Questions about rebuilt 25FSR
10-19-2004, 12:12 PM
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Questions about rebuilt 25FSR
Finished cleaning and rebuilding an OS 25FSR.
However, the bearings don't feel smooth. They click when I turn the prop. Does it mean they are rusted/damaged? Is it possible to replace the bearings without a special tool?
Also, the sleeve has some pink color at its upper rear section. Does it mean it overheated? (the fins are broken there due to a crash)
Thanks!
However, the bearings don't feel smooth. They click when I turn the prop. Does it mean they are rusted/damaged? Is it possible to replace the bearings without a special tool?
Also, the sleeve has some pink color at its upper rear section. Does it mean it overheated? (the fins are broken there due to a crash)
Thanks!
10-20-2004, 11:01 AM
#2
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RE: Questions about rebuilt 25FSR
If your engine's bearings have a rough spot, it could be due to damage to the bearing, or a piece of debris caught between the races.
You remove the bearings by heating the crankcase to 250-300 degrees F. A light rap on a piece of wood should let the bearing fall right out. Reheat the case and carefully slide in the new bearing. You don't heat the new bearing.
The pink coloration could be pigment from your fuel, if it's the pink stuff. Could be some other type of contamination, too. Overheating won't turn the metal pink.
You remove the bearings by heating the crankcase to 250-300 degrees F. A light rap on a piece of wood should let the bearing fall right out. Reheat the case and carefully slide in the new bearing. You don't heat the new bearing.
The pink coloration could be pigment from your fuel, if it's the pink stuff. Could be some other type of contamination, too. Overheating won't turn the metal pink.
11-08-2004, 01:21 PM
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RE: Questions about rebuilt 25FSR
Bill
Regarding the 25FSR, because of a crash decades ago, I needed to increase the size of the holes of the carburetor (and the engine, for the carb). Unfortunately, I increased the size without the O-ring gasket installed. I now do not have enough clearance for the gasket. I used Permatex high-temp gasket maker instead. Should it suffice? (doesn't seem like a high stress region)
Alternatively, I can remove the Permatex sealant, and machine down the o-ring to half the thickness and try to squeeze it then.
Which option is better?
Thanks!
BTW I ran in the engine without the gasket and although it started immediately, it sounded a rough.
Regarding the 25FSR, because of a crash decades ago, I needed to increase the size of the holes of the carburetor (and the engine, for the carb). Unfortunately, I increased the size without the O-ring gasket installed. I now do not have enough clearance for the gasket. I used Permatex high-temp gasket maker instead. Should it suffice? (doesn't seem like a high stress region)
Alternatively, I can remove the Permatex sealant, and machine down the o-ring to half the thickness and try to squeeze it then.
Which option is better?
Thanks!
BTW I ran in the engine without the gasket and although it started immediately, it sounded a rough.
11-10-2004, 04:24 PM
#4
My Feedback: (11)
RE: Questions about rebuilt 25FSR
If the carburetor seals without an air leak, then your mod is OK.
Rough running could be caused by an incorrectly-set needle valve. Put a 9 x 6 prop on the engine and see how it needles. If you can get it to full throttle and leaned to peak RPM OK, then the carb would be a reasonable match to the engine. If the carb bore's too large, you'll have fuel draw problems at full, with the engine tending to run too lean, even with a wide-open needle. If the carb's on the small side, the engine should draw fuel like mad, have a good idle, but be down on peak RPM. Tach it to be sure.
Rough running could be caused by an incorrectly-set needle valve. Put a 9 x 6 prop on the engine and see how it needles. If you can get it to full throttle and leaned to peak RPM OK, then the carb would be a reasonable match to the engine. If the carb bore's too large, you'll have fuel draw problems at full, with the engine tending to run too lean, even with a wide-open needle. If the carb's on the small side, the engine should draw fuel like mad, have a good idle, but be down on peak RPM. Tach it to be sure.
11-10-2004, 04:47 PM
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RE: Questions about rebuilt 25FSR
The carb was completely disassembles, cleaned assembled (it's the ORIGINAL). here are two things that may effect that rough operation (?):
1. The new nipple that I bought that feeds fuel to the needle valve seems to be large - larger than the exhaust pressure nipple - may this have to do with the engine operation?
2. Since I assembled the carb I did not touch the other needle (on the right - on axis with the throttle arm), which I think is a low RPM mixture needle. It is completely closed now. How should I set it for smooth operation? I did not see any mention of this in the OS manual.
Thanks
1. The new nipple that I bought that feeds fuel to the needle valve seems to be large - larger than the exhaust pressure nipple - may this have to do with the engine operation?
2. Since I assembled the carb I did not touch the other needle (on the right - on axis with the throttle arm), which I think is a low RPM mixture needle. It is completely closed now. How should I set it for smooth operation? I did not see any mention of this in the OS manual.
Thanks
11-11-2004, 11:45 AM
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RE: Questions about rebuilt 25FSR
The size of the hole in the nipple will have no effect on your carb's operation. If it fits and doesn't leak, you'll be OK with it.
The idle mixture should not be closed. You want it opened far enough that you can be sure it's too rich to idle. Start the engine at part throttle and advance it to full. Get the high-speed needle set to just rich of peak RPM. Slowly close the throttle and adjust the idle mixture as necessary until you can get a good idle.
It may be impossible to get a good idle if the piston/cylinder fit has been damaged or worn to the point where compression is too low to idle. That is also a cause for bad idle/acceleration.
The idle mixture should not be closed. You want it opened far enough that you can be sure it's too rich to idle. Start the engine at part throttle and advance it to full. Get the high-speed needle set to just rich of peak RPM. Slowly close the throttle and adjust the idle mixture as necessary until you can get a good idle.
It may be impossible to get a good idle if the piston/cylinder fit has been damaged or worn to the point where compression is too low to idle. That is also a cause for bad idle/acceleration.
