SeamusG

Based on my limited experience engine mounts seem to go pretty much unnoticed. So, time to get some input from you guys with years of experience.

How important is the choice of an engine mount? Kits come with a manufacturer's mount. Is that the right mount? What if I want to upgrade the engine from, let's say, a .46 to a .61 and the engine "fits" on the mount - is it good to go? How about a .91 that has the exact mount foot print as the .61 - is it good to go on the mount intended for a .46? If an engine fits between the rails of a "fixed rail" mount - is it good to go?

Ihappen to like Hayes AL60 (AS60)mounts because all of these engines (OS61 FX, OS91 FX, Saito 91, Saito 100, YS 110 and Super Tigre G90) fit. And the square backed fixed rail design provides a single common firewall bolt pattern irrespective of the choice of engine and whether it is mounted vertical, side or inverted. So, if my YS110 fits in the AL60 mount - is it good to go?

I am going to build a Great Planes Extra 300S60 kit. It comes with a GP generic mount with adjustable rails for .60 - 1.20 engines. Can I simply replace it with the AL60 (that currently has the YS 110 loaded and mounted on a 4Star60)?

What are the considerations? There are some expensive vibration isolating mounts out there. What are the benefits. Is the choice more or less important for sports, scale, pattern, 3D, racing applications?

Thanks for kickin' in your input. It's much appreciated.

David Bathe

I'd just use the mount that came with the kit, I've never had any issues with the GP mount.I've tiried/own many types, GP adjustable, CG beam mounts, Dubro isolation mounts, DB soft mounts, MK, YS and Hyde soft mounts.For a sports application I'd use what ever soild mount you have available. Don't even bother going the moft mount route.I've mounted 1.20 OS and YS four strokes and moki 1.35 engines on simple light weight Goldberg fiber mounts and they've never gave any problems.Infact the only engine mount I've never had any luck with was the DB soft mount. Stay away from that one.

Gray Beard

My Feedback: (-1)

Dang Sea, you come up with some good questions. I use a bunch of different mounts and for the most part none of them are anything the kits came with. Most the time the kits come with two piece mounts, nothing wrong with them at all but I find them harder to install correctly so I don't use them often. The number one mount I have used over the years is the Great planes adjustable mount. No reason other then every hobby shop has them in stock and I find them easy to use. It's that lazy thing I have going on
I can't recall if it was OS or YS that told me to use solid metal mounts with there four stroke engines? Been a while. They{?} told me that the four stroke case could crack from torque or expansion in a flexible mount?? Take that for what it's worth, I have been using the GP mounts for a lot of years and never had an engine case crack. I do have several solid metal mounts for four strokes though, for the most part OS mounts but they are great to use, all four holes line up perfectly with the engine, just nice to use.
I have several anti Vibe mounts of different makes, some I like more then others but yes, they really do keep the engine from shaking apart the air frame. My favorite is the one made by Jtec but if you want to use one on an ARF they aren't one I would advise. If you are building a kit then they are great because the fire wall requires some mods. They really work great though.
If people have found mounts that they like as you have I say just keep using them, if it aint broke why try fixing it!! If you have a plane that looks like it's shaking the air frame to pieces then by all means try a good anti vibe mount.
I follow no firm rules but I do have a number of different mounts in my shop. As I'm building I kinda give the engine some thought as to the vibration and size then rummage through my shop to find mounts for it then pick from what I have. I do try to use what I think will be the best mount but I don't over think it. {{Too Often}}
Good question!!! Can't wait to see the other answers.
Gene

carrellh

I think using the same mount for everything, if possible, is a good idea. If a mount breaks, you'll nearly always have a spare (even if you have to rob another plane). Your Hayes mount looks pretty sturdy. If the YS fits I would not hesitate to use it.

My brother and I use the Great Planes .40-.70 mount for .61 two strokes and .91 four strokes all the time. We also use it for 40 class two strokes and 70 four strokes.

SeamusG

I did an "engine database" that has specs for 267 different engines and it includes the mounting hole dimensions for most of them. I use that to see if one of these fixed rail (1 piece) mounts will work. Yea, I'm a techie (database stuff).

Seems to me that part of the mount discussion also affects what you use for a control rod for the throttle. Do you use a Dubro 4-stroke throttle linkage?

Gray Beard

My Feedback: (-1)

I don't buy linkage in kit form, I more often then not make up a cable system depending on how things are going to be run. I have a few items used for control line planes like bell cranks so if something like the Dubro is needed I have the parts on hand to make my own. I keep a lot of piano wire on hand in a bunch of sizes so I have often use that with bends or Us in them to get to the throttle arm. I do have a photo of the Dubro on my wall to remind me of a different way to do the linkage set up.
Gene

carrellh

I tried to use the Dubro four stroke linkage on my Astro Hog but the cheeks were so close to the engine mount that I could not make it work. The engine is an OS 70 Surpass I with the metal throttle arm. With the carb turned so the linkage was opposite the muffler, the needle was hard to reach without getting burned, and with it turned the other way the throttle arm was directly behind the cylinder. I left it with the needle opposite the muffler; shortened the threads on a pushrod, shortened the nylon socket on one of these http://www3.towerhobbies.com/cgi-bin...?&I=LXD900&P=0 , and it worked pretty well. The brass part was not used.

If the throttle arm is not behind the cylinder, bending a "U" in a pushrod and using a standard nylon clevis usually works pretty well.