150 xr2 4300 rpms max ????

[grendle]

I have a stock merc xr2 150 on an 87 stratos (run lightly loaded) with a 23p stainless prop. She fires instantly, idles ok (but does run rich at idle), when you throttle up it will rev to about 2.5-3k, studder for a second then rev right up to 4k (wot). Trimming it up will get it to 4300-4400 with a good rooster tail but thats it (these should run 5500-6k correct? ) . I have replaced a bunch of things since I bought it , and am starting to think I possibly have a bad stator. Spark advance has been removed, oil injector removed (pre mix 50:1), new plugs, new switch boxes, carbs rebuilt, fuel pump and lines replaced / rebuilt, bleed lines /check valves checked. any Ideas?

[fd203]

I have about the same setup and had a similar problem but my max RPM was 1700 and the mechanic advised me this is where the high speed coils on the stator kick in, so replaced it and everything perfect, my Xr2 had another prob around 4000 RPM and my carbs were not adjusted to open fully, not sure if it helps but just dont sound like a stator.

[grendle]

Did you adjust the carbs any differently than they say to in the manual?

[j_martin]

Try disconnecting the "advance" module. Second best guess would be throttle linkage (link n sync)

hope it helps
John

[wrechin2]

Good point...just check that you are getting full throttle as most hot foots have stops and may prevent wot, if running a hot foot. Also check the setting on your tach. It may be in the wrong position and showing lower rpms than it is actually turning. Ususally the crossover is around 3K for the low and high side of the stator.

I had a basicly stock XR2 with cut heads and it would turn a 26 chopper to 6K but would only pull a 23 laser to 5500 rpms. The laser did not lift the boat no where close to the chopper and was slower than the chopper due to lift. It shouldn't have any problems turning a 23P unless it has a 1:87 ratio lower, but you describe it coming out strong.

Do a simple test. Take a inductive timing light, one that clips on the wire, and cable tie the trigger on. Hook it up and lay it on back of you boat and watch it. It will flash if the cylinder is firing. Check all 6. If it is flashing that means it is firing. This will not tell you how much voltage is being produced, just that it is producing. I had on that #5 only would quit firing above 3K and it was a bad stator. Had never seen or heard of a stator causing just 1 cylinder loss, but it happened. ususally they will drop 3 cylinders.

[grendle]

advance module is gone , and timing has been reset :) I'm thinking it was with the carb linkage . By setting it as per the manual , lining up the roller and the mark it runs ok but tops out at 4k. There is a lot of play for the linkage though. I read on here from Trex that he likes to max out the advance before the carbs open I have about 1/4" of play to work with in the linkage. I have been trying to find a sweet spot, too much advance in and it seems to load down, too little and it bogs. funny..

[wrechin2]

Also check the throttle stop on the engine. If not correct, it will not allow full throttle.

[grendle]

I'll try the timing light thing , I was fouling 1 plug every so often , then I changed out my second switch box and so far so good. She pulls strong and spools up quick to 3 k , then pulls to 4k more slowly. It wont get on plane before that. I thought is was a fuel issue, but tapping the fuel dump just bogs the motor more. I've got a few things to try I guess. I just hate it when it dosent run right.

[wrechin2]

Could be a fuel issue within the top carb. WH carbs are basilly 2 carbs in 1 body. Could have 1 cylinder effected with a float/needle issue. When pusing the key in, you only supply fuel to the middle and bottom carb. How was the plug fouling??? There wasn't a aluminium substance on it was there?

I 2nd the Hate it when they don't run right comment. Just check the basics. Have you done a compression and leak down test?

