OS .21XZ-M inboard

[Richard Dahlheimer]

Just wondering if anyone here has run one of these? Maybe Grimracer will have some feedback? My new Tower book says this motor has ABN piston/liner. Perhaps a misprint? Thanks in advance. Richard D

 

[JeremyEdge]

Here it is on the OS page.http://www.osengines.com/engines/osmg1621.html

 

[Ted buckley]

Richard, that motor in Jeremy's link is very similar to the Motor I'm running in my sport20 Hydro. Except for the RP7 Turbo plug & the Silicon in the Crank it's almost identical. 0S21-RX-M

 

[Jerry Dunlap]

I have only had an opportunity to run this engine once in a JAE 21 Hydro. The engine comes without a collet or flywheel. A Nova Rossi collet/flywheel can be used.

Because I haven't really broken in the engine, it's hard to say what it's ultimate performance will be. Like all O.S. engines, it is nicely crafted.

JD

 

[RodneyPierce]

someone needs to let OS know that the boat market, and the buggy market are 2 different things (in relation to the price tag)

 

[Ted buckley]

I have only had an opportunity to run this engine once in a JAE 21 Hydro. The engine comes without a collet or flywheel. A Nova Rossi collet/flywheel can be used.

Because I haven't really broken in the engine, it's hard to say what it's ultimate performance will be. Like all O.S. engines, it is nicely crafted.

JD

Don't know if this motor will like the Higher Nitro(i.e.60%) - I know mine don't. 45% tops.

 

[Grimracer]

The new motor is ABC.

 

[LarryConrad]

I have only had an opportunity to run this engine once in a JAE 21 Hydro. The engine comes without a collet or flywheel. A Nova Rossi collet/flywheel can be used.

Because I haven't really broken in the engine, it's hard to say what it's ultimate performance will be. Like all O.S. engines, it is nicely crafted.

JD

Don't know if this motor will like the Higher Nitro(i.e.60%) - I know mine don't. 45% tops.

Why not?

 

[Jerry Dunlap]

I have only had an opportunity to run this engine once in a JAE 21 Hydro. The engine comes without a collet or flywheel. A Nova Rossi collet/flywheel can be used.

Because I haven't really broken in the engine, it's hard to say what it's ultimate performance will be. Like all O.S. engines, it is nicely crafted.

JD

Don't know if this motor will like the Higher Nitro(i.e.60%) - I know mine don't. 45% tops.

Why not?

The engine is in a friend's JAE. Last week when we went to run the boat the rudder servo went TU before the engine was even started.

JD

 

[Tim_Duggan]

The 21D carbs used on this engine have a progressive metering valve on the end of the carb barrel. The mid range was too lean FOR ME on 50% nitro regardless of where the adjuster was set.

I'm sure the engine itself is more than capable of handling high nitro, it's just that the supplied carb (as delivered) makes it tricky to tune with high nitro. If you don't like low end needle carbs, this carb will probably drive you completely nuts. It's not a matter of just winding out the low end or cutting the needle off - there isn't one!

 

[Ted buckley]

I have only had an opportunity to run this engine once in a JAE 21 Hydro. The engine comes without a collet or flywheel. A Nova Rossi collet/flywheel can be used.

Because I haven't really broken in the engine, it's hard to say what it's ultimate performance will be. Like all O.S. engines, it is nicely crafted.

JD

Don't know if this motor will like the Higher Nitro(i.e.60%) - I know mine don't. 45% tops.

Why not?

Didn't know if this was directed at me? On my OSRx-M the piston arrives tdc on the top of the sleeve. The 2 peice head with (1) 10 thousands shim fits over the sleeve and seems to be the only squish clearance for the set-up. The head-dome doesn't fit into the sleeve like other engines(i.e. NR/etc.) it just sit's on top of the shim/sleave. I don't know what the OS .21xz-m has for the head button, but I'm sure the engine is Higher performance than mine. When I tried higher Nitro(60%) - the engine sags(regardless of what pipe/prop/needle setting applied). When back down to 30-40% - Night & day difference.

 

[Niklas Edlund]

Has anyone measured the timings on this engine yet?

Carb neck is 15 mm?

 

[RobertWurster]

It says on there web site that it can run on 50 % nitro well its in the options .it says to break it in on 20 % i was told to break a engine in on the fule you plan on runing ?

 

[Jerry Dunlap]

Has anyone measured the timings on this engine yet?

Carb neck is 15 mm?

Carb neck is 15 mm.

I now have the engine in my Mini Mutt 20 Sport Hydro.

JD

 

[jaxracer]

The 21D carbs used on this engine have a progressive metering valve on the end of the carb barrel. The mid range was too lean FOR ME on 50% nitro regardless of where the adjuster was set.

I'm sure the engine itself is more than capable of handling high nitro, it's just that the supplied carb (as delivered) makes it tricky to tune with high nitro. If you don't like low end needle carbs, this carb will probably drive you completely nuts. It's not a matter of just winding out the low end or cutting the needle off - there isn't one!

Not to get too off topic, has anyone else had the same problem with this carb? I tried to run it on an O.S. .21 VZ-M on 65% nitro and the boat was screaming lean on the stand no matter how fat I turned the needle..

I figured, hey maybe this carb is just too big for a 3.5 because it's like a .390 bore. Switched carbs and the boat worked great. Then I tried the same 21D on a .45 Rossi using 65% nitro and I had the same issue of the motor being way too lean. Switched the carbs back to the Picco carb I was running and then engine ran great.

Any ideas or similar experiences?

-Mitch

 

[JAMEYGALLIHER]

The 21D carb will not flow enough fuel

 

[Two blades]

Not to get too off topic, has anyone else had the same problem with this carb?

Hello, I have run a 21VZM in my Ducer for 2 race seasons now, and it works well with the fuel I am using (Byron 16% nitro). I remember that it took me at least three days at the pond to break this engine in + to find decent needle settings.

I noticed important top rpm loss with 21J carb, but of course smooth transitions... Depends on what you are looking for !

Personally, I came back to the 21D (original one).

Pascal