06 Yamaha 50 two stroke timing way off!

[Ancells adventures]

New to the page and very hopeful! And I have a heck of a head scratcher. I bought a 2006 Yamaha 50 two stroke from a friend of mine supposedly ran just needed the carbs cleaned. Yeah. Anyway timing is way off after lync and sync at idle to 14 degrees after top dead center and factory spec is 7. Replaced the CDI and no luck same result. The flywheel key is perfect shape even used calipers to verify no wear. To achieve 7 degrees after top dead center the lever on the CDI box is directly in the center and will not allow linkage to attach and the measurements for the sync will not allow it either. I checked the flywheel for magnets slipped and there is no visible movement and the center shaft on the flywheel is tight no movement. This motor does have low hours and no one has been into it. His father bought brand new in 06. I have a strong mechanical background but this one is throwing me bad. The picture of the CDI is where I would need it to achieve 7 degrees by timing light. This motor doesn’t have a moveable base plate for adjustments and I can’t see why it’s so far out. What am I missing? Any help would be greatly appreciated!!!

 

[Still Afloat]

At least on older outboards it was possible to damage the key between the crankshaft and flywheel. Basically, the key would not shear entirely but, it would end up with a stepped shape and the timing would be off. This was typically the result of hitting a rock, a backfire or improperly torqued flywheel nut.

 

[RaisedByWolves]

First off welcome to the board!

Your statement about timing being 7* after top dead center didn’t quite sound right to me so I went looking and found this blurb:

“They make a device called a timing light. It is super easy to see if the timing is correct. 7* after top dead center, plus or minus one degree, is the correct fully retarded timing. Fully advanced 25* before top dead center. Plus 3 degrees or minus 1 degree.”


Retarded timing would only be desired at startup and shortly after it should go into positive numbers with a max at full throttle of 25* positive.

Hope this will clear things up.

 

[thill]

If it was running well before you got it, if at all possible, try to put it back exactly where it was before you decided to "fix" it. You should have just cleaned the carbs and tried running it before doing anything else.

I recommended that you NEVER touch the timing of a running outboard unless it's NEEDED and only do it while you are running it. There is a surprising amount of variation between motors. Some need the timing screw mostly in, some in the middle, and some most of the way out.

Car mechanics are often the worst. Often, they will dig into a good-running motor, thinking they are going to "get it really right." After they move stuff all around, it wont' run and they end up bringing it to me, thinking something is really wrong. Sometimes, they are so frustrated that they are DONE with this thing, and want to trade it in.

Almost always, they did something wrong in the timing. Sometimes, it's a sheared flywheel key or loose flywheel magnets. But 90% of the time, car guys mess the timing up.

And what really frustrates them is when I look, see that the set screw is way off, turn it to where it normally is, and then start the engine right up, no timing light or anything. THEN I pull out the light and fine-tune it and tell them to STOP MESSING WITH THE TIMING OF A 2 STROKE ENGINE! Unless someone messes with it, or you have to replace something that breaks, you NEVER need to adjust them.

Also, when the carbs need to be cleaned, guys new to an engine will often miss something. In a Yamaha, often there is a jet in the bowl screw that people miss all the time. The rest of the carb will be super clean, but the ports in that screw got missed, and it won't run.

All of this being said, I don't know you or your exact situation. Read the manual very carefully, and make sure WHERE in the throttle range, the timing should be at "X degrees BTDC or ATDC. Is it the factory service manual? Believe it or not, some of the cheaper manuals are sometimes wrong, using wrong year data when they copy-paste information. That is VERY frustrating! Ask me how I know.

Either way, I hope you find the issue and get it running well again.

 

[turbotodd]

yup 7 atdc is about right. Plus or minus 2 is fine, perfectly acceptable.

First things first though. Need to verify TDC on the pointer is actual TDC on the engine. You'll do this with either a dial indicator or a piston stop. (Google it). You can use a dial through the plug hole on #1 cylinder on that motor. Or screw a piston stop into the hole and do it that way, it's more accurate anyway.

--I've been throwed for the same loop and scratched my head for hours and hours (on the clock...) with a 25hp, to find out that the indicated tdc was incorrect. On the 25's the pointer is adjustable. I think it is on the 40/50 as well. I didn't see a lot of those, just a ton of 25ESH's.

If the indicated TDC is "way" off, you might want to have a look under the flywheel, at the key and also the pickup and charge coils. Make sure they're installed properly, nothing loose, broken, sheared, etc.

"usually" if the pointer's been fiddled with, it'll be off 2 or 3 degrees but not much more. "Usually"-meaning you never know when you buy someone else's problem child...

and lastly Yamaha seems to like retarded timing at idle. Yes that's correct. They will idle way down to about 450-500 rpm at 7 or 8 deg ATDC, so long as the motor's in good shape and the idle mixture is set right. If idle mixture is lean it'll sneeze. If it's rich, it'll just run rough, smoke, and load up/die. Once you get it right, they're sweet little motors. Just getting them right, is the challenge. Speaking from my own experience. Idle RPM should be around 700-750 as I remember. Just remember that during initial start, the cdi advanced the timing for a few seconds after starting, so if it sneezes and dies, and you restart it, let it settle down about 10 seconds before you go to messing with things.