I know it’s been discussed but the efi programs have changed I believe. The heads are decked the intake ported. I will put an exhaust on soon but I’d like to either do just efi now or carb exhaust upgrade now. With the way it’s currently set up I get 27 with just me. I don’t need a whole lot more speed but it’d b nice. More concerned with load handling. Is the prodrive efi kit set up for the head and intake work or are there even options. I really like the idea of efi however I’ve never had problems with my carb except for that stupid f ing mixture screw on top always breaking. . Now that efi for these motors has been out for a while hopefully I can get some good insight.

Look up my post on (Prodrive fouling plugs). Prodrive does have different tunes for heads cam etc. The ecotron efi is nice till I started having trouble. There are only a handful of people that will work on it. Prodrive and ecotron are the only places to get parts. Ecotron is kinda hard to get a hold of. From my experience they really don’t want to deal with you if you didn’t purchase the efi directly from them. You may be closer to one of the people that will work on it. I’m 7 and 10 hrs from one. Not talking bad about Prodrive. The functionality of everything else has been great except the bolt on efi kit. If I were you I would stay with the carb route or get a whole new setup with Briggs efi. There are some having trouble finding dealers to work on the Briggs efi to.


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Agreed, folks who can fix that efi are rare. I would go carb or Briggs efi

I would get a whole new setup with efi if your wanting something different but if your frame is in good shape you could prolly just get a power head and put it on.


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Couple things:

1) you didn't mention a cam. A good cam will give you the load carrying capacity your looking for even with the stock carb. If you heads are ported and decked (how much decking?), then adding a cam will only make the heads that much better.

2) the stock carb is ok and can be tuned a little. But getting a mikuni is way better,

3) the engine is nothing more than a big ass air compressor. More air in / more air out = more HP. You can have heads, cam, decking, the whole show, but if your carb is like a coffee straw and you exhaust has so many baffles and restricter plates, your not "breathing" so the engine will be limited.

Each mod will compliment the other.

The Mikuni HSR42 is a great after market carb that folks have been using for a while now, but its way too big for these applications. The main reason it was used is because it had an accelerator pump that would shoot fuel in the carb on immediate throttle to help with low end bog. Now if I remember, there are smaller mikuni's with the acc pump which would work better. Need velocity.

A good tuned carb will run just as good as a EFI, and much easier to work on in a pinch when your stranded. The EFI will give you better fuel economy. So if fuel isn't an issue, go with the ease of the carb. But thats my opinion.

Here is a thread I did a long time ago when I had a briggs and I did it in stages across two hulls of different sizes. You can see the speed differences with the different mods added.



Now, if your really wanting to spend a lil money, unbolt that piece of shit Briggs, throw it in the river and strap on a Kawasaki and never worry about load carrying capacity again. But again, thets just my opinion from running both.

Also, after seeing some of the PD efi Headwork I shy away. The ports are hogged out and fully removed the valve guide and guide boss on the port roof. They also had stock valves. The intakes were ported only and left with a rough but finish. Not that hurts anything other than aesthetics.
We were talking about velocity and a good way to keep it, is to shape the port roof and equalize the port size left and right of the valve, Smaller is actually better.

You have to have some knowledge to install the cam, because it entails valve adjustment and other stuff as well, but its not hard. As far as reliability, that depends on the driver. I always looked at it from this prospective.

Engine A - Stock
Engine B - modded

Engine A will have to run WFO to attain a certain amount of speed or load carrying capacity.
Engine B might only have to run 3/4 to attain the same outcome, but you do have "reserve" if needed.

Now if you get whiskey throttle and dog the hell out of it, then nothing will last.

also cylinder heads... people just stick valves in there and move on. Do they tip the valve for the head decking and base circle changes?
Camshafts, You need to debur the camshaft, check tappet bores for sticky spots, and lubricated the heck out of the lobes and gears.

Maxxis you nailed it. I believe there are still a few "true" engine guys still around. But lately (and thats why I have shy'd away from the site for a while) it seems that everyone is on a "money grab" to sell the latest and greatest shit and have no idea what it all means or what they are doing. They just copied someone else work, not nearly as good, and passes it on to the un-knowing newb.

I'm about making a dollar, BUT I want to provide as much to the end user as possible. They don't realize this
Porting takes me about 2-3 hours, Then I have to polish the ports about 1 hour, polish combustion chambers about an hour, then do a valve job, about 1.5 hours to get the vlaves seated properly without valve overlapping the seat causing a shrouding effect.
At that point I have to get them decked, clean them, assemble the valves, springs, stem seals, and then install..
I see guys charging a lot and they keep stock port shape, hog out the short turn, and stick stainless valve sin there and charge the same amount I do... Crazy....

PD heads are ported, decked, and use stock valves mostly.

I ordered the Mikuni kit and the bps q. Going to see what happens with that. I enjoy tinkering with it which beats the hell out of being inside changing diapers. With that said, next I will do the cam and I’ll mess with the heads then. Also prolly bore the cylinders and get the pistons. I’ll have to figure what and where from when I get there. Using Tapatalk for the first time and I missed a post or two. Maxxis where u at?


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Currently in Arnaudville, LA but moving to Tarkington, TX South of Lake Livingston.

Mr Darryle, I still will travel here.. I can always work out transportation for people wanting fair quality work.
Zach, i responded to your pm