OB MAC21?

[Tim_Duggan]

I'd try restricting it more - just make sure you start off richer on your main needle when you do your testing and work down to a proper needle setting. If you just restrict it without setting it richer it will probably go too lean after a lap or 3.

The carbon SPP pipes are more temp critical than alloy pipes and need a few laps to warm up before they really come on strong. The MAC engine also likes some heat in it to really sing. Before they are up to temp they appear to be too rich.

 

[Joe_Knesek]

If you continue to run the water cooled head you need to cut the water off to a trickle. I run the air cooled head with 3 rings of fins cut down to 1.6 inches and it never gets too hot and it runs much better than with the water cooled head. As Tim stated richen the boat up and don't lean it down until you have ran 3 hard laps but always stay on the rich side. More fuel = more HP and lubrication.

 

[MarkScott]

Jul,

What lower do you have the motor on now? When we practice again, this Saturday, I'll let you use one of two buggy heads I'm not using. We will see if this brings up the temp. My current buggy head one is a 2 fin, brought in 1/8". Pipe is a Garcia that has a smaller ID than stock. I've got a few other pipes (garcia, rossi, gadetcraft, cooper, irwin, etc) that we can try on your boat.. Then again, why am I helping my competition :wacko:

 

[Davidkrienke]

An asprin bottle muffler is made using brass tubing that slips tightly over the stinger, the bottle, and JB Weld Kwick.

1. Cut the tube sufficiently long to have at least 1/2" to clamp on the stinger and stick just a bit out of the end of the bottle.

2. Drill a hole in the bottle the size of the tube.

3. Drill 1/8" holes in the tube that's inside the bottle.

4. Glue the tube into the top of the bottle and glue the cap.

5. Stick some JB into the part of the tube that extends out the bottom of the bottle and set it down on wax paper so the JB will form a plug in the end of the tube.

6. Drill 3/16" holes in the bottle

7. cut a slot in the end of the tube that attaches to the stinger so it can be compressed onto the stinger with a wire tie or small hose clamp.

I'll post a photo of the one on my SB pipe later this evening.

JD

Jerry could you repost a photo of your pill bottle muffler? I would like to make one. Thanks Dave