What compression on 2 stroke 3hp?

willk · 22 March 2016, 22:44

I'm shopping around for a 2 stroke Mercury/Mariner/Tohatsu in the 2.5-3.5hp range. When the time comes and I find one, what compression level should I be checking for? With just the one cylinder, I won't be able to compare and contrast!

Thanks.

Mollers · 22 March 2016, 22:48

Quote:

Originally Posted by willk

I won't be able to compare and contrast!

Thanks.

Buy two.

willk · 22 March 2016, 22:52

Quote:

Originally Posted by Mollers

Buy two.

Thanks. What makes it worse is that I know that you know the answer!

Anyway - not like you to recommend twins?

Mollers · 22 March 2016, 23:03

The Mollers Guide to 2st Tiddler Buying.

Scan the bloke's garage/shed for boaty bits.

Give the thing a good coat of looking at.

Shove it in a dustbin half full of water, get the yer man to hold tight and you give it a good tug (there's ya comp test).

Let the tell tale piss over his trousers and knock it in and out of gear. Try to avoid smacking the bottom out of the bin when in gear, I've done it.

If all good, offer him half of what he's asking.

Don't get the comp tester out, you may risk getting you're arse kicked down his drive.

Feel free to use this in the Ribnet FAQ section.

spartacus · 23 March 2016, 01:20

Standard or long shaft? Just say the word and I'll put the hounds on the scent of 2-stroke oil.

kawasaki · 23 March 2016, 10:03

Quote:

Originally Posted by willk

I'm shopping around for a 2 stroke Mercury/Mariner/Tohatsu in the 2.5-3.5hp range.

Thanks.

Think I have just the thing you need . PM sent

Fenlander · 23 March 2016, 10:16

>>>Shove it in a dustbin half full of water, get the yer man to hold tight and you give it a good tug (there's ya comp test).

Hah ha that's what I thought looking at this last night. I never bother to comp test an outboard of 4hp and under... or a mower/strimmer/hedgecutter/genny/water pump etc.

Decent cold start... no excess smoke... hot restart OK... that's about if for me.

The Gurnard · 23 March 2016, 11:46

Please Sir..i think I know the answer ... or at least my workshop manual does

.

Below is passage from my Mariner 3.3hp 2 stroke manual.

Best wee engine I have owned..its a 2005 model so should have many more properly compressed strokes

willk · 23 March 2016, 13:37

OK guys - thanks for all of those replies!

I have a unit to look at tomorrow, so I'll approach it with a multi discipline approach. It's a bit on the geriatric side, so I'd be a little concerned about cylinder damage - multiple owners/users and all that

If she checks out by the Mollers/Fenlander list, I can always do the deal but pop the tester on before handing over the readies if I'm still concerned. She'll be warm at that stage anyway. I have a bin and fresh two stroke mix ready - so he'll have no excuses

Kawasaki, you have PM.

Spartacus - hold the dogs for now (thanks tho). I've had a couple of leads on UK based units but have to factor in the hassle/cost of shipping to Ireland. The usual suspects will not ship O/Bs by air, so have to use a palletised outfit like Codshift. Runs to over £100 which sours a deal on an older motor. I can buy one brand new from offshore but I really can't justify the cost for limited use I have for it.

willk · 24 March 2016, 22:37

So I went for a drive today. A 240 mile drive. During it I met a bloke who was selling the 3.5hp Tohatsu that prompted this thread. The wee engine was very clean (for it's currently undetermined age - but obviously 2005 or older). I suspect that it was used in fresh water - it lived in lake country. There is zero corrosion on it. It started, passed water and engaged gear. I decided to take Moller's advice and leave the snap-on tools in the back of the Isuzu

I'll get a better look at it tomorrow, but I suspect that a home service and bit of loving will reveal it to be a keeper.

Oh yeah, and he charged me a euro a mile for it.
That's £190 in Queen's Money...

Mollers · 24 March 2016, 23:06

Quote:

Originally Posted by willk

I'll get a better look at it tomorrow, but I suspect that a home service and bit of loving will reveal it to be a keeper.

Oh yeah, and he charged me a euro a mile for it.
That's £190 in Queen's Money...

She looks a little dear. A touch older than '05 I suspect, but it matters not.

