New sport 40

[glenng]

But slows on straights.

Hull- P.T. spt. 40 RN

Motor CMB 45 RS

Pipe- AB Parabolic @ 10.5"

Prop X447/3

Elevation 4300 ft.

Motor is new- just heat cycled about 20 Oz. of fuel thru it( Odonnels 50%) and put 6 short runs on it (maybe another 36 Oz).

Any suggestions?

Thanks,

Glenn

 

[FloridaScaleBoater]

Has the internal stinger of the AB Parabolic pipe been reemed out?

 

[P THOMAS]

Yes drill it thru with a 5/16 bit.

 

[NITROSNIFER]

I'm running the same set up at 3440ft CMB RS AB parabolic at 9" with a X448 pitched up. It screams and is super consistent not sure about the stinger I have never checked it's diameter. Thinking it's stock. I have room to move on the prop/pitch. What's the strut angle/depth at???

 

[glenng]

Yes drill it thru with a 5/16 bit.

Rick and Phil, The pipes internal baffle has been drilled to 11/32(.343") on the longer pipe and 13/32(.406") on the shorter pipe. The shorter one I ran Sunday when I noticed the problem.

Thanks,

Glenn

 

[glenng]

I'm running the same set up at 3440ft CMB RS AB parabolic at 9" with a X448 pitched up. It screams and is super consistent not sure about the stinger I have never checked it's diameter. Thinking it's stock. I have room to move on the prop/pitch. What's the strut angle/depth at???

Bottom of hull to bottom of strut= 1 1/8". Strut set up as per Phills instructions(about a 1/16" shallower at the front.

Glenn

 

[NITROSNIFER]

That's exactly where I have mine. Should go like stink.

 

[SayMikey]

Do you have the cowl open for air? And could the exhaust be getting back into the motor? Shaft gap should be almost a 1/4 inch

 

[glenng]

Do you have the cowl open for air? And could the exhaust be getting back into the motor? Shaft gap should be almost a 1/4 inch

All the above is O.K. Mike.

Thanks,

Glenn

 

[FloridaScaleBoater]

Someone else just had this problem with a MONO, is the radio box secure, not moving around?

 

[glenng]

Someone else just had this problem with a MONO, is the radio box secure, not moving around?

Rick, That was my good friend Tony we got his big mono SCREAMING on Sunday. Now my spt. 40's doing the same thing but the radio box is secure as are the servo mounts. I did get moisture in the radio box box Sunday and everything quit working around 2 PM. Just checked about an hour ago and everything seemed to work fine and servos seem strong(225MG on throttle and 3305 on steering).

Thanks,

Glenn

 

[FloridaScaleBoater]

Glenn;

I'm not a fan of the AB Parabolic pipes, just me,,,,

I have had great success with the Mac's exhaust 7.5 marine muffled & unmuffled (with stinger muffler)

on that same engine set @ 10-3/8"

B.T.W I don't think the sport-40 W/ the RS45 will spin a 646/3

Been there, done that

 

[jetpack]

I would just guess to say if its launching quick and bites the corners but falls flat on the straight your under pitched if your trim is at its best.

If you think your motor is behaving okay then pitch up within the same diameter if your rpms are close to what they should be. I wouldn't stay with that prop for any straight speed loading on that being a new motor and by your mention of run time on it, it's ready to load.

If it falls off at the end of your straight look to cooling at this point.

If it falls off early off the corner do the prop.

Stay with the pipe as you go along.

I might be off with the approach but wanted to bring up keeping the motor safe on the straight and not staying with that prop if its underproped.

 

[glenng]

I would just guess to say if its launching quick and bites the corners but falls flat on the straight your under pitched if your trim is at its best.

If you think your motor is behaving okay then pitch up within the same diameter if your rpms are close to what they should be. I wouldn't stay with that prop for any straight speed loading on that being a new motor and by your mention of run time on it, it's ready to load.

If it falls off at the end of your straight look to cooling at this point.

If it falls off early off the corner do the prop.

Stay with the pipe as you go along.

I might be off with the approach but wanted to bring up keeping the motor safe on the straight and not staying with that prop if its underproped.

David, Won't cost me a dime to give that a try. I did run the boat two weeks ago with a P-230(texas cut) and the pipe @11"-no rocket ship but the pipe may have been too long.

Thanks,

Glenn

 

[SayMikey]

Its not running to wet is it? did you sand the bottom of sponsons to get the shine off? Is the motor sagging or singing? my strut is shallow 7/8 and flat on table

 

[glenng]

Its not running to wet is it? did you sand the bottom of sponsons to get the shine off? Is the motor sagging or singing? my strut is shallow 7/8 and flat on table

Singing in the corners, sagging in the straights. I have never sanded the bottom of the sponsons on any boat. I'm pretty new to round nose boats but do understand you have to run the strut deeper than a pickle fork to keep em on the water. It is not glued to the water by the way-it is a very light boat and no weight has been added.

Thanks,

Glenn

 

[Duck899]

Its not running to wet is it? did you sand the bottom of sponsons to get the shine off? Is the motor sagging or singing? my strut is shallow 7/8 and flat on table

Singing in the corners, sagging in the straights. I have never sanded the bottom of the sponsons on any boat. I'm pretty new to round nose boats but do understand you have to run the strut deeper than a pickle fork to keep em on the water. It is not glued to the water by the way-it is a very light boat and no weight has been added.

Thanks,

Glenn

Have you tried different pipes? I had a cmb rs 45 in my mutt to start with and tried a few different pipes untill I got the one I have now. I tried the parabolic, the Irwin and then got a few Mac's 10cc aero pipes with after-mufflers. The 10cc aero woke the engine up like you would not believe. Mark Anderson recommends the mac pipe on his sport 40. The power is broader and turns wicked rpm's. I run a 1455/2 with 3.2" pitch.....something to think about.

 

[SayMikey]

Its not running to wet is it? did you sand the bottom of sponsons to get the shine off? Is the motor sagging or singing? my strut is shallow 7/8 and flat on table

Singing in the corners, sagging in the straights. I have never sanded the bottom of the sponsons on any boat. I'm pretty new to round nose boats but do understand you have to run the strut deeper than a pickle fork to keep em on the water. It is not glued to the water by the way-it is a very light boat and no weight has been added.

Thanks,

Glenn

Opps round nose different animal when you turn you loosen the boat up where is the cg are the sponson bottoms clean and sharp? how does it launch

 

[glenng]

Its not running to wet is it? did you sand the bottom of sponsons to get the shine off? Is the motor sagging or singing? my strut is shallow 7/8 and flat on table

Singing in the corners, sagging in the straights. I have never sanded the bottom of the sponsons on any boat. I'm pretty new to round nose boats but do understand you have to run the strut deeper than a pickle fork to keep em on the water. It is not glued to the water by the way-it is a very light boat and no weight has been added.

Thanks,

Glenn

Opps round nose different animal when you turn you loosen the boat up where is the cg are the sponson bottoms clean and sharp? how does it launch

CG is 3/4"-1" aft of sponson transoms. How does it launch? Well kinda like a F-16 with the afterburner on :lol: :lol: :lol:

 

[bsmtboy2]

I run a pt sp 40 with a cmb45 rs. It has a AB parabolic pipe set at 9 3/4 inches running 60% technology fuel turning a x646/3 blade prop. When you use a parabolic pipe I have found that you have to run it shorter on the rs. When I first switched to the rs I saw the same thing happening. Shorten it and hang on!!!!!!!