sportster has low top end

[fixin]

Hi all,I've been trying to help a friend to get his sportster Le/Le Di running better.
He bought it last year and it would only get up to around 28 mph,so he had a new impeller put in.No change then the starter went out-- end of boating season.He dropped it off Saturday with a new starter and new relay and asked if I would work on it and see what I could figure out about the performance issue.I replaced both and got it back to starting.Same issue of poor performance.So I figured best to start with a compression test
Rotax 947 compression 150/150.
I noticed on the muffler there is a whats called a reg-pression?That has a threaded female spot on it with nothing going to it.Wit the motor running it has a vacuum to it.I can't find anything that would have gone to it or anything online that shows What the hole is for.
Any help would be greatly appreciated.

 

[Dr Honda]

......... I noticed on the muffler there is a whats called a reg-pression?......

Hu????

If you looked it up on-line... I think you were looking at a french description.

Post a pic of what you are seeing.


That boat should be seeing upper 40's to right around 50. So... what RPM's is the engine getting to?

 

[fixin]

http://www.seadoopartshouse.com/hom...er_LE_DI,_2004/01-_Cooling_System/22818/22822

the tag #23
I'll have to put it back in the water to see what the rpms are...my bad

 

[Dr Honda]

OK...


That's the water regulator. It's job is to inject the water into the water box, and then into the tuned pipe.

So... if that's missing... and someone ran the hose from the fitting in the main feed hose, to the elbow in the tuned pipe... it would be SO WET in the pipe... it won't rev up. (It's very likely your problem) Not to mention... you would have an exhaust leak if there is an open hole in the waterbox.

 

[fixin]

The regulator is there and has one hose from water supply,and one from smaller hose that is coming from the side of black manifold on top of engine, and on the opposite side is the threaded hole in question.I'm not seeing anything that looks out of place or that could hook up to it?An exhaust leak somewhere definitely sounds possible,theres a lot of oil/water mix in the bilge.

 

[Dr Honda]

Let's make it easy... post a pic.

 

[Dennis]

I took a look at a reg I have on the bench. Yes, there's a 1/4 in hole on the opposite side of the 2 water ports but it is blocked off internally. Nothing gets connected there nor can there be a vacuum leak.

 

[fixin]

Sorry, I checked back a couple of times and it didn't show any new posts,..didn't think to refresh page.
Thank you Dr.Honda and Dennis for your time and responses.
With the motor running,if you put your finger over the 1/4 hole it definitely has vacuum,that gets stronger the longer you hold it.Can I take the thing apart and see anything or is there a way to test it?

 

[fixin]

Well I had the day off and messed with it a little more.I don't know if I was disillusion or what, but the 1/4 hole on the regulator doesn't seem to have vacuum now.I cleaned the coil wires and the plugs,checked fuses and put her in the water.
5600 RPM's and around 36 mph.More like it's missing.it will get up to the 5600 then down to 5000.It also will speed up and then slow back down at idle speed,trying to get it back on trailer with 25mph wind was fun.Mid-range throttle the boat seems to run strong and no miss.
Friend thinks he put new plugs in it last year,but they looked a little fouled.He's picking up another set and some premium fuel and I guess we'll go from there.