Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
09-29-2008, 09:40 PM
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Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Hello,
I've had this Magnum XL 91 RFS 4 Stroke Engine sitting in the closet for the last year and a half. I'm starting to put together another plane and I'm having problems getting this one started. Compression seems very low. Cranks over very very easy. I've used a couple of glow plugs and I know those are lighting up. It seems to be getting fuel but not very much. I c hecked and double checked the tank. It does pull fuel through with the choke all the way on. I'll will just crank over and not start. This motor cranks over but doesnt start. I've tried three diffrent glow starters and everyone one of them works. Does anyone know the high and low settings on these from the factory. I've messed them all up by now for sure. There seems to be three settings an idle screw it's got a spring on it. Then the low setting and the high valve stem setting. The manual doesnt say what the default specs are.
Thanks in advance.
I've had this Magnum XL 91 RFS 4 Stroke Engine sitting in the closet for the last year and a half. I'm starting to put together another plane and I'm having problems getting this one started. Compression seems very low. Cranks over very very easy. I've used a couple of glow plugs and I know those are lighting up. It seems to be getting fuel but not very much. I c hecked and double checked the tank. It does pull fuel through with the choke all the way on. I'll will just crank over and not start. This motor cranks over but doesnt start. I've tried three diffrent glow starters and everyone one of them works. Does anyone know the high and low settings on these from the factory. I've messed them all up by now for sure. There seems to be three settings an idle screw it's got a spring on it. Then the low setting and the high valve stem setting. The manual doesnt say what the default specs are.
Thanks in advance.
09-29-2008, 09:58 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Here is a link to the manual: http://media.hobbypeople.net/manual/210970.pdf
It does tell you in there how to reset the needles. Also, make sure you are using an O.S. F glow plug or some similar 4-stroke plug.
I have found that this engine can be a little difficult to start by hand so you may want to try an electric starter.
It does tell you in there how to reset the needles. Also, make sure you are using an O.S. F glow plug or some similar 4-stroke plug.
I have found that this engine can be a little difficult to start by hand so you may want to try an electric starter.
09-29-2008, 11:02 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Sense it was stored for a while, the ring could be stuck or a valve could be stuck too. You might flush the engine with a solvent to try to loosen it up just add after run oil after you do. Once the fuel is seen make sure the choke is opened back up(I took mine off). ply2win is right on the plug and starter.
09-30-2008, 07:03 AM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
I put a spinner on it and I'm using an eletric starter. I'll check out the manual thanks. What kind of Glow Plugs are you using. Manual says a Thunderbolt Four-stroke Glow Plug P/N 115490 is that what you guys are using?
09-30-2008, 12:01 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
I use the OS F plug for both my Magnum 91 RFS engines.
As previously mentioned, this is a ringed engine, and until you get fuel into the cylinder, you'll get low compression, and likewise low vacuum to draw fuel. Second the choke on these doesn't always seal very well, and if you have an upright setup, the carb opening downward is difficult to get the engine primed.
To get the LS needle set, put the carb in the idle position (small opening through the barrell, and blow through the fuel inlet to the carb. Turn the LS needle in (lean) until no air is going through, then open it to the point that air just starts to pass through. This isn't perfect, but its close. For the HS needle, two turns out from fully closed should be close.
Check your valve lash (described in the manual). If you're valve lash isn't correctly set, you won't get the proper compression and vacuum.
If the engine won't start, begin adjusting the HS needle leaner is small increments. You should eventually get to the point where the engine will start and continue to run with the glow igniter attached. Then you have to begin monkeying with the HS and LS settings to find the sweet spot.
Make sure you're fuel has some Castor oil in it. The varnish is necessary to coat the inside of the cylinder and ring to get a good seal as the engine breaks in.
When the engine starts, don't immediately run it to full throttle like you do with ABS and ABN engines. Let the engine warm up at a low throttle and then work your way up to full throttle. This will also help you build up the varnish on the piston and ring.
As previously mentioned, this is a ringed engine, and until you get fuel into the cylinder, you'll get low compression, and likewise low vacuum to draw fuel. Second the choke on these doesn't always seal very well, and if you have an upright setup, the carb opening downward is difficult to get the engine primed.
To get the LS needle set, put the carb in the idle position (small opening through the barrell, and blow through the fuel inlet to the carb. Turn the LS needle in (lean) until no air is going through, then open it to the point that air just starts to pass through. This isn't perfect, but its close. For the HS needle, two turns out from fully closed should be close.
