top end timing,yamaha 80

one eye · 18 May 2007, 20:10

Can anybody help with a timing issue please?

My manual says to move the arm to the full open position to check the timing.

It does not mention if it should be in gear? although i guess it should be!

It does not mention what rpm it should be doing,(if i just move the arm manually to the full stop position its not on full rpm as one arm stops on timing and the other will carry on past as the throttle is opend.

I intend to put the boat in the water with trailer attatched to test the timing on top end (strapped to the trailer of cause, and still attached to the car).

can anybody tell me the correct method and rpm please?

Thanks Jim

fast fred · 19 May 2007, 10:51

in gear, with test wheel, at 5000 rpms , 20deg BTDC, check TDC to zero first.

one eye · 19 May 2007, 22:55

Thanks fred

Is it possible to do without timing wheel, just using standard prop?

one eye · 19 May 2007, 22:58

Also my manual states 22 BTDC +/-1, are you saying it should be 20?

Regards Jim

fast fred · 20 May 2007, 02:01

my book is sayin 20 deg +/- 1, it's not the best idea, but , i have done it with a prop. run two ropes from the back of the trailer to the bow eye, strap the transom down, cranked right up to the post. back in till the cave plate is in,
still all strapped down , fire it up, trim up a bit so she's throughin a tail,make a pull, ckeck it at 5000rpms, i'd hit at 21, thinkin your rev limited. be careful, ya don't want it in your tow rig

watch your water pee toob .

or have a friend drive, on a flat day.

one eye · 20 May 2007, 12:45

Thanks fred ill try that.

Regards jim

kergoat · 20 May 2007, 16:55

you can check the timing without need to start your motor !
move manually the arm that control timing to the full open position to check the timing use crank motor to rotate motor but not starting it (remove spark and ground term cap) . check timing with timing belt

safer for motor it s not recomanded to test max rpm without charge (test tank water) on propeller

excuse my english i m french

kergoat · 20 May 2007, 17:07

normaly you must check / adjust idle timing motor in gear slow forward speed you book doesnt give some value ? .
and after adjust max timing 22 +/1

one eye · 21 May 2007, 22:43

My motor does not have a timing belt!

As far as i can see it is imposible to set static timing on this model!

Moving the timing/throtle arm on static does not move any visual timing.

PLease correct me if im wrong! but i dont think so.

Nos4r2 · 21 May 2007, 22:49

No insult intended here, but if you've got a manual and you can't do it then pay someone or you'll break it.

kergoat · 22 May 2007, 07:18

it s better to have a factory manual to check advance

i ve factory manual but it's for the 50G-60F-70 80A 90 Al yam 2 stroke

some info for merc here :

http://forums.iboats.com/showthread.php?t=168855

i ve made a tuto for merc 40 cv / 2 stroke in french

http://www.pneuboat.com/dossier_prat...cv_mercury.pdf

sorry in french you must translate :-)

http://img249.imageshack.us/img249/7241/10418331tb9.png

bye

kergoat · 22 May 2007, 11:19

and next

http://img515.imageshack.us/img515/3443/51728370pb4.png

one eye · 22 May 2007, 20:47

I am very mechanicly minded and have worked on my own engines all my life!

I have a V8 JAGUAR, if i can work on that im dam sure i can work on simple 2 stroke.

Amitedley this is my first outboard, and is a slightley different breed to motoring, but it does not take a rocket scientist just some good advice, witch is what i thought this forum was for!!.

Can you honestley tell me i can set the top end timing on my yam 80 without running the engine??.

I have had some good advice and help from this forum, i have also had some bad (BEWARE).

If you are mechanicly minded with a degree of common, have the right tools and the right advice there is no reason you cant do it yourself!.

If you cant do it then you have to pay somebody, it is the easy way but when you break down in the middle of the sea you will have no idea what is wrong.

Im sorry but i do take offence to the last reply!

Nos4r2 · 22 May 2007, 23:39

Quote:

Originally Posted by one eye

I am very mechanicly minded and have worked on my own engines all my life!

I have a V8 JAGUAR, if i can work on that im dam sure i can work on simple 2 stroke.

Amitedley this is my first outboard, and is a slightley different breed to motoring, but it does not take a rocket scientist just some good advice, witch is what i thought this forum was for!!.

Can you honestley tell me i can set the top end timing on my yam 80 without running the engine??.

I have had some good advice and help from this forum, i have also had some bad (BEWARE).

If you are mechanicly minded with a degree of common, have the right tools and the right advice there is no reason you cant do it yourself!.

If you cant do it then you have to pay somebody, it is the easy way but when you break down in the middle of the sea you will have no idea what is wrong.

Im sorry but i do take offence to the last reply!

Take all the offence you like-I said it wasn't meant that way. I'm just fed up with fixing other people's foulups when they said exactly what you just did.

1)Outboards are NOT just a 'simple 2-stroke'.They require a bit more than being mechanically minded with a bit of common sense-they require specific knowledge and certain special tools too. If you treat them as 'just a simple 2-stroke' you'll end up with the RNLI looking for you.Your life can depend on that engine and there's no hard shoulder if you break down.

2)When you break down in the middle of the sea there's very little you can do bar change a spark plug or a fuel bulb-so you have to have it right 1st time. You can't realistically do anything else on a boat that's rolling about.

3)I would suggest that on a job as critical as timing an engine that runs under heavy load for extended periods the best course of action would be to talk nicely to the guy you pay to do the job so you can do it next time-and get the specific tips you need for your specific engine.

By the way, you can make a test wheel by cutting down a spare prop til you can hit 5000 rpm in a tank. It'll make it a lot easier.

fast fred · 26 May 2007, 11:32

any who, 2 strokes are simple, but then again they are all vary simple,
you can cheat it, runnin in N, just advance the timin linkage, and short change it a1/2 a deg and you'll be fine.

the only one that can tell YOU what you can or can not do your self is you.
or your a puppet.