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Posted

I've been having some troubles after putting a cub motor together,thanks to everyone for any help the've given me along the way. Anyways i put new base gaskets on yesterday(used a thin coat of yamabond 4 on base of cylinder and top of case) and let it setup over night .I get up this morning go out bike fires up 2 kicks seems to sound better so i thought i had my air leak solved. So i spray some carb cleaner down under the carbs on top of the case and it died banghead I am ready to give up so if anyone could lead me in the right direction i would sure appriciate it

Posted

You plug up both exhaust spigots with air tight plugs and plug up both carb boots and put some air pressure in there. I think meat posted the parts he used... basically simple plumbing fittings.

I'll try to find it and post a link.

Posted

intake gaskets are sealed tight,and carb boots are brand new and checked both of these areas with carb cleaner(using the thin straw) and both seem to be sealed up

 

 

Thanks holyman i'll look forward to hearing from you btw how much air pressure i dont want to create any more problems???

Posted

You don't need alot of pressure less than 20 pounds should do it for a gasket or seal leak. I can't find the old info. All you need to do is get an expansion type freeze plug that will fit into the exhaust spigots OR you should be able to use the rubber plumbing caps that are used for PVC that have a hose clamp around the edge. The name brand is usually "Fernco" and they sell them at just about every home center in the world.

The intake boots should be able to accept a 1-1/2 inch male PVC glue fitting with a 1/2 inch female pipe thread. Install a "T" fitting and install an air gauge in one side of the "T" and a "schrader" tire valve and use a hand pump or REALLY low pressure hose to add air pressure. The clamp on caps should be able to handle 20 pounds.

After all that, mix up a batch of dish soap liquid with alot of water and brush it on all the areas you suspect are leaking. If it bubbles and/ or the gauge shows a drop in pressure, you've got your leak. Make sure you have your radiator cap off so you can see bubbles if you're losing pressure there too. Keep in mind that if you have the pressure on one side and the gauge on the other, you have a leak in your crank seal between the cylinders and the crank will need to come out banghead

Posted

Keep in mind that if you have the pressure on one side and the gauge on the other, you have a leak in your crank seal between the cylinders and the crank will need to come out

 

?????? would that be the gauge on one intake boot and the schrader valve on the other side and how would you determine whether or not your losing pressure at the crank seals

 

btw thanks for the info i will try it tomorrow

Posted
?????? would that be the gauge on one intake boot and the schrader valve on the other side and how would you determine whether or not your losing pressure at the crank seals

Yep, the schrader on the left intake and the gauge on the right intake for example.

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