Blowing smoke.

[Jtporter9]

So basically my right exhaust pipe blows smoke. It is not a lot and it has done it since I got it last year. It is just the right exhaust. I have heard that this might be because my right cylinder is loosing compression. I'm not really sure. I'm just wondering what you guys think about it and what might have to be done to it in the future to fix this.

 

[vsop-dk]

A good idea would be to set the top bolts to torque specs.

Allso do a compression test, this will indicate if there might be a compression issue like wear in the cylinders.

You Allso could check your plugs and adjust the carbs..

Again many things, but start torque the head.

 

[chizler62]

When does it do it? A bad valve guide seal will smoke first when started because when sitting oil will run down the valve and sit behind the intake valve. Then at high RPM when intake vacuum is at its highest the vacuum will pull oil down past seal etc

Compression test it. WFO both cylinders. Put 1oz oil in a cylinder and fo test again? The improved results are a direct correlation of mechanical compliance of the rings, piston and cylinder wear. Etc

Lead down test will also be needed here IMHO

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[rusty rocket]

Mine smoked out of the right cylinder I thought it was bad valve seals but it ended up being a scored piston. My bike sat for 7 or 8 years (at least thats what the po said) It must of got moisture in the cylinder and rusted the ring to the cylinder wall when I got it running it must have scored the piston. Hope yours is just seals.

 

[retiredgentleman]

So basically my right exhaust pipe blows smoke. It is not a lot and it has done it since I got it last year. It is just the right exhaust. I have heard that this might be because my right cylinder is loosing compression. I'm not really sure. I'm just wondering what you guys think about it and what might have to be done to it in the future to fix this.

A top end re-build required. Take the top end apart, measure and compare parts to the Yamaha Service Manual specs. Measurements will tell you what can be reused and what needs to be replaced. Always replace valve stem seals and front camchain guide. If engine has a lot of miles/kms on it then replace camchain as well.

 

[Brew]

carry lots of spare plugs and save your money for a top end job.

 

[XSLeo]

How long ago did you get this bike running?
A lot of bikes that have sat for a few years often smoke when you first get them running. As they set the cylinders and ringhs as well asthe valves get a bit rusty. It can take a few hundred miles to get all this rust worn away and let things seal up.
If you recently got a 20 year plus setting bike running, ride it awhile, it may clear up.
Leo

 

[Jtporter9]

It was sitting for almost 20 years yes, but I got it running last june. And I haven't been riding like crazy but I rode it a good amount ive put probably 1000 miles on it, and still smokes. But could be that. I plan on actually buying the big bore kit and re-doing the top end in the future. So if its not the second, I'm sure re-doing the top end will fix it. also I have messed with my carbs and all, that wasn't it. But still need to check valves and all, but good to know thanks guys!

 

[XSLeo]

Another thi ng it might be is after 20 years of setting the valve seals could be going bad. As they age they get hard. If you keep them running all those years they tend to stay softer.
Anyway once they get hard they start to leak. It could be the seal on the intake valve on the smokey side is starting to leak.
Oil burning can also be a bad head gasket. Sometimes as they fail, it happens between the cam chain tunnel and cylinder. It seems funny you won't notice this with a compression test but it happens. The leak lets the vacuum as the pisyon drops on the intake stoke to draw a bit of oil into the combustion chamber but not leak enough to drop compression pressure. Mayb the bad spot acts like a one way valve like bad rubber brake lines can as they go bad.
Retoqueing the headbolts may help. Do all the smaller bolts and nuts to stock specs but the 8 large nuts on top tirque to 30 ft./lbs. This may or maunot help.
At this point seeing as you plan on the 750 kit, I might just ride it till then. When you have it apart for the kit lap the valves and replace the valve seals. Might want to check valve stem to guide clearance.
When you do the kit be sure you do the cam chain and front guide.
When I did my 75 kit, the crank and rod bearings showed extreme wear. To the very outside of specs. I rebuilt the crank with new crank bearings and replaced the rods and bears with Mike's HP rods and bearings.
It runs very well with the kit. I think the new rods and pistons chagnged the balance factor enough so the rapid increase in rpms at about 4000-4500 of the stock engines was greatly reduced.
The 10-12% hp increase is fun too.
Leo

 

[Jtporter9]

so update on the smoke blowing. I shortened my pipes the other day and I notice that now not only is there smoke blowing out of the exhaust, but now oil drips from the exhaust, and smoke also blows out of the header. It seems to me that my cylinder is leaking oil... thoughts??

 

[retiredgentleman]

so update on the smoke blowing. I shortened my pipes the other day and I notice that now not only is there smoke blowing out of the exhaust, but now oil drips from the exhaust, and smoke also blows out of the header. It seems to me that my cylinder is leaking oil... thoughts??

refer to my post #5.