Paging Petel

Discussion in 'UK Motorcycles' started by Oldbloke, May 28, 2004.

  1. Oldbloke

    Oldbloke Guest

    As the acknowledged expert on extracting the most power from the smallest 2
    stroke can I please ask:

    Theoretically, if one was going to "modify" the exhaust port on a 2 stroke
    moped (for instance a TS50) where would one file, and more importantly,
    where wouldn't one file.

    TIA

    --
    Dan L (Oldbloke)
    My Bike 2000 Honda CB500
    M'boy's Bike 1990 Suzuki TS50X (Heavily fortified)

    BOTAFOT #140, DIAABTCOD #26
     
    Oldbloke, May 28, 2004
    #1
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  2. Oldbloke

    Fr Jack Guest

    The varlet known as Oldbloke did proclaim to all assembled:
    In bed.
     
    Fr Jack, May 28, 2004
    #2
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  3. Oldbloke

    Oldbloke Guest

    Next.....

    --
    Dan L (Oldbloke)
    My Bike 2000 Honda CB500
    M'boy's Bike 1990 Suzuki TS50X (Heavily fortified)

    BOTAFOT #140, DIAABTCOD #26
     
    Oldbloke, May 28, 2004
    #3
  4. The whole lot of ports need moving up.
    You need to make a spacer shaped like a base gasket from
    aluminium and sandwich it between two base gaskets,
    then skim the top of the barrel to restore the compression
    ratio.
    You will need to make a proper expansion chamber.
    You will need to put stronger springs in the
    centrifugal clutch so you can reach the power band
    while starting off.
    Get a book such as Bell's Performance Tuning - 2 Strokes
    to see where the ports should be.

    The last moped I looked into had an exhaust port that
    was oval instead of round, but it was obvious where
    it needed grinding.
    A bigger carb would help.
     
    Old Fart at Play, May 28, 2004
    #4
  5. Oldbloke

    Petel Guest

    Suzuki TS50? 1977--?
    TS50 has no centrifugal clutch..It`s multi-plate same as any geared bike.
    Couldn`t hurt.
    Not really, the idea is to make the best of what`s provided.In this instance
    and without details a mild tune would involve...
    [1] Reed valve induction...replacing the std metal reed petals with 0.3mm
    carbon fibre reeds (£9ish) this allows them to open sooner and close quicker
    allowing more induction a less blow back through the reed valves.
    [2] Rotary valve induction....carefully taking out 0.5mm of the leading edge
    of the circular valve to allow earlier and more induction without
    compromising the transfer.
    [3] Correct jetting...believe it or not any carb will run a bike [9]without
    a throttle slide or needle.. as long as the pilot system is set-up right and
    the cap is blanked the bike will run.
    Concentrate on the mid/full range which is controled by the needle position
    ( move the lil `E` clip UP the needle to weeken and DOWN the needle to
    richen, most have 5 slots)

    Don`t mess with a Dremmel and grind stone on the barrel ports, they make no
    real difference to performance until you start swapping exhausts, going into
    resonance and back pressure, etc.
    You can increase flow by flowing the exhaust port without touching the specs
    as it enters the barrel just by smoothing the ridges and polishing..however
    carbon build-up normally ruins all the hard work in the first 100 miles or
    so:-(

    Mail me for any probs you have as I can return diagrams etc better than
    posting it.
    Save UKRM loads of unneccessary 50cc shite as we know everyone on here is a
    wheelie hero/RTB/track God/and excellent mechanic and have no need of
    service mechanics/torque wrenches or advice ;-)
    --
    Petel .
    02 M2 Buell.
    C90-ZZR.
    [9] It does run but don`t touch the throttle, it`ll bog out.
    http://homepage.ntlworld.com/peteh1/website/index.html
     
    Petel, May 28, 2004
    #5
  6. Oldbloke

    Petel Guest

    AMMENDMENT:

    1990? Just read your sig!

    Twist`n`go or geared stroker?

    There is a huge difference between the two.

    I can help on both but need details on make /model and configeration...I.E
    geared/reed/rotary valve/carb make and size plus any more info inc. pre-mix
    or auto-lube oil/plug sizes and rating...easy just post a URL link to your
    son`s bike, a brochure scan or photo will be good enough and I`ll source the
    make and model.
     
