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Model Forum / Radio Controlled / Air Models / January 2007Magnum 4 stroke question
I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my first 4 stroke, so I have thoroughly read and re-read Magnum's instruction manual. Good and comprehensive break-in instructions that I will follow. But there is no mention of maintenance instructions especially on valve adjustments. I thought that this was critical for 4 strokes. What gives? >I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my first >4 stroke, so I have thoroughly read and re-read Magnum's instruction manual. >Good and comprehensive break-in instructions that I will follow. But there >is no mention of maintenance instructions especially on valve adjustments. >I thought that this was critical for 4 strokes. What gives? Good question. Proper valve train lash is certainly important - lack of lash will invariably impact performance and valve/valve seat longevity. Seems to me all of my OS 91FS's came with valve train adjuster wrenches and the target lash value was stated in the instruction sheets. /daytripper >> I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my first >> 4 stroke, so I have thoroughly read and re-read Magnum's instruction manual. [quoted text clipped - 9 lines] > > /daytripper Don't they supply a feeler gage thicker than the specified clearance, or was that Saito? >>> I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my first >>> 4 stroke, so I have thoroughly read and re-read Magnum's instruction manual. [quoted text clipped - 12 lines] >Don't they supply a feeler gage thicker than the specified clearance, or >was that Saito? They may have, but I can only remember the two wrenches, and a vague recollection of an Allen key as well. I also seem to remember they stopped including those tools in later kits... /daytripper >> Don't they supply a feeler gage thicker than the specified clearance, or >> was that Saito? [quoted text clipped - 4 lines] > > /daytripper OS now makes you buy the valve adjusting tool separately. The kit comes with a wrench, an allen key and two feeler gages. the feeler gages are .1 mm and .04 mm. >>> Don't they supply a feeler gage thicker than the specified clearance, or >>> was that Saito? [quoted text clipped - 8 lines] >with a wrench, an allen key and two feeler gages. the feeler gages are >.1 mm and .04 mm. Ah - you're right, it was two feelers, not two wrenches. I remember all the bits now - and that each small bit was individually wrapped in plastic film as well... Cheers /daytripper I did a bit of surfing and found the info from Magnum at http://rcsource.hobbypeople.net/faqs/4s-break.htm Somehow all of this was not included in my instructions. Are they cutting cost? > I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my > first 4 stroke, so I have thoroughly read and re-read Magnum's instruction > manual. Good and comprehensive break-in instructions that I will follow. > But there is no mention of maintenance instructions especially on valve > adjustments. I thought that this was critical for 4 strokes. What gives? Thanks for the link, Marlowe. I have a Magnum .52 4-stroke and a .70 4-stroke on order from my LHS. It's surprising how different Magnum's break-in instructions are compared to Saito's. >I did a bit of surfing and found the info from Magnum at >http://rcsource.hobbypeople.net/faqs/4s-break.htm Somehow all of this was [quoted text clipped - 6 lines] >> especially on valve adjustments. I thought that this was critical for 4 >> strokes. What gives? Marlowe -- I have an article titled "The Care & Feeding of Four-Strokes" at my Web Site; you might find some of the information useful. http://www.lymanslack.com/Articles&Archives/FourStroke.html Cheers -- \_________Lyman Slack________/ \_______Flying Gators R/C___/ \_____AMA 6430 LM____ / \___Gainesville FL_____/ Visit my Web Site at www.LymanSlack.com > I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my > first 4 stroke, so I have thoroughly read and re-read Magnum's instruction > manual. Good and comprehensive break-in instructions that I will follow. > But there is no mention of maintenance instructions especially on valve > adjustments. I thought that this was critical for 4 strokes. What gives? Good info, thanks. The reason I was asking about valve adjusting is that I was under the impression that 4 stroke engines were high maintenance, mostly due to the valve adjusting. However before my Magnum arrived, in our club we have an old hand at 4 strokes and he assured me that