My turn to rebuild a Force (with some pics)

[foxtrotboss]

Re: My turn to rebuild a Force (with some pics)

Hmm never underestimate the power of a good hone job. A buddy brought a flex hone over for me to use. He looked at my block ans said "bet you 5 bucks that all you need is a godd honing". Since the machine shop was not open and I had nothing to lose. Well in a few minutes the cylinders cleaned up just fine. So now I guess I'm out five dollars and going to order parts. Even though the ring broke I didn't run it long afterwards there fore saved the cylinder. Plus the ring went out the exhaust.

Am I lucky or am I missing the point somewhere?

Scott

 

[pnwboat]

Re: My turn to rebuild a Force (with some pics)

Every now and then even a blind dog finds a bone. Sounds like you may have lucked out. To be 100% sure you might want to mic the cylinders to determine exact bore size.

 

[Frank Acampora]

Re: My turn to rebuild a Force (with some pics)

Yeah, sometimes honing will do the trick, BUT: the factory tolerance for out of round, tapered, barrel shaped, or wear, is only .002. So if you get too ham-handed with the hone, you may exceed tolerance. And, since these are blind cylinders with no way to pass the hone out the bottom end, it takes a very skilled hand to hone accurately.

Remember: It is not only the sealing of the rings that determines engine condition. Compression ratio is only one part of the equation. The piston skirt must properly seal the crankcase.

Yeah, if you hone it out it will run, but if the tolerance is exceeded, CRANKCASE vacuum and pressure will suffer and the engine will not pump the full volume of air. AND: Fuel pump will not produce full volume. Thus: the engine will not produce its rated horsepower. How severe can this be? Anywhere from exceedingly mild causing only very minor losses that you might not notice, to severe enough that the engine will be a dog.

So, before you order pistons, mike the bore. Do it at the top, just above the ports, and at the bottom. Take two measurements 90 degrees apart at each position.

 

[foxtrotboss]

Re: My turn to rebuild a Force (with some pics)

Well I went down and talked to Franz of Franz Marine his shop is 30 miles away. Nothing is as cheap or easy as we would hope. To do this right the price is getting up there and the wife is balking at the costs.

 

[foxtrotboss]

Re: My turn to rebuild a Force (with some pics)

This thread is not dead yet LOL. I have done research and asked questions and even my wife bought an old powerhead which ended up being a donor, as a parts motor I had surgery a week ago so I couldn't hardly do much except supervise But between my 12yo son and my lovely wife we have made much progress. I have the motor honed to perfection in least than 15 secs. I have every part I needed out of the old chrysler powerhead except gaskets, and an impeller. My son has torn down the chrysler powerhead and helped reassembling the Force. My wife has taken over gasket making on certain gaskets we don't want to use rtv on. My daughters are constantly checking on me making sure I'm ok. Also the whole family scrubbed the block clean for reassembly ( my girls wanted to paint the motor pink for "Girl Power" but that was a no go) So now I have to wait for my brother to lift the powerhead back on. Then I will rewire the motor up for the intial test.

YZ450F: the cost of my rebuild deminished when my wife got the parts motor. I will have less than 200 dollars in the repair not rebuild because nothing was bored just bad pistons replaced. So the cost of a rebuild depends on what you want to do.

Reseal and clean: Gasket set $80, new water pump kit $60, and new fuel pump seals $25.

Bore and refresh the whole motor: $750 approx with machine work but it can go up to $1000 depending on where you get your parts who does your machine work and if you add on goodies like Boyesen Reeds. The pistons alone are $110 each and you can reuse your wrist pin bearings if done right.