Hello everybody, I have a 6.5 hp Briggs and Stratton engine that I want to modify and would like some feedback on my proposed plan. I am fairly mechanically inclined and have had a couple go karts growing up but have never opened one of these engines. For my current 6.5hp motor I would like to do the following; remove the governor, billet connecting rod, bigger cam, 18 lb valve springs, remove airbox in favor of a cone intake, larger carb jet, and straight pipe exhaust. I have been reading a lot lately about modifying these engines. My ideal would be to turn 5500-5800 rpm. The engine is from a pressure washer and has the heavier flywheel. I have read conflicting stories on whether or not a billet flywheel is needed for the rpm range mentioned above. So what do you guys think? I am open to your advice/expertise.
Plans for an engine build, seeking some advice.
- Thread starter bikerider
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ezcome-ezgo
G'me sumthin to write on
Is the output end of the crankshaft tapered?
I don't think so. I believe the entire output shaft was 3/4"
I believe it is an ohv. The two numbers from it came from a tab above the muffler. The first is; 123K12-0134-E1 and the second is 04061057
The project is the lower unit from an Evinrude 6hp and the Briggs mated to the top.
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mckutzy
Well-known member
I guess the better question is... Is this for use as a boat motor, or a motor on a kart?
If kart... then get a new motor as this is a vert motor and might aswell as spend the time/effort to getting a clone/212 ect to build up on that...
On a boat... there is some that have done work on these here, but most who have done work on boats have gone the long-tail or surface drive style route instead as they use standard horizontal shaft industrial motors....
If kart... then get a new motor as this is a vert motor and might aswell as spend the time/effort to getting a clone/212 ect to build up on that...
On a boat... there is some that have done work on these here, but most who have done work on boats have gone the long-tail or surface drive style route instead as they use standard horizontal shaft industrial motors....
This would be a build up for the boat motor. I know it's not ideal, but it was one I had already with very low hours on it and it was a great fit for the Evinrude lower unit. I have seen the mud motors in youtube videos. There are some impressive builds out there. For the lakes I go to, and boat I use, this engine setup works well. I am still interested in building this motor despite it being a vertical shaft.
mckutzy
Well-known member
The con rod will be the most odd part as this is a vert engine and they typically dont make those for stuff like this...
The Cam is also an odd duck as it is mostly plastic Delrin, typical for briggs. There might be a similar cam out there in steel or the like... but like I said, itll be odd and might cost a fortune to get made...
The Cam is also an odd duck as it is mostly plastic Delrin, typical for briggs. There might be a similar cam out there in steel or the like... but like I said, itll be odd and might cost a fortune to get made...
I'm fine with having to really look for the parts. You would think the connecting rod and other parts would be the same for vertical and horizontal engines. I guess my question to the forum now is; who here has built a vertical shaft engine and where can I find parts to do so?
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