jbloom

Due to a mental lapse, and a high velocity impact with the earth, my Saito .91 requires a rebuild. What would you do? Here are the facts.

1. Broken Cylinder head (Where muffler mounts)
2. Broken back plate flange where carborator mounts.

I know I need these two parts. Now, considering that the engine hit the ground before any other part of the airplane did, should I consider replacing other parts too? Oddly, the push rods are undamaged. Should I replace bearings? I'm assuming a new ring because of the new cylinder. New valves? Buy a new engine?

Do I need any special tools? Like a puller to get the crank shaft out? (assuming I'm replacing the bearings). Soak the parts in anything? Is there an comprehensive manual on this? Thanks!

John

Rudeboy

Did you hit earth or a hard surface?

If it was earth the bearings are probably fine... except of course if the front bearing has ingested dirt. On the other hand, a new set of bearings can hardly be called a big investment, so you might as well change them while you're at it. Get them at the local tech supply... original parts tend to be expensive, and are just the same as you would buy locally.

How much time did the engine have on it. If it is a high time engine, it might be worth replacing the valves too if your getting a new jug. If the engine only has a few hours on it, you "might" get away with using the old valves.

A new ring speaks for itself.

You need a puller to get the prop driver off the crank. Other than that no special equipment is needed.
Get yourself a small pulley puller... it will be a lifetime investment... and it sure beats the hell out of wrecking engines while trying to get the prop driver off.

If you now make your bill, and it comes out 50 bucks cheaper than buying a new engine... then buy a new engine, and sell the old parts to someone who needs them or on some marketplace

jbloom

I got the engine second hand, it's about three years old, but didn't fly for a year before I got it. I put only about 2 gallons of fuel through it.

Fortunately, if I can use that word in this context, it hit resonably soft ground. The engine was about 4 inches down. There is a gritty feel to the crank. So, I'm guessing I should go ahead and replace the bearings. Can't really hurt. The cost, not counting valves, is about $140.00.

I'm assuming an auto supply store would be a good bet on getting a small pulley puller.

wldcwbypilot

Check your crankshaft, if you hit hard enough to rip the muffler off you may have bent the shaft. I wouldn't worry about the bearings, wash the engine off, make sure you have all the grime off it. Try rolling it over if the bearings are ruff or you feel a flat spot in the balls or race change them. Since your in the US don't go to the local bearing dealer, im my experience Horizonhobby or Boca Bearing are less expensive and will provide you with a complete bearing set for less money. My local place requires you buy a minimun of 50 dollars worth of bearings and the bearings were about 5 to 10 dollars more per bearing.

Enough about that you can order them online from Gerbersrc.com.

will

wldcwbypilot

You do know for another $121.00, you can get a new engine and maybe find used parts later to repair your old one.

Check gerbersrc.com out, check out their online warehouse.

Will

Flyboy Dave

My Feedback: (21)

Personally, i wouldn't put that much money into a used engine, I would save
it for a parts engine. You can get a new Magnum .91 right now at Tower for
$150.00....less $20.00 on sale now. It has a nice warrantee, and all parts are
available for it....at about 1/3 the cost of Saito or OS parts.

FBD.

Mighty Mouse-RCU

My Feedback: (145)

Here is what I'd do. Replace backplate and then if only the muffler header area is what is damaged, have the cylinder repaired with a tig welder, install a helicoil or weld the header straight to cylinder. Cheap fix, but less money involved.

jbloom

What about the gearbox? I have to remove it in order to get the crank out to replace the bearings. Should I just mark the location of the crank using the piston pin or is there an actual timing mark I need to use. Seems like I could mark the crank, but then if I turn the gearbox after removal, then my piston mark is useless now. What's the correct procedure?

Woody218

My Feedback: (24)

The cam gear has a small spot drilled as a timing mark on the front face. With the crankshaft at top dead center, install the cam with that spot straight down.

You can go to Horizon's website and download the manual for a Saito.

http://www.horizonhobby.com/Shop/ByC...rodID=SAIE091S