just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

[55evinrude]

Hello everyone! after making the choice to go with a new (2011) last years model over a used motor as it was only a bit more $$$. I have decided to make it a 30hp buy removing the restrictor plate. question is some people say it comes set with 25 degree timing some say it doesn't.

how do i check to see if it is already set?? do i just look into the carb to see if the butterfly is all the way open? also briefly when the dealer was running the motor i was looking at it and i seen there where little marks under the flywheel do those have to do with telling what the timing is set to?? you guys let me know how to tell and i will check my motor to see if it is 25 degree timing. thanks!!

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

Remove cowl, place shift lever forward, full throttle, check flywheel timing marks and see if stops at 20? or 25? measured at middle case mating surface. With 25? will see carb throttle lever collar at extreme of end cam, with 20? will stop near cam groove. The same ones seen down here are facory set to 20?. You are not supposed to convert because of legal issues, mostly bearing a 25 HP cowl sticker when that engine is really a modified 30. You know, others don't...

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

thanks Sea Rider!! I will have to check my motor in the next couple days to see what the timing is! and than i will report back on my findings! thanks again

Nathan

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

I have not been able to look at my motor yet as it's at my cottage. but anyways a couple more questions. one: the restrictor plate is it metal or just a bit gasket, if so can you just cut the gasket out to the full size of the carb opening??

question two: do you have to adjust the mixture screws or rejet when you switch it to 30hp. thanks

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

The original 25 HP carb gasket is a rigid metal plate, the 30 is standard, unless you have a laser or plasma cutter at cottage will be real hard to match the internal countour of the 30 which has a much bigger diam hole. Just order a new one is cheap.

Most of the time no need to adjust mixture screw as this adjustment only works while engine is at idle, both models uses same size jets & props, it's only a gasket swap and +5? timing if needed issue. Install a good quality hour/tach on that horse, you'll love it.

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

alright sweet thanks Sea Rider!!

Nathan

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

UPDATE: I had a look at my motor this weekend at my cottage. results are a bit strange, the timing looks like your picture (20 degree timing) but yet the butterfly is open all the way 180 degrees at WOT in forward gear (and im looking at the fuel butterfly not the choke . so what does this mean?? I was looking at it and i cant figure out how you would even retard the timing to 25. so you guys let me know i posted some very fussy pics sorry.

also one more question i noticed there is a water separator on the side. do you just unscrew it and dump the contents and screw it back on? im just wondering for future reference. thanks

Nathan

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

also forgot to say that I love the outboard so nice!! finally got to put it on my 2012 16' ultracraft this weekend. a little rough at idle but it is also running at 25:1 for break in but sounds sweet at high speeds!! couldn't be more happier heres some pics of it on my boat

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

Hola Nathan,

If got you correct, you have 20? with 180? opened butterfly, right ? If so, you should have carb pawl white roller resting at extreme of the throttle cam, right ? Or it's matching the cam groove at middle cam ? Assume have changed the original 25 HP gasket, right ? Have you tried engine run prior to gasket swap ? If not, you cannot compare performance between gasket swaps.

If possible place pics at wot to check carb roller/cam position. You need to break in that horse with 50:1fuiel/oil ratio for the firts 10 hours for moving parts to settle down, don't use it with 25:1 ratio specially at wot.

The round filter is the fuel filter, must remove nut on top of filter to remove complete assy, has 2 internal oring's, don't lose any of them and screw back tight when asembling to avoid fuel spills.

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

thanks for the reply Sea Rider!

yes you are correct i have 20 degree timing with the butterfly open 180. yes the carb has a white roller and you can see it in pic #5 barley and its fully resting at the extreme part of the cam. I have not changed any gaskets yet just looked everything over.

ok what stopper moves the timing? the screw on the exhaust that you can see in picture #5 and in #2?? now about break in the mercury manual says use 25:1 for first tank of fuel and 50:1 after that?????? so thats what im doing. and i know break in is 10 hours as stated in the manual. thanks again!

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

Yes sorry it's 25:1 for break in, a mental diarrhea surely, why haven't you change the gasket yet. Here are pics of both 25/30 carb roller/cam position at wot, you must engage engine at forward first to achieve correct settings. Which prop pitch does your motor have, there must be a stamped number on prop body ?

Looking at pic 5, you are already are at max cam distance for the 30 seting, no need to move stopper any further. Are you shure you have measured correct timing distance at middle of both mating surface ?

