what do you get if you combine and RS 125 and a 640 LC4???

Discussion in 'Some Assembly Required' started by muttley92, Mar 30, 2013.

  1. muttley92

    muttley92 Adventurer

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    A quick update. The camshaft has been changed! The engine is back together with fresh water pump seals too. It should be back in the frame tomorrow. I have a higher pressure rad cap to put on and a filler neck to make up before it will run again. And then the tank needs sealing. Should be a good week
    #61
  2. muttley92

    muttley92 Adventurer

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    It runs! No nasty knocks or noises this time. Will soon have it back together. The tank has been sealed and should be leak proof. I've made up a battery box and had to relocate the filler neck, just waiting on some rad hoses and it'll be ready to mot! Can't wait to ride this thing!
    #62
  3. Kennon

    Kennon Been here awhile

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    good to hear how far its come now.
    #63
  4. LC4nicator

    LC4nicator Certified Wino

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    That's a great job mate.
    Agree with others regarding the front engine mounts versus vibrations though.
    Keep an eye on that.
    Once that LC4 starts to rev you'll feel it.
    I've had 2 LC4's now.....620SC & the 640 Adventure
    Bracing those mounts with some strips would be good insurance.
    Make sure that oil tank is filled and bled correctly.

    There's a great link on here on that subject:
    http://www.advrider.com/forums/showthread.php?t=57107

    Also put some wheely bars on it.....you wont be able to keep the front wheel down...HaHaHa!

    Will be great to see it run....please youtube.
    Cheers from Australia.
    Con.
    #64
  5. muttley92

    muttley92 Adventurer

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    Still waiting on cooling hoses so i knocked up a temporary system to run it up.
    http://www.youtube.com/watch?v=I71EnqFUtU4
    I'm not sure the temperature guage on the koso clocks read correctly though. It reckons 160C before the rad is even slightly warm and I somehow doubt it. May have to run a temp lowering coolant in it.

    On the other hand I bough a haiju battery which is excellent.
    [​IMG]
    It weighs 670g! No joke and was a very reasonable £75.99 it's around 110CCA and has a useful little tester button on top. It doesn't drop off like lead acid batteries do as they crank and it starts the bike no problem.
    #65
  6. dnrobertson

    dnrobertson Big Bike, Slow Rider

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    Just found this thread and was going to suggest you go with one of the higher lift cams for more performance, but no point now.

    Build looks nice.
    #66
  7. Mercury264

    Mercury264 Once you go Triple...

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    Is his name Richard by chance ? If so, small world.....he's my BIL.
    #67
  8. muttley92

    muttley92 Adventurer

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    It was indeed. Funny how small the world is really, especially in building bikes. My tank is now leak proof for reference. My cooling hoses have arrived, hoping to test the bike tomorrow depending on the weather.
    #68
  9. muttley92

    muttley92 Adventurer

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    So I took the bike up the road today and it is going to be awesome! wheelies in second no problem... However it is a sod to start when it's hot! I've never actually managed it yet, just to flatten the battery (and it's a long push home). Does anyone know roughly what the jetting is for an FCR 41 with performance exhaust and a cone filter on it? It would be much appreciated.
    #69
  10. pennswoodsed

    pennswoodsed lizards,bugs and me

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    More performance ?!? wouldn't it already have twice the hp and 3-4 times the torque of the original engine ?
    Best,Ed
    #70
  11. Randy

    Randy Long timer

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    Yeah, maybe so. But, if replacing the cam anyway... More is better, ya know... :evil
    #71
  12. muttley92

    muttley92 Adventurer

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    5 times the capacity, 4 times the power and 3 times the toque just all over the rev range rather than in 2k at the top :rofl just need to sort out the carb settings
    #72
  13. yokesman

    yokesman Been here awhile

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    try starting when hot with the fuel valve closed and no throttle.
    #73
  14. kellymac530

    kellymac530 motorcycle addict

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    Valve adjustment !!!

    On every Lc4 motor I have owned, 3 of them from 400 to 620, if the valves were out of adjustment even a little they were a bear to start especially when hot. It was worse when I swapped to FCR carb from the Mikuni CV on my 400...what a PITA.

    Really good valve adjustments always helped and once I got used to the Lc4's that is how I knew it was time to adjust the valves....that is all given that the jetting is right....Valve adjustments are a simple starting point though.
    #74
  15. muttley92

    muttley92 Adventurer

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    The clearances were done when the camshaft was replaced. Sorted the hot start issue by taking the air screw out by a half turn. The current jetting is 168, 85, 45. I might go a size or two up on the main depending on a proper test ride after the cooling is sorted. The cooling problem has been put down to the water level in the rad being below the level of the pump, need to make a header tank or get a secondary electric water pump. I'm in Germany for the formula student event at the moment and will be back Monday. Hoping to make some progress then.
    #75
  16. Roadracer_Al

    Roadracer_Al louder, louder, louder!

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    Handy guy to know!

    In for the rest. Nice work. I am a fan of motor swaps - I put a KX500 motor in a TZ250 chassis, and a XT600 motor into a GS500 chassis for racing friends about 15 years ago. I must be a curse, however: the KXTZ owner had a spinal infection that sidelined him from racing permanently, and the XTGS owner was killed in a car accident. Neither ever ran in anger.
    #76
  17. muttley92

    muttley92 Adventurer

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    So the cooling problem has been narrowed down to the water level in the rad being below the water pump. I scored these off of ebay for £2.20
    [​IMG]
    [​IMG]
    BARGAIN!!!


    I rigged them up from the bars so that they were of sufficient height and plumbed it as close to stock as I could.
    [​IMG]
    [​IMG]
    At 105C on the clocks the rad was hot! Result. So I need to make a header tank and possibly get a booster pump if it runs hot at idle.

    On a high note the bike now starts first time from hot :D
    #77
  18. mbrick

    mbrick Been here awhile

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    If I understand the problem with the first radiator... can you lift the front end up to 45° or so to get the air out of the pump and prime it, and put the rad cap on?

    Shocked at how cheap those dirt bike radiators were.

    Agree with the others, you should forego the oil tank due to bleeding and drain hassles, don't want some air going through to the big end of the rod.
    #78
  19. Krasniewski

    Krasniewski I don't ride much.

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    Just read the whole thread - great work so far! This is going to be a really sweet ride - can't wait to hear some riding impressions.

    Maybe my opinion doesn't count for much, but the build quality looks really quite good, and that includes the motor mounts.

    Best of luck in the completion. :thumb
    #79
  20. muttley92

    muttley92 Adventurer

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    Been busy recently with work but just bought an electric booster pump to try and sort out the cooling. Will hopefully get it fitted this weekend and get back with an update. The tank has started leaking again, not best pleased with that but it's a reason to make an alloy one. I'm going to get a tig set in a couple of months and I'm planning to make a fuel tank, a header tank, reinforce the engine mounts (not because anything has cracked, but since I'm getting a weld set I might as well do it) Make a bracket for the oil tank. And eventually start work on a frame jig for my next project, but going to finish this one first. I'll soon be after another set of rads too. Another update soon.
    #80