Nova 45 DD going lean?

[Andy Brown]

Not break in, not pipe or stinger dia, not fuel tank(tried more than enough of them, and yes with hopper), , not needle valve or placement(isolated didn't change anything), not temperature, not seals, not fuel, not plugs , we are not new at this.lol.

If the .430 carb is to big for the .07 spraybar would the problem not start shortly after the engine cleans out and reaches temp, and if the carb is the problem would not running at 3/4 throttle solve the problem?

Tim,

At 3/4 throttle there is still a large volume of space surrounding the spraybar. The restrictions are only in the front side and backside of the barrel, so the air speeds up going through the front side then SLOWS down as it passes the spraybar, then speeds up going through the back side.

Yes, the engine goes richer at 3/4 throttle, but the general drawing ability is still lacking. It sounds like the problem is showing up for you later in the run when the tank gets lower . This lower tanks level allows the fuel to wave front to rear. The inertia of the fuel weight moving to and fro pulls positive and negative pulses on the fuel lines and even the header tank.

Same thing going on in Olly's LONG tank.

A smaller carb that has great draw is the easiest way to overcome this problem.

There are Nova 21 carbs laying around everywhere. Grab one and bolt it on and see what happens.

Ultimately there seems to be something strange going on in the DD engine. Maybe it is just a certain batch and not all of the DD's, because some guys seem to have zero issues.

The seal clearance between the PTO drive and housing?

 

[Tim Kish]

Not break in, not pipe or stinger dia, not fuel tank(tried more than enough of them, and yes with hopper), , not needle valve or placement(isolated didn't change anything), not temperature, not seals, not fuel, not plugs , we are not new at this.lol.

If the .430 carb is to big for the .07 spraybar would the problem not start shortly after the engine cleans out and reaches temp, and if the carb is the problem would not running at 3/4 throttle solve the problem?

Tim,

At 3/4 throttle there is still a large volume of space surrounding the spraybar. The restrictions are only in the front side and backside of the barrel, so the air speeds up going through the front side then SLOWS down as it passes the spraybar, then speeds up going through the back side.

Yes, the engine goes richer at 3/4 throttle, but the general drawing ability is still lacking. It sounds like the problem is showing up for you later in the run when the tank gets lower . This lower tanks level allows the fuel to wave front to rear. The inertia of the fuel weight moving to and fro pulls positive and negative pulses on the fuel lines and even the header tank.

Same thing going on in Olly's LONG tank.

A smaller carb that has great draw is the easiest way to overcome this problem.

There are Nova 21 carbs laying around everywhere. Grab one and bolt it on and see what happens.

Ultimately there seems to be something strange going on in the DD engine. Maybe it is just a certain batch and not all of the DD's, because some guys seem to have zero issues.

The seal clearance between the PTO drive and housing?

Thanks Andy

I remember back when we didn't have fancy remote needles, if you got to greedy on the needle and the boat fell off during the heat you could sometimes get it back by backing off to 3/4 throttle, if you didn't destroy the plug.

I still believe it has to be a seal issue or just a plane volume issue with more surface area to seal using the same amount of fuel as a standard engine. We are going to try a smaller carb tomorrow and we have also tried taping a 1 oz tank right at the engine which helped very little.

 

[Tim Kish]

This is only on the DD engine Craig.

So the PTO assembly is suspect....

Are there any DD engines with the old cooling cap?

Just throwing stuff out there.

With me needing full cooling in the summer months and I'm running the old cooling cap that was suppose to be over cooling, wondering if the new cooling cap is not good enough?

Just some thoughts....

Not a cooling issue Craig.

 

[Terry Keeley]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

 

[ALLAN YUEN]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Can you show picture of Olly sport 40 where fuel tank? thanks

 

[Tim Kish]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Can you show picture of Olly sport 40 where fuel tank? thanks

Allan go back and read the posts, this is not just one boat having the problem.

 

[Tim Kish]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Going to try a couple more things tomorrow, but if you're not having any luck I doubt we will.

 

[dion smith]

I hope you guys continue with this and find your problems, for me, this has been the most interesting thread on here to follow in some time and I have learnt a bit from it. I also run a 46 but on an ob. Mine is the early version with a lights crank and pto. My main issue has been the flywheel. I have had the nut come loose and lost flywheels a couple of times, swapped to a locknut last time- nut didn't move but the brass collet failed and filled top bearing with brass dust. Each time engine has been put together by a respected engine guy so I'm scratching my head too lol

Again, great thread!!

