V4 crossflow jetting with 140 heads

[RACINCRABBER]

I have a 96 88 Johnson its .020 over and I put a set of 77 140 heads on it. will I be safe just going up on the mains to 67s in the smaller carbs? or do I need to get the 1 5/16 carbs too? if anyone has some jets let me know

Thanks

[71V153]

Unless you start monkeyin around with exhaust, I wouldn't think you'd need to change jets.

Wondering how/where you mounted the ignition coils. I have a set of '77 hi-comp heads and they do not have coil mounts?

[RACINCRABBER]

Mine have the the places to mount the coils but they aren't drilled and tapped. But they will be soon lol

[71V153]

Hmm. Now that's odd. Are you sure they're '77? What are the part #s?

[Schramer]

I would back the timing down 2 degrees if your not going to upjet.....X-flows love fuel! '77 heads dont have a place to mount the coils as they were the boomerang style but one can fabricate mounts to make it work but make sure ya get a good ground if ya have to do that.....

[EMDSAPMGR]

Replacing the old large-chambered bathtub heads with the 140 high compression heads will require more fuel to keep them cool, so you are correct to be concerned about getting enough cooling fuel into the engine. Be careful with jetting and the factory parts lists. If you stay with the original small bore (88/90 hp) carbs (probably 1 3/16" throats,) you need to jet up from the original .056 mains in those carbs. If you switch to the larger 115 carbs with the 1 5/16" throats, you need to jet up from the original .067 mains. If you just put .068 into the smaller bore carbs, it will likely overfuel to the point it won't run right. You'll get the most out of the new heads if you blow more air and fuel into the engine-that's the larger 115/140 carbs. I'd suggest you try a pair of those carbs with the .068 jets-as a starting point. After some testing, it's possible you may need to go up another jet size.

[RACINCRABBER]

Well i know they came off of my 77 140 i started taking it apart then katrina ate the rest of the power head. here is a pic of the old 88 heads and the 140 heads that are on it now. the 140 heads have a smaller chamber. so they are some vintage of 140s

[71V153]

A part # will tell for sure.

Do you have the '77 mid? That's the one with the bad boy megaphone tuner.

I'm no expert on carb jetting so don't listen to me. Just seems you'd have to lose the restrictive flat-back exhaust before you could force much more fuel through it?

[RACINCRABBER]

with that corrosion I doubt I can find a part number lol nope the old 140 mid is gone. but I have a 85 javelin mid I doubt its the same don't sound like the 140 did

[EMDSAPMGR]

All that 77 140 stuff is the best-including the one-year only tuner that 71V153 noted. Are the 140 carbs salvageable? Those are the ones I'd run with those heads. Even though they use the old mechanical choke plates. The 96 single pack ignition system is rev-limited at 5800 rpm's. Not sure it you can buy an aftermarket single unlimited pack, so, consider using the 77's ignition system: The old original 77 packs were unlimited-while they are NLA, you can buy the older aftermarket unlimited packs.

[71V153]

CDI's #113-4028 is not rev limited.

I might have a stray pair of 1 5/16 carbs kickin around but I think they are the old style with choke butterflies. I'll take a look.

Ya that tuner was actually on all V4 models. (85hp & up.) Yep '77 only.

[RACINCRABBER]

no I don't have the carbs. all I had left was heads and intake and reeds and reed stuffers. I already put those in the 88. I have that cd4 pack I looked it up its supposed to be unlimited. what ya want for those old carbs?

[71V153]

what ya want for those old carbs?

Had to find em first. Hell I dunno what I want for em. Whuddya got?

For what it's worth to the best of my knowledge these came off a '78 140:

Depending on how deep you wanna get into this project I probly have a bubble butt exhaust to fit. Be forewarned it ain't got no peehole, or lugs to mount the trim relay box. That all's on you ...

[Schramer]

Those are some old nice carbs! But in 78 & 79 (im pretty sure) they had 1 3/8" carbs for those two yrs only....I would not run those on a 85hp motor those....IMO, besides getting those 2 stage 1 5/16" carbs tuned for the 85 they never made better carbs than the 1 5/16" ones! Very reliable fuel metering!

[RACINCRABBER]

well I jus got an 84 140 today so I may jus end up putting the 88 to the side until later or use it for parts for these two. so now ill have 2 140s and 2 vipers ha