Cmb 67 Flywheel Loose?

[Tim Strange]

I have been trying to sort out some issues with a 1/8 PT 8255 hull and have been convinced that it has been having some fuel feed issues...hopefully I have that sorted out.

After my last run I noticed that the flywheel seems loose. I am fairly certain that the bearings are OK although they may be close to needing to be replaced.

Seems to me that a while back some have had issues with the flywheel...Can anyone enlighten me on this?

Tim

 

[Hydro Junkie]

I know there was something a while back about installing a spacer between the flywheel and case on a motor, don't remember which one it was though

 

[Tim Strange]

That's what I was thinking...Unfortunately the search function doesn't allow a search for three letter words or things like "CMB". "Loose Flywheel didn't get me any results either.

 

[Jeff Schindler]

Tim, what do you mean your flywheel is loose? You cannot tighten it?

I have a pack of stainless washers that you put between the tapered flywheel collet and the inner race of the front bearing. I have been giving these out to whoever needs them. This shims the flywheel out slightly so that it will not rub the case when you tighten it. If you can't get the flywheel tight, then you need a new collet, flywheel, or both.

If the flywheel is not loose, but is moving in and out more than just a slight bit, you're bearings have excessive end play. End play is an indicator of radial clearance (wear), and excessive radial clearance is a really bad thing for these engines. If you are worried you have too much end play, change the bearings before it causes more problems. If you don't, your crank will wear out the seal between the crank and the case. Then you will have a fuel draw problem.

There is a chance you are too late to just fix it with bearings. My engine had the same fuel draw problems and had to buy a new case & crank to fix it.

To test the crank seal of your engine, hook up a Boris flow meter to the carb. Put a glow plug in to seal that hole and cover the carb & exhaust openings with your fingers. Turn the Boris on and you should get a reading of at least 100. This is on a Boris where 100 is where a .21 is tuned.

 

[Tim Strange]

Thanks Jeff, That is the info I was looking for.

I managed to get the flywheel off with the help of a battery terminal puller. Looks like it is unfortunately end play....

Hopefully motor #2 will prove worthy...if not I'll have to try my old MAC silver head which is a good tight motor but probably not enough to keep up with the CMB's.

 

[Bill Brandt]

My experience with these issues is caused more by the flywheel collet becomes a little more pushed In to the flywheel when tightening. So what happens is the outside areas of the flywheel come in contact with the case rear housing. I tried spacers once and wasn't happy with the result. My solution was to chuck the flywheel up in a small lathe and turn town about ten thousandths being careful to not turn down to the center where hole is. Leave about 1/8" around the center unchanged and never another problem. No lathe, no problem. Send me the flywheel and I'll do it for you, just cover 6.00 return postage. (Small flat rate box)

Thanks,

Bill