Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

[TQA]

I have an 15 month old Tohatsu 18 hp 2 st short shaft. It is used on a small rib. Recently it has developed a harsh note at 3/4 throttle when getting onto the plane. Once on the plane I go back to 1/2 throttle and it smoothes out. It has also developed an appetite for the lower cylinder spark plug, needing a new one every month or so. Nothing about the throttle linkage seems loose or worn. I would return it to a dealer but as I am in Bequia and the nearest dealer in Grenada I am reluctant to sail down there for what may be a simple adjustment.

I suspect the timing is overadvanced and the engine is detonating. How do I adjust the timing, is it by changing the carb linkage to get full opening on the butterfly earlier?

It used to run smoothly. I would like to track down what has changed before making any adjustments.

 

[TOHATSU GURU]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

You will need a service manual, a rule and a pair of pliers.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Welcome to the forums,

Is it a dark grey or dark blue Tohatsu 2 strokes 18 HP engine ? Although both share same magneto timing settings, both have different measurements if going for the "quick" way of measuriing timing.

Happy Boating

 

[TQA]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Welcome to the forums,

Is it a dark grey or dark blue Tohatsu 2 strokes 18 HP engine ? Although both share same magneto timing settings, both have different measurements if going for the "quick" way of measuriing timing.

Happy Boating

It is black with red graphics.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

It is black with red graphics.

Actually, if you take a picture, the color shown will show a dark blue, but generally eye reffered as black. Will post some pics latter to help determine if overadvanced.

Happy Boating

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Ok, you can follow..

1-Advance throttle arm to a position where you can place a vernier tool or short metal ruler as in pic 1 so to read 28.0/28.3 mm between ball joint nut and rod snap body. If those readings match it's ok, if not will need to pull ball joint out, release nut and turn ball joint CW or CCW untill those numbers matches. Lube with grease ball joint and place it back, readjust ball nut tight as before.

2-Full throttle tiller to wot untill stops, place yourself in front of engine, both mating surfaces forms a middle line, that line must match mark position 25? as seen on pic 2. Will need to adjust magneto's plate stoppers to match a perfect 25? stop mark. Let me know if it's ok or needs an adjustment.

PD. The white rod snap shown in pic 1 corresponds to the dark grey 18HP which are short, the Dark Blue comes with black rod snap which is bit longer. The numbers posted corresponds to the 18 HP Dark Blue model.

Happy Boating

 

[TQA]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Ok, you can follow..

1-Advance throttle arm to a position where you can place a vernier tool or short metal ruler as in pic 1 so to read 28.0/28.3 mm between ball joint nut and rod snap body. If those readings match it's ok, if not will need to pull ball joint out, release nut and turn ball joint CW or CCW untill those numbers matches. Lube with grease ball joint and place it back, readjust ball nut tight as before.

2-Full throttle tiller to wot untill stops, place yourself in front of engine, both mating surfaces forms a middle line, that line must match mark position 25? as seen on pic 2. Will need to adjust magneto's plate stoppers to match a perfect 25? stop mark. Let me know if it's ok or needs an adjustment.

PD. The white rod snap shown in pic 1 corresponds to the dark grey 18HP which are short, the Dark Blue comes with black rod snap which is bit longer. The numbers posted corresponds to the 18 HP Dark Blue model.

Happy Boating

My linkage does not look quite like the one in your pictures. Here is what mine looks like at full throttle and idle.

I hope this helps with the identification of my problem.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Both engines are same, my first pics shows a non idle timing, second shows 25? mark timing, your posted pics shows :

1-Timing mark stops at 25?, (OK)

2-Idle stop (OK)

3-Set throttle to wot, (like pic 3) with fingers roll white roller on it's axis while resting against cam, does it roll smooth or hard ?

Happy Boating

 

[TQA]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

With the throttle wide open it is hard to roll it, with the throttle at idle it turns easily.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Your carb is out of correct syncronization with respect to magneto timing. At which degree of the magneto plate mark do you achieve roller begining to turn hard. 22?, 23? 24? ? To see how much off you are from factory sync.

Happy Boating

 

[TQA]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Your carb is out of correct syncronization with respect to magneto timing. At which degree of the magneto plate mark do you achieve roller begining to turn hard. 22?, 23? 25? ? To see how much off you are from factory sync.

Happy Boating

How can I adjust this? It does not look like the cam plate moves. The only adjustment that I can see is the grub screw on the short rod going down to the carb.

 

[pvanv]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

How can I adjust this? It does not look like the cam plate moves. The only adjustment that I can see is the grub screw on the short rod going down to the carb.

