MR-1 HO Compression

[96Pirate]

Does anyone know what the compression range should be on the HO MR-1's? I plan on looking at an 08 AR230 tomorrow and compression is 160 on all cylinders. Is that ok? I was thinking it should be higher. The dealer is saying that is fine.

Thanks

 

[Scottintexas]

mr1 compression per the mtc manual is minimum of 157 psi with no more than 14 psi difference per cylinder,
if your going for a test ride just make sure it's turning 10k rpms and going about 47-50 mph,
make sure the clean out plugs pull out easy,
crawl underneath and look up through the grates and see what the impellers look like, if the chipped you may ask them for a discount or replace them,
other than that, if it looks nice it should be good,
good luck

 

[96Pirate]

So I was misquoted. I just got the paperwork and compression is 155psi per. This is below the spec of 157. Does this chsnge your view Scott or anyone else? 165 hours total as well. Any concerns?

 

[Scottintexas]

I'm not familiar with the actual mechanics of it, only enough to read the manual,
maybe one of these guys might have a better idea of 2 psi less is something to worry about, if not sorry to include you with the @ feature,
@biglar155 @KXCam22 @Ryan Vogels @Speedling

 

[Speedling]

Don't need to worry about that as long as they are close to each other. You may have a little build up on the valves so some fuel additives may help. Also check the spark plugs after a run and see what they look like.
the psi can go up or down with temperature as well. Have them run the boat on the water for testing or whatever and then run it.
I wouldn't worry though. Thats well within reason.

 

[Speedling]

Btw the @ thing is sooooooooo nice.
I never knew I missed it!

 

[Magic]

Last compression check on our 2005 MR1's was 165 +- 5psi on all cylinders... We check at the end of every year in case we need to rebuild, we can take our time over the Arizona "Winter".....

 

[Bruce]

Reduced air density at higher altitudes will decrease the compression reading.

The compression numbers are equal. If it runs well I would not be concerned. But it is a good negotiation point.

 

[96Pirate]

Thanks guys! I appreciate the input.

 

[Ryan Vogels]

Sorry for the late reply. I was dealing with my Franken-engine. One thing you can do is put some oil down the cylinders spin it over for 20-30 seconds, then retest it. You should see this number go up a fair amount in each cylinder. This would let you know that it is the rings that are "losing" the compression. 155 is still pretty high for a lot of engines, but not the H.O. MR-1's. I agree that there could be other factors (altitude, etc) at play.

 

[96Pirate]

Thanks Ryan. I was able to pick up a different boat.

 

[johnniemesser]

I am looking at a 2005 SX230, supposedly with less than 400hrs (not verified yet). The shop sent me these numbers on compression
Port mtr
130-131-132-133
Stdb mtr
124-121-122-131

I'm not feeling good about that. Anyone think I should continue to pursue this one or pass?

 

[Jgorm]

I do compression with lanyard out, full throttle, no spark plugs, 10+ amp battery charger hooked up (I use a 200a), and crank until it doesn't go higher. Release pressure and repeats for s total of three readings. My boat mr1 non ho was 195, 100,165,205 tested cold, same readings when oil added. That is torn apart now and going for a valve job. My ski (same engine) was closer to 230, but that was hot.

 

[swatski]

I am looking at a 2005 SX230, supposedly with less than 400hrs (not verified yet). The shop sent me these numbers on compression
Port mtr
130-131-132-133
Stdb mtr
124-121-122-131

I'm not feeling good about that. Anyone think I should continue to pursue this one or pass?

Does the boat run? Can you take it out for a sea trial?
With the 2005 230 I believe you are looking at non-HO MR-1s that should rev up to 8,000+ RPM (unless you are at significant elevation). If the boat does that and runs anywhere close to 40mph (or above) I would not know what to make of these compression readings. There seems to be a lot of variation in the way those readings are taken by various shops. The compression numbers you were given seem low but even across the board (?).

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[Jgorm]

Non ho will do 10k rpms.

 

[swatski]

Non ho will do 10k rpms.

Not to my knowledge. The 1052 non-HO MR-1s, the 110hp variety - whatever one wants to call them, spin up to about 8,500RPM max at WOT, with proper tune-up and at low elevation.
I could be wrong. But I don't think I am.

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[Jgorm]

My 996 (998?) 140hp mr1s non hos do 10k, both the boat and the ski. (When they are working) both 2003/2004 variety.

 

[swatski]

140hp MR-1 is HO.
160hp 1.8l - HO.
110hp is non-HO.

Non-HO max RPM is~8,500, HO ~10,500.
1.8 is electronically limited to ~7,800 (varies for each cylinder)

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[Jgorm]

140hp MR-1 is HO.
160hp 1.8l - HO.
110hp is non-HO.

Non-HO max RPM is~8,500, HO ~10,500.
1.8 is electronically limited to ~7,800 (varies for each cylinder)

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I thought the mr1 that is around 1100cc and 160 hp was the ho version. No? The fx 140 ski has my non ho 140 hp version. The fx160 has the ho version. I'm not familiar with the 110hp mr1. What years were those made? I believe the 06+ ar230s had the 160hp mr1 ho versions. The 1.8L is not an mr1.

 

[swatski]

I thought the mr1 that is around 1100cc and 160 hp was the ho version. No? The fx 140 ski has my non ho 140 hp version. The fx160 has the ho version. I'm not familiar with the 110hp mr1. What years were those made? I believe the 06+ ar230s had the 160hp mr1 ho versions. The 1.8L is not an mr1.

I think you are right about the 160hp! I was wrong - the HO MR-1s are not 140hp but 160hp, like you said. The 1.8 N/As are 180hp - not 160hp - I must have really spaced out writing that.
I also finally looked for it and found it! - the thread where @Bruce collated all the info:
https://jetboaters.net/threads/does-anyone-have-detailed-info-on-the-various-mr1-versions-hp-and-impeller-questions.8478/

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