smoking, gas in oil

[angus67]

dang. 50 miles on this engine.
Its a 1980 with 1.50 over top end, stock size headgasket, don't know if that matters, but....
When I rebuilt it, one of the pistons that came out of it had the pin break free, scarring the hell outta the cylinder, the rod shoving the piston up. I found aluminum sand throughout the engine. I sprayed it all out, re oiled every surface/passage, got it all cleaned out. Bought the 1.5 over kit from mikesxs came with pistons, rings cylinder block. I had a machine shop check to make sure the pistons, rings and cylinders were all going to play nice. all good there.
But I wonder if the valve guides could be the smoking reason? They seamed smooth, and tight when I installed new valves, had the valve seats cleaned up. Ive retorqued the head a couple times to 30ft/lbs, changed the oil a few times, new cam chain,
valves set at in-.004"ex-..006".
I think its the head gasket, so I will wrestle this motor back out, take a look, and while im in there replaceing the head gasket, I think I will do the guides too. do I need to have the valve seats recut? Ive seen 5twins picture of how to prevent head gasket blowby with sealer around the four outter head bolts, and the cam chain slot. Didn't do that on the rebuild. Will do it this time.
Part of the fun, right?

 

[deadchef]

can you use a stock size head gasket with 6 over pistons?

 

[angus67]

yeah, I don't know. that's why I put that in there. in the post.
that's whats got me thinking headgasket. maybe the sealing ring isn't sealing. I seem to remember thinking it looked a little small, but to my eye-crometer, looked ok. guesse not? Maybe try another head torque? I did have it up to 50mph, frist time that fast. and was really pulling hard this time out. figured if its gonna break, want to do it only a mile from home base. guesse it broke.
By the way, I have bs34's with open pipes, john's needles, 4"unifoams and runs excellent, until now. just throwing this out there. probably not related, but since there is fuel in my oil......

 

[gggGary]

Gas in the oil has pretty much got to be a leaky petcock and at least a lazy float valve. Any rust in the tank, or coating that might be coming loose? My first thought is once the oil is thinned with gasoline it would easily go past piston rings valve seals etc.???
Dump the oil, refill, find out where the fuel leak is, fix it and go ride it, see what s up.

 

[angus67]

I have a new pingle style under a late clean 60's sporty. Last summer I had turned on the petcock, and gas started pissin out the carb on the left. gave it a rap with a screwdriver handle, and alls been good since. the smoke was white though. isn't fuel smoke dark ?
it would be nice if it was just the float. When I rebuilt these carbs, the floats floated. they are 1980's with the brass floats, not the later foam floats.
Now that I think about it, it was the same side that is smoking!! you may be on to something!!

 

[gggGary]

Brass floats tend to crack, remove, gas in them? Dip the floats in a cup of hot water, bubbles = junk. Were the o-rings on the float valves replaced? Could be rust or a chunk of fuel line stuck in a float valve too. Once the oil is thinned by gas it can be pulled in and burned. Do the fuel stuff now even if you end up going into the engine you will want to know your fuel system is A-one when you fire up your new engine work.

 

[shotgunjoe]

I had a similar thing happen on my first xs. Kept smoking after a rebuild... tore it apart, everything was fine. Oil had gathered in the exhaust, and after it burned off, all was well. May not be your issue, but I offer my experience for reference. It didn't smoke on cold start ups, only after warming up a little, or after warm starts.

Good luck Angus

 

[angus67]

I had a similar thing happen on my first xs. Kept smoking after a rebuild... tore it apart, everything was fine. Oil had gathered in the exhaust, and after it burned off, all was well. May not be your issue, but I offer my experience for reference. It didn't smoke on cold start ups, only after warming up a little, or after warm starts.

Good luck Angus

thanks joe for that.
gggary, I will pull the carbs in a few days. just checked to see if my pcock is leaking. no.
If I need a new float, were can I find them? I only find the plastic ones on mikes. Dealer maybe? I heard the mikes ones are junk and hang up all the time.

 

[shotgunjoe]

My gas in the oil experience was a stuck float needle valve, cleaning the carbs took care of that.

 

[gggGary]

Foam floats are a direct swap in. Several available on flea bay, a couple show the pivot with the insert which should have decent controlled action.

 

[angus67]

I just baught a set of plastic floats wich, according to the picture, are sleeved, 25$ each, and two new Viton tipped flaot valves. I wonder if the valves I have in my carbs are maybe swollen. they are from mikes, the new ones I just ordered are not.
Ggggary, I seem to remember you mentioning using a qtip on the valve seat? care to elaborate on that? the seats were new, but might as well do that too, eh?

