The Yamaha LS3 has a Mikuni VM20 carburetor. It's the same as the Yamaha RS100. As I couldn't find a repair set for the LS3 I bought the one for the RX100.
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| Yamaha RX100 with also a Mikuni VM20 carburettor |
The only difference was the air-mix-screw being a bit shorter. If it's not working I can easily replace it with the old original one.
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| Carburettor repair kit Yamaha LS3 - RX100 |
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| Exploded view Yamaha LS3 carbie |
This carb was in desperate need of some TLC.
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| Mikuni carb Yamaha LS3 - left |
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| Mikuni carb Yamaha LS3 - right |
Before I opened the carbie I cleaned the outside with wax and grease remover and with a couple of steel wool pads.
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| Carburettor in need of some TLC |
The bottom of the bowl was filled with gunk and rust, amazing how the bike ran with all the dirt in the bowl and main jet.
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| Dirty float bowl Yamaha LS3 100 |
After cleaning the bowl and taking out the main jet and banjo bolt I took off the floater so I could take out the valve seat and needle.
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| New and old valve seat and needle Yamaha LS3 |
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| Carburettor nozzle |
With some compressed air I cleaned all the passages and with a wooden toothpick you can reach and clean all the hard to reach corners.
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| Mikuni carburettor with hand choke |
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| Mikuni carburettor with hand choke pulled out |
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| Mikuni carburettor with pushed choke |
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| Original air screw longer than new one.. |
As the carburettor set didn't came with a new nozzle (for some reason they almost never do) I just cleaned it and for now I'll keep the original jet needle. When the bike is running again I'll try both needles and see which one is best.
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| Mikuni main jet and banjo bolt |
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| Float and new gasket Mikuni carb |
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| Mikuni carburettor with Yamaha Reed valve |
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| Mikuni carb attached to reed valve Yamaha LS3 |
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| Mikuni carb cleaned and ready to use |
