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Old 08 June 2013, 10:10   #1
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tohatsu 25 problem

Hi...bought a tohatsu sb and tohatsu 25 2 stroke today..put it straight into the water as soon as I got home...its got much less power than ny tohatsu 18 and doesn't like tickin over it seems to feel bogged down.

Iv changed the plugs
Taken the carb off and cleaned all the jets which looked ok....still running rubbish...

The fella iv bought it off has said he'll be cool about the situation so all good there...
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Old 08 June 2013, 11:30   #2
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Quote:
Originally Posted by woz72 View Post
Hi...bought a tohatsu sb and tohatsu 25 2 stroke today..put it straight into the water as soon as I got home...its got much less power than ny tohatsu 18 and doesn't like tickin over it seems to feel bogged down.

Iv changed the plugs
Taken the carb off and cleaned all the jets which looked ok....still running rubbish...

The fella iv bought it off has said he'll be cool about the situation so all good there...
If hes cool, take it back and get ur money back, could be a can of worms when u start lookin.... He might be fine with helpin out with a 100 quid bill but if it turns into a 500 quid bill bet he wont be so cool then!!!
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Old 08 June 2013, 15:47   #3
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Twatsoo 25s are generally bullet proof. Check fuel, check sparks, check carbs?
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Old 08 June 2013, 16:04   #4
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Hi...its running fresh fuel with decent oil..fitted a pair of new plugs..took the carb off and removed both jets and they are clean...the carb was spotless..that's about the limit of what I can do without some fresh advice...
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Old 08 June 2013, 18:30   #5
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My first plan would be to check the compression. If there is a loss in power it could relate to there being low compression caused by ruptured piston rings or ruptured head gasket.

When you say it doesn't like ticking over to you mean it runs at too high RPMs during tick over or it is just very lumpy and can't keep running in tick over. When my little 4hp was running badly (high RPMs) during tick over I replaced the carb gasket and it was fine. It also increased top end power.

Is the air filter clean? If it is all clogged up then it won't be able to breathe very well resulting in loss in power.

It might also be worth checking the RPMs it is running at then referring to the owners manual to see what they should be running at.

These are the checks I would do. Pretty simple and cheap. A carb gasket is going to cost you no more than a fiver and you can probably borrow a compression tester from someone you know if you don't have one already.

If you don't know how to do a compression test, all you do is take one of the spark plugs out and screw the end into into where the spark plug was. You then crank the pull starter until the pressure on dial stops rising, then repeat on the second cylinder. Simple

Also, you say you cleaned the jets, did you clean the bowl as well?

Henry
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Old 08 June 2013, 18:46   #6
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Hi henry...the engine feels heavy as its reving in gear.it doesn't have any zing to it.almost as if the chokes on...when its ticking over out of gear it gives a slight cough n stops.but this is reliably intermittent...after a run I checked the colour of the plugs and they were the right colour...ill take it to a tohatsu dealer and let them take a look...it almost sounds electrical???
Cheers woz
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Old 08 June 2013, 18:50   #7
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Originally Posted by woz72 View Post
Hi henry...the engine feels heavy as its reving in gear.it doesn't have any zing to it.almost as if the chokes on...when its ticking over out of gear it gives a slight cough n stops.but this is reliably intermittent...after a run I checked the colour of the plugs and they were the right colour...ill take it to a tohatsu dealer and let them take a look...it almost sounds electrical???
Cheers woz
I would be inclined to say it is a restriction of air flow. If it sounds like it is on choke then the fuel mix is too rich in the mixture of air and fuel.

Carb gasket gone me thinks, so there is no suction so the carb can't draw very much air. It is very easy just to wip off the carb and check the gasket, but before check the tubes that carry the air to make sure they haven't perished.

henry
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Old 08 June 2013, 19:39   #8
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Woz,

Have you tried the 25 with the fuel hose & tank of the 18, check. Other issues to check, when starting engine with choke (pull/push) check that butterfly doesn't stay at closed position. Choke knob could be fully in and butterfly jammed at close position inside carb.

Due to lack of lube, salt, etc in shaft, could be sticking and small spring will not have the sufficient force to open butterfly. Remove carb air silencer pull/push choque, check proper working condition. If ok, you could have a spun prop...perform a prop test.

