25hp - 30hp tear down two stroke.

[@devooski4751]

I've got the 25 hp merc/tohatsu 2012 model. The only problem I got is revving and going up to speed issues. In which i'm trying to solve by getting a new carb, impeller, filter, 3/8 fuel lines, prop, and prop shaft. Hopefully my baby will run after that. I had it for 7 years and it just started slowing down last year. Thanks for breaking yours down, it helps a bunch. Lastly costed me 2000 and I was 18 when I got her. And the good part about that motor is access to parts.

[@nordicdust]

The crank is allways my concern when I buy used outboards. I am no mechanic, but have learned all by watching you and others on youtube and fixing alot of outboards. I love cleaning them up and replacing parts and see and hear the difference.

[@25hpboatracerman]

Good to hear you love tinkering with outboards, I’m the same, it’s awesome 😎 Glad some of my videos have helped you, definitely fixing heaps of outboards is the key to learning. Yeah, the crank 👎 it is my concern too when buying a non runner outboard or low compression outboard. Often you can feel or work out if the crank is bad before pulling it down, sometimes you only know when your looking at the crank in your hands. If I’m wary of a crank on a outboard I’m buying, I try to set a price that I’m happy to pay that reflects the pain of trying to get a crank or I just use it as a parts motor. Keep up the good work, it truly is fun diagnosing, replacing parts, tuning and getting an outboard to run sweet when it was a bad runner. Cheers 🍻

[@mmuller3233]

If you do decide to attempt to consider the crank, please video if possible. I would love to see a crank tear down and rebuild, if it appear feasible and worthwhile for you. I find your maintenance / repair videos informative. As soon as the lockdowns end, I'm celebrating by buying a tinnie.

[@douger1517]

Good stuff…looking forward to the rebuild. Tohstsu make good motors.

[@25hpboatracerman]

Cheers mate 👍 Hope I can find a crank. Tempted to try and rebuild one of the cranks with a new rod and crank pin, might be a bit beyond me though. Cheers

[@25hpboatracerman]

👍

[@stevescott8764]

Come on Glenn you can do it , fix the crank pin take it on

[@25hpboatracerman]

Hi Steve, Cheers mate. Very tempted to try, I have the press, and think I have the correct measuring gauges etc. Might try with the two cranks I have to make one good one then no loss of it’s a fail. 👍

[@Robert-d2i2m]

Seems to be a common problem those bigends on the tohatsu/nissan/mercury/mariner 25 and 30 HP powerheads. ,same here on a 30 hp

[@25hpboatracerman]

Hi Mate, Yeah it is, I really don’t think it’s a manufacturing issue though. It is more likely people forgetting to run oil in their fuel (seen that a few times with people) or overheating due to not keeping maintenance up on the water pump or thermostat. Also overheating due to bags of picking up weed. They are truly one of the strongest motors I know, they just want fuel with oil and cooling water and your set. Cheers 🍻 Aussie Boat Guy 😎

[@Robert-d2i2m]

@@25hpboatracerman thnx for the reply Mate. Yes I totally agree. I like these motors too, but picked up a bad one ,bought it on a boat . want to fix it so bad because everything else is in good shape ,I'm trying to find parts ,but this powerhead or parts is hard to find in the netherlands. But love your video's, i keep watching. Love the prop and tuning videos . 👌

[@yogibear6432]

Great vid - I’ve got a 25 same vintage.

[@25hpboatracerman]

Cheers mate, Yeah they are awesome motors, love the two strokes, tohatsu is great 👍

[@yogibear6432]

Hi mate, just wondering if you have ever removed the restrictive plate from the 25 to make it a 30hp. Lots of conflicting info online, the 30 seems also to have a restrictive plate the same size as the 25…but some people have removed it all together - interested if you have tried this with the Merc/ tohatsu motors. There also seems to be a racing porting kit for the 25 carbs with bigger jets and adjusted cam….Cheers.

[@ididapoo]

Hi mate what would the diffrence be between a 2 stroke 25hp mercury and a 30hp I've read that it just the carburettor do you know if this is true? Thanks if you reply 😊

[@timsussenbach5376]

Restriction plate behind carb. And timing is off 5 degrees

[@qldshane]

Hey mate, any chance you could do a video converting a Merc 25hp to 30hp. I believe it’s a removing a restrictor /plate on the carby and timing adjustment. Does that sound right? thanks

[@25hpboatracerman]

Hi mate, You are correct, it is just simply the gasket behind the carburetor (just cut it to a full round throat instead of the restricted rectangle) or but the 30hp one then advance the timing a little. Very very easy upgrade mate. Cheers 🍻 Aussie Boat Guy 😎

[@qldshane]

@@25hpboatracerman thanks for the tip, I’m going to give it a go 👍

[@Deej_T_Amo]

Hey man , what’s the model ? Are all 30hp Mercury’s the same parts ? Or do I need to have the exact same part. Only ask as my model number sticker wasn’t on my 2nd hand outboard

[@25hpboatracerman]

Hi Champion, I think from 2003 onwards are very similar, even before 2003 parts seem to often be the same. Cheers 🍻 Aussie Boat Guy 😎

[@Justlookingok]

Have a 2006 Mercury and yes identical to them, still double check but, there are EU models and Japan models. The 100 hour service is all the same parts when ordered from eBay or similar

[@qldshane]

Hey mate, what’s the normal operating temp of a 2 stroke outboard? I’ve just purchased a 2006 25hp Merc Seapro Japan. Feels a lot hotter to touch on idle but warm water exits the tell-tail. Impeller is good, haven’t boat tested it yet. Thanks heaps!