[grendle]

The plug was fouling wet, no chunks or aluminum. it was the middle plug on the stbd. side, then the bottom one on the port side. I havent done a compression / leakdown test yet (scared lol ) but I have run into issues since purchasing it . Ran great when I tested it before buying, put 10 gallons of gas in and thats when the ethanol issue started. replaced all fuel lines , rebuilt the fuel pump as well. when it first had the issue I could feel it dropping cyls. on the way back to the ramp (1 time only). replaced one power pack , ran "OK", replaced plugs , rebuilt carbs , and replaced the second power pack. Thats where I'm at now. runs pretty good , but a little studder in the mid range and the 4k rpm top end. I have gone through about everyting I know of. I know a rebuild is in the future at some time (it is an 87 that wasnt run much from the looks of it ) but funds wont permit that right now. I may have to live with it as is for a wile. I read a lot on the upper rpm stator issues (which to me is what it seams like ) and am currently looking for one in my price range. I figure worst comes to worst at least everything else is good when I rebuild it. one other thing I failed to mention , the motor runs hot on the gauge (head temp?, temp sender is in the water cover , pressed to the head) Could be a bad gauge , water pump has been changed and it pees well . Stats were out when I got it , replaced them with the fender washer mod . i'll get there , or go broke in the process lol

[grendle]

I got it out yesterday , and decarbed and played with the linkage. She runs pretty good now :) my tach may be off a bit (we'll see) but all in all it runs good. I got rid of the bog (carbs opening too late actually) and she's kickin butt :) Thank you everyone for all of the help :)

[wrechin2]

Good deal!!! A little link and sync like J_martin said!!! Thanks for the update.

[T-REX]

I got rid of the bog (carbs opening too late actually)

Glad ya got it goin...But if it's not responsive with tha time'in at full time'in, U still have a problem, U juss kinna cover'd it up...

I run my time'in at full advance on my play bote, and I do it for instant response...U have to advance tha time'in before tha throttle opens, or it won't git up, it boggs....

Git #1 up to TDC, and check your flywheel for accuracy ov time'in mark...Then check with time'in light to see if the center magnet may have spun a lil...I have had several do this, and it will make ya pull ya hair out...It don't have to be a race mota to spin, I have found them spun on a 135 2liter!!....JMO

[grendle]

Glad ya got it goin...But if it's not responsive with tha time'in at full time'in, U still have a problem, U juss kinna cover'd it up...

I run my time'in at full advance on my play bote, and I do it for instant response...U have to advance tha time'in before tha throttle opens, or it won't git up, it boggs....

Git #1 up to TDC, and check your flywheel for accuracy ov time'in mark...Then check with time'in light to see if the center magnet may have spun a lil...I have had several do this, and it will make ya pull ya hair out...It don't have to be a race mota to spin, I have found them spun on a 135 2liter!!....JMO


Thank you , and I agree, it runs ok but I still think there's an issue somewhere. I know Trex is the man on the 2.0 's and I have read your posts on timing vs throttle opening which is why I set it up the way i did originally . I will check it . I have a LOT of play in how late i can let the carbs open, not play in the linkage but I can move the roller about a 1/4 " ahead of the cam in gear. If i let too much advance in it bogs (wants to rev but sounds like it's sucking against the butterflys. I'll look and let ya know.

I'm still leaning toward a bad high rpm side in the stator. A good friend had a very similair issue and chased his tail for months until the stator was all that was left. I'm getting close lol ...

[T-REX]

Good luck...Stators kan put a few grey hairz on ya hed too!!:thumbsup:

[wrechin2]

That is the truth!!!! I would have bet big money on that one. Even though it all tested good, I knew it had to be electrical to drop a cylinder. Put known good parts on it one by one and the stator was the last. Thought I had moved something and put the old one back on, miss came back. Put a new stator on, issue went away.

[grendle]

Good luck...Stators kan put a few grey hairz on ya hed too!!:thumbsup:


Lucky for me I shave em all off LOL! :rolleyes:

There's no way you can fed-ex me a seafood po-boy from out that way can ya? lol I miss that stuff. I spent a year in Biloxi and everyother weekend in LA. good times ...

[T-REX]

There's no way you can fed-ex me a seafood po-boy from out that way can ya?

I could...but they loose thier tastiness in transit...Lol.....Soggy poboyz juss ain't tha same az SLOPPY ones!!!

[grendle]

True that ! The seafood ones from the green po boy place on burbon st. are the best I think I've ever had. There was a great place in slidel also.