K&B 7.5 mod kit

[Bob]

I have new in the box a mod kit for my 7.5 k&b outboard.Do these kits really increase the performance that much?I have had this kit for a few years now and was wondering if it is worth it to install it.Thanks

 

[moparbarn]

what hull are you going to run it on? the prather mod kit was designed specifically for their spitfire ob hydro. removing the carb leaves a HUGE hole, & most setups will bog. really only works on a very light, free running boat. if you want to use it, try to find a k&b venturi from one of their older 7.5 ex. throttle motors, that way the intake size is better matched to the motor. it will have to idle higher, & the driveability (throttling) will suffer. ex. throttles are closer to an off on switch than a throttle. but, if you use a venturi with the needle in it, you don't have to permantly mod the motor, you can always go back to a carb. you'll never know 'til you try B) .....

 

[MarkScott]

I've run the kit on a K&B 3.5 years ago. It was better with a pipe.. Got even better when I switched to the Gardner XXL throttle unit. If you do try, don't cut the skeg off and put the Prather unit. If you open up the exhaust ports, it will be very loud. Be ready for the tree huggers to come out and complain. If I were you, I'd put the venturi on as Robin stated and pipe it. Leave the skeg alone. Motors have come a long way since those mod units were sold.. But heck, give it a try.

 

[Bob]

Thanks guys,It was for my prather spitfire 2 that i got a few years back and was just curious if it was worth it.I think im going to get a htb tunnel for the engine and go racing.When i got the spitfire a few years ago i didnt know that it wasnt raced anymore.Would a stock 7.5 water cooled engine be somewhat competitive in the tunnel class in D2?Thanks

 

[shoboat]

Bob,

In D-2 we don't have a lot of tunnel boats that race

anymore. I would go with a JAE 12 or 21 if you want

to race this next year. Saginaw will be the closest

race from where you live. You are more than welcome

to come over and do some testing if you would like.

Thanks,

Mark Sholund

231.590.3023