 

[gggGary]

Were the valve seats replaced?
The oring that seals them to the carb body is a notorious leaker.

Yeah cheap SOB's put some chrome polish on a q-tip chuck it in a drill and polish the seat of the float valve body.

Note; you will need to use the foam float, H-on height spec when you set them.

 

[angus67]

seats were replaced, O-rings too. got stuff on order, now I play the waiting game

 

[shotgunjoe]

lol... seems waiting is all I do angus...

 

[angus67]

got my parts in. the floats are sleeved with brass. new float valves, will polish seats with chrome polish as suggested by gggary. I also have a new choke rod ball and spring to go back in. lost one side during rebuild. (tiny things). Choke detents with just one side, but ide like to have ball/springs on both side, so in the future when I lose a spring again, I can have the other side work as they are now.
Also have my tach drive with washer to put back in, and the cap screw pressure plate bolts mod will go in too.
As for the tach itself, its a mikesxs tach, ive heard they break quickly. If anyone can confirm, I will just do without, and just cap the tack drive. I have the matching speedo, and it seems to work well. not jumpy.
At least this will force me to open up the carbs/ clutch side to see how everything is doing. Bike runs fine as is, but worth a peek.
At least the oilgas mixture prob cleaned out the entire engine. cleaning filters too.
wish me luck. bike started out as a blown basket case, ive done ALL the work on it, so mechanically I got it covered.
When I wired the bike, I accedentily ran a bundle of wires thru the middle of the carbs(bs34's) between the sync and the fuel 't', so I have to address that too, before I can pull the carbs.

 

[XSLeo]

The Q Tip thing is from XSJohn. He recommended taking a Q Tip and pulling the cotton of one end, wrapping 4 0 steel wool around the end of the Q Tip so as to have a steel Q Tip. Use this by hand to polish the float valve seat. Even new parts can have a burr on it that can prevent proper seating.
On old seats this removes any build up as well as any burrs on the seat. Leaving a smooth clean seat for the needle to seal against.
Checking the needle for burrs and such is also a good idea.
Leo

 

[angus67]

thanks leo. saw your response after putting them back together. oops. at least I had a chance to clean all the passages. Everything was clear. The new plastic floats I got are tour max, black box, red oval. they looked sleeved like how everyone says they need to be, but the sleeve isn't exactly round.
I used a regular cotton qtip in a drill, polished the seats that way. the seats were new a couple years ago. probly polished for nothing. they are shiny in there ,though. anyways, whenI pulled uot my old valves, one of the rubber tips came off. The other one was loose too. thought the rubber tips were in there better than that? maybe that was the problem?
I floated the old brass floats in hot water for a few minutes, no air bubbles came out, and shaking them made no sound. Although, one of the floats looked twisted, kinda cock-eyed. Now, the loose tip, and the crooked float were not on the carb blowing smoke, they were in the rite carb, but since the two carbs are linked, could the rite carb have been flooding, into the left carb, and making that cylinder smoke? the left carb was a little oily from intake bell, all the way thru. By the way, I have the barbs on the intake boots linked with vacuum tubing.
On with the clutch mods. be back in a few.

 

[5twins]

Sounds like the float needles were the problem, not sealing properly or maybe not sealing consistently (sometimes sealing, sometimes not). There have been reports of bad ones from Mike's. The rubber tip goes bad, apparently can't handle the gasohol.

You will find floats twisted like that many times. You simply twist them back is all. Save those old floats. They may end up back in there if the plastic ones don't work out. My buddy couldn't get plastic ones to work in his '80 carbs (of course, they were from Mike's and he is "carb challenged"). He ended up springing for new originals from Yamaha. All is well now with his carbs. The new floats helped but probably having me do the work instead of him helped more, lol.

 

[angus67]

5twins, so those rubber tips are not supposed to pull rite off? I figured that. I did get them from mikes. The new floats are tour max. cant recall if they are the same carried by mikes. I will save those brass floats.
On a side note- My carb boots that I did get from mikes aren't coming apart yet. maybe I got good ones'eh?

 

[5twins]

I think they had a bad batch of carb boots and that problem has been remedied. I have older Mike's boots, probably 6 or 7 years old, and they've held up fine. No, the rubber tip isn't supposed to come off too easily. I never tried but you could probably pry a good one off with a little effort.