Logo
FULL SITE MENU

2005 Yamaha 225 4 Stroke Flywheel Binding Issue

M

manny l

New member
I have a knock issue when my 2005 225 Yamaha engine is running. I removed all spark plugs, turn the flywheel by hand and as l turn the flywheel it gets stuck at the same point of a full rotation. I apply heavy pressure at the stuck point and it bumps over what seems like an obstruction somewhere under the flywheel. Has anyone ever experienced a bad flywheel or stator which can cause such an issue?
I have checked compression, all good. Static water test thru water tube (lower unit removed) no water coming out of exhaust port.
I cannot find any posts which relate to a broken stator or loose magnets on a flywheel (not sure if this engine has magnets on flywheel).
Any help would be greatly appreciated.
 
If it happens at the same exact point every revolution when turning by hand, I wouldn't suspect the stator coil. That sounds like the timing is wrong, and the piston is hitting a valve during the compression stroke. I would get the service manual and check the valve clearances. You have to remove the head cover, but I wouldn't keep rotating that thing if you feel an obstruction like that. It could be that the damage is already done, but I wouldn't risk doing any other tests until you confirm the valves are ok. It's a pain (and you'll need to buy a new gasket), but worth doing if there is an internal problem and you want to save the engine before more damage is caused. If you find the valves are ok, then change the timing belt according to the service manual.
 
So if your theory is correct, whichever piston is at the top of its stroke, that piston should be the piston hitting the valve.
Thanks
 
Right. It's hard to say if it is a timing issue or not, but feeling resistance like that at the same point in every revolution is, to me, a smoking gun that something is broken/bent internally.
 
I just noticed a few thin medal bands that go around each of the stator coils broken off in small pieces. Tension belt was replaced 400 hours ago by Yamaha dealer, and all timing marks alien on flywheel and cams. I am going to try a camera scope in the cylinders and probably pull the flywheel as well. Engine was runing exceptional smooth even with the thump/knocking, thats what baffling. Thank you for your insight l will keep updating post
 
That's a good sign if the engine still runs smooth. The broken stator could be indirectly related to your problem (and should obviously be fixed), but I really doubt that a broken coil would make it that difficult to turn the flywheel like you described. A broken stator just means your battery won't charge as fast (or at all).

Another easy test to perform (and I should have recommended this before) is a leakdown test. It's more involved than the compression test, but if there's an issue with one of the valves, you'll hear air hissing out when you do the test.
 
Im going to pull the valve covers one at a time as you suggested as well. Looks to be fairly easy and peace of mind to check valves anyway. I also did the halfway down stroke piston check for any play which should show bad rod or crank, with no play whatsoever.
 
rejesterd said:
If it happens at the same exact point every revolution when turning by hand, I wouldn't suspect the stator coil. That sounds like the timing is wrong, and the piston is hitting a valve during the compression stroke. I would get the service manual and check the valve clearances. You have to remove the head cover, but I wouldn't keep rotating that thing if you feel an obstruction like that. It could be that the damage is already done, but I wouldn't risk doing any other tests until you confirm the valves are ok. It's a pain (and you'll need to buy a new gasket), but worth doing if there is an internal problem and you want to save the engine before more damage is caused. If you find the valves are ok, then change the timing belt according to the service manual.
Click to expand...

The 2005 F225TXR is a non-interference model. The valves and the pistons cannot strike each other no matter what the timing happens to be.
 
Zero clearance at both intake valves cylinder #2, at any low point of camshaft.
Point where camshaft starts to open valve is where my binding is occuring.
 
I cant make heads or tails. All the valves move in and back when l apply light pressure to them so it seems that all are in good working conditions. If it was a timing issue the motor would not run as smooth as it did before my teardown. It has to be something under the flywheel or worse case senario a bad crank or piston. It continues to get stuck at the #2 tdc at each turn of the flywheel.
 
Has anyone experienced movement, up and down, just under an 1/8 of an inch movement, when you pull up on the flywheel? Flywheel has not be removed and feels as if the crank is moving up and down as well.
 
manny l said:
Has anyone experienced movement, up and down, just under an 1/8 of an inch movement, when you pull up on the flywheel? Flywheel has not be removed and feels as if the crank is moving up and down as well.
Click to expand...
The flywheel is bolted to the crank shaft. If the flywheel moves up, then so too will the crank shaft move up.

Sounds to me like your thrust bearing is the problem. There should only be a few thousandths of an inch of vertical movement when the crank shaft is lifted upward. No damn bueno.
 
I've never tried yanking on the flywheel vertically, but I would guess no. Maybe that's why the stator coils got damaged. Tough one.

btw, have you turned the wheel by hand with the lower unit removed? Forgot to ask that before just to rule that out.
 
Sure, I just think it would become catastrophic very quickly, so I didn't consider that before. Maybe you got lucky (in a sense).
 
Can anyone advise if both sets of cams should be aligned at the same position when the engine is at TDC. My cams do not line up at same position
Service manual only has reference to one set.
 
Last edited:
As you pass through TDC, intake and exhaust valves should not be transitioning and moving.. so if you see one closing and one starting to open as you pass through TDC, that's wrong. So I would check each set independently. As for aligning both sets, there are marks on the timing chains and the camshaft sprockets for each set. So you line those up, then you just align the hash marks on the driven sprockets after you put them back in the head.
 
So both sets are not aligned at marks at TDC. My port side cam shafts are way off. They align at 3TDC and of course starboard side is then not aligned.
Port side valves open at TDC are #2 exhaust and #6 intake.
 
manny l said:
Can anyone advise if both sets of cams should be aligned at the same position when the engine is at TDC. My cams do not line up at same position
Service manual only has reference to one set.
Click to expand...

Which TDC? On the compression stroke or on the exhaust stroke? Remember that the cam shafts only turn at one half the rate that the crank shaft turns.
 
At TDC on the compression/power stroke all valves should be closed. By use of the word "active" are you saying that they are open?
 
Yeah, #2 exhaust and #6 intake. All four timing points are perfectly lined up...flywheel, cam gears, and crank plate under flywheel.
 
What are you trying to do or accomplish now?

If you think something under the flywheel is the problem remove the flywheel and rotate the motor.

If you think the valves are the issue remove the cam shaft drive belt and rotate the motor.

If the problem persists remove the cam shafts and rotate the motor.

If the problem persists remove the heads and rotate the motor.

If the crank shaft has a noticeable vertical movement then that is a problem that also needs to be fixed. It could be THE problem. Not unheard of.
 
this is my first ever post, my 08 yamaha 250 started making what sounded like a rubbing noise under the flywheel- my mechanic told me sometimes the thin stainless steel liner betwheen the stator and the flywheel (glued to the inside of the flywheel) can come loose . we pulled the flywheel and sure enough he was right!! easy fix -replace flywheel. hoping I got it in time and did not harm stator! only problem is the cost of a new flywheel 1000$ I am curious if anyone else has experienced this issue
 
Back
Top