That is why you want the Factory service manual

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

That is why you want the Factory service manual

Sorry my friend, that info it's not stated on the service manual. The service manual for 2 strokes horses is very old, has not been updated and will not be updated, writen tech issues & photos as magneto plate, carb timing, are only theoretical references, they don't state physical adjustments procedures whatsoever...

Happy Boating

 

[TOHATSU GURU]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

The new manual came out five years ago, has procedures, specs and photos and even an idiot can use it as it was designed for consumers. The third world may get them in the next ten years.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

The third world may get them in the next ten years.

What's the purpose of Tohatsu forums, reading tech guys answers providing automatic non helpfull Buy a Service Manual replies. Place yourself in someone else's shoes. Is that what you would like to expect to read as an answer if you had a engine problem and knowing not a bit about outboards.

You love being picky & derogatory with posters specially me, if you think being so "helpfull" with others and having the " new manual" on your desk, why don't you help poster syncronizing his carb. The last service manual in use was sent by Tohatsu Tech Service 4 years ago, so it's the last one available. I see you have modified your 3 Golden Rules. Should change number 1 to : Buy a Tohatsu Service Manual from me first, then ask me if it's correct as I'm the Non Plus Ultra Guru...

Happy Boating

 

[TOHATSU GURU]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

I've said it before and I'll say it again. You are a pointless little troll who knows nothing about the subjects you post about. You either regurgatate what others have previously posted, give retarded advice or ask pointless dumb questions. Why Paul put's up with you is beyond me.

As to your attacks on me...It's pretty rare for me to offer to sell someone anything on iboats. I almost always direct them to "any Nissan or Tohatsu dealer." The reason I want people to have a service manual in front of them is so that they can avoid costly mistakes. A service manual can prevent people from taking the bad advice, incorrect and the incomplete instuctions provided to them by people who do not have any knowledge about what they post about. And that brings me to another point. I DO NOT TELL PEOPLE HOW TO FIX THEIR OUTBOARD ENGINES. I will point someone in a direction. I will give a tip or two. I will tell them to stop when they are on the wrong track. Sometimes I will even burst their emotional bubble by informing them that they do not have the ability to use a hammer...And it's always in their best interest when I do so. I get zero enjoyment from telling people when they are wrong. But every time someone like yourself post's incorrect information it ripples along and will cost some poor guy down the line money.

 

[pvanv]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

You kids play nice now, or Dad will not be pleased.

 

[TQA]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

Hey guys I do need some useful help on this. This is my essential transport for getting from my boat at anchor to shore and the trade winds are blowing hard just now so rowing my RIB is not an option

The chances of me getting a workshop manual in Bequia are between zero and minus one.

I need someone to tell me HOW TO ADJUST THE TIMING on this as I strongly suspect it is overadvanced and I am getting detonation when I am at or near full throttle but the engine is bogged down a little due to the dink not being up on the plane.

I am familiar with the sound of detonation as I used to race 2 strokes, ah the smell of Castrol R and the crackle of a Bultaco on a tuned pipe.

SO SOME USEFUL GUIDANCE PLEASE ON MY PROBLEM.

 

[TOHATSU GURU]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

The dealer in Grenada would be your best bet for technical help.

T: 473-439-1983

F: 473-439-2037

You can call them and ask them to fax you the relevant pages from the manual.

 

[Sea Rider]

Re: Tohatsu 18 hp 2 st seems to be overadvanced. How do I adjust the timing.

TQA,

Being so far away, will save you the trouble to contact dealer, including buying a service manual, one of a kind know it all guy has finally provided a pathetic low class tech answer that's totally inconsistent with the magesty of the forums

Follow.

Get a extra mate as you will need 3 hands..

-Throttle to wot and remain there, mate must hold carb pawl down (metal plate) for carb to remain at open position, with wrench or screwdriver loose roller nut briefly to free rod, lower trottle lever a bit, with finger raise other side of screw untill white roller rest with light pressure against upper hill of cam. Secure screw lightly adjusted at the moment.

-Throttle down to 3/4, full throttle again to wot, roll white roller between 2 fingers, a good adjustment will be for the roll to turn freely against cam. Roller must have no axial play whatsoever, play/adjust with lever/screw untill this position is met. Adjust screw tight to rod once finished. Lube white roller axis with 2 drops of thick oil.

Have been seeing lately some engines with this factory flaw, dealer should inspect and correct this issue before delivering engines to clients. Place an induction tach and check max rpm at wot with you alone. Engine should be achieving 5500 to 5800 rpm.

Happy Boating