    Petel, May 28, 2004
    #6
  7. Oldbloke

    Oldbloke Guest

    Okay, details as follows:
    1990 Suzuki TS50
    http://www.motobykz.co.uk/Suzuki/Suzuki.htm
    2 Stroke with Autolube, 49cc Bore: 41mm, Stroke: 37.8mm, compression ratio:
    7.1:1
    Reed Valves, 5 manual gears
    Trail type bike
    Mikuni VM15SH Carb, 67.5main jet replaced with a larger one (not too sure,
    but it's about a 97 I think).
    Plug: NGK BP6ES
    Bike currently maxes out at just below 40mph, ideally we would like to get
    nearer to 50mph.

    I have inspected the piston /barrel, and they seem fine (no scoring), also,
    I decoked the head and exhaust port last week, and the reeds appear okay to
    me. This weekend we plan to replace all the gaskets, as the barrel to
    crankcase one is a homemade cardboard one, and there is evidence of loss of
    compression around the head gasket. The exhaust bolts are fucked, so I plan
    to replace these with studs to get a good gas tight seal. Also, the inlet
    side of the barrel seems to have been filed out to a circular profile,
    whereas as standard it is oval. I decoked the exhaust a few months ago, but
    that is another story altogether which resulted in an eye / caustic soda
    interface. I may fire up the barbie and cook the fucker tomorrow to loosen
    any stubborn crap.

    Any advice you can give would be much appreciated.

    Regards


    --
    Dan L (Oldbloke)
    My Bike 2000 Honda CB500
    M'boy's Bike 1990 Suzuki TS50X (Heavily fortified)

    BOTAFOT #140, DIAABTCOD #26
     
    Oldbloke, May 28, 2004
    #7
  8. Oldbloke

    Petel Guest

    <snipped>

    Morning ;-)

    There are several ways to go...Big-bore..Tuning the std bike... etc but it
    all involves money and luck!

    The first thing I`d do is take out the reed block and check if the petals
    are plastic (normally a white/biege colour) or metal (use a magnet) then
    replace them with carbon fibre items.
    An old part # but it might help is BY8610 for Boyer carbon petals for the
    TS50X.

    Big Bore is £75ish. That takes you up to 69cc and into the Gray Zone as far
    as law and 16 year olds is concerned.
    Part# is IM8BBTSX.

    My apoligies to the guy that suggested a bigger carb last night ( and I
    dissmissed the idea) because it might help with both the above.

    Get yourself to a breakers and grab a Mikuni VM20ss off an old Yam DT
    100.You might have to cut away part of the rubber boot from the VM15 to make
    it fit or get the original rubber inlet manifold with the deal. Should`nt
    cost more than £20ish depending on the breaker.
    ID# on the carb is 3A360 and they run a #130 main as std.
    Suggest going down to a #100 and try from there.
    Air screw out 1.5 turns.

    Air filter....Your call....Junk the airbox and run a K+N onto the original
    rubber boot that went to the airbox, not direct onto the carb mouth as
    resonance with too short an inlet tract can ****-up the jetting and you need
    a sort of plenum chamber to get the carb to work properly over a wide rev
    range.
    Use the original airbox but make sure all the airways and inlets are at
    least the same surface area as a 20mm carb.
    Surface area of a circle is Pi x R squared (I think) ;-)
    Might mean drilling some holes in the box in the quest for speed but
    remember most of these airbox designs are not for maximising power but for
    minimising noise and emmissions.

    Exhaust...Your call...Junk it and find and expansion chamber from an old RD
    or simply lessen the baffleing by drilling more holes.

    All this will create more noise and might weaken the auto-lube mixture to
    the point of seizure!
    I`d reccommend setting the oil pump to normal spec (where the marks align)
    then going 2-3mm over the line so the pump is running richer, use a good
    synthetic oil and check it`s not Pre-mix only! (I`ve done that and pre-mix
    dos`nt work well in an auto-lube system).

    Finally go colder on the plug. Try a BP7ES or if you can get one a fine wire
    race plug # BP7EG.

    HTH and g`luck.
    --
    Petel .
    02 M2 Buell.
    C90-ZZR.

    http://homepage.ntlworld.com/peteh1/website/index.html
     
    Petel, May 29, 2004
    #8
  9. Oldbloke

    Oldbloke Guest

    The reeds are (I think) Boyesen Racing Reeds (according to the sticker on
    the side panel), but they look more like plastic to me.
    Don't really want to flaunt the law to that extent
    We are currently scannin ebay for a VM 20 Carb
    Tried changing the filter for a small jobbie my lad bought from the local
    car shop, but the inlet was just too small. We have resorted to the the old
    airbox, which has been drilled, and we have halved the thickness of the
    filter media. We will look for a K and N cone type with a similar diameter
    to the carb inlet.
    There is no baffling in the exhaust, and the end can is a Dep tuned jobbie.

