1980 2.0 front half swap help!

[Merc 2.5]

Hey guys I have a 150 merc vertical motor that I want to do a horizontal swap to it. Can some please guide me through this process, I'm gonna purchase a 2.4 front half carbs and all. Can someone tell me what all needs be done to make this work or Is it a straight bolt on? Thanks for any info

[faztbullet]

May I ask why????

[Merc 2.5]

It's really just a experiment for me. I have a ex motor laying round and would like to see what I can do with it without porting or any block work

[FORBESAUTO]

I haven't done it, but think it should be a straight up swap. I can tell you that anytime you swap mating front halves with blocks you need to remove the alignment pins and let the crank do the centering. Also you need to remove the wear grooves from crank rings to prevent side pressures and poor sealing on crank rings. Chances of the wear grooves lining up in the same location is slim to none. Make sure the crank turns freely after mating and torqueing half on indicating a good alignment.

[FORBESAUTO]

Also make sure the center mains are all the same size. I know some had the smaller o/d mains, but don't remember which mota had them.

[Keaten]

Wat carbs can be run with that combo and jet sizes ? say wh 20s with wat size main jets and wat size idle jets ? How do you remove any old wear groves on front from crank?

[FORBESAUTO]

Wh 20 or 22 would work good. The 20 seems to run harder on top end, while the 22 seems better down low. Prob somewhere between 72-78 if all is stock on mains and around 48 on idle (44 is stock, but if run larger than 76 mains the 48 makes for more crisp throttle response). I would start rich and work down.

You need a cylinder that's a tad smaller than the diameter and will fit between the main bosses. Wrap 400 grit paper around it. Take your time and work just the edges down to the depth of the groove. You can change the pressure points with your hand to keep it even. I use a big socket that just happened to be the right size. Some guys use a pcv pipe that they turn down just a little to make it the proper size.

[FORBESAUTO]

Remember, I ain't never swapped halves between two different lita motas, so ain't fo sho it it'll even bolt up. Just be conscious that there are two different size center main o/d's. I would prob start with 84 mains and work my way down. All my modded 2.5's take mains in the 80's, but stock jets are 74 I believe, so just think you will be close to that if not making major changes and running an air box, if no air box will need more jet also. Always a good idea to start fat and work your way down:thumbsup:

[90 5.0]

I was young at the time so I don’t remeber exactly but it seems like this was a common thing to do with thebbass crowd when the xr-2’s were popular.

Seems like i can remeber this being discussed at the shops and think one of my dads xr -2’s was this way.

Dont take that as gospel, just rememberings from being young and around high perf stuff at the time

i can look next time I’m at the shop I recently got one of my xr-2’s back and the front half is not original to the block it’s on.

I haven’t looked down it to see what it is I just know that a mechanic “detuned “ it for the last owner to make it more friendly everyday.

so it’s possible it has or had a 2.4 front and either still does or doesn’t anymore.

[Capt.Insane-o]

I liked 46's better on the 2 liters than the 20-22's. 400 rpm gain on a 76 1750 going to a horizontal front and reeds using the same wh-1 carbs. 67-6800 on a viper with a 26 72-7300 after.

[Krazymaan]

Isn't there something about alignment dowels? Although they are technically in the same location, they could be off a bit. Plus those bearings sizes Forbes mentioned.

[FORBESAUTO]

Yeah, you need to remove them and let the crank do the centering.

[tlwjkw]

bearing "size" (id and od) is same on all 2.0/2.4's till '91.. its tha plastic versus steel cage that's different on tha 2.0/2.4 cranks.. so he has no problem there as long as he keeps tha center bearings and cranks straight..........