yamaha 225dx smokes like a chimney

[BigDave]

i have had my 225 for about a year now and the smoke has gotten unbearable. I was just wondering what could be the problem rings, piston, valves, or seals just have no idea where to start. it smokes at idle, at RPM, and there is oil residue at the end of the tailpipe.
I have not been able to do a compression test due to the cold weather. if it happens to be the rings or valves would it be possible to fix them without removing the motor from the frame.

any help is much appreciated
- thank you, from the deep freeze of Wisconsin

[VtamRLN]

i have had my 225 for about a year now and the smoke has gotten unbearable. I was just wondering what could be the problem rings, piston, valves, or seals just have no idea where to start. it smokes at idle, at RPM, and there is oil residue at the end of the tailpipe.
I have not been able to do a compression test due to the cold weather. if it happens to be the rings or valves would it be possible to fix them without removing the motor from the frame.

any help is much appreciated
- thank you, from the deep freeze of Wisconsin

You can pull the head and jug in the frame. I would bet that your ring end gap is excessive. When you take the jug off the piston, take the rings off the piston and put them in the jug to verify end gap. Also check that the piston wall clearance is proper as well. If the piston is loose in the bore, the rings will rock and they cannot stay sealed.

[emmie357]

As VtamRLN said, the top end will come off with the motor still in the frame. Just be careful not to drop the timing chain down in bottom end or you'll have a lot of fun fishing it out. And be careful taking off the chain tensioner, they like to shoot across my garage. Otherwise they are a pretty easy top end job.

[DohcBikes]

When i quit smoking ten years ago, i quit cold turkey. Maybe you could try the patch? Maybe the Yamaha would have better success with a nicotene substitute?

Ohhhhhhhh..... wait a minute. Trikes cant smoke cigarettes, my mistake.:D

Its nice that the top end comes off on the dx without needing to pull the engine, because to pull the fully assembled engine requires that you remove the swingarm.

I'm giving you some imaginary points for not excluding the valve seals and guide clearance as possible sources of smoke, as this is often overlooked. I'm sure you are thrilled.:lol:

Once you have it apart, do yourself a favor and rebuild the whole top end.

[BigDave]

thanks for the infor. and help and how would one check the valve Clarence. it seems like the place to start. and other then the timing chain dropping into the crankcase and the time chain tensioner is there any other things I should be aware of.
its going to be a tropical 35 degrees this Friday so I might start looking into it.

thanks again from the freezer

[barnett468]

Hello;


Ok, providing that your oil level is correct and it does not have 5 qts in it like your car does, and the smoke is lite gray [not black], your cylinder likely needs a rebore, even though you rings might be worn out as vtamRLN suggested. As Dohc suggested, do the entire top end. Of course measure it first which will also tell you how big of a piston you will need. .

It is IMPOSSIBLE [yes I said it] for a bike to smoke like a “chimney” if only the valve seals are bad and the valves and guides are excessively worn. It simply cannot happen.


VALVE OD – See manual in the link below for spec.


VALVE TO GUIDE CLEARANCE – There is no way to accurately measure the id of a WORN valve guide. The valve od is checked and the valve gets inserted in the guide and it is check for correct play by “feel”. Yup, EXTREMELY unscientific, but EXTREMELY accurate when done by a seasoned pro.

If the valve od is within spec, grab it by the head and stick it in the guide from the combustion chamber side until the tip [other end] is flush with the top of the guide then wiggle it side to side. The head of the intake should move around .002” side to side and the head of the ex should move around .003”. If they move LESS this is good. If they move much more, they are bad.


CYLINDER REMOVAL – If it doesn’t easily wiggle off, whack it GENTLY with a rubber mallet alternating from side to side. If you break a fin, you will know that your definition of “gently” is different than mine. If your cyl is unimpressed and refuses to move, you can get a putty knife, sharpen one side only, round the corners slightly, put it between the cyl and the cases and whack it good with a hammar until it penetrates around 3/16”. Go to the other side and do it again. Alternate sides and always start in a new place. Stop occasionally and try to wiggle it off or use the hammar.


CYL CHECK - Clean the carbon ring of the top. If you feel a lip/step after cleaning you need a rebore. Measure cyl 1/2" down from top, middle and 1/2" up from bottom. Measure in two locations at each elevation 90 degrees from each other to determine out of round. If it is more than .0015" out in either taper or roundness I would bore it. If the taper and out of round total more than .002" I would bore it.


Free online manual. It may not download.

http://www.oscarmayer.net/atc/manuals/Yamaha/ytm200-225-fm200l.pdf





Maybe you could try the patch? Maybe the Yamaha would have better success with a nicotene substitute?Is this the best ya got? I hope your a better mechanic than you are a comedian, cause if you're not, I'd be lookin for a new line of work like perhaps some sort of government job.

http://www.freesmileys.org/smileys/smiley-laughing025.gif (http://www.freesmileys.org/smileys.php)