Check your valve lash (described in the manual). If you're valve lash isn't correctly set, you won't get the proper compression and vacuum.
If the engine won't start, begin adjusting the HS needle leaner is small increments. You should eventually get to the point where the engine will start and continue to run with the glow igniter attached. Then you have to begin monkeying with the HS and LS settings to find the sweet spot.
Make sure you're fuel has some Castor oil in it. The varnish is necessary to coat the inside of the cylinder and ring to get a good seal as the engine breaks in.
When the engine starts, don't immediately run it to full throttle like you do with ABS and ABN engines. Let the engine warm up at a low throttle and then work your way up to full throttle. This will also help you build up the varnish on the piston and ring.
09-30-2008, 01:08 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Thanks
I got her started this morning. The manual indicated 2 1/2 turns for HS adjustment and 4 1/2 turns in from all the way out position. It starts pretty easy but I let it run for a while to warm up but it just keeps cutting off. Idle seems fine while it's running then it just dies out. Do I need to lean it out a little on the low setting? It seems to be running a little rich from all of the smoke comming out. I was thinking of running the engine with two full tanks of gass for break in. But I'd like to figure out why it's just cutting out on me. Any thoughts?
The engine fuel is Wildcat Model Engine Fuel it doesnt say anything about castor in it. I do have a gallon of Morganfuel Omega it's pink it does say castor synthtic. I do remember reading using castor oil. I guess I should be using this one.
I got her started this morning. The manual indicated 2 1/2 turns for HS adjustment and 4 1/2 turns in from all the way out position. It starts pretty easy but I let it run for a while to warm up but it just keeps cutting off. Idle seems fine while it's running then it just dies out. Do I need to lean it out a little on the low setting? It seems to be running a little rich from all of the smoke comming out. I was thinking of running the engine with two full tanks of gass for break in. But I'd like to figure out why it's just cutting out on me. Any thoughts?
The engine fuel is Wildcat Model Engine Fuel it doesnt say anything about castor in it. I do have a gallon of Morganfuel Omega it's pink it does say castor synthtic. I do remember reading using castor oil. I guess I should be using this one.
09-30-2008, 11:19 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Hi,
Right now your engine is set very rich on both needle valves.
Leave the glow driver on the engine and once it is started run it up to about 1/2 throttle.
Run it for about 5 minutes in this condition.
Go to full throttle and take off the glow driver.
You are going to need to use a tach to set the high speed needle, in my opinion this is not optional.
Watch the tach closely and lean the the HS needle very slowly, four strokes take "a little while" to respond to needle changes so going slow and watching the tach closely is important.
The engine will speed up and then when you reach peak one more click and it will slow down, as soon as you see the rpm drop (even a little bit) richen the HS needle so you drop 300-400 rpm. With 15% fuel and a 14x6 prop you can expect peak to be in the high 9000's.
Once the HS needle is set reduce throttle to idle, with factory setting on the low speed needle reliable idle might be 3k or higher, lean the low speed needle about 1/2 turn, run the engine up to full throttle for several seconds to clear it and check idle again, most likely you will still be rich on the LS needle but it should idle reliably at a lower rpm.
Repeat the LS needle adjustment (1/8 to 1/4 turn) clear the engine again at full throttle, right now 2200-2500 on the idle is good, continue to tune the LS needle until the engine will idle reliably for several minutes and transition smoothly to full throttle, the engine should transition without any studdering or hesiation to full throttle with a quick transition or a slow transition.
Once idle is set to your satisfaction (be critical the engine is capable of excellent performance) readjust the HS needle and you are ready to fly.
With more run time the idle will become reliable at 2k or a little lower.
Right now your engine is set very rich on both needle valves.
Leave the glow driver on the engine and once it is started run it up to about 1/2 throttle.
Run it for about 5 minutes in this condition.
Go to full throttle and take off the glow driver.
You are going to need to use a tach to set the high speed needle, in my opinion this is not optional.
Watch the tach closely and lean the the HS needle very slowly, four strokes take "a little while" to respond to needle changes so going slow and watching the tach closely is important.
The engine will speed up and then when you reach peak one more click and it will slow down, as soon as you see the rpm drop (even a little bit) richen the HS needle so you drop 300-400 rpm. With 15% fuel and a 14x6 prop you can expect peak to be in the high 9000's.
