Vintage Rotax 640 HRM question


Nov 26, 2007
Brainerd, Mn
Ok guys, I know there isn't a lot of vintage talk here but I'm positive you guys dealt with this stuff in the past. I'm sure I'll get ripped for this but here it goes...

I'm working on a 76 alpine 640. It has a HRM carb on it that will idle fine but as soon as I apply any throttle it floods itself out. I tried a HD that I had laying on the shelf but have had no luck with that either. Is it just a carb kit for the HR or am I missing something simple? I've tried inspecting the HR and the gaskets look good but maybe its something that can't be seen at a glance?

If it is just a carb kit, will any HR kit fix my problem?

I had one guy suggest the exhaust is plugged which could very well be the problem since the airbox and carb were full of acorns and mouse nest but I'll have to check that tomorrow night.

Any help would be greatly appreciated, the beer fridge has taken a beating over this one!!!

Thanks in advance.
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