Seems Merc likes to play a bit with timings, props and gear ratio to difference from it's Tohatsu manufacturer as to complicate things. Will check that model tech specs to see if matches with the Tohatsu 30.

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

Yes sorry it's 25:1 for break in, a mental diarrhea surely

Happens to the best of us haha . and i haven't changed the gasket yet because i haven't had time and haven't ordered it from the dealer yet. but i will this week. and my engine looks like the 2nd photo. where the roller is at the bigger part of the cam while its in forward at wot.
i would have to check to see what pitch prop...why do you ask?

now im wondering why my 25 carb is set up like a 30 but has 20 degree timing??? thanks for all your help much appreciated!!!!

Nathan

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

in reply to your edit: maybe im measuring my timing wrong and i have 25 degree timing already! im not quite sure how to measure it.

EDIT: i found another thread where he has a sea pro 2009 model with 25 degree timing already also!! he has pics and where his timing is a wot is the exact same as where mine is. http://forums.iboats.com/showthread.php?t=458899

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

well i ordered the 30hp gasket today and will pick it up this week and install it on the weekend. I will do a gps before and after to see the difference!!!

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

Nathan,

Order a Tiny Tach as well, you'll love it, perfect for idle rpm and wot checks as well for preventive, corrective maintenances. Both 25/30 gear ratios matches same Tohatsu's models.

With respect to timmings & restrictions, have seen 25 Mercs and Mariners come factory adjusted :

25 HP restricted carb gasket, at 20?, with roller cam stopping at middle cam groove, will need 5? timing advance + gasket swap.
25 HP restricted carb gasket, at 25?, with roller cam stopping at cam end, no timing advance needed, just gasket swap.

And latest
25 HP restricted carb gasket at 20?, just gasket swap; roller/cam resting position are OK + probably magneto link rod sync to 25?

The only way to maintain timing restricted to 20? when cam/roller are stopping where they should, would be to have the magneto plate small link rod and ball joint set at a shorter distance compared to same Tohatsu 30 HP rod distance. To clarify the question, would it be posible to measure the upper magneto link rod distance between both ball joint ends in straight line ? Could use outter clips of a vernier tool for a precise mm reading. Next week should have new 30 HP engines to compare readings with yours.

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

thanks for the reply Sea Rider!

I will have to measure the distance between the ball joint ends on the magneto rod and get back to you. Im hoping to just have to install a 30hp gasket and call it a day lol. the tohatsu website says the M25 and M30 are both set to 25 degree timing so lets hope mercury didn't play with that. anyways thanks again i will report back soon.

And i will do for getting a little tach, I also figured out i need a different prop i think it's a 13 pitch right now i need a 14-1/2 so i will have to get one of those also

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

With Mercury you never know, won't like boaters swaping $ 8 carb gasket and upadating that easily to a 30 and in the process losing $$$, as 30 costs more. Before you order a new prop, have engine well updated, place a tach and go wot, check max rpm achieved and work from there.

To definitely know your actual timing stop do the following : with left hand finger raise white roller by side fully upward untill stops, without releasing it, with right hand, full throttle grip to the max it will rotate untill cam meets/stops with roller, without releasing both, check at which timing? mark magneto plate is stopping with respect to crankcase mating surface ?

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

well im not able to do the timing check as i have not been to my cottage yet. but when its at wot in forward the ball joint end on the magneto link rod is about 1/4 inch away from the mating surface. anyways does that mean it's only 20 degree timing?? if it does mean only 20 degree timing how do you make it 25 ...do you just loosen the jam nuts on that link rod and move the ball joint towards the mating surface? thanks for all the help!!!

Nathan

 

[Sea Rider]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

If possible take a vernier tool to cottage and measured with outter claws in milimeters, will compare to new 30 HP horses and check if differs, which probably does. If carb is sucking more air/fuel mixture in, definitely will need more timming to compensate or an overheat of some kind, burn a piston at wot could happen. Your motor seems to have come gasket & timing double restricted from factory. Yes, a matter to disengage rod joint from magneto plate, turn loose both nuts and shorten rod distance by rotating both extremes evenly untill 25? is achieved at magneto plate marks & mating surface.

Happy Boating

 

[55evinrude]

Re: just bought my new mercury sea pro (Tohatsu M25) and have a question about timing

ok thanks sea rider, I am heading to my cottage today and will re port back in a couple days!