he only adjusts the valves on his many 4 strokes about once a year. He does give them a thorough lube job with after run oil after every flying session. I cannot wait to fire it up! > Marlowe -- > [quoted text clipped - 14 lines] >> especially on valve adjustments. I thought that this was critical for 4 >> strokes. What gives? > I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my > first 4 stroke, so I have thoroughly read and re-read Magnum's instruction > manual. Good and comprehensive break-in instructions that I will follow. > But there is no mention of maintenance instructions especially on valve > adjustments. I thought that this was critical for 4 strokes. What gives? It is there in the instructions or, search for the US Magnum dealer who has downloadable instructions which include the valve lash settings. 0.02 - 0.04mm I think is the common setting for most Magnum 4 strokes.  SignatureThe Raven http://www.80snostalgia.com/downloads/batfink/sounds/wings.mp3 Thanks for the suggestion, I found this resource too: http://rcsource.hobbypeople.net/faqs/4s-break.htm >> I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my >> first 4 stroke, so I have thoroughly read and re-read Magnum's [quoted text clipped - 6 lines] > has downloadable instructions which include the valve lash settings. > 0.02 - 0.04mm I think is the common setting for most Magnum 4 strokes. > Thanks for the suggestion, I found this resource too: > http://rcsource.hobbypeople.net/faqs/4s-break.htm Break it in according to the Magnum instructions (OEM or dealer). I broke mine in according to the US Dealer instructions with minimal alterations (eg. I shut it down whenever I thought it was getting hotter than I liked). Big trick is to keep measuring the head temp (finger on head) and when it gets hot back off or shut down. SignatureThe Raven http://www.80snostalgia.com/downloads/batfink/sounds/wings.mp3 >It is there in the instructions or, search for the US Magnum dealer who has >downloadable instructions which include the valve lash settings. 0.02 - >0.04mm I think is the common setting for most Magnum 4 strokes. That would be .002 -.004 Inches, or .04 - .1 mm Ken >>It is there in the instructions or, search for the US Magnum dealer who >>has >>downloadable instructions which include the valve lash settings. 0.02 - >>0.04mm I think is the common setting for most Magnum 4 strokes. > > That would be .002 -.004 Inches, or .04 - .1 mm Thanks for the clarification. SignatureThe Raven http://www.80snostalgia.com/downloads/batfink/sounds/wings.mp3 My theory is if it ain't broke don't fix it when it comes to four stroke maintenance. After run oil is about all the maintenance they get. I have one 91 four stroke that is over three years old and it has never had any adjustments except needle valves and the low end has only been set once. My other four strokes vary between 3 years old and brand new and none of them have had the valves adjusted either. I did buy the OS valve adjusting tools from Tower to get my order up to 150 so I could use the 25 off code, just in case one of the engines do eventually need the valves adjusted. Based on my Magnum 91 engines once it is broken in I think you can realistically expect 10300 - 10500 sustained RPM using 15% nitro and an APC 14x6 prop. If you stick with 10% nitro 9800 - 10000 rpm sustained is what I got. Regards, Charlie > I'm the proud owner of a Magnum XL-91RFS 4 Stroke engine. This is my > first 4 stroke, so I have thoroughly read and re-read Magnum's instruction > manual. Good and comprehensive break-in instructions that I will follow. > But there is no mention of maintenance instructions especially on valve > adjustments. I thought that this was critical for 4 strokes. What gives? Charlie, You have made some great points. I am breaking in my Magnum 91, following Magnum's break-in instructions. That is 5 minute runs, full throttle at ever increasing RPM. Using 15% nitro, 20% lube and a 14x6 prop. Everything is going great until I push it above 8,800 RPM and I get an increase in vibration where I cannot proceed. I started with a balanced prop, but I don't have the capability to balance the spinner. I'm going to recheck the prop and try to give the spinner a try. Marlowe > My theory is if it ain't broke don't fix it when it comes to four stroke > maintenance. After run oil is about all the maintenance they get. [quoted text clipped - 20 lines] >> especially on valve adjustments. I thought that this was critical for 4 >> strokes. What gives? |
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