NR91 water jacket removal?

[Greg Wannamaker]

Anyone know what the trick is to remove or turn the water jacket on a NR 91? I want to give mine a 1/4 turn to move the water inlets to better fit under my cowl but that sucker is on there really tight!

 

[Bradley Ward]

Large soft face hammer? Can you press it off or out? I will have a look at 1 and see? Is it the purple head you need rotating or the aluminium one? Tried the heat the engine and cool the head trick? Tried the leather belt technique? Wrap a leather belt around the head to make it bigger so you can grip it better! Or the old lid openers used by arthritis sufferers to open jars! Last throw it on the ground in disgust!!

 

[Greg Wannamaker]

It’s the aluminum mid cylinder one, it must be pressed on and lock tighted at the factory. Haven’t tried heating it yet, having never had it

off, wondered if there are any internal o rings that wouldn’t do well under the flame.

 

[Buckshot]

Looks like it is part of the case and not movable according to the exploded view on Novarossi's website.

TO-BE-91-DDA.pdf

 

[Jack ODonnell]

Or sale it and buy a cmb .

J.

 

[Greg Wannamaker]

Or sale it and buy a cmb .

J.

Yup, could do that but I like this engine, it’s a beast, finally found its sweet spot! Not ready to abandon it just yet.

 

[brad nichols]

Did you get ahold of Ron and ask him? Doud has a NR 91 too I think? Could be like the old PICCO's with O rings I'm sure and they can be sticky.

Brad

 

[Danny King]

It is pressed on. No o-rings. It can be turned or removed with heat. There is a possiblility if just turning it, it could not seal. I would just remove it.

 

[Greg Wannamaker]

It is pressed on. No o-rings. It can be turned or removed with heat. There is a possiblility if just turning it, it could not seal. I would just remove it.

Did it come off fairly easy with heat? When put back in place did you use anything to make sure it sealed again?

 

[Danny King]

It is pressed on. No o-rings. It can be turned or removed with heat. There is a possiblility if just turning it, it could not seal. I would just remove it.

Did it come off fairly easy with heat? When put back in place did you use anything to make sure it sealed again?

I have only taken them off.

 

[Greg Wannamaker]

It is pressed on. No o-rings. It can be turned or removed with heat. There is a possiblility if just turning it, it could not seal. I would just remove it.

Did it come off fairly easy with heat? When put back in place did you use anything to make sure it sealed again?

I have only taken them off.

You run them without? Doesn’t seem like there’s much remaining substance in the case for general integrity strength??

 

[Danny King]

No failures of any kind. There is plent. I wish the cases werent machined for the ring and still has the heat sinks. But they dont.

The only boat I would be leary of not using it is a scale. But no issues.

 

[David Ashcroft]

Greg rather than try remove,,perhaps plug the original outlets and drill and tap new ones where you want them..

 

[Greg Wannamaker]

Greg rather than try remove,,perhaps plug the original outlets and drill and tap new ones where you want them..

Thought of that already, the water passage way is so shallow there isn’t enough space to work a tap through and get proper threads into the jacket material.

 

[brad nichols]

You would need to use a bottoming tap to finish the hole.

Brad

 

[Mike Hughes]

That and or a custom ground one. would do the trick too. One that broke works best for this.

 

[Greg Wannamaker]

That and or a custom ground one. would do the trick too. One that broke works best for this.

Good solution, until today, didn’t know such a tool existed, very cool!

 

[Mike Hughes]

https://www.mscdirect.com/basicsof/taps

Greg,

Some good info on types in here. Gives you the basis.

 

[eagletwin90]

Great info there Mike,,, Thank you for posting this. James

 

[brad nichols]

The 3 tap types are taper, plug and bottoming. use the plug tap as your starting tap because of shallow hole then the bottoming or your ground off broken tap to finish. I would not use the broken tap in ant steel taping as they break easier.

Brad