Typical GS500 Motor Weight?

[spdracer75]

Hey all,

Yes, I've returned from a long abscence.
(see sig)

For those of you who tinker with GS's and make stripped down race bikes,
what would you say is the weight of a GS Engine with carbs and air box?
Less than 100 pounds?

The entire bike weighs a bit over 300, so it cant possbly be more than that. Can it?

[dgyver]

140 pounds not including carbs and air box

[werase643]

ALMOST ANY OTHER ENGINE WOULD BE BETTER than a GS

CR/YZ/RM/KX 125 has almost the same power (low-mid 30's) and....60-80 # lighter

[dgyver]

Yeah a 2-stroke would be the way to go, especially since you do not need any torque.

[spdracer75]

Hrm,

I had thought the GS motor weighed far less than that.

I only need 40 HP, and I know the gs motor handles that (rejet/V&H/etc.).

Plus I loved my GS , and thought it fitting to use that nice humming motor in my plane.

So, 125 CC 2-stroke you say?  It has to be OVER 40HP
Almost wondering if a 250CC 2-Stroke would pull it off.

I dont like using a 2-stroke though, since I hate mixing oil and Gas,
plus if I get the engine a little lean at say, 3,000 feet a 4 stroke wont seize.

Some people are using 1/2 VW engines (90lbs w/o carbs)
in the plane I'm building, but at 3 freakin' grand it's a bit much to handle.

So, motorcycle engine and a belt/gear reduction
(cant swing the prop at 8K RPM's)

Anyways, much to think about.

[GeeP]

Be careful!  

[Blueknyt]

dude, 440 rotax 2 cyl 2 stroke, used in ultralights for years. think some early aircooled snowmobile engines is the same.

like this.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4551943009&category=46093&sspagename=WDVW

the power to weight ratio for the GS engine kinda sucks for aircraft engine, but might work ok as a single seater Airbox engine. hmm, were to find a small pusher prop.

[john]

Man it would be fun to shoehorn a 250 smoker into a GS.  It would boogie :mrgreen:

[werase643]

yeah,
and it would have more HP
250 cc dirtbike engines are 50-60 hp

[luke1645]

Man it would be fun to shoehorn a 250 smoker into a GS. It would boogie

what about the torque? i rode a 01 cr250 and yea it was fast but didnt have a bottom end to save its life.  now if its going to be a motocross engine you slip in the gs spars why not make it a 450 stroker?  more power than the gs all the way round and a helluva lot lighter.  maybe consider an older yamaha yz400f or 426 motor for that project plane. it might be easier to come across and since its an "obsolete" motor you could get it relativley cheap. it would be a Buddha Loves You to kickstart that plane though  :lol:

[spdracer75]

Kickstart? Hehe,  just flip the prop and pray.

As for a Rotax 440/447, that is what the plans call for,
but you can go all the way up to a 1/2 VW Engine with a wet weight of about 100 pounds.

I've seen perfectly running GS motors go for about 100 bucks, and they have electric start

Quite a few people in the past have used small 2 and 4 stroke motocycle engines in small aircraft.
I've even seen some decent sized planes with Harley engines.  
There are even some nuts out there with Turbo Hayabusa engines in their planes.

Anyways, thanks for the ebay listing.  By the time I got to it,
the auction had been ended early.

As I said earlier, I just had it in mind to see if it was feasable to drop a GS motor in my plane.  
I loved how my GS Sounded at 6K RPMS with the V&H Exhaust.

[spdracer75]

Oh, and did I mention I hate 2-strokes?


I know.... I know.... the HP/Weight ratio cant be beat.  LOL

[luke1645]

Kickstart? Hehe, just flip the prop and pray.

do you realize the compression those motors put out?  either way, sounds like a fun project!

[spdracer75]

Yeah, I know the compression ratios.

Ever hear of that weird phenomenon called "leverage"?

Usually it takes one flip of the prop,
but having to flip the prop isnt very desireable.

