So I brought home this engine and the guy said it was setup to run on alcohol. So I have some questions. One what would be the proper oil/alkey mix. Two how would I tell if it was actually set up to run alcohol. Three if I tried running an oil/ gas mix could it hurt anything or if it wasn't set up for alcohol and I used a oil/alcohol mix could it hurt anything. Any info would be great, I'm a noob to two stroke and alcohol. I have other questions about these motors so if anyone is familiar with them or you know anyone familiar with them please get me in contact with them.
Help with mcculloch mc70.
- Thread starter james ackerman
- Start date
- Tags mc70 mcculloch
Post up a pic of the engine and specifically the carb. It takes twice as much fuel to run alky! The carbs will be very different. They will typically be a "double stack" to supply enough fuel. The alky does tear up the gaskets and seals. I would not try and run it unless you open it up and make sure the bearings are free and there is no corrosion. It does not take much to grenade one of these engines! Leaky seals will make it run lean...and that is bad! Good luck!
I make gaskets for a couple of McC rebuilders and can give you a referral if needed
I make gaskets for a couple of McC rebuilders and can give you a referral if needed
The BDC carbs would be set up for either gas or alky in that configuration. First thing you should do is get rid of it! I do make replacement flapper valves like in the first stack, but the diaphragms are expensive. Secondly look down the trhoat of the carb. It goes straight through with little or no venturi. Not great for part throttle applications. Remember, this is a racing motor...WFO or idling!
Vince at intake has an adapter and carb that is a steal! He reworks the Tilly clones and makes them useful! DO NOT buy one from eBay and expect it to work outta the box! Get the carb and the red adapter plate. I use both pieces and Vince knows his stuff! Tell him "Eric the gasket man" sent you!
If you want to open it up and inspect, send me a PM and I will make you a deal on a gasket set...or if you want to sell it?
Vince at intake has an adapter and carb that is a steal! He reworks the Tilly clones and makes them useful! DO NOT buy one from eBay and expect it to work outta the box! Get the carb and the red adapter plate. I use both pieces and Vince knows his stuff! Tell him "Eric the gasket man" sent you!
If you want to open it up and inspect, send me a PM and I will make you a deal on a gasket set...or if you want to sell it?
Eric is right, you should open it up to check out the inside, if you can't do that at least pressure check the engine to make sure you don't have any air leaks. If it pressure checks ok, pull the top plate off the carburetor to make sure there is no corrosion in it, if there is that means the previous owner did not flush the engine after running alcohol. If the carb is clean then run a flush mix through the engine with no load and low to mid rpm for a couple of minutes. I use pump gas with 12 oz of Marvel Mystery Oil as a flush. You will probably need to lean both mixture screws down to get it to run clean. When you run alcohol use a good degumed castor, Burris or Blendzall, 8 oz per gallon of alcohol and always flush the engine after running alcohol with the above flush mix or pump gas and a good two cycle oil, do not use synthetic oils. If you run pump gas with castor you still should flush the engine as the caster will gum up the bearings if allowed to set.
Vinces carb would be much more rideable. WFO open is great...sometimes! But not all the time! It is worth rebuilding. It is a nice motor and worthy of the investment. You should not have a problem trading for a WB 820.
Alky just seems like too big of a pain for a minibike...too much maintenance.
The BDC carbs were great for karts, but you don't want to fool with it. They have what is called a "duckbill" valve that is problematic. They are hard to find and prone to breakage from the fuel. I guarantee that the one in the carb now will turn to dust when you try and get it out! Go with a China Tilly from Vince or a real Tilly from EC Carburetors
Alky just seems like too big of a pain for a minibike...too much maintenance.
The BDC carbs were great for karts, but you don't want to fool with it. They have what is called a "duckbill" valve that is problematic. They are hard to find and prone to breakage from the fuel. I guarantee that the one in the carb now will turn to dust when you try and get it out! Go with a China Tilly from Vince or a real Tilly from EC Carburetors