Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

[SoSlow]

Hey all,<br /><br />I just had my 95 Evinrude 90 V4 rebuilt due to a bad cylinder. It's on a 16 ft bass boat. We went with a 115 block and all-new internals. When the mechanic was testing the boat, he said he couldn't get more than 5200 RPM with the Rapture 21, so before I came to get it he put on a SST 19 and said "Let me know how it runs". He also raised the motor to the second hole from the top on the mount. <br /><br />Got it out today. Improved from 37 to 45 at WOT with no trim, turning 5700. I go to trim it up and the engine spins up to way over 6000!!!! eeekkk!!! It actually broke loose a couple of times when it was at bottom trim, knda when you turn REAL sharp and the prop loses grip. But the 19 really makes it JUMP out of the water when it does grip.<br /><br />So, should I put the 21 back on or lower the motor back down? Or am I missin something?<br /><br />Thanks

 

[ob]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

Sounds like it is propped fine.I would lower motor one hole and water test.

 

[Dhadley]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

Provivding the water pressure is good I would leave the X dimension alone. It sounds real good to me. Remember - you made two changes at once! Go get your prop back and try it. Once you test that then you will have made two changes one at a time.<br /><br />I think all you need is a prop with more bite. There are props that have more than the Rapture but it certainly has more than an SST.<br /><br />Sounds like fun! Good luck!

 

[SoSlow]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

Thanks guys. I think the mechanic was a little over zealous with raising the motor and dropping 2" off the prop. I'm going to put the engine back down first and see what it does. <br /><br />The prop he put on was an SST II. It seems to bite well when it's got enough water around it.<br /><br />Any tips on lowering the motor? Can it be done with a floor jack in the garage? Or should I take it back and let the shop do it?

 

[ob]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

It can be done easy enough with a floor jack since the control cables keep it from teetering too much and you can just back off the bottom ones without removing.Make sure and pad the point of lift to prevent slippage and once final setting is achieved and water tested seal the bolts with silicone.You can do that by removing them one at a time after water test.

 

[Solittle]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

SoSlow - My comment has nothing to do with prop or hight - I hope you are going through a break-in process with that rebuild. From your post sounds like you skipped the break-in - not good.

 

[SCO]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

Ther is something wrong here. With the rpms listed, you should go faster with a 21 at 5200. I'd retest with both props. 5700 sounds like it's in the red. Whats the recommended wot rpm range for that engine?

 

[ob]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

On your V-4 engine is best to prop it to be capable of 5500 rpm.If it is able to attain 5700 ,that doesn't mean that you have to operate it there for sustained periods before backing off to the recommended range.In short,best to slightly underprop than to slightly overprop.Throttle response will be crisper and you won't tend to lug engine.Only a watercheck using both props will confirm.

 

[SoSlow]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

SoLittle - Thanks for the concern, but I'm not going to waste this engine after $1,800 <br /><br />SCO - The range for WOT is 5250 - 5750. <br /><br />Here's the whole story - shortened a bit.<br /><br />The 90 was dying when put into gear over the summer. I was getting 42 mph trimmed. I don't know the rpms, the tach was jumping all over. So I take it in for a tune in Jan. They check pressure - #3 was at 60. So they open it up and find #3 cylinder and piston shot. I order a 115 rebuild. They dyno the "new" at about 111 last week. They take it out with the 21 Rapture and get 44 mph with no trim. Shop owner said he thought rpms were too low (around 5200). So he slapped a 19 SST II on and raised the X dimension one hole. Today I run it - first attempt to get on plane, it spins out and I kill the throttle; same thing happens on attempt #2. I'm getting pissed....after feathering up to plane, I run for one hour at half throttle, then take her up to WOT for about 30 secs. 45 with no trim. This was fully loaded for a day of fishing with 380 lbs of humans and a full tank. I couldn't trim at all - it would blow out.<br /><br />We'll just keep tweaking til it gets right. <br /><br />Thanks guys!

 

[Dhadley]

Re: Rebuilt Evinrude 90 to 115...prop from 21 to 19...new problems

The easiest thing to do is try another prop. If you get one thats suited for a higher X dimension your overall performance will grately improve. Personally I would lean toward a 19" Turbo 3 blade. <br /><br />Your rpm's are in the right area. Shoot for 5900 with an average load. <br /><br />Good luck!