I'm rebuilding a mac91 m/c (red/white) and am in need of a flywheel. Does this take a standard or 5 degree advance wheel? As far as I can tell from the info I have found, the part number is 68280. Is this the correct number?
Also, the carb is a Walbro bdc22. Are there any rebuild kits available anywhere? Is it worth kitting? I've had no luck looking. Thanks.
Mac 91m/c questions
Moderator: Rob Voska
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Jim Veenstra
- Posts: 3
- Joined: Wed Jan 09, 2008 2:41 am
- Vintage Karting items owned: 1973 Mc91 m/c engine
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steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: Mac 91m/c questions
Jim,
The motor takes a 5 degree flywheel and you can find them on ebay all the time. It will run just fine with the standard flywheel but the 5 degree wheel is better especially if you run the motor up to high rpm. The carb parts are also available on ebay frequently or you can get them from Terry Ives or Vince Hughes.... possible Hansen Duncan too. Sometimes the old parts are still in good condition and sometimes they are junk. The pumpers usually are fine as long as the black gasket material hasn't deteriorated. The metering diaphragm (the one with the metal disk) must be very flexible and have no holes... if it is stiff throw it away. The rubber duckbill valve is probably mush... if so it must be replaced with a new valve and you should get one of the new valves that do not swell up when exposed to modern gasoline. Look at the home page here for contact info of the guys who have the parts.
Steve O'Hara
The motor takes a 5 degree flywheel and you can find them on ebay all the time. It will run just fine with the standard flywheel but the 5 degree wheel is better especially if you run the motor up to high rpm. The carb parts are also available on ebay frequently or you can get them from Terry Ives or Vince Hughes.... possible Hansen Duncan too. Sometimes the old parts are still in good condition and sometimes they are junk. The pumpers usually are fine as long as the black gasket material hasn't deteriorated. The metering diaphragm (the one with the metal disk) must be very flexible and have no holes... if it is stiff throw it away. The rubber duckbill valve is probably mush... if so it must be replaced with a new valve and you should get one of the new valves that do not swell up when exposed to modern gasoline. Look at the home page here for contact info of the guys who have the parts.
Steve O'Hara