Evinrude 90 questions
 

Along with the Checkmate came this engine that the prior owner says he rebuilt with high performance parts. This is why he sent me as to what he did to it.

Is this something interesting or is it just crap?

That engine has been bored out 30 over . And re sleeved. It has forged Wiseco racing Pistons. The block has been ported 4 high flow. The heads are milled for high-compression. Polished and balanced racing crank. Exhaust tube has been shortened and opened up. The lower unit has been drilled out to let the exhaust out before it goes through the prop. For higher acceleration at lower speeds. Bigger carburetors with bigger Jets. Advanced timing. The engine runs just fine on 90 tes pump gas. It does have more power if you use 115 leaded racing gas. But it's not necessary

Well that’s pretty much what you to do to hot rod a 4 stroke car engine Jorge. I’ve never heard of this done with a 2 stroke. I’d ask for receipts. Personally why go to all that effort for a 90hp 2 stroke? $ /hp would be relatively high to me.

The old saying about no replacement for displacement applies to boring out pistons.

Shaving the heads will bump up compression. Hopefully no issues burning up seals. But with engine burning “hotter” hopefully no 2 stroke gunk in exhaust. But keep an eye on head gaskets.

The carbs are interesting choice. Most guys throw big carbs and big jets on engines but they’d be better off putting a spacer in. Often what happens is the bigger carbs and jets provide too much fuel and the engine becomes rich. Modestly bigger is ok. But modestly bigger with a spacer is better. One of the reasons I like efi. But for sure run rich on 2 stroker, never lean.

Timing, exhaust, and fuel octane makes sense. Never heard of anyone doing it. but that’s roughly what I’ve done to my LS. Or how I’d treat a 454 to 496 or 350 to 383.

Again why? Just b/c you can doesn’t mean you should.

When I bought the boat I never intended to use or even start the engine. And I agree with you...why go thru the efforts of doing this to a 90? I have the engine for sale to anyone that wants it locally and have disclosured what was done to it .
If you want bigger HP get a bigger motor

A coworker used to race a 85hp(?) 4 cyl. Hydro yrs ago we were taking about it and he of worked course worked at a Mercury dealer. At the time they had the 115hp in-line 6 that would overheat and blow the top cyl. Numerous rebuilds left tons of connecting rods and pistons that were the same #’s as the 85 parts he matched up the lightest rods and pistons as it was a STOCK class engine,but said it was amazing how much smoother,quicker,and faster it ran resulting in numerous tear downs (balancing can make a world of difference)he could twist it an extra 1000rpm! I used to raise the ports on a Kawasaki 90 I had as a kid again it increased the rpm range . The only real difference between the old Evinrude 200hp and a 225 was the size of the carb and maybe some timing adjustments. I think that might be the case with the 90 and the 115/120/140 4 cyl Evinrude’s as well. Kind of like the old small block Chevy

Sold the engine today glad to get it gone before I started fooling with it