I have an '04 5hp XL. Picked her up at a sale a few years ago, 5yrs old at the time, but unused still in the poly crate. £200 under the hammer. The QS2.3 will plane will my hefty carcass onboard at 12knts+.

willk · 24 March 2016, 23:18

Quote:

Originally Posted by Mollers

She looks a little dear. A touch older than '05 I suspect, but it matters not.

I have an '04 5hp XL. Picked her up at a sale a few years ago, 5yrs old at the time, but unused still in the poly crate. £200 under the hammer. The QS2.3 will plane will my hefty carcass onboard at 12knts+.

Oh, I have NO IDEA what age it is! Like you say, doesn't matter until I need spares! The 5hp is a cracking motor. Interestingly, there seem to be quite a few 2 strokes still in their packaging. donegaldan bought a 9.8 L/S in the original box - still in the plastic seal.

I'll try to get this wee puppy wet ASAP on the 2.7m

C-NUMB · 25 March 2016, 00:21

Looks mint that one! The age should be about mid/late 1990's to 2005, later they changed to
aquamarine blue. I have a identical looking 3.5, that's a 2000 model. Brilliant engines.

willk · 26 March 2016, 15:53

I got a better look at it today. Under the covers is very clean - absolutely no corrosion or dirt - just a bit of the black mould growth that I associate with petrol fumes. There were two of the countersunk cover screws missing, but amazingly, I found a couple in my spares box. I pulled the sparkplug (a tad oily), cleaned and gapped it and ran her up in the test barrel. She runs just fine - an easy starter, hot and cold - once you remember to switch the fuel on

. It's 13 years old.

I'll order a service kit and will get that done before I use it in anger. I must say, I'm very pleased. Little things that turn out well always cheer me up.

I bet the leg bolts are seized!

The Gurnard · 26 March 2016, 16:04

Nice OB Willk..looks exact same with the hood open as my wee 3.3hp. I know nothing about outboards.. I just use them...but I have noticed mine can go through the prop sheer pins quite quickly ?

I have not hit anything except perhaps a bit of floating seaweed and opps..there it goes again.

Perhaps consider carrying a couple for spare if you are using it a lot. Apologies it that sounds obvious.. anyone else have that issue ?..or suspect the sheer pins I have are the wrong ones ..they were sold as my brand for the 3.3hp ?

willk · 26 March 2016, 16:20

Quote:

Originally Posted by The Gurnard

Perhaps consider carrying a couple for spare if you are using it a lot. Apologies it that sounds obvious.. anyone else have that issue ?..or suspect the sheer pins I have are the wrong ones ..they were sold as my brand for the 3.3hp ?

Cheers - absolutely. The old Yammie has a small rubber clip for spare pins - so I'd assumed they were a must have. I'll be ordered a few to add to a wee spares/tool kit specifically for her.

I'm not surprised you need them BTW, you're a fierce speed merchant.

ShinyShoe · 26 March 2016, 16:23

Aye and he does more miles in the average trip than most small outboards do in a year.

C-NUMB · 26 March 2016, 18:13

Quote:

Originally Posted by The Gurnard

Nice OB Willk..looks exact same with the hood open as my wee 3.3hp. I know nothing about outboards.. I just use them...but I have noticed mine can go through the prop sheer pins quite quickly ?

I have not hit anything except perhaps a bit of floating seaweed and opps..there it goes again.

Perhaps consider carrying a couple for spare if you are using it a lot. Apologies it that sounds obvious.. anyone else have that issue ?..or suspect the sheer pins I have are the wrong ones ..they were sold as my brand for the 3.3hp ?

I had the same issue, the prop sheerpins went without hitting anything. The original ones, slightly brass like colors did not last. Then got another type, looks like SS, then the problem went a way. But still good to have spare ones onboard.

Mollers · 26 March 2016, 19:10

Select a HSS drill bit of the correct diameter. Chop to length from the blank end.

The Gurnard · 26 March 2016, 22:14

Hey I got that one right Mollers ..well almost. I sheared three the year before last..in quick succession..so thought..its not on.. I put a brass rod the same diameter thought the hole...and no problems since.

I wondered and though I would ask as I dont want the gearbox damaged..but hoped the plastic prop would give before the gears ..if I hit anything. I have never hit any solid object in my life..but it could happen. I might retry a couple of new SS ones as mentioned by C Numb.. my old ones were brass'ed coloured