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G38 Problems need solutions and honest advice

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G38 Problems need solutions and honest advice

Old 12-07-2012, 04:51 PM
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Rocketman612
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Default G38 Problems need solutions and honest advice

I purchased a used BUSA SE5a here on RCU last month. It has an older G38 in her that is not new to this plane and supposedly Ralph Cunningham balanced the shaft. The tank was a mess lines hard bad stopper. Cleaned the tank converted to a 3 line system with new stopper and tubing throughout. The mount was cracked and I replaced it. Tried to start the engine and she wouldn't fire seemed starved. Pulled the carb and installed a carb kit. The inner screen was >75% clogged, diaphragm stiff. Used carb cleaner got all the varnish out and reassembled . I noticed the phenolic spacer was changed to an off white softer composite material that rotated the carb 90deg. Plug oil fouled so a new one also installed with the proper gap.

Was able to start the engine but it was difficult started with the base needle settings 1 1/8 low and 1 3/8 high. After some tweeking she ran well getting 7K with a Zinger 18x10 idle at 2k. Took her up for the maiden flight and just as I was completing the downwind leg when the engine died. Was able to dead stick land with no problem and no damage. Noticed the velocity stack was gone along with the bolts and the carb was hanging by the fuel line and pushrod. the spacer has striped threads. Called B&B Specialties and got a new Easy Link adapter kit to mount the carb, new gaskets and velocity stack.

Tried to start the engine again and after choking I could get her to pop a few times. I richened the low needle and am out about 4 turns and still can't get it to run. I have to use an electric starter to get the plug to fire. Had checked for spark with hand flipping and no good will only spark with the starter turning the engine. Thought about the space between the flywheel and the magnet but there is no adjustment.

Did I miss something??

I see three options

1) New G38
2) send this G38 off to be looked at
3) Place a DLE 35 in the plane

The firewall is set for the G38 as is the plumbing and pushrod. A major rework would be needed to accommodate a DLE. Cant add a spring starter to existing engine as the back end of the crankshaft has been cut nearly flush with the rear bearing.


I know buyer beware. I asked all the right questions and got lied to. Was not able to really take things apart at the time of possession as we each drove 2hrs to meet off the interstate.

Pete
Old 12-07-2012, 05:49 PM
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CK1
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Default RE: G38 Problems need solutions and honest advice

Since the engine ran untill the carb fell off I would think the spark is adequate as long as it does spark . You have to hand flip a magneto engine pretty fast to get a good spark.

I would check the carb spacer and gaskets to be sure that the pulse holes for the carb are in alignment from the enigne through spacer and gaskets to the carb
then reset needles to 1-1/2 turn each and tune from there .
Old 12-07-2012, 05:51 PM
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Default RE: G38 Problems need solutions and honest advice

The 7000 rpm is correct for that engine and prop.

With an old engine that has not been run in a while, It will start up at first, but with in the next time you run it, the engine will not run right. The engine will be rich or lean or back and forth.

The carb needs new diaphragms
Old 12-07-2012, 06:21 PM
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Default RE: G38 Problems need solutions and honest advice

If the engine has good spark & good compression look for a air leak between carb & engine. Also the carb should have a new kit installed. Also take a look at the seal area where the rear of crank was cut. If it was cut by a method that heated that seal up...it may need replacing. None of this is no big deal...with help from guys on this forum, you should be able to get that G38 running good. Capt,n
Old 12-07-2012, 06:32 PM
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Default RE: G38 Problems need solutions and honest advice

I forgot to mention that on some of the older G38 engine the carb bolts may be a little long for the newer adapter . The bolt may feel like it is tightening down but it may be bottoming out and not allowing the gasket to seal enough .
Old 12-07-2012, 07:20 PM
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Default RE: G38 Problems need solutions and honest advice

Thanks for the suggestions fellas.

Sorry I was a little verbose in my initial post.

The carb has been rebuilt with all new parts including diaphragm. New gaskets for the spacer and carb, was careful to make sure the holes lined up but will recheck this. Also I am using fresh Avgas mixed 50 to 1 with Redline synthetic 2 stroke racing oil.

Going flying on Sat am and will work on the G38 in the afternoon.

Pete
Old 12-08-2012, 01:26 AM
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Default RE: G38 Problems need solutions and honest advice

Pete,
I had a G38 that kept stoping after about 3mins running time and found that the coil was bad, replaced with an Rexel electronic conversion, easer starting, smother idle and saved weight(450grams), also as CK1 said about the carb mounting bolts, check the length.

Cheers
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Old 12-08-2012, 05:32 AM
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Default RE: G38 Problems need solutions and honest advice

If all else fails and you don't need the additional weight of the magneto system up front to help balance the model, then I would opt for your option 2 and send the engine to Ralph and have him both service and convert it to electronic ignition.

Karol
Old 12-08-2012, 11:53 AM
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Default RE: G38 Problems need solutions and honest advice

Karolh,

Will need the weight of the magneto to balance which is another point against the DLE 35.

I tried to look up Ralph Cunningham and could not fine current contact info if anyone has it please post.


Prtr
Old 12-08-2012, 03:25 PM
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Default RE: G38 Problems need solutions and honest advice

Here you go:

Ralph Cunningham
1783 Whitehall,
AZ 86046
Ph. 928-220-5721

Karol
Old 12-10-2012, 07:07 PM
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Default RE: G38 Problems need solutions and honest advice

Karolh,
Thanks a bunch for Ralph's contact info.

Well I carefully removed the carb and the gasket here was properly aligned. I then tried to pass a 4-40 rod into the air channel in the spacer back to the cylinder and couldn't. I could snake a thinner wire smaller than 2-56 back into the cylinder head. I pressed the 4-40 rod firmly into the gasket to indent it and when I removed the phenolic spacer you could see a crescent mark on the gasket where it partially covered the hole. I carefully enlarged the opening in the gasket and then lined it all up again using the 4-40 rod as a guide. I thought I was careful in doing this the first time but apparently not. Got it all together and this evening was able to start the engine with my son's help in the garage. Couldn't do much other than to grossly tune it as the fluorescent lights made using the tach impossible. Will fine tune things in the daytime.

At least I know she runs and will likely be fine. As usual it's the small details that can get you scratching your head. Used OEM Zenoah parts and didn't expect that aligning things would be problematic. Will post Tach data

Thanks for all the help.
Pete
Old 12-11-2012, 06:17 AM
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Default RE: G38 Problems need solutions and honest advice

Good for you

Karol
Old 12-13-2012, 07:38 PM
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Default RE: G38 Problems need solutions and honest advice

Was able to fine tune the G38 today. Tached out at 7200rmp peak with the zinger 18x10 prop and a steady idle at 1900rpms. Good transition.

I really appreciate all the help getting this engine sorted out.

Pete

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