    I barbecued the exhaust today for about 2 hours, and managed to loosen quite
    a lot of crap.
    I haven't investigated the pump yet.
    We are currently currently running a BP6 so a plug change is next on my
    list.
    Many thanks. Today I removed the head and Solvol'd the combustion chamber
    to a mirror finish with a Dremel clone.
    I also Dremelled the exhaust port to a smooth profile (it was very rough)
    and polished, as recommended.

    The bike still maxes out at 40, but doesn't feel so stressed. Also, at 40
    it is only at 8000 RPM, so I reckon changing the front sprocket to a smaller
    one may release a few more revs.

    I will keep you posted.

    --
    Dan L (Oldbloke)
    My Bike 2000 Honda CB500
    M'boy's Bike 1990 Suzuki TS50X (Heavily fortified)

    BOTAFOT #140, DIAABTCOD #26
     
    Oldbloke, May 29, 2004
    #9
  10. Oldbloke

    Petel Guest

    They did two types under the `Racing Reed` name.
    You really need to go carbon fibre, it`s a lot more flexible but with the
    right amount of stiffness to stop blow back and loss of crank compression.
    We swopped plastic for carbon on a new Suzuki Katana twist`n`go and the
    differrence in throttle responce was instant.
    Don`t limit yourself... A VM 22 will fit as will a Dell Orto 21mm. It`s all
    in the jetting.
    You can custom build the airbox by buying Mallossi Red Filter foam.
    It`s always better to run with an airbox of sorts (no matter how many holes
    in it ;-)
    Do a Google for .....Taffspeed...PMtuning...Chiselspeed..and Beadspeed.
    Any of them stock this filter foam and it`s very free-breathing.
    Cost...about a fiver for a sheet.
    Er... do it!
    What`s the red-line?
    8 grand seems about right to me.
    Most 50cc strokers make max power at 8-9k and gain nothing over this
    benchmark.
    Remember we are talking a single cylinder here...not a Kwack triple or
    Aprillia RS250.

    Leave the front sprocket (14/15tooth?) go down on the rear.
    From EG. 40-38 or 36-34. This will give you more top-end but decrease
    accelleration slightly. Also it means you won`t need a longer chain, just
    nick out a link if the chain is too slack,

    Let me know how you get on.

    --
    Petel .
    02 M2 Buell.
    C90-ZZR.

    http://homepage.ntlworld.com/peteh1/website/index.html
     
    Petel, May 30, 2004
    #10
  11. Oldbloke

    Oldbloke Guest

    M and P seem to do CF reeds for the TS, this could be the next mod, although
    whoever replaced the last set severely overtightened the retaining screws
    and fucked up the heads, which will mean a major struggle to get them out,
    and replacement of the screws (could I replace them with conventional hex
    head bolts, or is there some technical reason for them being cross head type
    machine screws?)
    Will the carb to head casting be the same size on the bigger carbs, or will
    I need to have an adaptor plate made up?
    This very much seems to be the case, with no airbox it runs crap, and with
    just a gauze over the end of the airbox connecting rubber it runs crap. As
    the "media" is actually the packing foam from a set of crystal glasses,
    replacement with pukka stuff (or a K & N type thing is in order. Also, for
    some reason the standard airbox connecting rubber is too short, and has a
    habit of parting company from the carb.
    Will do.
    Indeed, the bloke we bought the bike from gave us the Dep pipe, as he had to
    remove it due to complaints from the neighbours.
    We did a long run yesterday (see separate BOTAFOT thread) and lubrication
    does not seem to be a problem ATM. Also, when on the move it produced very
    little smoke (this is a good thing, yes?)
    Around 11,000
    It'll rev over this through the lower gears, which is why I suspect the
    sprocket sizes (I could be wrong though).
    Watch this space
    Why not the front sprocket ?
    Will do, cheers for your guidance, it's much appreciated.
    Having test run the bike by screaming around the local lanes, I can confirm
    that small strokers rock mightily. Now I definitely know I should have had
    one as a teenager.

    --
    Dan L (Oldbloke)
    My Bike 2000 Honda CB500
    M'boy's Bike 1990 Suzuki TS50X (Heavily fortified)

    BOTAFOT #140, DIAABTCOD #26
     
    Oldbloke, May 31, 2004
    #11
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