Happy Boating
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Old 08 June 2013, 20:07   #9
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Hi...I haven't bothered with the tank supplied with the 25 because it was bone dry so I used the tank and fuel pipe off my 18 I already had 20 ltrs mixed up. I checked movement of the choke butterfly in situ and when I stripped the carb..all well greased and free moving..

What do you mean spun prop??
It doesnt sound happy (sweet) either in or out of gear almost running on 1 .1/2 cylinders..when ticking over it gives a little cough n cuts out..when reving in gear its flat...out of gear it free revs ok ish but doesn't zing . Sounds boggy
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Old 09 June 2013, 02:46   #10
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I think you've had a fair go at it so I'd suggest you take it back to the seller for a refund if you have this option before you go any deeper. Get him to take it to the Tohatsu agent and then buy it once done. If you do it the other way around you'll end up footing the bill, which may be harder to recover from the seller if he already has his sale.... Carrot & Stick

If you do too much more, he may try to renege on any agreement on the basis of "tampering" . As it stands you seem well covered so don't put yourself on a sticky wicket.

www.BoatsandOutboards4Sale.co.uk
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Old 09 June 2013, 02:58   #11
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Dodgy coil?

If the coil failed completely then one spark plug would be soaked in petrol, but it might be working but not 100%

Unfortunately it's not easy to test a coil
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Old 09 June 2013, 04:44   #12
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Hi guys. The fella iv bought it off has said three times now he is happy to refund me. Refund me get it sorted n have the deal when the engine is sorted...refund me put engine on a pallet send to him hell sort it and send back. .
I beleve the fella that has sold it to me had no idea the engine had issues and will be honourable about the deal...iv booked it in to my local tohatsu dealer and they said for n hrs labour the will diagnose and quote....so its goin to go over on Monday..I'll keep you all posted..
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Old 09 June 2013, 10:01   #13
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Carb (air mixture setting )
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Old 09 June 2013, 10:09   #14
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Played with mixture and tick over..runs best were it was so counted back the turns and left it alone..lol
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Old 09 June 2013, 12:29   #15
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Mixture screw works only at slow idle (ralenti setting) so useless playing around. Before sending engine to dealer, swap and test 18 ignition coil on 25 horse, secure well coil body to ground. Both are "swapable" the only difference are spark cables lenghts, longer on 25 than on 18.

Probably that's the culprit, if it's ok, could be a CD related issue, or a faulty head gasket, which I doubt being a horse with low hours use, right ? Spun prop is discarded, you mentioned that engine lacks punch and bogs down at neutral or in gear when accelerating.

Is 380 planes fast with an 18, imagine what a 25/30 will do, will fly you to Mars..

Happy Boating
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Old 09 June 2013, 13:06   #16
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With the 18 on and weight well back it will stand the boat vertical with the boat correctly trimmed its straight on the plane with no water washing over the transom...can't wait to get the 25/30 running as it should... I thought about moving the 18 on but its in such nice condition I think I'm goin to hang onto it....cheers woz
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Old 09 June 2013, 16:27   #17
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A 380 with a Tootsie 18 HP is a very nice combo if it will be used with max 4 persons in order to plane fast, If needing more punch swap the 18 for the 30. I have both too, but the 18 is my favourite, great punch with lighter weight to place and retrieve from transom compared to the 30.

Good to know that you don't have water splashes at back transom. By building the sib with 46 diam tubes and not standard 45 diam tubes, engine leg will sit at a much better height to deal with water flow. If boating alone move your weight forward and have extreme fun.

Happy Boating
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Old 11 June 2013, 13:46   #18
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What happened at the dealer yesterday?
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Old 11 June 2013, 14:01   #19
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I did a 120 mile round trip..got there the fella was stand offish and had a couldn't care less sort of attitude..iv explained the problem and asked for the details of the the report ie..compression readings. Pump pressure..meter readings of coil pack and control unit..iv spoken to the fella I bought it off as he is also a member on hear and we will post the outcome when we know all the facts....
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Old 12 June 2013, 02:35   #20
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Who's the dealer?
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