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Author Topic: Possible engine upgrade for the Javelin  (Read 2825 times)
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DumHed
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« on: January 02, 2017, 04:47:35 PM »

It's been a while since I've been on this site!

The Javelin has been getting occasional use the whole time - but had been in storage most of 2016 until we took it out for new years eve Smiley

For the last 5 years or so it's been running a 70hp 3cyl Mercury that I got for free. It's very low on compression on the bottom cylinder but runs fine and has really performed quite well.
It's missing the power tilt and the reverse tilt lock which is a bit of a pain though!

The other week I picked up a "suitable for parts" Mariner 115hp inline 6 (appears to be a 1983 model) for 99c on ebay (had to round up to a $1 coin on pickup though!)
Overall it looks very good, and came complete with the controls, cables, power trim pump, etc. The only thing missing is the prop.

It didn't turn, and after a quick inspection it was obvious that it had swallowed some seawater. There are salt deposits in the conbustion chambers, but nothing looks badly damaged and I can't see anything on the intake side.
After a bit of a WD40 soaking and a careful turning of the flywheel it freed up easily - but I've only turned it a few degrees to avoid causing damage before I clean out the cylinders.

Plan A was to give it a quick clean up and see if it'll run - but to get to the bottom cylinder I had to take the powerhead off the leg anyway so I'll strip it down a bit more and make sure the bearings, etc are not rusty.
I already broke some bolts pulling the cooling cover off the head so it may as well get a more serious cleanup.

I've ordered a manual for it before I get too deep in the dismantling process Smiley

Are there any specific things to look out for with these engines? Any recommendations for a propeller?

Is there any chance of finding a short shaft leg for it?



Thanks!

Andrew


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Mark S
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« Reply #1 on: January 03, 2017, 02:06:29 PM »

Hi Andrew, cheap engine, good buying.

Also check for water entry to cylinders through exhaust port(s) from exhaust plates. Sometimes the inner plate can weep, located in behind the exhaust plates. Should be easy to see evidence of salt water weepage.

In good tune I would run a 19 pitch prop on a Javelin.

Mark S.

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DumHed
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« Reply #2 on: January 03, 2017, 03:47:26 PM »

thanks for the info! Smiley

I was wondering about that exhaust plate. There has definitely been some weepage on the outside, so no doubt there has been some inside too - which would explain the water in the cylinders.


I was thinking a 19" pitch prop would be about right too. I'll track one down as soon as I'm confident I can get the engine going Smiley
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MERCMAN
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« Reply #3 on: January 04, 2017, 03:49:14 PM »

Hi Andrew,
What a great buy! As usual I concur with Mark, check the exhaust plates and rear water jacket (head as you called it). I6 Mercs /Mariners do not have a Cylinder head, it only looks like it!
Hold throttle lever (on Port side of motor) wide open and hose the WD into the carbie throats as well. You need to protect the Crank and Rods as much as you can.

My Dad had a 15' Savage Pursuit with a 1965 Merc 1000. It could easily turn a 19" at 5200 RPM which was maximum RPM for that particular motor. I feel the 115hp you have, may be able to turn a 21" prop on a Javelin, but the hull design will be your speed limitation. Stay with the 19" prop, it will be a good stump puller.


Buy the way, if your gear box is free from water and works well, it alone will bring $500 on ebay, every day!

MERCMAN.

 
  
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DumHed
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« Reply #4 on: January 04, 2017, 05:34:17 PM »

that's good to know!

I figured I couldn't really lose on this one, even if I just used a few bits from it and scrapped the rest - but it did look a bit nicer than the average parts engine Smiley


I'll keep hosing it with WD40 until I have cleaned it up enough to try to get it running, and then hopefully it'll be a fairly straightforward upgrade for the boat!

I plan to change to a push-pull steering setup if this engine does make it onto the Javelin.
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MERCMAN
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« Reply #5 on: January 05, 2017, 11:36:45 AM »

Whoops,
I forgot to answer your question about a short shaft leg. Mariner never produced anything in short shaft except for small fishing motors.
However, Some Merc short shaft legs will bolt under your motor provided the donor motor was built after 1974. See year models below:

4 Cyl - 80, 85hp and 850XS.
6 Cyl - 140, 150hp and 1500XS.
Merc did not make a short shaft 115hp.

These donor motors do appear on ebay from time to time.

MERCMAN.

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DumHed
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« Reply #6 on: January 05, 2017, 03:21:59 PM »

cool, thanks.

I'll keep an eye out for something, but otherwise can just run the transom plate setup I have on there already (maybe with some extra bracing!)
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DumHed
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« Reply #7 on: January 08, 2017, 05:32:00 PM »

It looks like the exhaust plates could be the issue - plenty of evidence of salt water in there.
I haven't removed the inner plate yet - but will do after a clean up of the bolt heads.

The pistons generally look pretty good. Only one has some scrapes down the side. I've seen much worse before!



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DumHed
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« Reply #8 on: January 13, 2017, 09:13:46 AM »

I had a little bit of time yesterday evening so I pulled the transfer port covers off (all bolts were very loose, but still had factory paint over them) so I could see if there had been water into the crank case.

Turns out there was! So, it will need a full strip down and cleanup. Hopefully the bearings all had enough oil in them to protect them.
It'll probably be a while before I have time to sort it out properly but it might be a nice winter project ready for next summer Smiley



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MERCMAN
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« Reply #9 on: January 17, 2017, 07:03:03 AM »

Hi Andrew,
The Crank is rather rusty. However, I feel you can salvage it provided the bearing surfaces are OK, as you say.
As for the piston scrapes, they might clean up too.. a slight hone may save the bore on number 2.

There is a guy in town here who has been saying to me over recent months... if I remove his old 150hp I6 (& controls) from his Haines, I can have the motor.
I can't recall what's wrong with his motor, but he wants to repower his boat. I'll be seeing this fellow at the local Show Girl Ball on this Friday night, I'll ask what's going on with his idea of repowering his Haines. If I eventually receive this motor, I'll provide you with what you need.
Keep digging!
 
MERCMAN.
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« Reply #10 on: January 17, 2017, 07:55:27 AM »

thanks!

As soon as I get some more bench space available I'll strip it down completely and see where it's at.
I figure even if it's not perfect it'll do the job since I don't do a lot of hours, and won't really need to run it flat out (that often Smiley

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