ASP/MAGNUM FS400AR Rebuild/Overhaul
#2851
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Well I will try to give you the steps I took
1. I tore down the engine because it was not run for 15,20 years
2. The inside of the engine was full off junk ( castor ) I replaced the main bearings, remove the piston rings and cleaned the ring grove,all parts were cleaned. # 4 ring was replace, I broke it, this is one of cly. that has no compression. Thats why I wonder what I did wrong.
4. How do you perform a leak test?
5. Cam timing was good I lined up the spots on the gears. I made sure the it was right on.
Because of no compression I removed plug and inserted a dowel. I then turned until rockerarms did not move. Piston was at high point. I then ajusted valves. With the head off, I put my hand over the cly. and I thought I had good compression.
Thank you Don Cunningham
1. I tore down the engine because it was not run for 15,20 years
2. The inside of the engine was full off junk ( castor ) I replaced the main bearings, remove the piston rings and cleaned the ring grove,all parts were cleaned. # 4 ring was replace, I broke it, this is one of cly. that has no compression. Thats why I wonder what I did wrong.
4. How do you perform a leak test?
5. Cam timing was good I lined up the spots on the gears. I made sure the it was right on.
Because of no compression I removed plug and inserted a dowel. I then turned until rockerarms did not move. Piston was at high point. I then ajusted valves. With the head off, I put my hand over the cly. and I thought I had good compression.
Thank you Don Cunningham
#2852
Join Date: Jul 2010
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Hi Don
You say you have no compression? now when you say 'no' do you mean none or that its very weak? if it is weak I would not worry too much and as long as you can turn the engine smoothly I would run the engine and see if the rings come in. use a small ish prop and get the rpm up and the engine leaned out (not fully) fairly quickly. I would run it for about 2 minutes to warm it up and then open it up. Don't screw the life out of it, but you need to get the engine upto temperature and the rpm up a bit as well.
If you have no compression at all do as bj suggested and put some oil into the cylinder. Swirl it around so the ring and valves are covered in oil and see if you still have nothing. if so then most likely a valve is stuck
You say you have no compression? now when you say 'no' do you mean none or that its very weak? if it is weak I would not worry too much and as long as you can turn the engine smoothly I would run the engine and see if the rings come in. use a small ish prop and get the rpm up and the engine leaned out (not fully) fairly quickly. I would run it for about 2 minutes to warm it up and then open it up. Don't screw the life out of it, but you need to get the engine upto temperature and the rpm up a bit as well.
If you have no compression at all do as bj suggested and put some oil into the cylinder. Swirl it around so the ring and valves are covered in oil and see if you still have nothing. if so then most likely a valve is stuck
#2853
Join Date: Jun 2009
Location: Melbourne, AUSTRALIA
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The other thing to maybe look at are the valve seats/faces and/or guides themselves...?
Everything is pretty small on these things, but it might be worth giving the valve seats and faces a decent eyeball - make sure there isn't a ding somewhere due to ingesting a bit of junk, or a scratch or burn-out excessive wear... or just bad engineering somewhere (??)
BJ
PS - I'm guessing there's no cracked rings... holes in piston crowns or anything else obvious...?
Everything is pretty small on these things, but it might be worth giving the valve seats and faces a decent eyeball - make sure there isn't a ding somewhere due to ingesting a bit of junk, or a scratch or burn-out excessive wear... or just bad engineering somewhere (??)
BJ
PS - I'm guessing there's no cracked rings... holes in piston crowns or anything else obvious...?
Last edited by BJ64; 03-25-2014 at 05:15 AM.
#2854
Join Date: Jun 2009
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Keleo arrived today
Will have to fire the 400 with 'plumbers pentagon' pipe and do a quick vid - then fit the Keleo and do the same... just for a sound comparision if nothing else.
I have no idea if there's any performance gains etc. to be had with the Keleo, but I'll say one thing for sure - it's a work of art. The workmanship is impeccable.
Simply Divine.
BJ
Will have to fire the 400 with 'plumbers pentagon' pipe and do a quick vid - then fit the Keleo and do the same... just for a sound comparision if nothing else.
I have no idea if there's any performance gains etc. to be had with the Keleo, but I'll say one thing for sure - it's a work of art. The workmanship is impeccable.
Simply Divine.
BJ
#2855
Join Date: Jul 2010
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I was able to fly my 400 on Saturday having mixed up my new fuel. The engine ran pretty well but judging by the colour of the mess coming out of it I feel it really is not long for this world despite improved performance. Once this gallon of fuel has gone (I have about 4 flights worth left) then I will retire the engine for the time being
#2857
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Lol yeaaa, but this time I think it really is final as I desperately need the space in the hangar. I have another model I can hang the 400 on if I want to, but right now its awaiting a new laser for me to test fly before it goes into the sea fury
#2861
Join Date: Dec 2004
Location: Haverhill, UNITED KINGDOM
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#2862
Join Date: Dec 2004
Location: Haverhill, UNITED KINGDOM
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I've a question about valve clearance as I'm about to look at mine.
