quote:

ORIGINAL: Oupagryse

Hi Does someone have a complete manual for the 15cc engine? I'm glad i read this forum, would have never thought to check the timing of the engine.

I was looking for the performance curves of these engines but could not find them. Sent a mail to the manufacturers but they replied with a statement saying they don't have any... How is that possible? They state the kw rating of the engine but they don't know at what rpm they achieved it or anything... Stated bore and stroke is also wrong. It's 31mm and 24mm stroke. If you take into consideration the exhaust port ect it does come out at 15cc, so atleast they wern't lying about that.. Anyway, if anybody could help I would appreciate it.

Fuel consumption vs load and power vs rpm and fuel vs rpm


The Old Grey Grandpa AKA Oupagryse in Afrikaans


@ ACERC     P.s a Nylock nut is only suppose to be used once... The plastic bit should be threaded, you can use them about 3 time before they stop the nut from vibrating loose..

quote:

ORIGINAL: aussiesteve

quote:

ORIGINAL: Oupagryse

Hi Does someone have a complete manual for the 15cc engine? I'm glad i read this forum, would have never thought to check the timing of the engine.

I was looking for the performance curves of these engines but could not find them. Sent a mail to the manufacturers but they replied with a statement saying they don't have any... How is that possible? They state the kw rating of the engine but they don't know at what rpm they achieved it or anything... Stated bore and stroke is also wrong. It's 31mm and 24mm stroke. If you take into consideration the exhaust port ect it does come out at 15cc, so atleast they wern't lying about that.. Anyway, if anybody could help I would appreciate it.

Fuel consumption vs load and power vs rpm and fuel vs rpm


The Old Grey Grandpa AKA Oupagryse in Afrikaans


@ ACERC     P.s a Nylock nut is only suppose to be used once... The plastic bit should be threaded, you can use them about 3 time before they stop the nut from vibrating loose..

31mm bore and 24mm stroke comes out at 18cc.

quote:

ORIGINAL: aussiesteve

Yes I am aware of the ''effective sweep volume '' of the piston however the standard takes the entire stroke into account for displacement calculation. In a running Engine, even while the exhaust port is open there is still transfer taking place and cylinder charging taking place whilst the port is uncovered.

Comparing on the same measurement basis - sure makes the DLE 20 appear to be a significantly better desing than the others doesn't it - it uses 20cc of total displacement - including the port open volume.

Sorry guys - ya walked right into that one.

Back to the original programming.

And Kudos to BP for taking care of Roberts shaft.

quote:

ORIGINAL: aussiesteve

Ya reckon so?

It is about Engineering and marketing STANDARDS.

The STANDARDS for stating displacement is Bore and stroke - not minus anything else.

Funny thing is - if the company involved atated the actual displacement based on those same standards, they would probably sell more enignes becaus ''everybody'' knows people will buy an 18cc over another brand of 15cc because it is bigger for the same sized package.

But then maybe ALL the other 2 stroke manufacturers in the world don't know what they are talking about. Honda, Kawasaki, Yamaha, DA, 3W, MVVS, Detroit Diesel, and the list goes on and on.

Those companies use the full stroke and bore to state cubic capacity. By using the same basis for stating it on an RCGF / GRPro / SV product it really shows up a low power to displacement. Eg - the 15cc is really 18cc using the STANDARD method of statement, the 20cc is really 23cc using the same method of statement - now use those and compare power outputs against the opposition products.

That is all I am saying on the subject - back to the normal channel now - buy and fly what you like.

Oh, I almost forgot - ''Nice plane''

(seems to be a pretty common answer for ''Darned if I know the answer to the question posted'' around some parts of the forums these days)

From personal experience I recommend BP Hobbies. They have taken care of me very well. I have three as well and have a couple guy's at the field that have gone to them. They all start first flip, idle well and seem stronger than expected. For example the 26cc specs call for a 18-8 @7100, I'm running a 18-8 @ 7400. Will almost hover my 17lb waco.

quote:

ORIGINAL: acerc
I have three as well and have a couple guy's at the field that have gone to them. They all start first flip, idle well and seem stronger than expected. For example the 26cc specs call for a 18-8 @7100, I'm running a 18-8 @ 7400. Will almost hover my 17lb waco.

That all sounds good. But for the price difference, MVVS @ $499and RCGF @ $226,  I'll take the loss of 600rpm. Of course once my new JTec pipe comes in that will probably only be a loss of 400 or less. And then add in that BPHobbies has outstanding customer service (where I buy mine) , and that amounts to one happy me.

quote:

ORIGINAL: aussiesteve

quote:

ORIGINAL: airtime82

How can you tell if the engine you have is in timing when you get it?

If you got it through a decent dealer, it will have been checked. If you didn't get it through those means.
Check that it is firing somehwere between 25 - 30 degrees BTDC. (28 is ideal but a couple of degrees either way is not going to make one iota of difference to the final outcome).

For a quick and dirty test

Find TDC by looking at the piston through the exhaust port. - mark a pencil line across the prop hub and the crankcase at this point.

Method one for finding the right firing point
Get a strip of paper and wrap it around the prop hub. Cut it so it is exactly the length of the hub circumference.
Get that piece of paper and cut it in half - discard one half.
Get the piece you kept and cut it in half again - discard one half.
Get the reamianing piece and cut it into a 1/3 length - discard the 2/3rds length.
That last peice you kept is now ''30 degrees'' long. Make a mark from the exisiting mark on the hub to the length of that paper before TDC (to the left of the mark looking from the front of the engine.

Method 2 for finding the firing point.
Measure the diameter of the prop hub and muliply it by 0.244 - that is the 28 degree length. use that measurement to amke the BTDC mark.

Now power up the ignition, and listen to the spark plug cap - it will make a ''crack'' noise when it fires. Do it slowly and don't overdo it. There is no need to have a spark plug in there for this test as the occassional use of it this way woun't hurt a thing.

Now you will most likely have discovered that the timing is way out - go dril some new mounting holes for the sensor screws or start filing the senso slots to get the sensor to the right place as my experience has been they are either close enough or a long way out.

quote:

ORIGINAL: WindGap

I've seen them post the 40cc twin now.
http://www.bphobbies.com/view.asp?id=F3693949&pid=F3693948

And video is alread posted online.
http://www.youtube.com/watch?v=HYPascJ62aQ

I'm truly interested in this engine...it's performance and reliability. Now to find an airframe for it....

quote:

ORIGINAL: Captmicom

Hey Blake,

Not sure it will fit in the 70'' planes because of the plug angle. Plug hole to plug hole is 7.5” plus two times 5/8” for the plugs and CDI caps comes out to 8.75” might be a good fit for one of the 85” war birds though.

Captmicom