Once the HS needle is set reduce throttle to idle, with factory setting on the low speed needle reliable idle might be 3k or higher, lean the low speed needle about 1/2 turn, run the engine up to full throttle for several seconds to clear it and check idle again, most likely you will still be rich on the LS needle but it should idle reliably at a lower rpm.
Repeat the LS needle adjustment (1/8 to 1/4 turn) clear the engine again at full throttle, right now 2200-2500 on the idle is good, continue to tune the LS needle until the engine will idle reliably for several minutes and transition smoothly to full throttle, the engine should transition without any studdering or hesiation to full throttle with a quick transition or a slow transition.
Once idle is set to your satisfaction (be critical the engine is capable of excellent performance) readjust the HS needle and you are ready to fly.
With more run time the idle will become reliable at 2k or a little lower.
10-01-2008, 12:34 AM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Thanks,
I'll give it a shot.
I'll give it a shot.
ORIGINAL: chashint
Hi,
Right now your engine is set very rich on both needle valves.
Leave the glow driver on the engine and once it is started run it up to about 1/2 throttle.
Run it for about 5 minutes in this condition.
Go to full throttle and take off the glow driver.
You are going to need to use a tach to set the high speed needle, in my opinion this is not optional.
Watch the tach closely and lean the the HS needle very slowly, four strokes take "a little while" to respond to needle changes so going slow and watching the tach closely is important.
The engine will speed up and then when you reach peak one more click and it will slow down, as soon as you see the rpm drop (even a little bit) richen the HS needle so you drop 300-400 rpm. With 15% fuel and a 14x6 prop you can expect peak to be in the high 9000's.
Once the HS needle is set reduce throttle to idle, with factory setting on the low speed needle reliable idle might be 3k or higher, lean the low speed needle about 1/2 turn, run the engine up to full throttle for several seconds to clear it and check idle again, most likely you will still be rich on the LS needle but it should idle reliably at a lower rpm.
Repeat the LS needle adjustment (1/8 to 1/4 turn) clear the engine again at full throttle, right now 2200-2500 on the idle is good, continue to tune the LS needle until the engine will idle reliably for several minutes and transition smoothly to full throttle, the engine should transition without any studdering or hesiation to full throttle with a quick transition or a slow transition.
Once idle is set to your satisfaction (be critical the engine is capable of excellent performance) readjust the HS needle and you are ready to fly.
With more run time the idle will become reliable at 2k or a little lower.
Hi,
Right now your engine is set very rich on both needle valves.
Leave the glow driver on the engine and once it is started run it up to about 1/2 throttle.
Run it for about 5 minutes in this condition.
Go to full throttle and take off the glow driver.
You are going to need to use a tach to set the high speed needle, in my opinion this is not optional.
Watch the tach closely and lean the the HS needle very slowly, four strokes take "a little while" to respond to needle changes so going slow and watching the tach closely is important.
The engine will speed up and then when you reach peak one more click and it will slow down, as soon as you see the rpm drop (even a little bit) richen the HS needle so you drop 300-400 rpm. With 15% fuel and a 14x6 prop you can expect peak to be in the high 9000's.
Once the HS needle is set reduce throttle to idle, with factory setting on the low speed needle reliable idle might be 3k or higher, lean the low speed needle about 1/2 turn, run the engine up to full throttle for several seconds to clear it and check idle again, most likely you will still be rich on the LS needle but it should idle reliably at a lower rpm.
Repeat the LS needle adjustment (1/8 to 1/4 turn) clear the engine again at full throttle, right now 2200-2500 on the idle is good, continue to tune the LS needle until the engine will idle reliably for several minutes and transition smoothly to full throttle, the engine should transition without any studdering or hesiation to full throttle with a quick transition or a slow transition.
Once idle is set to your satisfaction (be critical the engine is capable of excellent performance) readjust the HS needle and you are ready to fly.
With more run time the idle will become reliable at 2k or a little lower.
10-02-2008, 01:30 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Engine seems to be running very rich I'm about 2 full turns and I still see a lot of white smoke. Also engine hesitates a bit when going to wide open throttle. Any suggestions? I'm going to contiue to run the engine for 5 min at a time while leaning it out a 1/4 turn at a time.
10-02-2008, 02:15 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Hi!
Probably too rich idle ! Turn it in . The engine should first be set using the high speed needle to near max rpm. Use a 14x6 prop.
Then the idle or low speed needle should be set. All it takes is ear...!!
Probably too rich idle ! Turn it in . The engine should first be set using the high speed needle to near max rpm. Use a 14x6 prop.