 

[Glenn Quarles]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

 

[Elias Vazquez]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

I was going to offer the same thing Glenn. As far as testing goes!

 

[Tim Kish]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

Glenn you Rock (yes that's a good thing for you older guys.lol) your support in this hobby is amazing, you listen to what people want and you try to make it happen at a reasonable price, we all appreciate that.

We will give Al's motor another try today and see what happens, if not I am going to take it to work and measure the clearance between the two shafts and the case. I sprayed Corrosion X in the motor and turned over slowly and noticed a lot of air bubbles around the crankshaft looking through the hole where the carb mounts, seemed to be more than normal.

Tim

 

[Ted buckley]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

Glenn you Rock (yes that's a good thing for you older guys.lol) your support in this hobby is amazing, you listen to what people want and you try to make it happen at a reasonable price, we all appreciate that.

We will give Al's motor another try today and see what happens, if not I am going to take it to work and measure the clearance between the two shafts and the case. I sprayed Corrosion X in the motor and turned over slowly and noticed a lot of air bubbles around the crankshaft looking through the hole where the carb mounts, seemed to be more than normal.

Tim

"Crankshaft:

The crankshaft is grinded to increase the mixture flow and has a special shape to reduce turbulences inside the crankcase. The balancing is done by two inserts made of tungsten alloy and the inlet has a silicon filling to reduce the weight of the crankshaft to improve acceleration".

Poor Adhesion during manufacturing?

Mmmm. Some have this problem, Some do not? Make me wonder.

 

[Tim Kish]

Funny part of all this between Olly, Terry, Al and myself we have about a thousand years experience with these little motors.lol

 

[Terry Keeley]

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

Glenn:

Your commitment & support of our hobby is without question, you are always there to donate for the prize table and your work with Nova Rossi to bring us top quality stuff is unwavering.

We're really stumped on this one, we tried everything we could think of, and as Tim said we're not new to this.

I'm sure Olly will take you up on your offer, I'll let him know.

Thanks again!

 

[SayMikey]

CorrosionX is a no no on motors with the rubber ramp.

 

[Tim Kish]

CorrosionX is a no no on motors with the rubber ramp.

Thought that was only wd 40?

Thanks Mike will stop, no damage yet though the ramp looks fine.

 

[Glenn Quarles]

I think Olly's gonna burn it, sorry Mate, I tried.

Sealing the PTO with silicone didn't help.

Then we put a very small (8.5mm) CMB 21 carb on it, no joy.

Finally we tried a new tank Walt (Tanks-2-U) sent, it has an internal hopper, still surging.

The only thing left is the seal area around the crank and PTO, or something really out there like porting or head design or...

Hey Terry, If you guys want to send me the motor, I will run it in my boat to see what happens. If it doesn't work and I can find some kind of manufacturing flaw I will fix or replace the motor.

This has been a very good thread and I'm sure lots of folks have learned something regardless what kind of motor they run. Thanks for the detailed descriptions on everything you guys have tried.

GQ

Glenn you Rock (yes that's a good thing for you older guys.lol) your support in this hobby is amazing, you listen to what people want and you try to make it happen at a reasonable price, we all appreciate that.

We will give Al's motor another try today and see what happens, if not I am going to take it to work and measure the clearance between the two shafts and the case. I sprayed Corrosion X in the motor and turned over slowly and noticed a lot of air bubbles around the crankshaft looking through the hole where the carb mounts, seemed to be more than normal.

Tim

"Crankshaft:

The crankshaft is grinded to increase the mixture flow and has a special shape to reduce turbulences inside the crankcase. The balancing is done by two inserts made of tungsten alloy and the inlet has a silicon filling to reduce the weight of the crankshaft to improve acceleration".

Poor Adhesion during manufacturing?

Mmmm. Some have this problem, Some do not? Make me wonder.

Ted, the silicon ramp would have no impact on this...some guys even remove it completely.

GQ

 

[Elias Vazquez]

CorrosionX is a no no on motors with the rubber ramp.

According to Glenn it is safe to use Corrosion X on the Nova Motors with the silicone ramp?..was advised not to use WD 40.

 

[Glenn Quarles]

Yeah I use Corrosion X and have not had a problem.

GQ

 

[Tim Kish]

Well it's a no go for Al's motor, tested a couple more things quickly with no change and packed it in.

Tim