Glowgeek

Acdii, have you flown that TF P51 with the FA125 yet?

the Wasp

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LOL that sounds like what my grand mother would say, she was from Kentucky

Jim

the Wasp

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yeess, cause up here in Vt we don't say water, we say wader, and we don't say Vermont, we say Vermon, we cut off the 't'

sO, if you need a drink, get you some wader and think about Vermon

Jim

the Wasp

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(Jim scratches head) haa??? what ???

acdii

Nyet

only been out once this year and wind was not ideal, gusty and from the right.

Dwayne

I have a Saito 125 that only gets 8300 rpm on a MA 16X6, Cool Power 15% nitro, I've checked the timing and valve lash they are good fine, very good compression, I've read the low end needle can effect top end rpm, is this true? Anything else I can look for?
Thanks guys.

Glowgeek

A few questions:

1. Will the engine idle at 2000 rpm for a long time and transition ok?
If so, your lsn is pretty close to being right and wouldn't affect the hsn much. If the lsn is set way rich you would have to lean the hsn a lot at wot. If the lsn needle is set way lean you may have to richen the hsn a lot. The hsn needle setting for most saitos will be 1 to 2 turns out from lightly seated.

2. When's the last time you checked the valve lash?
Really loose valve lash will affect power output.

3. Are the bearings noisy?
Bad bearings will affect power output.

4. How sure are you that it's a 16x6 prop?
I've made that mistake before.

Dwayne

Thanks for the reply, valve lash is good. bearings are new and the engine idles at almost 100 rpm...lol Well maybe not that low but it has a very low idle and puts out allot of smoke at idle. at the end of a flight there is oil all over the place.

Glowgeek

At idle the engine shouldn't put out a lot of smoke. Lsn may be too rich.

Is this a new engine, or is it an engine you've had for a while that's recently down on power?

Are you absolutely sure you're running a 16x6 prop? 8300 rpm is the correct rpm for an FA-125 spinning a 15x10, 16x8 or 17x6 prop.

Dwayne

Engine is used, I bought it at an auction, I knew the bearings were toast so I replaced them, today was to first time I ran and tached it, I just tried a APC 15X6 and only got 8900 rpm.

Dwayne

What about air leaks? Maybe new O rings?

the Wasp

My Feedback: (1)

OK, so you are turning APC 15x6 at 8900, that's down for that prop. the 125 should turn an APC 16x6 at 9000 accordingly to Horizon! and I would think an a MA 16x6 would turn lower than an APC 16x6, some anyway.

so you replaced the bearings, did you put a new Cam in it ? the cam could be worn, keep working on it, if you can't find the problem it could be you need a new cam.

edited> it seams like the cam is timed correctly, so try a new plug
Jim

the Wasp

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it wont hurt to change them, but check the muffler to see if it's plugged

Glowgeek

Yep, it's definitely down on power if it will only turn a 15x6 at 8900. An air leak in the intake tract won't effect wot power, you would simply richen the hsn to compensate for the additional air. An air leak would cause idle and transition problems but you say it idles fine (although smokey due to an overly rich lsn).

I agree with Jim (wasp), try a new OS-f plug or Saito SS plug. At least you will have eliminated that as a possibility.

There is also a chance that you hit a "false peak". Sometimes when leaning the hsn there can be a place where a couple of clicks leaner seems to do nothing, no increase in rpm, so we think we have peaked the rpm when we really haven't. Then a click or two more lean past the false peak and the engine continues to gain rpm until the real peak is reached. This false peak usually occurs when the lsn needle is set way too rich.

As a rule, when attempting to find peak rpm I deliberately lean the hsn until there is a noticeable sag in rpm and then quickly richen the hsn to avoid overheating. Doing this completely eliminates the chance of settling on a false peak.

How old is your fuel?

Dwayne

Thanks guys, I've done everything including turning the needle until it sags, the only thing I can think of is the cam and since I didn't pay allot for this engine and it has great compression I think I might replace the cam, lifters and valve springs.
I'll keep you posted.

Glowgeek

If you need any help along the way, let us know. There's always a few knowledgeable people here willing to assist.

Take pics as you progress, they speak a thousand words.

Glowgeek

Dwayne, is the fa-120 going in your Fokker D8?

the Wasp

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I don't think it was asked or said, how long have you run the engine since replacing the bearings ?

Jim

Dwayne

It is going in the nose of a modified Kadet Sr. my D8 has a 60cc gasser in it. Have we met?

Dwayne

It has about 20 minutes on it now.

Dwayne

Figures, the cam is back ordered at Horizon and Tower, anywhere else I can find one?

the Wasp

My Feedback: (1)

good luck there, most on-line stores drop ship from Horizon. but you should call Graves RC and ask, over the years I have seen people post you should call them because they have a lot of stock they do not post on line

or ask on RC Groups for a new cam. if you do post the part number too.

Jim

Hobbsy

My Feedback: (102)

https://www.hobbyplastic.co.uk/index...oducts_id=2848

Here it is at MacGregors, same as the 65.

Hobbsy

My Feedback: (102)

I installed one of Gary's handy works on my best looking Saito 50 GK, and began to make one of my own for some others. I lack an M-5 die, but will have one Friday.


8 mm brass, on the flats

Glowgeek

Only in the virtual world. I checked out your "Threads Started" page.