If I understand correctly, the cams actually rotate at 1/8th crankshaft speed and have 4 sets of cam profiles. Is it safe to assume that the 'land' between the cam lobes (and therefore the valve gap) will be consistent on all four, or should the clearance be measured for all four sets of gaps if you see what I mean?
If I understand correctly, the cams actually rotate at 1/8th crankshaft speed and have 4 sets of cam profiles. Is it safe to assume that the 'land' between the cam lobes (and therefore the valve gap) will be consistent on all four, or should the clearance be measured for all four sets of gaps if you see what I mean?
#2863
The 180 has replaced the 150 model....same size, just larger bore.
Tim, it should be messured all sets, as the cam gear is not perfectly centered......you will see when you measure :-)
Even my new moki manual says to check the clearance 2 places, as it has 2 sets running in a planet gear.
Tim, it should be messured all sets, as the cam gear is not perfectly centered......you will see when you measure :-)
Even my new moki manual says to check the clearance 2 places, as it has 2 sets running in a planet gear.
Last edited by SJN; 04-16-2014 at 03:43 AM.
#2864
Join Date: Jun 2009
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Sensational motor, SJN.
But... over AU 4 grand??
That's a bit out of my league.
I notice you said "not that much bigger than the ASP 400".
The ASP is 60cc, the Moki 180cc. Are they just running bigger bore/stroke?
BJ
PS - just looked at your pics. A bit deceptive at first glance, but I reckon it's a lot bigger. And probably quite a bit heavier too?
But... over AU 4 grand??
That's a bit out of my league.
I notice you said "not that much bigger than the ASP 400".
The ASP is 60cc, the Moki 180cc. Are they just running bigger bore/stroke?
BJ
PS - just looked at your pics. A bit deceptive at first glance, but I reckon it's a lot bigger. And probably quite a bit heavier too?
Last edited by BJ64; 04-16-2014 at 03:53 AM.
#2866
Join Date: Dec 2004
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#2867
Yea, is is ofcourse a lot larger CC wise, but I ment the dimensions are not that much larger :-) . It weighs 4.3kg, and the ASP if I remember is about 3kg....i think.
Cant wait to get it installed, and fired up....and wont miss the corrosiveness of methanol and nitro :-)
Cant wait to get it installed, and fired up....and wont miss the corrosiveness of methanol and nitro :-)
Sensational motor, SJN.
But... over AU 4 grand??
That's a bit out of my league.
I notice you said "not that much bigger than the ASP 400".
The ASP is 60cc, the Moki 180cc. Are they just running bigger bore/stroke?
BJ
PS - just looked at your pics. A bit deceptive at first glance, but I reckon it's a lot bigger. And probably quite a bit heavier too?
But... over AU 4 grand??
That's a bit out of my league.
I notice you said "not that much bigger than the ASP 400".
The ASP is 60cc, the Moki 180cc. Are they just running bigger bore/stroke?
BJ
PS - just looked at your pics. A bit deceptive at first glance, but I reckon it's a lot bigger. And probably quite a bit heavier too?
#2871
Senior Member
Imagine what a 25% power boost on methanol would be like.
#2873
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Telemaster is correct, glow fuel is no problem as long as its not left to sit in the engine. When that happens it attracts water and things go very nasty. Generally 4 strokes are more resistant to rust than 2 strokes as they never have any raw fuel in the crankcase which is why I personally think the intake mod for the 400 is a bad idea as raw fuel is being introduced to the crankcase. That said, if an engine is run regularly its far less of a problem
#2874
Senior Member
Telemaster is correct, glow fuel is no problem as long as its not left to sit in the engine. When that happens it attracts water and things go very nasty. Generally 4 strokes are more resistant to rust than 2 strokes as they never have any raw fuel in the crankcase which is why I personally think the intake mod for the 400 is a bad idea as raw fuel is being introduced to the crankcase. That said, if an engine is run regularly its far less of a problem
On the FG84 it turns a 23X12 @ 6240RPM. That's about 7.75HP & the CHTs are within 4F on all 3 cylinders. The stock backplate only baseline turned that prop @ 5600RPM & CHTs varied widely.
#2875
Senior Member
I think the biggest problem there is lack of adequate crankcase breathing. That leads to condensation build up. Unlike singles & boxer twins, there are no positive/negative pressure pulses to move crankcase gasses out & pull fresh air in.