Overfilled with oil and ...

i dont have any idea really but when you kick the engine it moves the piston so my guess would be maybe a messed up piston rings or cylinder wall problem. ive never messed with pistons before and neve had to do any internal engine work so im probably wrong but figured its just something to check. :thumbsup:

You may have a valve sticking, that would explain why sometimes it'll turn over and run and sometimes it locks up. Did this just develop when you took the bike out of storage? Condensation can form on the valve stems causing surface rust to form which can hang up the valves in the guides. The springs are very light so they aren't able to pull a sticky valve closed.

If your engine is locked up now, try turning it slowly backwards with the flywheel or simply be putting it in gear and turning the rear wheel backwards. If it does free up, try turning it over slowly with the kickstart and decomp lever in, and see if you feel a sudden stop or if it gradually increases resistance until it binds. My valves used to ice up and stick open causing a similiar problem that you have.

Well, I just checked in on the bike again, and I put it in 2nd and rolled it backwards which freed it up again so I can now kick it over freely with the de-comp lever pulled in. I kicked it over around 75 times and it was as free as it ever has been. It felt 100% normal while NOT running. The bike was not in storage or ridden in cold wet weather. Garage kept and street ridden mostly for the past months... 5 rides or so.

So its just when it is running it binds and stalls, then it is very hard to kick over (even with de-comp lever) until I free it up by putting it in gear.... pop it back in neutral and it kicks to spec?

I havnt checked my timing yet as I have no means to do so, other than taking it into a shop. I also have not checked the valves for adjustment as I dont have a manual yet... Any other ideas on what this is?

Until then.. Thank you all! I

Welll, I checked the oil filter and found alot of fine shavings in the oil. Figured it was fairly serious so I pulled the motor and took it in to the local Yamaha dealer. Probably bottom end bearings... It may have just been a coincidence that it was overfilled with oil???

Anyhow, Im thiking of doing the HotCams YZ450 cam at the same time just for fun, is this in fact the cam to use?

Thanks

Bump^

What did your problem turn out to be? I'm seeing a similar problem with my bike, and would like a little more info...

My original post:

initially, the motor just stalled mid-corner, locking the rear up...after letting it sit for a while, I was able to kick it over again, and go for a few more minutes, but then it just locked up chugging down a straight, so I decided it was time to try and limp home...got it running again for a few more mins and headed back...but then, same thing...

Right before it died, it was kind of surging, basically like it wanted to stall, but kept going for another rev or two before it did...

Coolant level was normal, but it could be heat-related (dead water pump?)...

It definitely seemed harder to kick over, and felt like the piston wasn't moving as smoothly as normal, but that could've all been in my head...

Well, well, well boys. My bike has been seriously out of comission and she's almost back. It was the bottom end bearing... and that fried the crank which baked the rest of it. So the long and short is I replaced the crank with a 426 and got a 444 big bore kit from Lukes, hotcams intake and exaust, new clutch... a bunch of other crap that it totally didnt need. I guess the oil overfill was just a coincidence? The moral of the storey is...check your frickin oil filter when you "check the oil".

Well, well, well boys. My bike has been seriously out of comission and she's almost back. It was the bottom end bearing... and that fried the crank which baked the rest of it. So the long and short is I replaced the crank with a 426 and got a 444 big bore kit from Lukes, hotcams intake and exaust, new clutch... a bunch of other crap that it totally didnt need. I guess the oil overfill was just a coincidence? The moral of the storey is...check your frickin oil filter when you "check the oil".

I've got the same Lukes motor in my WR. Can you say power!!

Did you get the auto-compression cam too. I did, but I notice with the big bore it takes a big kick to get it started ...even with the auto cam. It's a good thing I did not go with the hi-compression piston!

How does yours start?

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