Stihl 65cc 4-mix on 30% Edge
 

Here are a few pics of my KMP 30% Edge on maiden flight today...

Stihl 65cc four stroke 50:1 mix
22x10 prop
(5) 200 oz digital hi torque (Tower Pro) servos
(2) Futaba 3004 throttle and choke
7 channel Futaba RX
2500 mah nimh battery

This engine sounds AWESOME!!! Especially at lower RPMs, and has tons of torque. I'm still breaking her in so I was afraid to do any hover type maneuvers, but this thing rolls very axially and flies pattern very well. May try bigger prop, any suggestions other than 24x10?

RE: Stihl 65cc 4-mix on 30% Edge
 

Tripp,
Could we get some pictures without the cowl? What is the rpm with the 22x10? Too many questions. Any further details would be great.

Thanks, Dave

RE: Stihl 65cc 4-mix on 30% Edge
 

here are some pics

RE: Stihl 65cc 4-mix on 30% Edge
 

Any chance of capturing the sound? That is a fantastic result, finally a 4 stroke conversion flying an aerobat. Allot of these competition guys are going nuts over noise, what will win out, the result of the conversion engine or the prestige of having the proper popular engine?

RE: Stihl 65cc 4-mix on 30% Edge
 

Ken,
Great solution for a lefthanded engine. Nice pictures.

Dave

RE: Stihl 65cc 4-mix on 30% Edge
 

that is the engine that is on tripps plane.

RE: Stihl 65cc 4-mix on 30% Edge
 

Hey Ken,
I love this engine, thanks again! I have since cut some of the unecessary aluminum off the engine so this thing looks like nothing but cylinder and carb when the muffler is off:D I wish I could capture the sound of her but I dont have a camcorder.
I stihl haven't tached the engine with the 22x10 and honestly it doesn't appear to be turning all that fast, but it turns it with such authority I think I could even go a little larger, maybe...
(note the .095 weedeater line used for choke and throttle;)= no glitches)
12 volts wouldn't think about cranking her so I had to get a 24 volt Sullivan. Now it starts so fast its almost scary. I am curious about battery ignition but don't know if I have many options being 4 stroke, plus the mag seems to work pretty well.
Oh btw, I am using lots of expo on throttle b/c of low end power, almost ran me off the runway. I think I just need to adjust linkage at servo to adjust travel, and reduce ATV on Tx.
Engine is off again now as I'm cutting firewall back two inches to fit cowl properly
Here are some pics, one with engine still mounted. was considering Zenoah G62 but since this one is a keeper, the firewall is getting cut and the Stihl is going back on...[>:]

RE: Stihl 65cc 4-mix on 30% Edge
 

What is the big hose going to bottom of carb for? How about vibration at different speeds? I bet the sound is great. The 4 strokes have a longer push on the piston...making more torque. The windows in the cylinder on a 2 stroke....cause a loss of that push. Capt,n

RE: Stihl 65cc 4-mix on 30% Edge
 

For all the world, that looks like a PCV setup (positive crankcase ventilation) to me. I can see a lot of places to reduce weight on that engine.

How much did the engine cost? TIA

RE: Stihl 65cc 4-mix on 30% Edge
 

the hose is an impulse line that uses crankcase pressure to work the fuel pump on the carb.;)
Vibration is not bad, but a slightly high idle helps, epoxy and tri stock are your friends.
accelerates VERY hard but no blistering top end like the 2 strokes...

Cap'n, I've always liked your quote, and you'll find it holds true with this one.;)

RE: Stihl 65cc 4-mix on 30% Edge
 

From the looks of the ignition setup, there's no timing system other than fire-every-revolution, so there's no reason you couldn't use electronic ignition. I'm sure there would be a nice gain if you used a spark advance as well.

