2001 400EX ATV starting to smoke on cold start

[Zaedock]

I went on a trip last weekend up to northern NH and rode around 100 miles all weekend. I didn't push the bike too hard. It currently has dino 10W40 as I expected colder than normal temps and knew it would be just a cruising ride. I usually run Castrol Syntec 10W40 when it's cold out.

The bike started fine all weekend without issue. It sounded fine as well (you can generally "hear" when there are problems). When my wife and I got home, I unloaded the bikes from the trailer. I started mine up and it smoked (blue...it's oil) for around 20-30 seconds and then it was fine. I drove around to heat the oil and then changed it with 10W40 again. It still smokes some when it's cold. At this point I am thinking rings or valve guides, but some searches on forums seem to indicate that a synthetic 20W50 (either Valvoline or Mobile non-energy conserving) would stop the smoke.

Anyone here have any experience with a 4 stroke smoking and a heavier oil correcting it, at least for a while? Thanks.

 

[IslaVistaMan]

If it's the valve guides, a heavier oil will probably help. A 20W-50 would also assist in ring / cylinder wall sealing too, but may not be ideal for cold start lubrication.

Might want to run a dose of Cycle-RX through it before you switch to a synthetic. You won't have any problems with your clutch while running it (BTDT). I just finished 1,300 mile clean and 500 mile rinse phases on my bike using Chevron Supreme 20W-50, and it worked as advertised.

Go here: http://www.cycle-rx.com

For an interesting read on the benefits of Cycle-RX, go here and click the "continued" link down at the bottom of the page:

http://www.cycle-rx.com/carlos_test_overview.html

No interest, just a satisfied customer.

 

[Blake Sobiloff]

Sure, thicker oils will not slip past rings and valve guides as easily, so it will work. Blue smoke on startup is usually caused by oil flowing past the valve seals. It may be getting close to replacement time for those seals. However, you might try some Auto-Rx and see if there's just some grime in the engine that's causing your poor sealing.

 

[Gary Mintz]

Zaedock

The Cycle-RX sounds like a good idea just read up on it. They should have used an Amsoil filter during the test phase on the Suzuki instead of a Fram filter. As to the Castrol you should try ATV Oil from Amsoil

 

[Zaedock]

Thanks Gary. You know, my oil cooling tank had a broken plug, which I needed to heat the tank to remove (out of the bike), the heated oil probably sludged and I may not have cleaned it all out. I didn't even think about it!
I re-cleaned the tank recently and rinsed with SuperTech 10W40, which was pretty dirty for only being in for a 1/2 hour. I rinsed again(drove around the yard for 1/2 hr), which was clean and then filled with Syntec 20W50.

I have started the bike when it was 20*F (don't worry, the Syntec has a low pour)as well as when it was warmer (45-50*F) and there is absolutely no more smoke. The Syntec was recommended from several other ATV'ers on other forums(they also said that the 400EX is picky on oil).
Don't worry though! I am going to order some Cycle-Rx before the next season and really clean out the ring packs. The Amsoil ATV oil looks good too, although a little $$$.
Hey, pay to play, right?

Thanks again!

 

[Quadzone]

I've been a 400ex owner for 5 years now and race it yearly. I"ve rebuilt the motor several times including boring the cylinder, new cam, blah, blah, blah. Made it a race motor.

YOur problem is vavle seals and it is common in a 400ex. The fix is replacing them or not worrying about it. You shouldn't see a loss in oil do to this problem.

I run amsoil 20w-50 full synthetic in mine and wouldn't dare run dino oil in it.

 

[ddrumman2004]

For the record....my girlfriend's 04 Yamaha Bruin started burning oil on start-up but stopped after it warmed up...leaky valve guides/seals.

I just recently changed the oil to Amsoil 0w-40 that is made for atv's and snowmobiles and the oil burning at start-up has ceased.

Sure it's higher in price but it has saved me money on doing a head job on the motor, which can be expensive on a Yamaha atv.

Now if it continues to not smoke with the Amsoil remains to be seen. I'll keep you posted.

 

[Zaedock]

Quadzone
Junior Member
Member # 11648

posted January 20, 2006 05:14 PM
"I run amsoil 20w-50 full synthetic in mine and wouldn't dare run dino oil in it. "

I've always been a Castrol fan and so far, the Syntec 20W50 hasn't let me down. We had a wicked warm spell last week, so I went for a ride. Not one bit of smoke on startup, cold or hot.
I've never run dino in my bike before except for that one trip, and I never will again.

 

[wileyE]

Not sure if this fits the situation but many of the atv motors are motorcycle derived. The way the heads are cast oil doesn't usually pool around the valve seals. When repackaged into a quad or whatever often the engines are tilted in such a way that the oil will pool around the guide or seal, some leaks by and they smoke at startup. Much like a bmw does when left on a sidestand. IMO, not a problem.

 

[Vstrom]

If that is the same motor that's in my XR400, and I think it is...then this common. Mine has done it most of the time since new...doesn't use any oil to speak of so I just live with it....it's gone in a minute or so anyway.