Johnson J4RLEEA Long to short

TSB240

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I am considering converting our LS 4 hp twin 2 Stroke to Short shaft. It is only being used as an occasional back up to our Main O/B and it is a too big for the flubber dink with the LS.

A long time ago I did this on an old baby evinrude light twin by:
removing the power head from the leg (4 Bolts?)
Removing the extension at bottom of leg (2 bolts?)
Cutting the drive shaft and water cooling pipe down by length of extension. putting it all back together.

Would the same principle work on this newer model?

I will take the usual precautions when dismantling soft stainless bolts. Heat, Hot water, Penetrating fluid. Sharp tap on the bolt heads to break free threads before attempting to undo.

I also seem to remember that there was a plastic insert in the power head to which you must get a good seal with the water cooling tube or risk overheating.

Anybody have a link to a workshop manual or exploded parts drawing for this model? would be much appreciated.


Steve
 

DownWest

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Your problem is no4, the driveshaft. Cutting and joining could be achieved by using a sleeve and brazing. I did this for something land based, but baulked at a friend's outboard. The bits for a Tohatsu 3.5 were £130, so he stuck with the LS.
What did you do last time for the shaft?
A
 

VicS

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You will have to
remove the leg extension piece,
replace the drive shaft with a standard length one.
replace the shift rod with a standard one
shorten the water tube by 5"

If you can shorten the drive shaft by 5" it solves that otherwise look out for a dead standard shaft model ( Various ones will have the same shaft .. you can get them listed from the parts catalogue.)

You may be able to shorten the shift rod , otherwise get one from a dead engine.

No problem shortening the water tube

In oder to shorten the water tube or replace the shift rod you will have to remove the power head from the leg.

Renew the grommet at the top of the water tube while you have access to it.

A new drive shaft is $204 and a shift rod is $56

Usual advice dispensed is don't bother ... look out for a standard shaft model! Sell the long shaft one.

Diagrams at http://www.boats.net/parts/search/BRP/JOHNSON/1999/J4RLEEA 1999/parts.html may be useful
 
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steve28

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yes it does work, i have done it to a few 3.3 mariner/yamaha types. make sure the shaft is cut with a sensible join. i made up ajig to hold it whilst welding with stainless wire on the mig.
gear shift and water pipe are easy.


steve
 

TSB240

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Thanks for all the info..

Not quite as simple as I thought.

Vic you are probably right about swopping for a SH shortie. Alternative I will have to keep looking out for a dead one given those spare prices.

Dont really want to let this one go as it is immaculate and has never failed to start 1st pull! Still in my opinion the best lightest 4hp two stroke twin ever made.

The only pity is it doesnt have a 12v charging facility option.


Steve
 

William_H

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Johnson OB

A warning re drive shafts. A story.
Back in 1980 I bought my present boat (21ft sailer)on a trailer. I towed it down to the marina for the first time with a brand new Johnson 6HP LS. I fitted the O/B to the transom bracket and prepared to back the boat into the water. In a fit of non good sense I removed the safety chain holding boat to trailer and disconnected the winch cable. I reasoned that I could jump on the brakes at the right time and the boat would slide into the water.
It turned out the boat rolled really easily on rollers, the boat slid off the trailer too soon, bounced on the concrete and slid into the water. Unfortunately the prop of the outboard hit the concrete and broke 2 of the blades of the Al prop. Apparently no other damage to engine or hull. (Bit of gel coat off the skeg.)
I replaced the prop and started using the engine regularly.

After some use the drive shaft broke. so I replaced the drive shaft. After a while longer the drive shaft broke again and was replaced again.(new shafts were cheaper then) Eventually I realised the whole exhaust tube/leg was slightly bent. The whipping of the drive shaft fatigued the shaft causing failure. I managed to straighten the leg with a build up of epoxy under one side of the extension piece to bring it all a bit straighter.

My point being I would not be too confident about weld joining a cut shaft. good luck olewill
 
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