What is the difference between HO MR-1 and MR-1 engines besides 20hp

[zipper]

I just looked at the output stickers on my engines and the tag lists 104.5kw which translates to 140hp. I never did the conversion before because I thought the "HIGH OUTPUT" badges all over the boat and engine cover meant they were 160hp each. I am confused now. Did Yamaha put derated stickers on my engines and hatch or did some A**ho** put high output graphics and stickers on a regular MR-1 boat. Or is the 140hp considered high output by Yamaha. Any insight on this would be helpful. I peeled the AR230 "high output" graphic off the hull yesterday, but the engines' air filter cover says it is. P.S. top speed is 48.6 on GPS speedo

 

[zipper]

@Bruce @Scottintexas Any information about 140hp being "high output" or is it derated like some high HP autos.

 

[Bruce]

All of the MR1 HO engines are rated at 104.5 kw / 140 HP. It is believed that Yamaha underrates the engines.

Here is a similar thread that I started https://jetboaters.net/threads/does-anyone-have-detailed-info-on-the-various-mr1-versions-hp-and-impeller-questions.8478/

 

[Bruce]

There were a number of CARB certified MR1 engines between 75 and 104.5 KW.

 

[Georg]

998 vs 1052 ccm?

 

[zipper]

@Bruce Thank you, feeling a bit of relief after reading thru your thread from Feb. 2016. I thought it had to be something like underrating, due to the published info on HO MR-1s that i have read both pre/post purchase. I was on a different thread earlier today about someone wanting to buy a 2006 ar230 and whether it had HO engines. I went to look at mine and saw the kw rating and did the conversion. I was confused as I thought we bought a 320hp boat. Again thank you and I apologize for tagging you on Easter sunday. Great stuff from you as always. David

 

[swatski]

@Bruce Thank you, feeling a bit of relief after reading thru your thread from Feb. 2016. I thought it had to be something like underrating, due to the published info on HO MR-1s that i have read both pre/post purchase. I was on a different thread earlier today about someone wanting to buy a 2006 ar230 and whether it had HO engines. I went to look at mine and saw the kw rating and did the conversion. I was confused as I thought we bought a 320hp boat. Again thank you and I apologize for tagging you on Easter sunday. Great stuff from you as always. David

With that color label on the engine cover and doing 48+mph, you definitely have the HOs!

--

 

[zipper]

Man the information gleaned from this site is phenomenal. I keep coming back because of the expertise that is evident in your responses. Well Done. You took a big weight off my shoulders yesterday, as for an hour or two I thought I was scammed. @Bruce Your Data base and command of these boats is top notch, I cannot thank you enough. @swatski Your attention to detail in your mods and write-ups, make you outstanding in your field or river. Pun intended. Well done gentlemen, keep it up.

 

[Jgorm]

Subscribed

 

[sethman919]

I suspect they have a standard block with the right configuration of other components and ECU code makes 140hp and with another configuration makes 160hp. When the block is manufactured in japan they label it as the standard configuration and slap a sticker stating that rating along with another sticker to stick in the hatch. then when it gets installed the additional tweaks needed to make it a 160hp motor are done. Intake, exhaust, ECU programming ..ETC.

 

[Jgorm]

The ho version has 100 more mL. Probably due to a longer stroke, but I'm guessing.