Merc xr4

[Robertrosen]

Ok, I asked this once before and got the answer I was looking for. However my computer crashed and lost the info. I did a search on here for it but no results. I have a 89 merc xr4 150 and I want to get more power out of it. I was told there was something with the tuner, advance timing module and something else to make it a 200hp. Does anyone know about how to go about this and can Ido it myself? I have the motor hanging a 96 Procraft 185 dual pro with a 6 in jackplate and only getting 53mph. Im running a 25 trophy and wot is 5600. But I have no hole shot and need a whale tail just to get her on plane.

[David]

The XR4 hop up as I understand it:
Tuner, reeds, add compression, remove timing module.

Having said that, I think the tuner hurt my hole shot. I didn't touch compression or remove the module.

[rhickox]

I have been told putting a 2.4 200 horizontal reed front half on it makes it a 200.. From what I was told, the vertical reed front half is how Mercury de-tuned it to make it a 150.. On mine I did remove the oil injection and with the right KIT it get's rid of the timing advance.. Mine has 136-138 comp on all 6 so I just left the heads alone.. Removing the oil injection along with the timing advance seems to have helped mine. I think I locked the timing @ 24 degrees..???.. Heck it's worth a try anyway,,, can't hurt and the parts won't bust your wallet up!!! LOL

[rutro]

Hey Robertrosen, I had that same question a while back and here's a link to the thread with some excellent replys, http://www.screamandfly.com/showthread.php?207670-150-2.4-to-200&highlight==. Also something I noticed a while back, when you log on and go to a page like "Technical Discussion" check at the bottom of the page where it says Thread display options. If it says "Last Day" under where it says "Show threads from the...." then you need to click the drop down box and choose a time frame far enough back to pick up the thread you're looking for. Good luck with your XR4, gota love them ol' Black Maxxs.

[wrechin2]

They are very good engine in deed. There is a lot of potential from them if they are apart. The verticle to horizontal upgrade is about 25HP but the XR4 was probably closer to 165HP in stock form. I am still working on this one for a guy. I have ported it to 83 200 specs which was a little more aggressive then the later years. I could get a lot more power than I am out of this one but I have the weak link of the 1:78 gearcase. What case do you have?