RPM's & Prop

[reelapeelin]

Originally Posted by Joker2

I am only getting 4-4200 RPM's with my prop 15- 1/2 x 15 Alum. get 32 mph on gps. One person, no gear, 20 gal. gas, trim adjusted. The boat is light, recently rebuilt the whole transom and rear deck, totolly dry now.Checked the linkage at motor, it is maxed out. Engine height is OK the fin on lower unit is even with keel. Engine just repaired, runs great. Could a prop change make up 1500 RPM's ? I don't know what else to try.

Good example of why it's helpful to post yer boat/motor in your profile info...can't remember what motor you have...but obviously you've got some RPMs to make up, but my thought is a 17-19 P prop of same diameter..and look into the suggestions others have made...

[THEFERMANATOR]

Originally Posted by reelapeelin

Good example of why it's helpful to post yer boat/motor in your profile info...can't remember what motor you have...but obviously you've got some RPMs to make up, but my thought is a 17-19 P prop of same diameter..and look into the suggestions others have made...

He's got a mid 90's OMC 150 2 smoker, pretty simliar set-up to tsubaki's boat I believe. With all the problems he's had I stil lthink something is up with this engine. It should have around 120-125 pounds of cranking compression out of that engine I believe. I know some only had 90, but those were engines with idle reliefs(the late 80's-early 90's 200/225's), but some others have a140(my old 85 140 has 155 out of it, but it is built up a bit).

[reelapeelin]

Originally Posted by THEFERMANATOR

He's got a mid 90's OMC 150 2 smoker, pretty simliar set-up to tsubaki's boat I believe. With all the problems he's had I stil lthink something is up with this engine. It should have around 120-125 pounds of cranking compression out of that engine I believe. I know some only had 90, but those were engines with idle reliefs(the late 80's-early 90's 200/225's), but some others have a140(my old 85 140 has 155 out of it, but it is built up a bit).

Yeah, that much variation in compression is a problem...he needs to find another mechanic who's not trying to "defend" the motor....

[aussie]

yes he probley dont want to do the engine again free of charge and is trying to cover his workmanship in my eyes 100psi is too low for a 2strokes all u need is a small scuff mark in the bore and it kills the performance of a 2 stroke pull the heads of and check the bores