[@25hpboatracerman]

Hey mate, A lot of outboard motors run at about 60 degrees Celsius (which does feel a bit warm to touch) With your motor - is the exhaust plate cool and the head really hot? The head heat is controlled by a thermostat (often they get stuck shut). It’s in that little cover at the top of the head. Not a bad idea to replace it anyway. The exhaust cover should be reasonably cool, if it’s very hot then the cooling flow is probably restricted somehow or the flush muffs are not sealing properly. If you splash a few drops (not a big splash as if it is overheating that may crack the block) of water on the motor when it’s to temp the drops should not boil, if they do it’s definitely running too hot. I believe you can also get some different heat sensitive stickers or pens that you can place on the block to really see what’s going on. Please keep me posted mate. Cheers

[@qldshane]

I bought a electronic temp gauge & cross reference first. The outboard at the piston block was 45deg before starting. I was 38deg on my arm and my V8 ute I just parked was 100 deg on the block. After several minutes but less than 10mins the piston block reached 100deg on idle with the outboard in a large water bucket. Unsure of the water jacket temp. I will purchase a new stat and gasket this week. The compression is 120psi after 6 pulls on both. Will keep you posted...cheers!

[@25hpboatracerman]

@@qldshane Good job mate 👍 You are on to it 👌

[@qldshane]

The Aussie boat guy. Hey mate, I’ve replaced the thermostat and gasket on my 25hp Merc but it’s still reaching 100deg on the block and even higher on the head. My 25hp Yam runs up to 65deg. If it’s pumping water and has a new stat any ideas? Is there a poppet valve I should look at? What temp does your 30hp Merc idle at? Thanks!

[@25hpboatracerman]

@@qldshane That’s weird mate. So frustrating, good man for being patient and switching off before damage 👍 Definitely too hot if your temp gun is correct. Is it pumping plenty of water or is the flow weak? Is there water coming out the leg exhaust relief as well as the tell tale? Is the water coming out boiling hot? There is no poppet valve in the Japan built 25 - 30hp two stroke. Could be a lot of things unfortunately. If the water pressure is low - it could have water gullies partially blocked, or a bit of old impeller blade somewhere reducing flow. - the water pump case may be sucking air or not sealing the water tube properly. - old mud wasp nest up in the leg exhaust relief. - water gullies full of salt sludge. - even had one with a hole in the inner water jacket ( bad casting from factory) that was squirting water directly into bottom cylinder. Just a few thoughts but still interested in water flow and if cooling water is coming out of leg - exhaust relief hole. I have also had an aftermarket impeller that was not tall enough to seal in the pump case properly, only genuine from now on. Please keep me posted mate. I hope it is ok 👌 Cheers

[@davegeorge7094]

Why are outboards so expensive?

[@25hpboatracerman]

True, and getting more so 😭

[@bcbrando7678]

You modding this engine at all?

[@25hpboatracerman]

Hi mate, Not modding this one. I have found a crank for this motor now though, a mate dropped off two more broken blocks and one had a really good crank 👍. Cheers

[@bcbrando7678]

@@25hpboatracerman right on man! Hey I have a question regarding shaving the head on a 25/30 Tohatsu im going to be milling mine this winter and wonder if you remember how much you guys shaved off yours ? I read on an older form Ausseracer says there’s a lip on the cyclinder head you can shave down too but I can’t see it. Any info or advice? You’re my only hope!! Haha Cheers man

[@25hpboatracerman]

No one really wants to say as if it’s done badly it can damage the motor. I’m happy to say what I did but you will have to decide yourself how you want to do it. I used to bolt the head on without the head gasket and see if it spins over freely with out the head gasket installed. If so then you know you should be safe to remove the thickness of the head gasket from the head. I never measured the exact amount unfortunately but from memory one of my racer mates said he removed 20 thousands of an inch (which is only about 1/2 a mm). I feel like I took more than that. Of course you need to do this stuff at your own risk and this is not advice, it’s just what I did. We did get a fair bit more torque but no extra top end speed. Cheers and keep me posted. I’m sure there is a better way and someone should know the exact amount to take off, keep searching. 👍👍👍

[@bcbrando7678]

@@25hpboatracerman Awesome man ! Thank u so much for the info makes sense to me. I was planning on measuring the squish and go from there I have a mill at work I can use it’s just making a proper hold down that may be tricky. Thanks a lot for all the info as always love the channel!

[@25hpboatracerman]

Cheers mate 🍻

[@محمدراسيدعبدالحميد]

Mercury 30 hp running no speed