Sounds rich....blows plug

[FloridaScaleBoater]

Yep, there not worth a crap!!

May as well box them up, and send them to me. I guess I like frustration?

Rick

 

[Joe Warren]

Trying to resolve a problem with my daughter's scale boat. We've been fighting the same problem at the last 2 races. At the pond tonight, she was just doing laps at half throttle and there was lots of smoke in the air which made me think it's rich. Then it dies after 4 laps with a blown plug. Tried it again...same thing. We're using 50% fuel in a CMB 67 with new bearings and using a CMB black belly 67/80 pipe at 11 3/4" (c/l engine to weld on pipe). We've also tried different fuels and the results are the same.We tried a different engine and although it still seemed to 4 cycle, it didn't quit nor did it blow a plug. All I can come up with is that the first engine is leaning out but I can't find out where.

Anyone got some ideas???

Mike Check the cooling system too. make sure the engine is not leaking around the cooling jacket o`ring. The water must move thru the cooling jacket completely to move the heat. Water leaks on the cooling jackets have drove me crazy on Twins & single engine hydros...... Someone mentioned pipe pressure fitting? Especially The 90 degree 2 piece pipe pressure fitting almost always over lap each other & prevent the pipe pressure from reaching the tank. Also check the pipe for cracks. especially in the welds or @ the weld.

 

[Chris Wood]

Yep, there not worth a crap!!
May as well box them up, and send them to me. I guess I like frustration?

Rick

and i will take what rick can't use lol..

chris

I did have the same problem with the pressure fitting this year.. run fine die.. may launch may not.. die.. it is a aeromarine 90 degree.. use a drill bit and make sure it bottoms out on the fitting.

also, and this is just a shot in the dark.. we have had some and i say SOME, not all cmb's that the backplate is warped.. dad got one in that was 4 1/2 thousands off from top to bottom.. wouldn't seal and it wouldn't run that way..

just something else to look at.

chris

 

[Don Ferrette]

You guys crack me up. :lol:

Never said that big belly pipe wasn't good, it was one of the baddest pipes I ran on my 67 hydros, just too touchy on the scales. With the crazy weather patterns we see here in the mid atlantic area it made for a very inconsistent pipe on a heavy boat. :blink:

 

[Mike Hallam]

I just want to thank all of you who have taken the time to offer some advice. I've got lots of things to look at this weekend.

Thanks again...............Mike

 

[DAN MCCORMICK]

I tried the CMB big belly pipe on my scale boats a few years back. When you get everything just right it is fast BUT was a pain in the you know what to keep consistent & the needle range of adjustment from too lean to too rich was about 3 or 4 clicks total. It is not really a good pipe for a heavier boat like a scale, very unforgiving and a bigger prop is only going to make it worse. :blink: The 13cc pipe like Joe suggested is a good choice, that one always worked for us. Start at about 12" with a X457/3 and keep shortening the pipe until it falls off in the corners then go back out 1/8" or so, you'll probably wind up about 11 1/4" to 11 1/2". What carb is on the motor? We always run the OS 9B on the CMB's in the scales.

DON: Could you share with us what specifics your scale would go through that gives you the indication that the large cmb pipe is to tempermental? What weight and nitro do you use? Also what compression ratio and carb setting do you use (rich/lean) ? I have always heard nothing but positive about that pipe in a scale. I t is one of the largest volume 67 pipe ever made and has triple taper angles . I am not saying you don't know what you are doing just trying to understand were you are coming from. DAN

 

[FloridaScaleBoater]

Don't worry about what everyone here is saying.

I have made it my mission to relieve the boating community of anything that causes problems, heart aches, and just general pains in the butt!

My mission starts right here with this pipe that doesn't work well on scale boats.

So, pull them all out of your boats, and I'll give you an address to send them to, later!

Rick

 

[Preston_Hall]

Mike,

Before you go and re-engineer your engine, get some color info like Joe said. Is the coil shiny or dull and what about the rim of the plug? If the coil is shiny, you are not lean. I guess the head clearance is a little tight. As for the pipe, that thing is the biggest pain you will ever have. I bet that most who think it works aren't working it in the first place. It's too touchy, I have seen WAY too many attempts at using it. But to make the rest happy, yes it can work.