have 03 triton tr21 recently repowered with 250 sho, took off a merc 250xs it was a fantastic engine and would run 78-80 anytime, now with the yamaha im happy with everything but my speed is"nt anywhere close to where id like to be. 25-t1 ventless tourny load 69mph 5600rpm's im guessing i need to get some more rpm's out this baby? what should i be turning loaded 2 people? 1.5in above pad. should i try vented prop? any idea's feel free
I'd check to make sure the hot foot is getting full throttle at the motor. Or see if it's running on all 6 cyl... Sounds like 5 to me.
Marks Props 317-398-9294, 1850 East 225 South, Shelbyville, Indiana 46176 propellerman59@gmail.com http://www.marksprops.com/index.html
Something is not right.
I get 74-75 @5600 any day with a 21 Phoenix with a 27 ventless and 8 in plate. Check throttle linkage. On the SHO, you are opening an accelerator position sensor which opens a throttle position sensor. This should be checked and confirmed as well.
Lower the motor to 3.5 and start over with your engine height.
With a 25 I would expect 74 + @ 5900 at least. Venting the prop will not help high speed.
What size plate do you have???
Post back if you find anything and good luck. You will love this motor.
Modified by falcooon at 6:41 PM 11/15/2011
I would also make sure that you are getting WOT. The throttle on this engine is mechanical/electical. It has an electric motor that opens the the throttle based on the TPS that is moved by the cable. I took an EFI 225 off and put a 250 SHO on a 203 Champ running the same prop a 26 pitch Fury it runs with in 2 tenths of a mph the same speed. I turn 5900 74.6 mph is my best. Thats the one thing that I was a little disapointed in with my SHO I thought 25hp would gain maybe a couple mph. You should be closer on your mph then 69 I would think.
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by hooken203 »</td></tr><tr><td class="quote">I would also make sure that you are getting WOT. The throttle on this engine is mechanical/electical. It has an electric motor that opens the the throttle based on the TPS that is moved by the cable. I took an EFI 225 off and put a 250 SHO on a 203 Champ running the same prop a 26 pitch Fury it runs with in 2 tenths of a mph the same speed. I turn 5900 74.6 mph is my best. Thats the one thing that I was a little disapointed in with my SHO I thought 25hp would gain maybe a couple mph. You should be closer on your mph then 69 I would think.</td></tr></table>Trying raising the engine on up the sho will run much higher than the 225 efi
"Luminous beings are we not this crude matter." Yoda
He says he is 1.5 "above pad"...
I think he means 1.5 "below pad"...
Either way he is high enough or too high and his numbers don't jive! There is something else at play here...
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by mercmerritt »</td></tr><tr><td class="quote">my jackplate is 8 hydro detwiller</td></tr></table>
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by falcooon »</td></tr><tr><td class="quote">He says he is 1.5 "above pad"...
I think he means 1.5 "below pad"...
Either way he is high enough or too high and his numbers don't jive! There is something else at play here...</td></tr></table>
+1 He has a hydro jackplate Im sure he has tried it higher and lower
I have raised it til the water pressure drops or the speed drops. Raising the engine is not always the answer it depends on the prop you running. The SHO is not all that great on top end.
Prop slippage of 9%. If he had 0% slippage it would be 76mph.
my detwiller is coming off i hate it, it needs seals so for now im manualy moving it up and down, in process of getting a new bobs but i agree my numbers dont jive because my merc 250xs on same jp 78-80 anytime i have loss serious speed. I love this engine if i can run 74ish loaded i'll b happy right now im running a 25-t1 ventless has not been worked yet its brand new.
Something else is not right. Prop, height etc would not account for the major difference you are getting. Take it to your dealer and check the throttle linkage and confirm that the aps (accellerator position sensor), throttle valve, and tps (throttle position sensor) are working properly. The SHO is somewhat a fly by wire system...Good Luck...
Get rid of that Yamaha junk..........mercury 250xb baby.
Something is wrong. The SHO should run right there with the 250XS. I've had both engines.
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