Johnson V4 85 hp to MOD or Transform into 140hp

[spybot]

HI all im getting ready to start my winter project, but it could go one of two ways.
The basics my engine a 1980 V4 85hp crossflow.
It needs a rebuild ( Crank seals are shot) It only runs on 25/1 premix.
I have fitted a new charge coil and a good second hand trigger coil. (no spark on port side) Solved.
I have gathered all the parts needed to turn my humble 85hp into a 140hp
I have been reading and asking questions for months now regarding the transformation, but now I am in two minds as to what to do.

These guys have helped me immensely: emdsapmgr, jimmbo, V153, interalian, Faztbullet, Joe Reeves, and F_R
Thank you for all the words of wisdom.

So
Option 1
Transform into 140 ( I have all the parts ready to go)
Strip my motor down
Fix Crank seals.
Machine Bottom rib for bubble exhaust, Fit exhaust fillers and machine flat,
Port to 140 spec (hopefully get it right, Lot of cash if it goes wrong )
Smooth out flow of ports.
Possibly Scallop piston and crank. (need feedback on this please)
Balance rods wrist pins and pistons
Smooth out flow form carb throats to reed cage on inlet manifold (need feedback on this please)
Fit 140 reed stuffers
Fit CCM sport reeds match cage to reeds
Port match whole engine
Fit 1 5/16[SUP]th[/SUP] Carbs and convert carbs from flap choke to primer,
Fit 140 H/C heads

Option 2
Make her a very tight smooth 85ish
Strip my motor down
Fix Crank seals.
Smooth out flow of ports.
Possibly Scallop piston and crank. (need feedback on this please)
Balance rods wrist pins and pistons
Smooth out flow form carb throats to reed cage on inlet manifold (need feedback on this please)
Fit 140 reed stuffers
Fit CCM sport reeds match cage to reeds
Port match whole engine
Fit 1 5/16th Carbs and convert carbs from flap choke to primer,
Fit 140 H/C heads

Option 2 is basically the same as 1 but I will spend a lot of time sorting out the flow and remove all casting marks ect ect.
Im not sure on the inlet manifold it seems to me as the fuel mix leaves the carb throat it has to take a sharp 90 degree turn to enter the reeds. Is there any benefit of reducing this turn or smoothing the flow to the reeds?
Also regarding the reeds I have talked to chris carson about this and he said to get them as flat as possible using glass and wet and dry paper but I have also been told that I can increase the reed cadge cutouts to match the reeds ????
Anyway guys that’s what I have planned so any pointers would be great.

All i want is a fast reliable with a normal maintenance schedule, that will be used every second weekend for pleasure no skiing or tubing.
My boat weighs 660lbs and is a 15 foot deep V hull Similar to a 16ft Sidewinder.

 

[Faztbullet]

What are you going to do with motor???? Race? ski? pleasure? How much maintenance do you want and reliability?

 

[spybot]

Fazt I want a reliable fast pleasure speedboat no skis or tubbing, Regular maintenance or a bit more the boat ill only be used every second weekend

 

[Faztbullet]

I want a reliable fast pleasure speedboat

Fix Crank seals..................yes
Machine Bottom rib for bubble exhaust, Fit exhaust fillers and machine flat,...................yes
Port to 140 spec (hopefully get it right, Lot of cash if it goes wrong ).......................yes
Smooth out flow of ports...............................wont hurt
Possibly Scallop piston and crank. (need feedback on this please).............no
Balance rods wrist pins and pistons..................................no
Smooth out flow form carb throats to reed cage on inlet manifold (need feedback on this please)............no
Fit 140 reed stuffers.........yes
Fit CCM sport reeds match cage to reeds...............yes
Port match whole engine......................no
Fit 1 5/16[SUP]th[/SUP] Carbs and convert carbs from flap choke to primer......yes
Fit 140 H/C heads................yes

The questions answered no are only needed if turning the engine over 6000RPM (reliability drops) and racing. You need to remember that this is not a prop rated engine so it only going to be 115-120HP at prop. You would be better off taking the money that going to be spent and sell your engine/parts and buy a late model 120/140 looper(prop rated)

 

[spybot]

Thanks Fazt i have taken all that on board. I will as i have always said post the work on here.
If i had the chance of picking up a 140 i would in a heartbeat but over here (Scotland) They are mega hard to get a hold of.
Hence the build

 

[spybot]

Can anyone give me he exact size of the ports from a 140hp
Were they just milled the same as the 85hp but with a larger bit ?

 

[Chinewalker]

It's not just the size of the ports that is needed. You need to know port height, when they open/close. Can't just hog them out and expect the motor to run well.

 

[interalian]

No Title

Can anyone give me he exact size of the ports from a 140hp
Were they just milled the same as the 85hp but with a larger bit ?

I know I said otherwise earlier, but since I plan to take my motor off my boat for the winter and will be stripping the wiring and other bits that don't get paint, I'll pop off a port cover and measure them. Can't help you with the exhaust ports though as that would require R&R of the bubble butt and the fillers (the exhaust ports ARE larger).

WAG: from the photos I have seen, the 140 ports appear to be on the same centers as the lower HP model, just a larger hole. You've seen these pictures before (not mine, V153's maybe).

 

[spybot]

Thanks interalian I tried to blow them but it was hard to try and get a size

 

[Faztbullet]

Also the exhaust ports need modified.....

 

[interalian]

Thanks interalian I tried to blow them but it was hard to try and get a size

You could probably get real close by printing the photos and measuring between the mounting holes, measure the port size on the photo then measure the actual bolt hole spacing and work it as a ratio.

 

[spybot]

Fazt have you any idea on the exhaust sizes ???

 

[spybot]

Good one inter i will give that a try

 

[Faztbullet]

I will get em for ya this week as bought a 110HP today for lower unit($35). Powerhead shot as it was on a sunk boat but good enough for measurements.....

 

[spybot]

Thank you bud

 

[spybot]

Ment to say. I pay ?35 for 1 head gasket about $47 thats only 1 head gasket.:grumpy:

 

[spybot]

Just a quick question
Would a 1972 125hp have the same size ports as the 140 ?

 

[spybot]

I will get em for ya this week as bought a 110HP today for lower unit($35). Powerhead shot as it was on a sunk boat but good enough for measurements.....

Hi Bud any luck on those port sizes ?

 

[racerone]

??----A 1972 model 125 block can not be used for a 1980 model motor.

 

[spybot]

I was after the port sizes from either a 115 or a 140
I have the 125 block but now i know it wont fit / be of use to me. So think it will be a practise block. Are the ports on the 125 the same as the 115.140????