CMB 45HR in a Sport 40

[Mike Starrett]

Is anyone having good success running a CMB 45 HR in a sport 40? I've been struggling with getting it to stay on the pipe. If you have to let off the throttle for any reason it may not come back up. If you have one that works well would you mind sharing your setup info with me. I have a new boat but won't race it due to this motor problem. I've tried different pipe lengths, different pipes, different props and It has done this in 2 different boats with different tank setups. I've included some pictures of my present setup. Thanks in advance for your advice.

 

[wayne middlemiss]

providing more info on the setup will be of more assistance ; ie pipe length, prop info, fuel.

 

[Mike Starrett]

providing more info on the setup will be of more assistance ; ie pipe length, prop info, fuel.

I've tried pipe lengths between 10 3/8"-11.5". Fuel is 50%-18 oil. I,ve tried X447,x448 and x450 props. I put new swiss bearings in it last fall. I've had this problem with it since I bought it new.

 

[Bert Dygert]

Mike,

What size pressure fitting is in the pipe? Also how many fuel tanks and what size brass tubing are the inlets and outlets?

My experience with the HR motors is that becuase of the 45 slant they have a hard time drawing fuel. Also I would rotate the pipe so that the pressure fitting is to the top of the pipe. A very wise boater told me to keep the pressure fitting higher that the fuel tanks.

Walt Barney is the best fuel system man around maybe he can chime in.

Bert Dygert

 

[Duck899]

Have you tried a different engine?

 

[Ray Sametz]

Mike,

What size pressure fitting is in the pipe? Also how many fuel tanks and what size brass tubing are the inlets and outlets?

My experience with the HR motors is that becuase of the 45 slant they have a hard time drawing fuel. Also I would rotate the pipe so that the pressure fitting is to the top of the pipe. A very wise boater told me to keep the pressure fitting higher that the fuel tanks.

Walt Barney is the best fuel system man around maybe he can chime in.

Bert Dygert

Bingo, give that man a cigar. Raw fuel in the pipe will clog the pressure fitting. Get it off the bottom, also looks like your tapped on the wrong side of the weld.....==={}

 

[glenng]

Robert Holland built a Mutt with a HR that later ended up in Utah. Ran very well with a parabolic pipe and pitched up X448.

 

[BlueBlaster]

I have a HR in my sport 40 roundnose. Tanks are in nose line comes out to third channel needle comes out up to carb. Have AB Andy brown pipe on it. Have to measure distance but sounds in the same area as yours. Mine runs fast and can come back on pipe from slowing. Hope you get it figured out. If your at Evansville fall race you can come check my setup out.

 

[glenng]

Mike,

What size pressure fitting is in the pipe? Also how many fuel tanks and what size brass tubing are the inlets and outlets?

My experience with the HR motors is that becuase of the 45 slant they have a hard time drawing fuel. Also I would rotate the pipe so that the pressure fitting is to the top of the pipe. A very wise boater told me to keep the pressure fitting higher that the fuel tanks.

Walt Barney is the best fuel system man around maybe he can chime in.

Bert Dygert

Bingo, give that man a cigar. Raw fuel in the pipe will clog the pressure fitting. Get it off the bottom, also looks like your tapped on the wrong side of the weld.....==={}

I would not rotate the pipe-plug or weld existing hole and put your fitting 90 degrees or more above the C/L of the pipe.

 

[anthony_marquart]

Ive never seen a pipe pressure line clog,.. mine have always pointed down to get the line out of the way asap,..

 

[Mike Starrett]

Have you tried a different engine?

Not in this boat. I had an RS in a Whiplash (before this boat) and it worked fine. When I put the Hydro in that boat these problems started.

 

[Glenn 787]

How is that engine getting air with that cowl?

 

[Duck899]

How is that engine getting air with that cowl?

This may be the answer too, Had this issue on an Eagle SG way back when I figured ya didn't need the big hole up by the carb for air. Cut a slot in the cowl (like all SG cowls) and off it went.

 

[Mike Starrett]

How is that engine getting air with that cowl?

Just thru the open back end.

 

[Jeff Schindler]

Mike,

I had an HR in my sport 40 from Teddy. He got so frustrated with it he sold it. I also got frustrated with it and sold the motor to Eric Canto, who was also going to put it in a sport 40. The engine seemed like it would be great in a rigger, but it just didn't like the 10 lb boat it was in.

It looks like you've done everything right so far! I put a hopper tank next to the needle like you have and it helped a lot but still wasn't reliable. There may be something to that fuel draw issue someone mentioned. I never tried a smaller carb, do you have one that will fit?

 

[Samuel Hagan JR]

Mike I have a AB pipe you can use. I would also try with what Bert said. Point the exhaust pressure fitting up.

 

[Mike Starrett]

Mike,

I had an HR in my sport 40 from Teddy. He got so frustrated with it he sold it. I also got frustrated with it and sold the motor to Eric Canto, who was also going to put it in a sport 40. The engine seemed like it would be great in a rigger, but it just didn't like the 10 lb boat it was in.

It looks like you've done everything right so far! I put a hopper tank next to the needle like you have and it helped a lot but still wasn't reliable. There may be something to that fuel draw issue someone mentioned. I never tried a smaller carb, do you have one that will fit?

Actually I have tried a carb from an RS. It has a smaller ID than the hydro carb. I even had a stuffer turned for the housing to keep the ID the same from the crank up. In the end there was little to no difference. Gotta say Jeff, I haven't seen many of these in Sport 40's and wouldn't be surprised if there is reason for it.

I will try opening up the cowl in front some to get air in. Also trying a different pipe with a large opening in the fitting and moved the fitting to the top of the pipe to try that. Also thinking of lowering the compression just a little to see what that does.

 

[anthony_marquart]

In my boats,.. if I lowered the compression it was even harder to get on and off the pipe.. but I guess it could be over compressed too.. does it take plugs? that can be a sign of over compression.

 

[Samuel Hagan JR]

I wouldn't go any lower then .006" Mike.

 

[anthony_marquart]

I thought 0.012 - 0.016 for 45's ,.. is that not true?