I imagine that hose comes from a difference source than a 2-cycle's fuel pump pulse, since a 4 stroke needs fuel every other rotation - even if there's no air intake the pump will still spurt out fuel as the throttle is still open

RE: Stihl 65cc 4-mix on 30% Edge
 

The hose comes from the crankcase just like a two stroke...There is just enough of a pulse to operate the carb...There is a misconception about the pump function in the carb, it just fills the cavity under the diaphragm, it can't pump fuel out of the carb..
There is also a misconception about spark advance, the only engines I know of that benefits from more advance are the FPE engines that were set up at 18 degrees...
Timing at 28 or 30 is the best, there is no noticeable change a few degrees one way or the other from there....Too much advance makes the engine miss, too little makes less power..

RE: Stihl 65cc 4-mix on 30% Edge
 

Ralph,
weren't you running a walbro sdc80 on this engine with good results. I ended up using the stock carb and had to mix my choke and throttle servos together to close the choke just a hair at half throttle for max power. adjusted carb but did not help, turned high speed screw out until it fell out in my hand with engine running, and STILL was asking for more gas...

RE: Stihl 65cc 4-mix on 30% Edge
 

YES! electronic ignition is VERY possible. just talk to the nice folks at C & H ignitions & they'll build you one. actually, they've already done some conversions on that engine including electronic ignition.

to the guy who was wondering about the "firing every stroke" factor... yes, the spark plug fires every stroke, but the valve train only introduces air/fuel mix every other stroke.

the 'large hose' from the crankcase... it uses the crankcase pressure to 'supercharge' the engine so to speak. exact same principle as the YS 4 stroke engines. in fact, wouldn't surprise me at all if StihL didn't copy the YS design. they were the first to do this. 4 stroke heaven? would be if Saito & StihL would 'hook up' and design a super light weight, high compression, methanol powered version of this engine. then comes 80 & 90cc versions. weeeeeeee

RE: Stihl 65cc 4-mix on 30% Edge
 

That is a nice looking engine. What would that have come out of? I'd like to find one.

RE: Stihl 65cc 4-mix on 30% Edge
 

Stihl BR550 or BR600 backpack blower.

RE: Stihl 65cc 4-mix on 30% Edge
 

It doesn't look like this engine uses a supercharging principle. It looks like the carb is attached directly to the head. It is a brilliant idea though, to attach the carb via a reed valve to the crankcase, and then run an intake runner from the crankcase via another reed valve to the intake port. This would take care of lubricating the bottom end of the engine as well as pressurizing the intake mixture.

RE: Stihl 65cc 4-mix on 30% Edge
 

Tripp3d

Do you go to the giant scale fly in at Hot Springs AR Oct, 12, 13 and 14. If so let me know so can be looking for you. I would like to see this set up.:)

RE: Stihl 65cc 4-mix on 30% Edge
 

has anybody tryed the 25cc? 4-mix ? thanks Erik:D

RE: Stihl 65cc 4-mix on 30% Edge
 

has anybody tryed the 25cc? 4-mix ? thanks Erik:D

RE: Stihl 65cc 4-mix on 30% Edge
 

check out the animation on StihL's website. it shows it clearer than I can explain it in words. but in the long run? they force feed the fuel air mix using the pulses from the crank case.

RE: Stihl 65cc 4-mix on 30% Edge
 

drdrain,
I've been on stihlusa.com and have not found any animation or other that explains that their 4-strokes work that way. I know exactly the principle you are talking about, and I believe a European engine manufacturer made a 4-stroke using this principle. The particular engine in this thread does not look like it operates that way, I mean, the carb. is attached on the head, not the crankcase, and there is no visible manifold running from the crankcase to the head.

Ig you have a link you can post, I'd be more than happy to look into it.

