1975 340/5

[Deleted User]

Is there some special reason I can't pull the flywheel on this engine? I've got the recoil and belt drive pulleys off, but I can't get the flywheel to pop. Is there another retaining device, or something else that I am missing?

Thanks

[HoosierDeereMan]

You will have to remove the fan tower also. The ring gear on the flywheel will not clear the opening where the recoil mounts. They can be very stubborn. I usually have to put pretty good tension on the flywheel puller with a ratchet. Remove the ratchet and smack the nut on the puller a few times with a rubber mallet or a brass drift. Put the ratchet back on and and retension the puller and smack it again with a rubber mallet. You may have to repeat this several times. Be prepared to hear a big "pop" when it finally comes loose. Good Luck!

[Deleted User]

I got mad enough to really put some torque on it and it popped right off. Thanks a lot.


Yooper

[Deleted User]

Alright, now I have some more technical questions:
First, I have a 1975 400 that had a Tillitson HR carb on it when I bought it. Last season it broke down on me and I determined that it was having fuel supply problems. So I pulled apart the carb and cleaned it all up. There wasn't much there to clean, as apparently it must have been just about brand new.

I figured if the problem wasn't in the carb, it must be somewhere in the process of getting fuel to the carb. The only place I could figure that would be happening is if I wasn't getting any vacuum from the crankcase to the carb. I check the vacuum line and it was fine, so I'm thinking that there isn't any vacuum in the crankcase, bad seal or what have you. I ripped the engine down (hence the original question), and found that there was no gasket around the crankcase. So I cleaned and wet sanded both sides of the gasket surface and put down a layer of clear silicon RTV. Now I am getting a little bit of vacuum as the piston moves up, but I am getting A LOT of back pressure pushing out as the piston comes back down.

Now to the questions:
1. How much vacuum should I be expecting or need to run the fuel pump?
2. What else can I check for a vacuum leak?
3. Is the back pressure going to be a problem?

Thanks in advance.

[400brian]

I hate to tell you this, but RTV is not the proper sealant, Yamabond, Kawabond.

No gasket is used between the case halves.

Put new seals in while it was apart?

The case pressure pulses both ways.

[Rodimus Prime]

oh this is techincal.. first off i doubt an hr would fit probably an hd tilliston.

Second two cycle engines pulse because as the piston comes down it pushes the fuel mixture into the chamber and as it goes up creates a vacuum that sucks the fuel in from carb.

Tillistons carbs are usually problematic with the inlet needle and seat being gummed up and or not set right. although there is a handy little pressure tester for testing these it isnt completely nessary.

while you had it apart i hope you had crank rebuilt or at least check the rubber center seals for cracks.

[HoosierDeereMan]

About the fuel pick up problem, there is a fuel check valve attached to the end of the fuel pick up line inside the tank. It is a small screen with a spring around it with ball check inside. If the gas line has rotted inside the tank the check valve may have came off. The check valve may be faulty as well. Old 2 cycle gas takes a toll on these. If the check valve is bad or missing, the crankcase vacuum will not be able to pull gas from the tank to the carb. I have also seen the gas pick up line come off the tank fitting and fall inside the tank and will cause the same problem.

Another lesson I learned the hard was not to use automotive black gas line. 1st you can't see the gas in the lines to know what is happening. 2nd it will collapse and can come apart inside restricting fuel flow. The clear see through line is best. That way you can see the fuel moving in the hose to the carb and returning from the carb to the tank.