Valve stem seals question

[p5200]

My trx300ex appears, to put out some bluish oil smoke for about 30 seconds when first started in the mornings. Would this most likely be due to worn valve stem seals? After the first start of the day, it doesn't smoke. Thanks

[Gwbarm]

Thats exactly what it is, oil is leaking down into the combustion chamber from bad seal, doesn't really cause any problems, I just don't like seeing the smoke. I have a John Deere that does that, it started doing it after the second year of service, and it doesn't have many Hrs on it it bugs me but I try to ignore it.

[p5200]

Yeah, I know what you mean lol! It bugs me too. I imagine, who ever put that tack weld on top of one of the valve stems didn't help the situation any.

[Mech]

Yup almost certainly the valve guide seals.. 

oil's cheap.. 

Edited March 10, 2023 by Mech

[Gwbarm]

The sad part , you could have replaced them very easily when you had the head off.

[p5200]

18 minutes ago, Gwbarm said:

The sad part , you could have replaced them very easily when you had the head off.

I think, all I took of was the top cover to change the timing chain or, do they make a spring compressor for ATVs where you don't have to pull the head to the back side of the valves also? Please, correct me if I'm wrong working on atvs is a new adventure for me.

[Gwbarm]

You are right. I was remembering wrong.

[p5200]

I've heard of using an air hose in the spark plug holes to hold the valves from dropping while replacing the seals on a car/truck but, I've never tried it myself.

[Mech]

Yeah it can be done(if the keepers aren't welded in), with air, or a long cord poked down the sparkplug hole and then the piston at TDC..

[p5200]

Well, I'd say one set of keepers is welded in on mine LOL! I guess if I ever decide to replace the seals and have to remove the head, I might as well do the whole top end. 

[Mech]

Yeah, with that weld I'd just put oil in as needed and wait till it needed work..

[Gwbarm]

 I forgot about the welded keeper, As long as it works, but im sure the seals were fried when he welded it.

[p5200]

Yeah, that's what I'm going to do. I've got to find out what's up with my rear brakes now. I must have a leak somewhere the rear master cylinder level is really low with no resistance at all to the pedal. I wired the pedal down when removing crank case cover and forgot to release it. I guess being under pressure, the fluid found a weak point to exit. Seems like one thing after the other lol!