HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Nov 22, 2005, 05:34 PM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
5,081 Posts
Magnum 91 XL 4 stroke

Can someone provide the specs for valve adjustment on a Magnum 91 XL 4 stroke or a link to the info? Engine was purchased used by a flying buddy, seems to run well but he wants to check everything over before flying it.

Thanks in advance,

Sean
seanpcola is offline Find More Posts by seanpcola
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 22, 2005, 05:44 PM
Registered User
Dushore Pa. & Arcadia Fl.
Joined Jun 2002
110 Posts
.004" both valves.
Robert Bauer is offline Find More Posts by Robert Bauer
Reply With Quote
Old Nov 22, 2005, 06:17 PM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
5,081 Posts
Thank you Robert Bauer!
seanpcola is offline Find More Posts by seanpcola
Reply With Quote
Old Nov 22, 2005, 09:32 PM
Confederate AF Pilot
Hope Hull, Alabama
Joined Dec 2003
328 Posts
Quote:
Originally Posted by Robert Bauer
.004" both valves.
Are you sure that's inches? I will have to go back and check, but I think that my Magnum 70 called for .04mm, which is roughly .0015". Like I said, I could be wrong...
hillbilly is offline Find More Posts by hillbilly
Reply With Quote
Old Nov 23, 2005, 05:56 AM
Registered User
Dushore Pa. & Arcadia Fl.
Joined Jun 2002
110 Posts
[B]Hillbilly, You are probably correct on the .04MM but I am sure you will not see any difference or bad effects between .04 MM and .004" in fact every time I noticed a need to adjust valves they were at about .010" or greater. I would rather go to the loose side of error in setting them than tight. A tight setting below .0015" could result in valves not opening enough and poor running. Just my personal experience.
Robert Bauer is offline Find More Posts by Robert Bauer
Reply With Quote
Old Nov 23, 2005, 05:22 PM
Confederate AF Pilot
Hope Hull, Alabama
Joined Dec 2003
328 Posts
I agree, Robert, it would be better to be a little loose than too tight, leaves room for expansion when operating temperature is reached.
hillbilly is offline Find More Posts by hillbilly
Reply With Quote
Old Nov 23, 2005, 05:49 PM
Registered User
Cincinnati Cin N.Knty, Ohio, United States
Joined Sep 2004
1,037 Posts
How often do you check valve specs?
chris8105 is offline Find More Posts by chris8105
Reply With Quote
Old Nov 23, 2005, 07:42 PM
Grumpa Tom
Kmot's Avatar
United States, CA, Los Angeles
Joined Sep 2003
23,599 Posts
Quote:
Originally Posted by Robert Bauer
[B] A tight setting below .0015" could result in valves not opening enough and poor running. Just my personal experience.
Actually, it's just the opposite. The tighter the clearance, the more the valve gets pushed open.........
Kmot is online now Find More Posts by Kmot
Reply With Quote
Old Nov 23, 2005, 07:44 PM
Registered User
Dushore Pa. & Arcadia Fl.
Joined Jun 2002
110 Posts
Chris -- I don't really know how often, but in the 4 years I am running my 91 I am sure I haven't done it more than 3 or 4 times. Some run their engine more often than other, mine has been run a fair amount. I generally run till I feel there is a loss in power, or till I just get the itch.
Robert Bauer is offline Find More Posts by Robert Bauer
Reply With Quote
Old Nov 23, 2005, 10:34 PM
Registered User
Joined Sep 2005
66 Posts
Food for thought....when you run valves on the loose side in an ic engine,you change the relative timeing of the engine.Loose valves moves the maximum tourqe to a lower rpm.Good for large props that tend to slow engine down anyway.....Guy
nubebuilder is offline Find More Posts by nubebuilder
Reply With Quote
Old Nov 24, 2005, 08:24 AM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
5,081 Posts
Thanks for the great responses from all of you!

Have a happy Turkey Day!!
seanpcola is offline Find More Posts by seanpcola
Reply With Quote
Old Nov 24, 2005, 12:39 PM
You win again, gravity!
Muxje's Avatar
Rotterdam, NL
Joined Jun 2004
280 Posts
Hillbilly, the manual for my Magnum .70 specifies the gap should be in between 0.04-0.1mm (0.0015" - 0.004"). A 0.04mm feeler should slide through the gap, while the 0.1mm feeler should feel tight. Those are the 2 feelers included in the OS valve adjustment kit, by the way.
Muxje is offline Find More Posts by Muxje
Reply With Quote
Old Nov 24, 2005, 12:43 PM
S.A.D. member
ivanc's Avatar
United States, TX, Round Rock
Joined Dec 2004
9,420 Posts
On Magnum 70 and 52 as well as OS FS-70SII a .04mm (.0015") feeler gauge is a GO, a .10mm (.0040") is a NO GO. I'd assume that the .91 Magnum is the same.
ivanc is offline Find More Posts by ivanc
RCG Plus Member
Old Nov 24, 2005, 09:40 PM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
5,081 Posts
Well folks, we got around to doing the valve adjustment today. Set them to .04MM and the thing runs MUCH better.

Again, thanks to all.
seanpcola is offline Find More Posts by seanpcola
Reply With Quote
Old Nov 25, 2005, 11:40 AM
Confederate AF Pilot
Hope Hull, Alabama
Joined Dec 2003
328 Posts
good to hear!
hillbilly is offline Find More Posts by hillbilly
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold magnum xl 4 stroke 52 pugstrip Aircraft - Fuel - Engines and Accessories (FS/W) 1 Aug 05, 2007 08:52 PM
Sold Magnum 91 RFS (4 stroke). NIB. rheumatical Aircraft - Fuel - Engines and Accessories (FS/W) 0 Aug 04, 2007 01:55 PM
For Sale magnum 52 xl 4 stroke john howard Aircraft - Fuel - Airplanes (FS/W) 4 Nov 28, 2005 11:06 PM
Wanted Need Magnum 91 RFS 4 stroke engine yttutty Aircraft - Fuel - Airplanes (FS/W) 0 Jun 29, 2005 12:31 AM
OS .91 surpass 4 stroke with mount, fuel filter, tank, prop, spinner Steve H. Aircraft - Fuel - Airplanes (FS/W) 2 Jul 01, 2004 09:01 PM