I'm checking a few things to see if the GS motor will work.
The plane can fly up to a 250/275 lb pilot.

I'm 200 and some "change".
By the time the plane is in flying condition I should be down to 190.

Soooooooooo.

40 HP - 4 Stroke, plain gas, electric start.  
Maybe 10-20 lbs heavier than a 34 HP 1/2 VW Engine.

I prolly wont be able to go with the 12 gallons of gas
I originally intended, but hell, a GS does fine on 4.

If the mods dont mind, I'll post on occasion my progress.

Unless I find a DAMN good deal on a rotax 447 or 503,
I think the GS motor is gonna win.

[Blueknyt]

If your dead set on using a GS engine, then time to lighten the load alittle.

get rid of the Coutnerballencer shaft and have the crank reballenced,  dont know what kinda charging system your planing to use but i imagine the GS one will suffice.

yeah the 1/2 Vw engines are neat and produce around 30-50 hp, the 1/3 corvair engines run about 50-60.

[dgyver]

Bore it to 78mm and drop a little over 1 pound.

[spdracer75]

Well,  my reasoning for the GS motor:



38+ HP
4-Stroke
Electric Start
12v Generator

And I know the motor well from all the work I did on my GS.

Now, the nice thing is there is some leeway on the plane,
so I can probably live with the extra weight.

See, the thing is with 1/2 VW engines, is you can use them direct drive,
just bolt the prop on and go. The 1/2 VW Engines wont spin a decent prop too much faster than needed.  
I've seen corvair engines, but never heard of a 1/3 corvair engine (Yikes!)

Some of the Rotax and other 2 cycles need a reduction drive,
so while the engine may weigh less, you have to add in another 10-15 lbs ( I think) for a gear/belt/chain reduction drive,
and... most Rotax's are pull start. There's 8 more pounds if I want electric start!

One Idea I had was to possible take advantage of this,
and just stick the transmission in 1st gear, which, by using a chain or belt drive
(People do this on Harley Engine powered planes)
takes care of my reduction and gets me to roughly a 2.46:1 ratio

One of the things I'm going to have to deal with is the transmission.
That could end up being my 20lbs right there, however I might add back in  10 lbs, with a reduction drive. (Unless I'm thinking the ratios backwards)

However.... Isnt the GS casing Magnesium?
(Oh, please , oh please, oh please tell me it's Aluminum......)

As for the counter balancer.... I'm prolly gonna need it. and then some.

[Blueknyt]

yeah, its aluminum.  1/3 corvair engine is 4 cyl removed and some other cyl and heads are used.  i admit ive heard of folks useing VW engines but untill you wrote about 1/2 Vw i never knew of them being used that way.

[spdracer75]

Wheee! Aluminum means I can rework the engine case
if I decide to dump the tranny.

Yeah, 1/2 VW's are the same concept as a 1/3 Corvair,
except 1/2 VW's use the VW heads and such.

Anyways. I think I am dead set on the GS engine,
unless the airframe designer says the GS motor
does not have enough torque.

I'm going to reserve my N-Number this weekend,
and on Tuesday I'm putting in my Aluminum tubing order for the fuselage.

For the curious:

Handle grip:
http://www.aircraftspruce.com/catalog/elpages/infinitygrips.php

Main landing Gear:
http://www.acehardware.com/product/index.jsp?productId=1277436&cp=1254884.1255128.1260442&parentPage=family

Tail Wheel:
http://www.jackssmallengines.com/caster_hard.cfm#anchor%20Swivel

Yes, the plans call for WHEELBARROW Wheels. LOL!

I'm shopping around for the Altimeter, Horizon, Air Speed, Tach, Radio, and Fuel Gauge.  

Wonder if I can tap into the engine and get oil pressure....

If you are interested, you can read about the plane I'm building at:
http://www.affordaplane.com

[TheGoodGuy]

yes you can tap into the engine for oil pressure.. ask srinath.. he has done it. Or search teh archives.