

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    performance-tuning-graham-bell P10.jpg

    Picture courtesy A Graham Bell - Two Stroke tuning
    #28
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  9. greasyfatman

    greasyfatman Long timer

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    D10411DB-7BBA-4ED9-A051-5F3DC636D0BD.jpeg
    definitely head shape is not great. Piston was hot had black on the back side of the piston, burnt oil. Motul 800
    #29
  10. bikerbill2021

    bikerbill2021 Adventurer

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    Followed you over from the BW thread, good shit here, so that replacement crank you picked up, was that a PW crank that was 18 degrees out on the woodruff key? If so, ill have to send the PW ebay crank back and have my local crank shop rebuild the crank, or do it myself since I do have a press to do it with :hmmmmm
    #30
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  11. greasyfatman

    greasyfatman Long timer

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    That was a china crank. RMATV also uses this think mine was nitch ind. maybe for the clone py80. I looked at replacing the whole ignition with PY80 parts but decided its a step in the wrong direction.


    What was wrong with your BW crank that an ebay crank was better? Think I had millennium rebuild mine with PROx parts.
    #31
  12. bikerbill2021

    bikerbill2021 Adventurer

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    Hmmmm Ill have to check when I get home, crank was an ebay special so def Chinese. Bikes have been living in what looks likes the Georgian swamps for the past 20 years with no jugs on them, so cranks are all rusted up. Not a huge deal to clean them up and get some fresh bearings, but if I can get away with just dropping in a new crank assy, I will. Just a play bike so if it blows up from the China crank then its a fool me once kind of deal, I'm not too worried about it
    #32
  13. greasyfatman

    greasyfatman Long timer

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    I don’t think it can handle 18^ of advance. May have to slot the hell out of the stator plate

    how does the rbay crank look? Silver or black? 3360E8A3-74E9-4B99-8A72-E547D088082C.jpeg
    #33
  14. villageidiot

    villageidiot Long timer Supporter

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    Could just have another jetway broached in the crank, no?
    #34
  15. greasyfatman

    greasyfatman Long timer

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    I haven’t found a local machine shop that can do anything competently. One shop held my steering stem for 3 months and never did the pressing. The next shop pressed it out but didn’t knurl the new stem they anti seized it instead.

    So a better problem statement maybe I don’t know how to find a good shop. Getting millennium to rebuild the stock crank was probably a better product then the china crank. Quicker turn around to, good company to work with.
    #35
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  16. villageidiot

    villageidiot Long timer Supporter

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    fair enough. Sucks that you can’t find good services anywhere.
    #36
  17. bikerbill2021

    bikerbill2021 Adventurer

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    Crank is all silver, but is the same niche industries crank that you said yours was.

    You said that you thought swapping to the PW 80 ignition was a step backwards? Parts are so cheap for these things and most of the shit on my bike is destroyed from the elements, so I dont mind swapping parts to the PW spec, had planned on running a second ign coil to get a lighting coil and get some lights on it, so ill be playing around in that area anyways. Like you I plan on tinkering around with the squish and what not, been reading a bunch of threads on here and thumpertalk about guys hopping up PWs/BWs, nothing extreme like some of these mad scientists do, I still want a reliable machine like my little ttr90, just want to give her a bit more pep.

    I'm wondering why the woodruff key is placed different on the PW crank? Did Yamaha advance/retard the timing to help with the bigger wheels of the BW maybe?

    I havent laid eyes on my bike yet, buddy is shipping it to me tomorrow, worst case Ill either rebuild the stock crank or send it out, my only concern is mushroomed ends from some one in its past getting frisky with a hammer
    #37
  18. greasyfatman

    greasyfatman Long timer

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    PY80 a china clone bike. Not pw. I have some notes on port timing and head shaping. Mine run well keep up with TW200 faster than honda monkeys.
    China cylinders suck ports are in random places. Best to bore and port your OEM cylinders. If you buy a PW OEM carb keep your slide and needle. I buy two fastace shocks and swaps springs see the BW thread. I have two 500lb non adjustable shocks if you’re interested. You can get a seat from china take the seat foam and put a good cover on it.
    BW80 seat pan is not replaceable.

    there fun as hell, I have my 701 on the lift now but will get back to the 80 in a few weeks. Need to find someone that will do my squish band machining.
    #38
  19. bikerbill2021

    bikerbill2021 Adventurer

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    Ah gotcha, makes sense on the PY80 clone.

    Well, I'll see what i come up with in terms of finding OE parts off ebay for this thing, or local boneyards. I dont have any of the stock top end, so ill either have to find a stock jug or just use what I have. Ive got a whole PW plastic kit with a seat b/c alas, the seat pan was missing too. Ill make things work though, not my first rodeo making plastics from another bike work on a different bike.

    Will those shocks you have bump the ride height up similar to moving the mount hole on the frame? what are you looking to get for one of them?
    #39
  20. greasyfatman

    greasyfatman Long timer

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    Shocks won’t move the ride hight just stiffer. I still bottomed some times with the 500 went to 1000lb/in also have an external front spring.

    I put links to the shocks I used in the BW thread. IF I didn’t have to go somewhere to ship them I would I would say cost of shipping plus 10$ but I don’t know when I could.

    I thought about an aluminum seat pan. It would stiffen the bike a good bit.
    #40
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