140 Johnson prop question. - The Hull Truth

Big Ox · 08-14-2007, 01:40 AM

Hi, I have a 20' maycraft cc that is in the shop and the mechanic tells me I need a new prop. I thought it might be the case but I thought I would ask you guys. It has a 14X21 now so they say. I don't know much if anything about props except not to stick my fingers in there

. I am turning maybe 5200 rpm. Any thoughts? They say probably 14X18 I think? Thanks for any help!

Chris

eggsuckindog · 08-14-2007, 04:30 AM

I would say any standard 19 will work fine, and give you about 3 to 400 more RPM and thats perfect. An 18 may be some prop that they make more money on and personally I think a 19 would be pushing it at 5500/5600 you don't want to turn it higher unless its a looper, but you didn't mention that.

Big Ox · 08-14-2007, 09:10 AM

Sorry, 140 4 stroke. Made by suzuki.

Inlander · 08-14-2007, 10:02 AM

I have the 140 on a 17' using a SS14 x 20. It turns @ 6,200 + rpm whenlightly loaded on flat water, 5,900 to 6,100 when heavily loaded. That seems perfect for that motor. Since the 20' is a much heavier boat, a 14 x 18 sounds about right. Running @5,200 is too low, so your present prop has too much pitch.

Jon G · 08-14-2007, 10:04 AM

I have a 14x18 on my 20' Seacraft with the Suzi 140 and it runs WOT right at the max of 6200, I tried the 14X20 and it only turned 5700 WOT which was still with in the recomended range but I like being propped right at the top end, great holeshot better milage and when the boat is really loaded it still runs right up there, you DO NOT want to lug that engine. Sounds like you need a 18, The props I have are stainless and my 18 is a Stilletto about $249
http://www.dansdiscountprops.com/Buy...cfm#advantage1

Big Ox · 08-14-2007, 06:35 PM

Well I was wrong about the size they were going to try. They put a 14X17 on it today and they said it was no good, slipping.? They want to try a 19 tomorrow. The tech also said wot with the 21 was 4850 rpm!? can this prop make enough difference or is somthing else wrong?

baypro21 · 08-14-2007, 07:38 PM

I ran a stock 3 blade aluminum 19" pitch on my 140 4 stroke/ 21' seapro bay model. You need to get wot rpm's up to 6000. Sweet spot for cruise on that motor is anywhere between 4000-4500 rpm's.