Sunday, September 8, 2013

The Champ

Nothing is more depressing than to get your new-old Yamaha Champ LC50 scooter home only to find that there is not much info about it.  What I've tried to do with this blog is create a place for Champ owners to discuss and share information, gripe and generally have fun with these old bikes.

One of the most interesting and vexing aspects of these little bikes is over the top engineering, if you have ever taken those two top covers off you know what I'm talking about.  If you have never taken the cover off, be prepared for the shock and awe of what surely must have been the result of Japanese engineers at Yamaha in the late 70's totally baked on crack and steroids trying to out engineer the guys at Honda, Suzuki and Kawasaki!  I think they succeeded!  You be the judge.

This is only a 49cc 2 Stroke


I'm still in somewhat of a state of shock with all the pumps and vacuum hoses in this little 49cc engine.  While getting the carb dialed in can be a task it has a surprising amount of pep for such a little bike.

My Champ is just shy of 4000 miles as of the writing of this blog and gives no indication of slowing down, however one of the most common problems that can afflict the Champ is the bimetal valve (BMV) which sits on top of the cylinder head and acts as an automatic choke, it's a temperature actuated spring thermostat. These are not manufactured any more and when they go are problematic to deal with since you're Champs engine will run as if the choke is on. In later posts I'll go over a hack that should give you some options for running with BMV that's toast.

Otherwise here's a lamp shot of my Champ with my XR 250L in the background.  Love the look of that chrome and glass on the Champ!





19 comments:

  1. Hey folks not sure when a post was last put up here however I'm in a mess here my little dog and I :-) are trying to get this lc50 champ running but its so hard given the lack of clear photos of the area near the battery can someone out there email or post some clear photos of where all the wires go in the battery area ...? do i even need a battery given the kicstarter ... thanks you in advance ...Michael ....littlecroatia@gmail.com

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  2. Hi John, I was reading through your posts and was wondering about the BMV hack... Haven't been able to find it and would love some info. I realize this post is 2 years old, but figured it was worth a try. Also, your blog is awesome!

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  3. I would also like to know about the BMV hack... I also need the petcock!! Can't find one anywhere

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  4. Anyone get their champ running with the bad BMV???

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  5. Anyone get their champ running with the bad BMV???

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  6. Anyone get their champ running with the bad BMV???

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  7. Anyone get their champ running with the bad BMV???

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  8. Ebay a yamaha pw80 carburetor and choke cable, they're cheap and bolt right on the intake manifold. I add a open foam style air cleaner also cheap on ebay.

    Just cut and plug vacuum lines at the cylinder head for the Bmv. Next remove the old carburetor all vacuum lines and fuel petcock.No more Bmv....

    Run a gas line from gas tank to new carburetor with a inline shut off valve and filter.Oil injection line will fit on the new carburetor.

    Also the pw 50 big bore kits on ebay are cheap and will bolt right on this bike. You'll get you more speed and take off power. The carburetor and cyinder work very well together. Good luck

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  9. So does the PW80 carb require any rejetting. My petcock went bad so I set up gravity feed to engine. When I turn fuel on gas poor out back of carb. Have to assume the carb has a bad float (already cleaned and reassembled) and the vacuum petcock has been hiding the problem. Also will any fuel petcock work on the bike. The original is non existent.

    If I do the pw80 carb should I do pw50 60 bore to help the carb. Assuming jetting is different.

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  10. I'm the proud owner of a champ.... And it's for sale! Any interest?

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  11. anyone know where i can get a fuel cap from?

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  12. where do i find a fuel pump kit??

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  13. i have an 81 champ that i will be selling. Blue with 1500 miles. Has the lower fairing which is cracked and a basket on the rear.
    Any interest out there ?

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  14. I'm looking for a mellow white front fender - any ideas about where I could buy one?

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  15. I should have stated that it's for a 1980 Champ - yellow and white. Thanks!

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