I got this bike with less than 12k miles. it has about 16k now, thats less than 1000 per year so it has sat, a lot.

now, knowing these engine are fairly bullet proof and knowing the carbs needed work when i got it, i have been running it with various cleaners in the fuel to try and correct the carb issues. it has worked on and off for a few seasons.

I finally broke down and had the carbs cleaned and tuned. Huge difference now. Except there is some smoke at startup and a little bit when down-shifting. Blow-by, I guess.

This has been the case since I've had it although just prior to doing the carbs it had stopped. It was not running well at all and I suspect it was not running on all 4. The carb cleaning was great. Now the smoke is back

I've taking the new plugs out and dropped some Marvel Mystery Oil into the plug holes, about 2 cc's each. I've rotated the crank very slowly every hour or so, baybe a 1/4 turn. It's been in the a few hours now. I plan to fire it up in a few more hours.

Anyone have any advice on this?

Thanks
David

 

How did your plugs look when you pulled em? Are you positive its a stuck ring? What color is the smoke? I know I ask alot of questions, but it makes it a lil easier to offer suggestions and think "outside" the box. For example, I had a leaking valve cover once that was causing a similar issue. It was leaking around the plug well and seeping into the the threads of the plug. Not on my current bike, but on a previous one. Also, have you checked your valve clearance?

 

Have not checked the valves, have not had the top apart, was hoping i wouldn't have to. My neighbor mechanic works on bikes and cars and believes it's not the valves. but it could be

The smoke is blue and although these plugs are brand new, they look clean. there was oil on them, however, when I removed them, on tow of them. two of the cylinders were blowing oil on the old plugs as two were nasty with goo. the other two were fine. The oil had been filled too high according to my neighbor. I swear i check it all the time and always read it as a bit low, i never get a good read on that stick.

after the carbs were cleaned and synched, there was still a loping sound to the firing pattern, it was not perfectly smooth, so we changed the plugs, thats when we noticed the two fouled ones and replaced them all. I then changed that oil and filter and began doing a shock treatment of Yamalube Ring Free, as recommended my the Honda dealer./ I am still running that tank

My neighbor said the carbs were full of crap and were cleaned of all deposits and gum.

It may ultimately need a ring job or valve adjustment but everyone I talk to says, "nah, these things are bulletproof, it's probably a stuck ring." I want to believe that I guess Now that the carbs are clean it runs like a beast but the smoke will get me back to crap land soon I think so i want to address it. It smokes at startup and down-shifts

one other weird thing, whenever new plugs are pout in, they are torqued down to spec. when i check them again after a week or so, they are very easy to loosen. hardly any torque needed. is this normal? I use the Honda anti seize thread grease. i thought perhaps some air was getting in through the plugs if they were not tight enough

 

I put the plugs back in, I cleaned them and noticed that again, on two, the tips are black, even in this short amount of time. no build up yet so i think they are not fouled. I have the bike on a stand and may leave it overnight to start in the morning and fill the neigb with smoke

btw, I hand tightened the plugs and wrenched them about 1/4-1/2 turn till it felt snug....

sound right?

Thanks

 

These things are pretty much bulletproof, even with lack of maintenance and total disregard I have seen plenty of life left in them and them rebound with proper care. The recommendation is usually a valve check at 16000 I think. If you can change the plugs, you can check your valves, not that hard and all you would have to do is remove the valve cover and use a feeler gauge, there is a write up somewhere, step by step. I'm not saying it is or isn't valves, but never hurts to check. Just takes time, otherwise, long as your valve cover gasket is good, its free. Then you would eliminate that possibility.

I would imagine, with two plugs doing the same thing, it would be something besides a stuck ring. Are they on companion cylinders? Like cyl 1 & 2 or 2&3 etc?
Aside from the loping, is there any noise? Like ticking, tapping? The oil on the plugs is what I would try to track down first as it seems the oil fouling your plug is the issue.
Is it when you let off to shift, or after you have shifted and are applying load again that you get the smoke?

And yeah, thats how I've always tightened my plugs...

 

I did see that write up about valves. seemed daunting but I think like everything else, once I'm in it, it will work out

the smoke happens on startup, just a puff, and when under load, as in downshifting to slow. my buddy said he saw it while accelerating but noticed in more when gearing down in turns. I think the bike sat in a garage for over a decade and the kid before me rode it, but with the smoke. I should have dealt with the carbs when Ifirst got it.

if this mystery oil thing does not work I guess I'll look at the valves

I forgot to note which cylinder they were i want to say 3 and 4, or 2 and 4.....why?

Thanks

 

I asked about cylinders cause it helps narrow down symptoms. If they are side by side then it could be an issue with something that affects both cylinders, like a blown head gasket will. Not that that is what it is, just giving an example.

You will most definitely make it through checking valve clearance. No worries there. Seems complicated but once you physically start, it falls into place. Hopefully you wont have to check, although when its out of season, it would be worth checking just for your own info.

You have a good start on fixing it. And as with anything the more you can replicate (remember where when and how) the issue the easier it will be to fix without throwing parts at it.

If the oil doesnt fix it, another easy thing would be a compression/leakdown test. If you have access to a compression tester. For now though, unfortunately your stuck in the waiting game.
I'm sure other members will stop by with more tips too

 

I'm no expert by any means but, I've heard leaky/dried out valve seals cause smoke at start up and down shifting. Like when you let the engine slow the bike down from high rpm's. I would think since it smokes on start up, the oil leaked in from up above while the bike was sitting/not running.

 

thanks for that opinion, is that a top job to fix that or is it more extensive?

 

well, I started it up this morning and there was a bit more smoke but it died off rather quickly. I expected much more from the mystery oil, maybe I didn't put enough in there.

I took the plastics off and checked the plugs again. they all had oil on them, on the threads. I also noticed a leak from somewhere onto the pipes right below the front where they go parallel to the ground. It could have been me spilling MMO but i don't think so. where the pipes come out of the front of the engine I see oil buildup at the connection at #3. There was also some oil on the inside of the main plastic cowls at the bottom where the two pieces join.

I think I may have a big problem. I am thinking the valves need adjustment but perhaps the seals and gaskets? I'm thinking of having my neighbor do the work as I don't really have the time, patience or tools for this. I paid him 200 for the carbs and tune up. I wonder what he'll charge for the valves. If I talk to him he may convince me do do the work, which I should. I just don't want to start it and have it sit all winter... His price was 1/2 of the local shop and this is his work, so..

Anyone have any insight to this situation? I appreciate it

David