yamaha 40 hp 2 stroke owners required

beamishken · 31 July 2009, 21:11

Hi I posted a question a couple of weeks ago but still not resolved the problem i have with my 2001 yamaha 40 veto 3 cylinder 2 stroke when on tick over the engine runs on 2 cylinders move the throttle forward and the lever on the side of the cdi moves up and it goes onto 3 and the revs pick up general opinion is that it should run on 3 all the time but tried another cdi unit and no different swapped coils no different
i'm not totaly convinced that it isnt supposed to do this and would like to here from another owner if theres is the same its number one cylinder that goes off at tickover (i have herd of other engines shutting down individual cylinders to achieve a low enough idle speed

there must be someone who has one of these who can pull no 1 plug lead off and convince me one way or another

come on guys HELLLLLLLLLLLLLLP

cheers

Jizm · 01 August 2009, 11:16

never heard of the yam triples shutting down to two on tickover before

pilot jet in the carb blocked?

spartacus · 01 August 2009, 15:13

I've not aware of it running on 2 cylinders at tickover. There is an auto-choke on the Yamaha 2-stroke Autolube. After starting it will automatically lower the revs after initial start-up.

Try posting the same question here - on the forum. Their technical guys may be able to help. Be as descriptive as possible, giving the age of the engine, model number, etc.

http://yamahaoutboardparts.com/

beamishken · 01 August 2009, 17:38

cheers for your input guys but its definately spark related as there is no spark on no 1 cylinder untill you lift the lever on the cdi unit then its like you switched the cylinder on

i'll try the link posted by spartacus

thanks

Jizm · 02 August 2009, 07:09

the lever on the cdi is adjustable, make sure it is set to the spec in the service manual.

beamishken · 03 August 2009, 08:45

cheers jizm but the adjustment would only alter the time/throttle position when the cylinder cuts in what i need to know 100% is should the engine drop on to two cyls at tick over or not if not what could be wrong with it?

everyone says "dont think it should or never heard of that before" but nothing 100"% what i realy need is for someone with the same engine to pull off no1 plug cap at tickover and say mine does/doesnt do the same

thanks
ken

Jizm · 03 August 2009, 08:50

ring yamaha direct, they are usually very helpful.

9D280 · 03 August 2009, 09:12

Unless it's fuel injected and so fuel can be cut as well as spark, shutting down one cylinder will do nothing apart form oiling up said cylinder.......

beamishken · 03 August 2009, 17:27

Hi thanks for the input guys
I did speek to yamaha who could only suggest taking it to a dealers and pluging in the diagnostic computer but I havent had chance yet & there isnt a dealer localy i'd trust

BHG were most helpfull and sent me a used cdi unit on sale or return but it made no differance

I take the point about fouling the plug but it doesnt the engine ticks over reasonably once warm and picks up straight away once you open the throttle I tried screwing in the idle screw on no 1 cylinder as it doesnt run on it so doesnt need fuel (or so i thought) but the engine then starts to missfire on no3 & eventualy drops that cylinder must be a ballance port across the crankcase

so still not convinced I know it sounds illogical to anyone familiar with the workings of an engine (me included) but i have herd of this before on a small suzuki 3 cyl 2/ which dropped a cyl on idle

still need an owner with the same engine for a comparison

anyone recommend a good honest dealer in either the north east england or north ayrshire
scotland

regards
ken

jyasaki · 04 August 2009, 16:28

It is possible to get the software and kit to run the diagnostics yourself. Not real cheap, though, as I remember. I think it runs on a laptop, but have no idea how it plugs into the computer... (needless to say, I haven't done this.)

jky

beamishken · 04 August 2009, 22:44

I wouldnt mind buying the test gear as i like to be independant but yamaha wont release it and i havent seen it for sale elseware if anyone can suggest a source for it i'd be very greatfull

cheers

ken

outboardtech · 05 August 2009, 21:15

ken first of all this engine of yours DOES not have the technology for the software to connect to the engine . Your motor is a straight forward carb , cdi ignition system and there is no ECU etc for all the different output sensors on it . You to me sounds like float level or a Intermidiate jet blocked in the top carb . How do you know it dosent spark on tick over . have you put a proper spark gap tester across the HT leads ? cheers baz

beamishken · 06 August 2009, 22:37

Hi outboard tech I thought that this was a simple cdi unit that wouldnt have the capacity to store codes etc but it was yamaha's own tech who sugested it should be conected to the diagnostic software

the guys at bhg said immediately that it would be the cdi but they sent me a used one sale or return which was exactly the same they then suggested trying yamaha themselves but even the guy there seemed a bit vague about it (given his suggestion about reading codes)

I have tested the spark and it definately doesnt have a spark until you move the leaver on the cdi unit then you immediately get the spark and the revs pick up dramaticaly even with the linkage disconected so the throttle butterflys dont move

i've been in the motor trade for 25 years so i know my way around an engine but apart from changeing parts untill the fault goes away i dont know what to do next (expensive too cdi unit is £700)

i'm still not 100% convinced that its not supposed to do this because its not particularly bad when its being used just a bit lumpy on tickover once up an going it goes like hell

would love to find an identical engine and check it i wouldnt be surprised if it was the same

thanks for everyones input but i need someone to take the hood off one and investigate

cheers ken

jwalker · 06 August 2009, 23:12

Hi, I don't know your engine but it is common to have two ignition charge coils under the flywheel - a low speed one and a high speed one. Their characteristics are different and one takes over from the other automatically as the engine is revved - the output of one falls as the other rises. The ignition charge coils pump up a capacitor, which is inside the CDI unit, to a voltage of approx 200-300v. This current is released through the primary winding of the ignition coils and again increased in the secondary winding to a value suitable for arcing across the sparkplug electrodes.

I guess, if your motor has this system, that one of the low speed charge coils could have failed.

Philozzie · 15 July 2010, 11:52

Hi Guys,

I seem to have the same problem with my 40 Veto, the motor spikes in power when in use and bottom spark plug is cold when not running right?

Did we solve beamishken's problem?

Cheers,

Phil

Jizm · 16 July 2010, 08:47

Quote:

Originally Posted by Philozzie

Hi Guys,

I seem to have the same problem with my 40 Veto, the motor spikes in power when in use and bottom spark plug is cold when not running right?

Did we solve beamishken's problem?

Cheers,

Phil

try to PM him, you may get a response

Sea Witch · 19 July 2010, 20:55

hi guys

posted message dis morn . mine at full throttle drops a cylinder not sure which one yet but after throttlin off and on /off it come back on 3 cylinders . have cleaned the carbs several times .

cdi box is suited for a 40 / 50 hp engine . have u got it aligned on the correct setting pick up on cdi box .