Black Max XR2

[Bassin_Gambler]

hey guys i know very little bout 2 stroke motors. i purchased a 18' gambler and it has a 150 blackmax xr2 on the back ( no jack plate ) and has a 25 4 blade prop( no markings as to brand or such ) the issues i am having is these boats are fairly stern heavy and it wants to lift the bow a good bit on hole shots but it just doesn't jump on pad like i would expect . also when putting it on pad it wants to sputter , but it clears up and runs once it finally gets on pad and u start trimming it up .

1. what could be the causes of the sputter during hole shot ? this is the biggest concern

2. any one have any experience with gambler 183 GT boats here? if so i have read people running everything from 6-14 " jack plates and 23 and 25 4 blade props. any knowledgeable help here would be great

3. who is a good reasonable boat mechanic that would be highly recommended ( not wanting to pay $100 + an hour)

4. i have a good bit of confusion when i run the serial number on the motor . the cowling is a 150 black max XR2 ( which i know can be easily replaces and purchased ) but the serial comes back and says 1987 135/150 HP how do i know for sure what motor this is ?

Thank you in advance for any advice .

 

[lafae7]

Vapor lock.... Check for it to see if the gas tank is venting properly

Also it sounds like maybe just maybe the height of the engine needs to come down.

Just a wild guess. It could be few other things.

 

[Bassin_Gambler]

I will get a prop to pad measure this weekend . it looks like it is sitting a little too deep but i haven't put a tape on it to check the height yet

 

[lafae7]

Ohh wait a second. Eureka....A 25 pitch prop is too high for the 150 hp XR2. I think that is your problem. You need to come down to at least 21-23 pitch prop.

The sputter at take off you feel is the prop over gripping and slipping in the water instead of pushing through.... I hope that makes since. I had a 19 pitch 4 blade on mine if I can remember and it made my xr2 plane out in seconds.

 

[Bassin_Gambler]

ok any ideas on what a good prop would be in 23p ?

 

[lafae7]

Mercury tempest/trophy plus I think... I have not shopped around in a while so I can't remember emogeezer. Good luck to you I hope you get it purring like a kitten.

 

[ditchdoc666]

I run a 23 lazer 2, a trophy 24 pitch 4 blade and a 24 short ear chopper,I think a 25 pitch is too much and as said above slipping,what are your rpm' when taking off,that would help solving problem

 

[Bassin_Gambler]

I'll check hole shot rpm and top speed rpm Sunday when I go out

 

[kingcab]

Go with Ditchdoc...to much pitch .

 

[Mielke]

Too much prop. I have a 23 tempest for sale, you can test run it of you are interested.

 

[porthos33]

Yeah I have an 88 merc 150 xr4 and have a quicksilver laser 2 22p on mine and it has great hull shot and Will hit 58 with just me in it with the motor all the way down on the jackplate.

 

[Bassin_Gambler]

Thinking it's carb issues .. Hole shot. Was mediocre today have a 8" jack plate for it... With me and my buddy in it it ran 67 today trimmed all the way and was wanting more trim... This boat sure loves trim

 

[lafae7]

that's very impressive. Was that with the 4 ear 25 pitch prop?

 

[lafae7]

What was your RPM at full throttle? yeah them xr2 engines are basically Racing engines. I use to watch boat racing back in the day and for the most part it was ruled by mercs xr2.

 

[Bassin_Gambler]

Yes sir... I never expected the boat to run what it does . I was willing to be happy with 60 with me(305 lbs ) and my buddy (350 lbs) I seen alot of impressive numbers when doing research on the boat before I purchased it and thought they was stretching the the moh they was running ...

 

[Bassin_Gambler]

Was at 5900...

 

[lafae7]

Indeed...sounds like you have a monster... sounds like it may be bored over by Atleast 25... Or block has been changed with one that has been bored over which is why serial numbers don't match. All in all it sounds like beast and a good purchase emotoast. Those speeds and RPMs do match up with the 25 pitch prop your running which is good. All I'd worry about is strain on the engine from using too high of a pitch. It's kinda of like running too big of tires on a truck... It will make it go fast but will strain other components. I wouldn't mind seeing that boat go down the river though. I bet that was fun!

 

[Bassin_Gambler]

The strain is a concern ... I want it to be dependable

 

[lafae7]

also... Another thing you can check besides switching props is to: with the engine off, take engine cowl off, keep eye on carbs, move throttle forward, look to see if carbs are 'all' opening at the same time. The rods that move the carbs are plastic and they can fall out of place or snap. I had that problem before. I fixed it with a tie wrap because I couldn't find a replacement part anywhere.

 

[Bassin_Gambler]

Thanks for that bit of advice I'll check into it ...