Then the idle or low speed needle should be set. All it takes is ear...!!
10-02-2008, 02:19 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Thanks for the reply so do I adjust the HS needle while in full open throttle? I'm using a 14x6 prop too.
ORIGINAL: jaka
Hi!
Probably too rich idle ! Turn it in . The engine should first be set using the high speed needle to near max rpm. Use a 14x6 prop.
Then the idle or low speed needle should be set. All it takes is ear...!!
Hi!
Probably too rich idle ! Turn it in . The engine should first be set using the high speed needle to near max rpm. Use a 14x6 prop.
Then the idle or low speed needle should be set. All it takes is ear...!!
10-02-2008, 09:22 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
ORIGINAL: Fidy$Trainer
Thanks for the reply so do I adjust the HS needle while in full open throttle? I'm using a 14x6 prop too.
Thanks for the reply so do I adjust the HS needle while in full open throttle? I'm using a 14x6 prop too.
As long as you use the tach and adjust the HS needle slowly so the engine has time to react to the change you will be fine.
Do not worry about how many turns the needle is at, use the tach to find peak rpm then richen the HS needle so the engine slows down 300 - 400 rpm.
Yes the HS needle is always adjusted at wide open throttle.
Set the HS needle first, this is important.
After the LS needle is set, richen the HS needle 4 clicks and then use the tach to find peak rpm (again) then richen the HS needle so the engine slows down 300 - 400 rpm.
10-03-2008, 07:29 AM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Thanks Charlie,
My buddie is comming over today and he's bringing his tach. I'm going to make sure he reads both post and will get er done.
My buddie is comming over today and he's bringing his tach. I'm going to make sure he reads both post and will get er done.
ORIGINAL: chashint
Study what I posted before, and follow the instructions carefully, and you should be able to tune your engine.
As long as you use the tach and adjust the HS needle slowly so the engine has time to react to the change you will be fine.
Do not worry about how many turns the needle is at, use the tach to find peak rpm then richen the HS needle so the engine slows down 300 - 400 rpm.
Yes the HS needle is always adjusted at wide open throttle.
Set the HS needle first, this is important.
After the LS needle is set, richen the HS needle 4 clicks and then use the tach to find peak rpm (again) then richen the HS needle so the engine slows down 300 - 400 rpm.
ORIGINAL: Fidy$Trainer
Thanks for the reply so do I adjust the HS needle while in full open throttle? I'm using a 14x6 prop too.
Thanks for the reply so do I adjust the HS needle while in full open throttle? I'm using a 14x6 prop too.
As long as you use the tach and adjust the HS needle slowly so the engine has time to react to the change you will be fine.
Do not worry about how many turns the needle is at, use the tach to find peak rpm then richen the HS needle so the engine slows down 300 - 400 rpm.
Yes the HS needle is always adjusted at wide open throttle.
Set the HS needle first, this is important.
After the LS needle is set, richen the HS needle 4 clicks and then use the tach to find peak rpm (again) then richen the HS needle so the engine slows down 300 - 400 rpm.
10-03-2008, 05:03 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
My tach will only work with sunlight, if you will try this at night, be aware that not all tachs work with some artificial lights.
10-08-2008, 07:48 AM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
Hey Charlie,
Yes engine is running great. I've put 3/4 of a gallon of fuel through it so far. Starts up easy and transitions with very minimal hesitation. We put the tach on it and I think we were getting close to 10k RPMS. The motor is in a CAP232 right now and that plane is way beyond my ability. I'm waiting for my budy to take her up and break in the motor some more. Thanks for the help.
Yes engine is running great. I've put 3/4 of a gallon of fuel through it so far. Starts up easy and transitions with very minimal hesitation. We put the tach on it and I think we were getting close to 10k RPMS. The motor is in a CAP232 right now and that plane is way beyond my ability. I'm waiting for my budy to take her up and break in the motor some more. Thanks for the help.
ORIGINAL: chashint
Just wondering if the engine is running correctly or not ?
Just wondering if the engine is running correctly or not ?
12-10-2008, 02:44 PM
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RE: Need Help Magnum XL 91 RFS 4 Stroke Engine Wont Start
you said u were adjusting the high needle and mentioned the small screw thats the low or idle the bigger one is the high side carefully screw in the low until it stops go slowly u dont want to bottom it out hard just slightly see where it is should be 2 to 3 turns then do the high side the bigger one the same see where it is they can be as much as 5 turns out to start see where it is try that
