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Old 10-12-2009 | 09:24 AM
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Default I broke my engine!

Trying to tighten down the rear bolt on a clamp style mount, I put a little pressure on the needle valve and the plate that holds it snapped off.
This is an OS .46LA. The plate on the back of the engine is also what holds the needle valve in place.
This is an older bush engine that I bought used. Runs great but not allot of power.

How difficult is it going to be to purchase and replace this part?
While I'm at it should I do anything else to this engine?

I used epoxy to reattach but havent started the engine.
Seems like the needle valve would still function. The only thing holding it ( if not for the epoxy ) would be the fuel lines.
I would like to fix it properly over the winter.

Thanks

Pop
Old 10-12-2009 | 09:27 AM
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Default RE: I broke my engine!

The back plate on an LA engine is only a few bucks, and it is a very easy repair.

If the part that seals up the back of the motor is solid, and your repair is just holding the needle valve on, then you should be fine. If it comes loose, you can just zip-tie the needle valve to the motor mount until you can get a new backplate.

Good luck

Edit:

http://www3.towerhobbies.com/cgi-bin...?&I=LXPV83&P=Z

OK, maybe more than a few bucks, but still worth fixing.
Old 10-12-2009 | 09:39 AM
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Default RE: I broke my engine!

Thanks.
I see they now sell it as two separate items for $16

Should/could new bushings be put on this engine? or anything else to pep it up?

If not, and if the break didnt cause a leak in the back plate I will probably just leave it...


Thanks

Pop
Old 10-12-2009 | 10:00 AM
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Default RE: I broke my engine!

The bushings in that engine are not replaceable, they are put into the crankcase at assembly. If they are badly worn, you would need to repalce the crankcase and possilby the shaft. They are, however, quite durable and if treated properly will last a long time. I would agree that if you can secure the needle valve to the engine mount or the firewall, the engine should run fine as long as the back plate is still tight. You can even use a little longer fuel line between the needle and the carb if you need to in order to mount the needle.
Old 10-12-2009 | 10:05 AM
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Default RE: I broke my engine!

I don't know about bushings. I see that the piston and cylinder liner are replaceable, as is the crankshaft. If the engine runs, I wouldn't spend any more money than necessary. I have been running one of my .46LA's for three years now, gotta be hundreds of flights, and it still runs great. I have to think that it will eventually wear out.
Old 10-12-2009 | 10:10 AM
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Default RE: I broke my engine!

I would agree on the bushings. They will hold up a while. I am using an OS 40 FP, which is the engine the LA replaced in the line. The biggest difference is the remote needle. It is at least 14 years old.

These two parts may be all you need.

http://www3.towerhobbies.com/cgi-bin...2910&search=Go


http://www3.towerhobbies.com/cgi-bin...7120&search=Go


This link will get a parts breakdown of the engine.

http://www.osengines.com/parts/exploded-views.html
Old 10-12-2009 | 02:28 PM
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Default RE: I broke my engine!

As you already know, what you need is http://www3.towerhobbies.com/cgi-bin...?&I=LXPV86&P=V and the problem will be solved. Rebushing the engine is possible but a major pain you DON"T want to undertake unless you have a machine shop handy. Better to buy new parts.
Old 10-12-2009 | 03:32 PM
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Default RE: I broke my engine!


ORIGINAL: Popriv

This is an older bush engine that I bought used. Runs great but not allot of power.

Pop

Dittos to all the above Yes, the part is easy to replace at a price and no it does not need to be attached to the the engine and attaching somewhere else is a common repair, read cheap.

Now on the your statement above and why it does not have a lot of power. The LA's with the excecption of the forty are not old engines but a still in production series. The are intended to accomplish two things, the first being the lowest cost of OS's for their displacement. The other is to be extremely user friendly for beginng glow engine operators. This they accomplish very well being very easy to learn to adjust and start with reliability.

Power is deliberately dumbed down in these engines first by using a much smaller venturi size for their displacement which has the direct effect of increasing fuel draw characteristics and makes for a far more reliabilty with even poor tank to carb relationships from poor installed tanks. This has a tendency to also increase idling reliability as well a a greater tolerance for a poor needle valve setting.

These engines also include far less aggresive port timing of the more expensive and powerful FX and AX series engines of the same displacements. Another item is the bleeder carbs which will work acceptably over a wider range than the common double needle type. Yup another concession to being easy to learn to operate.

So your statement that it runs great but not much power simply means its doing its job well and nothing is wrong so don,t fix it.

John

Old 10-12-2009 | 03:53 PM
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Default RE: I broke my engine!

If you feel your engine is in need or rebuilding there are a lot of used ones on the market that may even exceed your engine for a minimal price. Contact me if you need any more info.
Old 10-13-2009 | 10:24 AM
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Default RE: I broke my engine!


ORIGINAL: JohnBuckner


ORIGINAL: Popriv

This is an older bush engine that I bought used. Runs great but not allot of power.

Pop

Dittos to all the above Yes, the part is easy to replace at a price and no it does not need to be attached to the the engine and attaching somewhere else is a common repair, read cheap.

Now on the your statement above and why it does not have a lot of power. The LA's with the excecption of the forty are not old engines but a still in production series. The are intended to accomplish two things, the first being the lowest cost of OS's for their displacement. The other is to be extremely user friendly for beginng glow engine operators. This they accomplish very well being very easy to learn to adjust and start with reliability.

Power is deliberately dumbed down in these engines first by using a much smaller venturi size for their displacement which has the direct effect of increasing fuel draw characteristics and makes for a far more reliabilty with even poor tank to carb relationships from poor installed tanks. This has a tendency to also increase idling reliability as well a a greater tolerance for a poor needle valve setting.

These engines also include far less aggresive port timing of the more expensive and powerful FX and AX series engines of the same displacements. Another item is the bleeder carbs which will work acceptably over a wider range than the common double needle type. Yup another concession to being easy to learn to operate.

So your statement that it runs great but not much power simply means its doing its job well and nothing is wrong so don,t fix it.

John



A good explanation of the LA series! I'll use it for what it is then.. If the brake didnt cause a leak at the back of the engine I will use it as is.

Thanks

Pop

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