DKjens

RE: Stihl 65cc 4-mix on 30% Edge
 

Try this

http://www.stihl.ca/4mix/francais/videos/video4mix.htm

RE: Stihl 65cc 4-mix on 30% Edge
 

And for for the equivalent Shindaiwa C4 can be downloaded from here.

http://www.t2500.com/downloads/index.html

RE: Stihl 65cc 4-mix on 30% Edge
 

there used to be a place on stihL's site where you could view an animation of the innerworkings of this engine while running. I got a good look at it about a week ago while at a friends' house. I was WRONG about the hose. it only operates the pump, just as tripp3d says. however, in the diagram, it shows the crankcase pressure being 'pumped' past the valve train, building pressure, then releasing into the intake valve. has anyone else seen this animation? past a link on here perhaps?

RE: Stihl 65cc 4-mix on 30% Edge
 

yah! that's the one ms9. thanks.

RE: Stihl 65cc 4-mix on 30% Edge
 

If you are curious about the different induction methods for these four stroke utility engines do a patent search. McCulloch, had a read valve crankcase inducted four stroke patented in 1994. The YS patent relates mostly to their fuel management system, which is why OS was able to borrow the supercharging method but had to use their own electronic fuel metering method. Webra was probably the first one with their crankcase supercharged four strokes back in the early 80's. It worked just like the animatino link in MSS999's post shows it.

Shindaiwa's C4 shows 1.4HP for the 2.1ci engine so I think the induction method is mainly to lubricate the engine rather than supercharging. Honda's GX35 at 2.2 ci makes 1.3HP, so there is very little gain in power.

RE: Stihl 65cc 4-mix on 30% Edge
 

Where might one find a prop hub for one of these Stihl 65s?I e-mailed lamberts RC but they said they didn't have any.
Thanks

RE: Stihl 65cc 4-mix on 30% Edge
 

Try this link:

http://cgi.ebay.com/ws/eBayISAPI.dll...:X:RTQ:US:1123

RE: Stihl 65cc 4-mix on 30% Edge
 

Thanks Ralph,
That one wasn't for the 65 but he said he could make one.

J

RE: Stihl 65cc 4-mix on 30% Edge
 

Here is another question.
On the cam there is a compression relief lever.Would it be a good idea to disable it?It would be difficult to impossible to remove it without destroying the cam/cam gear piece,but I might be able to disable it.

J

RE: Stihl 65cc 4-mix on 30% Edge
 

Look up my post " Stihl 4 stroke lubrication " from 5-25-06 . Interesting disscusion.
motorhd

RE: Stihl 65cc 4-mix on 30% Edge
 

Thanks guys,
One more question if I may. Does anyone know what the thread size is for the shaft on the fan (propeller, in this case)side is?

TIA,

J

RE: Stihl 65cc 4-mix on 30% Edge
 

Yep, M12x1.0 :D

RE: Stihl 65cc 4-mix on 30% Edge
 

Thanks!,you're the greatest!:D

J

RE: Stihl 65cc 4-mix on 30% Edge
 

well after all this time is there any tach numbers?

RE: Stihl 65cc 4-mix on 30% Edge
 

Hopefully I'll have one of mine running on the test stand in a week or two.I just got my EI unit in the mail so I still have to hook that up.

J

RE: Stihl 65cc 4-mix on 30% Edge
 

just jumped in to see if anyone had any updates on the stihl 65cc 4stroke. tach reading w/prop size? how about vertical performance on that 30% edge? and by the by... what's the weight of the engine once you got it 'trimmed'?

RE: Stihl 65cc 4-mix on 30% Edge
 

Still haven't run mine yet.As for weight.I weighed one with it's mount, prop hub and carb mount w/carb on but without the EI unit and exhaust tube(haven't made one yet) and it comes in at 5lbs 4oz.Hopefully I'll get one running by the end of the month.

J

RE: Stihl 65cc 4-mix on 30% Edge
 

I picked one of these up, actually got it today.

It's already converted. Prop Hub and C&H ignition.
I was told when I bought it that the 65s have an issue transitioning from and idle.
I talked to Ralph at rcignitions and he said he made a new base gasket for the Carb with a smaller hole in it.
He mentioned another Carb. But had not personally tried it.

So is there a "Good" fix for this problem?

Thanks everyone.