OS Engines

[James n TN]

Hey guys not sure who here knows me but I had raced a few yrs ago and was a member of the Music city Buoy Dodgers.

Anyhow i have aquired another Twin Hydro after selling all my stuff when I got burned out and took a break. Right now it has a pair of 67 Piccos in it and I'm going to swap them out for some 80's i currently have an opportunity to purchase a NIB OS 81 for 1/2 price can any of you tell me the good or the bad in these engines? Things have chaged a bunch since I left so I'm playing catchup. Any info would be much appreciated my next option are the CMB's.

James

 

[Don Ferrette]

Hey guys not sure who here knows me but I had raced a few yrs ago and was a member of the Music city Buoy Dodgers.Anyhow i have aquired another Twin Hydro after selling all my stuff when I got burned out and took a break. Right now it has a pair of 67 Piccos in it and I'm going to swap them out for some 80's i currently have an opportunity to purchase a NIB OS 81 for 1/2 price can any of you tell me the good or the bad in these engines? Things have chaged a bunch since I left so I'm playing catchup. Any info would be much appreciated my next option are the CMB's.

James

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Hi James-

The stock OS81 is not a bad motor however those Picco 67's, if they are EXR's, will smoke the OS motors speed wise, but I've seen some modified OS81's run well. You'll need to do some grinding on the OS motors to really make them go like they should. The CMB motors are good motors, I've run those & was happy with them. Not as fast as my MAC's I now run though. B)

 

[James n TN]

Thanks,

I'm not sure which Piccos these are and really not sure how much life is in them the boat came with 3 of them. As for the Mac's they are o 80's in stock and John didn't know when they would have any in. For them CMB's I had a pair in my old twin that Harry Gerhart now owns and man those motors were bullet proof and unstopable ran like timex.

My thinking on the OS engines was purchase the 81's and then add the 90 sleeves and pistons to them since the 90 and 81 are same size cases and OS don't actually make a marine 90 engine.

James

 

[Don Ferrette]

Thanks,
I'm not sure which Piccos these are and really not sure how much life is in them the boat came with 3 of them. As for the Mac's they are o 80's in stock and John didn't know when they would have any in. For them CMB's I had a pair in my old twin that Harry Gerhart now owns and man those motors were bullet proof and unstopable ran like timex.

My thinking on the OS engines was purchase the 81's and then add the 90 sleeves and pistons to them since the 90 and 81 are same size cases and OS don't actually make a marine 90 engine.

James

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James are the Picco's disk or drum valve engines? As for the OS motors if I recall it ain't that simple. There were guys that coverted the OS ducted fan motors for marine use. Those new green head CMB 80's run rather well & will bolt right place (as will the MAC's) of those Picco's if you go that route.

 

[James n TN]

Don,

I'll have to break one down and see which they are.

For the OS what I was going to do was purchase the 81's and then purchase the .91 piston and sleeve and just slip them in the 81 case since the cases are the same size the big difference on the 91 case and 81 case is which side the exhaust port is on. I wasn't going to conver the ducted fan engine just use there internals in the 81 case. I may just go with the CMB's since I can't get any Mac's

James

 

[Don Ferrette]

Don,I'll have to break one down and see which they are.

James

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Send me a pic to my regular e-mail - [email protected] & I'll tell ya what they are.

 

[Terry Keeley]

Unless they came with Nelson liners i wouldn't run them, the nickle liked to come off.

 

[Don Ferrette]

Unless they came with Nelson liners i wouldn't run them, the nickle liked to come off. 

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Wow, forgot about that. Terry's right, they don't like to hold the nickel well in higher nitro, higher rev applications like we use. I've seen them do ok in cat hulls but I remember a couple guys having the fit go away real quick in riggers, one guy in less than 1/2 a season. :unsure:

 

[NAMBA860]

Don,
I'll have to break one down and see which they are.

For the OS what I was going to do was purchase the 81's and then purchase the .91 piston and sleeve and just slip them in the 81 case since the cases are the same size the big difference on the 91 case and 81 case is which side the exhaust port is on. I wasn't going to conver the ducted fan engine just use there internals in the 81 case. I may just go with the CMB's since I can't get any Mac's

James

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if you are not going to buy those .81s would you be willing to tell me where to buy them for the price you were going to get them for i just need one of them

 

[gil sonsino]

Stock con rod also use to blow off (low end).

 

[Piston1]

WELCOME BACK JAMES

Here's My experience. Last year I was running OS 81s on a Twin. The only modification that I did to them was replacement of the flywheels with OPS flywheels. They are good motors very easy to tune stock out of the box. They have lots of torque. The AB 67 pipes are the perfect combination. There are two major problems with these engines. Conrods like to spin crankshaft bushings, and they like to vibrate at high RPMs.

JOSE ORTIZ