Seeley Mark 4 poor mans Supermono project

Discussion in 'Some Assembly Required' started by OldDog, Mar 22, 2013.

  1. OldDog

    OldDog aka Hugh Jarse

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    So, I have this replica Seeley Mark 4 frame thats been sitting in my shed for ages. It was originally built to take an XS650 motor with TZ running gear (i think). Anyway, the other day I was given the remains of a ZX10R ie front forks, wheels swingarm etc for a carton of beer (!) so decided, what the hell and have so far nailed the forks onto the frame to make a roller

    [​IMG]

    you'll notice the Ducati dirt bike "Il Mostro de Enduro" lurking in the background looking on in disapproval:D

    So the plan is to graft on the rear suspension, maybe even make it a mono rear shock as well. But the trick is....what engine? I was initially tempted to fit a 750 Norton twin to it, but I have plans for a cafe racer for that engine.
    I'm thinking a poor mans Supermono with a heavy hitting single will be a neater solution...but what engine??? I want an air cooled motor to save weight and complexity, I'm going for that stripped down look as well. So far on the list is an XR600 motor or possibly a Rotax motor. What other engines are out there that would a) be air cooled, b) relatively inexpensive to modify and c) make a huge amount of grunt? I'm thinking 4 stroke, but what 2 strokes would do the trick? Obviously a bullet proof 2 stroke, I don't want to be forever fixing it!:lol3

    Suggestions welcome

    Cheers

    Bill
    #1
  2. FatBoyCrash

    FatBoyCrash Buckle up SpankY!!

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    Well.... Air cooled single..

    The obvious choice would be a yamaha IT 490, only because it has a 5 speed 'box. Heaps of them around, just gotta find one not attached to one of those special owners that doesn't think it's worth it'sweight in gold... which they are not.. I used to (think 10 - 15 years ago) track day with a bloke that had shoe horned one into a RZ 250 frame. It went well, once you got it started.

    The air cooled kinda narrows it...

    I have a VOR 530 sitting in the shed at my nephews in Newcastle. You can have the donk if I get the suspension and wheels for my "Il Mostro" :-)
    #2
  3. Kennon

    Kennon Been here awhile

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    XT 660 engine are quite common around me not sure in the Australia though, BMW 650 engine?

    Kennon
    #3
  4. bk brkr baker

    bk brkr baker Long timer

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    The air-cooled Rotax is tough, powerful and proven to make big H.P. Get one and be happy !
    #4
  5. MODNROD

    MODNROD Decisions, decisions

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    You can make good grunt out of anything man, easy-peasy. :deal
    Starting with a KLX650/KTM690/XR650 will help a lot though!

    What about a ER6 Kwaka motor? Light, compact, at least 20HP up on the singles to start with.

    Nice Ducketty! :clap
    #5
  6. Jimmy the Heater

    Jimmy the Heater Tilting the Horizon

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    DR650 engine?? There is a 780? big bore kit for it now. Can't get much more grunt than that.

    Also like the 650 Rotax if you can stomach water cooling.
    #6
  7. OldDog

    OldDog aka Hugh Jarse

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    Hmmmm well sitting in my little shop of horrors are several XR600 motors and one pre -96 DR600 or 650 motor (how dya tell?). Mind you i'm not so sure theres much in the way of aftermarket modification stuff available for the old DR motors.

    Shannon what does that VOR have in it? A Rotax? Oh and when are you gonna buy that Duc so we can start doing evil things to it:evil Is it air cooled? I don't want the added complexity of water cooled....plus heaps of fins will look cool. I suppose I could be tempted by an IT or WR490 motor...hell any of the big bang motorcrossers would be an option....KTM495 anyone?

    Rod & Kenno thanks for the input but I have a bee in my bonnet over aircooling at the moment, not sure why but everything I'm building is air cooled all of a sudden:huh
    #7
  8. FatBoyCrash

    FatBoyCrash Buckle up SpankY!!

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    Mate!! No brainer! XR600 motor. Especially if it's one without the silly twin throat carb idea that honda backed themselves into a corner with. Strong motors, plenty of easy to find go fast bits out there for them.

    The VOR has it's own brand 500 odd cc liquid cooled motor, so that's out.

    I'm looking for the right Duck to molest! I have the money but want a pre 98 carbed version. I thought I had one but the vendor went all squirrelly and dissapeared. I notice it's back on fleabay but I'm very wary of it now. I'm thinking pay a bit more for a good'n so I don't have to rebuild the bloody thing from tyre valves up.........

    Keep your eyes open for me!! :-)

    I hear you about air cooling. I have some 'rules of thumb' about buying bikes now. Air cooled, no more than two cylinders and under 5k. Anything else feels like tearing up $50 dollar notes for the fun of it...
    Plus, Phil Irving wrote something in his biography about more than two cylinders that has stuck with me. He wasn't complimentary, shall we say... :-)

    #8
  9. NortwestRider

    NortwestRider TRIPOD ADVENTURER !!

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    We had a TZ250 frame with a LC KX500 2stroke motor in it back in the 80's.MAN o MAN talk about a handfull !!,we smoked all the 4stroke singles in the class before they out lawed it.
    We were making 65+ Hp at the rear wheel.
    I would love to build a supermoto someday with a KX500 motor in it..


    Sent from my iPhone using Tapatalk
    #9
  10. FatBoyCrash

    FatBoyCrash Buckle up SpankY!!

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    My ultimate dream build would be a Aprilia RS 125 or Cagiva mito with a Husaberg FE650 motor in it.... Yeeha!!
    #10
  11. OldDog

    OldDog aka Hugh Jarse

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    Hmmm bad news, the XR600 motor doesn't fil the gap in the frame, looks all wrong like a unit Triumph motor in a featherbed frame:hide .....but good news, I have a spare Triumph 955 Daytona motor sitting here:huh Maybe I should make a Super 3? This weekend I'll try and lever it into the frame and this time I'll get some pics!

    Shanon, may have to move the Il Mostro project on to free up some cash for next years trip to the USA, let me know if yer interested maybe we can do a deal.

    Cheers

    OD
    #11
  12. FatBoyCrash

    FatBoyCrash Buckle up SpankY!!

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    Hey mate!

    Yup, interested. Much easier to buy one where all the hard work is done.... Pm me a target!!! :-)
    #12