Need Tune Pipe

[John Smith]

Hi, I have a 7.5 K&B Pro outboard part #7500. I am looking for a tune pipe and header to run on this motor. Does any one have a new or used one for sale or what's the best and who sells them? Are they a waste of time?

Thanks, John Smith

 

[Jerry Dunlap]

JS,

The two most popular tune pipes are those from Irwin Performance Products, [email protected] or the Silver Bullit from HTB Boats - website - htbboats.com. I believe both places can provide you with a header.

Generally, without making any modifications to the motor itself, a tune pipe exhaust system will provide an additional 3-4 mph.

Jerry Dunlap

 

[John Smith]

Thanks for the quick reply. What other mods can I do? I've matched the exhaust port with the standard exhaust muffler. An help is greatly appreacated.

Thanks, John Smith

 

[JOE GRACE]

Hi John. I like the SILVER BULLIT PIPES that Mark Hopper & Buddy Carter build. To me you can get a better throttle transition with them. htbboats.com

Joe

 

[JohnBoy]

Joe I have emailed Hopper to purchase their tune pipe. Does anyone know of some other mods I can do?

John Smith

 

[Propjockey]

Is your engine "pipe ported"?

 

[JohnBoy]

It is stock 7.5 Pro air cooled. What is pipe ported?

John Smith

 

[lohring]

I've run a piped K&B Pro for two years. I did not modify the engine. I found that the air cooled head overheated and the power sagged off after a few laps. I changed to the watercooled Semi-pro head and that problem was fixed. I also could not get the large carb to draw with pipe pressure. (I always run the 11cc carb on my stock engine.) The old 7.5 carb works well , but an 11cc Geraghty carb will also work and is faster. I run an Irwin pipe with the stinger sleeved down to .318 and lengthened 1/4". If you use the copper elbow header, leave 1/2" space between the header and the pipe. The longer pipe really helps with accelleration out of the turns and doesn't hurt the top end..

Lohring Miller

 

[JohnBoy]

Has anyone run a 7.5 Pro air-cooled with a tune pipe without overheating the motor?

Thanks, John Smith

 

[Tim Fulton]

Hi John,

I sent you a e-mail. Check us out. ;D

Tim,

precisionboatsracing.com

 

[Propjockey]

John--this is a shot of a pipe ported engine. See the little extra cut out on the top side of the port? It It lets the resonant wave from the tuned pipe stuff a little more of the unburned air/fuel back into the chamber, just before the piston closes off the port.

 

[Propjockey]

This is a stock K&B pipe ported sleeve.

 

[JohnBoy]

Ok I see. Mine looks like a different sleeve. My exhaust port is open with no bridge in the middle. The sleeve opening matches the aluminum cylinder outlet pretty well on its way to the pipe. Do I have to cut into the aluminum cylinder and sleeve with this notched port? Also any other tricks to keep the piston from catching a burr as it passes the notched area?

Thanks,

John Smith

 

[Propjockey]

I don't recommend cutting into the sleeve itself, but I wouldn't hesitate to do a little Dremel work on the aluminum to get a smooth flow from the port.