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May 22, 2019, 12:34 PM
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Last edited by Solomaster; May 22, 2019 at 12:36 PM. Reason: wrong thread
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May 22, 2019, 02:46 PM
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Quote:
Originally Posted by I-Love-Jets
I just found out that all of the 2.5 cc OPS aero engines except for the super hot VAE (#8150) - come with the crankshaft #1230 featuring only 7 mm of bore diameter. So a maximum carb bore of 7 mm is feasible here (better is 6.5 mm)!

In contrast the #8150 VAE engine features the large-bore crankshaft (#1231) with a 9 mm diameter passage.

The VAE also comes with one of the mentioned high-timed liners and the big-bore speed venturi #1261 instead of the standard venturi carb # 3260 of the other non-R/C 2.5 cc FIRE and FISE engines.

So the very high rpm numbers the VAE .15 engine is capable of (well in excess of 30.000 ) is also the result of considerably improved mixture flow. Therefore it wouldn't be promising to put the high-timed liner of the VAE into one of the other (in this case too restrictive) 2.5 cc OPS engines...
I went ahead and disassembled the engine a bit and did some measurements. I tried to measure the timings using the timing wheel provided in this thread on page 3. Please forgive me if some mistakes as this was my first time measuring timings.

I got that intake port opens 40degrees after BDC and closes 45degrees after TDC so it is open for a total of 185degrees.
Exhaust port opens 85degrees after TDC and closes 80 degrees after BDC so it is open 175degrees.

These are approximate values just eyeballed with the cardboard timing disk but to me they sound like a pipe timed engine right?

Crankshaft has a passage of 9mm so it seems to be the #1231 crank altought it is marked as OPS 323?

Also head seems a little rough cast to me but very clean otherwise. Backplate has some little wear so this has possibly been tested. Might have been tested at the factory or by the previous owner.

One thing that I am unsure is the nice sprinkler type venturi that it has. It is only 4mm in bore. Is that supposed to be like that or does it have a wrong venturi?

regards
Ollie
May 22, 2019, 05:49 PM
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earlwb's Avatar
The venturi may be a restricted one as per rules for some contests. So it is likely the correct one. If the engine has to draw fuel itself, it needs a smaller venturi than does a engine that uses a pressurized fuel tank.
May 23, 2019, 11:38 AM
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Anyone have the OPS big bore speed venturi OPS art #1261 and can measure? Been looking around and it seems that F2A engines have huge bore venturies. Does anyone know if the OPS accepts the Rossi venturi or the Ucktam/MDS venturi? Those might be more easy to find.

Edit. Diameter of the venturi is 12mm and it is 8,7mm deep. There is a round recess for the NVA and NVA is 4mm in diameter.

-Olli
May 24, 2019, 05:30 AM
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pmackenzie's Avatar
The head looks like it has been blasted by a blown glow plug.
I have lots of them in F2D motors that look exactly the same.
May 24, 2019, 08:13 PM
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downunder's Avatar
Quote:
Originally Posted by Olli-Matti
Exhaust port opens 85degrees after TDC and closes 80 degrees after BDC so it is open 175degrees.
Pretty sure you meant the exhaust opens 85 degrees BBDC .
However the difference you have between the opening and closing times indicates one of two things. Either the crankshaft is Desaxe (offset from the cylinder axis which is rare in model engines but not unknown as all Mercos and the Fox 35 are Desaxe for instance) or the timing wheel wasn't quite set at TDC. Assuming it's not Desaxe then the exhaust timings are 82.5 degrees before and after BDC and a similar 2.5 degrees difference in the crank port timings.

Just checked and there's a report on the Speed 2.5 here.
Last edited by downunder; May 24, 2019 at 08:20 PM.
May 26, 2019, 06:57 AM
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Venturi


Anyone have knowledge if OPS speed venturi can be replaced with some other venturi? And what is the correct diameter of the big-bore venturi passage?

For example Ucktam, Rossi 15, Irvine R15, Cox Conguest venturi?

OPS has 12mm fitting and is set up for 4mm NVA. Venturi is 8,7mm deep from the o-ring, but this could be possibly adjusted to suit.
Jun 09, 2019, 10:29 PM
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Identify OPS motor ?


The other day I saw this RC boat at a lawn sale for 20 bucks with remote control and what looks like an entire boat,receiver and all.
It looks quite old but in good shape. The motor turns easily and can feel compression...also hear it.
Batteries for radio obvious need to be removed/replaced and clean up.
I see markings on the motor and for sure OPS boldly on one side and other markings in other areas of the motor.
I see OPS 824 on the crank cover and OPS3 near exhaust outlet but could be some other digits behind that vacuum line?
I am familiar with RC planes but know nothing about boats or OPS motors...a first I heard of these.
Jim
Jun 10, 2019, 10:08 AM
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Quote:
Originally Posted by JimmyZ911
The other day I saw this RC boat at a lawn sale for 20 bucks with remote control and what looks like an entire boat,receiver and all.
It looks quite old but in good shape. The motor turns easily and can feel compression...also hear it.
Batteries for radio obvious need to be removed/replaced and clean up.
I see markings on the motor and for sure OPS boldly on one side and other markings in other areas of the motor.
I see OPS 824 on the crank cover and OPS3 near exhaust outlet but could be some other digits behind that vacuum line?
I am familiar with RC planes but know nothing about boats or OPS motors...a first I heard of these.
Jim
I think I have an OPS .21 (3.5cc) SE motor ? What kind of performance can I expect from this setup? Is there a video of what I may expect ?
This looks it could be a lot of fun !
Similar motor - https://www.worthpoint.com/worthoped...gine-293556132
Jim
Jun 10, 2019, 01:53 PM
Registered User
Hmmm... kinda looks like a marine version of the SL .45. Do you know vintage, I'm guessing mid '70's? Doesn't look like any recent OPS marine engines.
Jun 10, 2019, 04:32 PM
Boats on the brain!!
green-boat's Avatar
Looks to have a Perry carb on it.
Jun 10, 2019, 08:38 PM
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I know nothing about these boats and only have an RC plane with K&B 45 SPORTSTER . For 20 bucks,nothing to lose really on this if the motor runs.
Tomorrow going to take it to hobby shop.They tell me the "boat" guy will be there. I do not want a money pit...so for now,see if the motor will run then will see what the radio is doing.Batteries are obviously beat. Controller is Futaba 4 channel FP=T4L and you can see receiver is packed inside that aluminum box with 200 screws in it Just going to see if I can put the 4.2v on RX and 9.6 on TX to test. Already I see the TX had got water in it so pulled one of the PCB`s that looked like some corrosion on it and will re-solder all joints.If it does not work,will grab one off ebay. I have no interest in sinking a bunch of cash into it.
Jun 10, 2019, 08:47 PM
Registered User
I replied about the motor but it did not post.
The OPS people replied back by email and said -
Your engine is a .21 (3.5cc) SE.
Looking at the carb fiited it is probably pre 1990
Jun 10, 2019, 10:04 PM
Registered User
Controller now works.Cleaned the PCB a bit and touched up some questionable solder joints and she works !! I do not know what the DC voltage used for this receiver...looking online seems to give a lot of details about nothing you need as usual. I am gonna guess 4.8v so tried a 3.7 LIPO and it wanted to work...so maybe 3.7 not quite enough.Going to search a bit more just in case.
Jun 11, 2019, 06:16 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Normal voltage for that would be ~5 volts, 4 cell NiCd pack.


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