Smokey Exhaust

[minnesota750]

Hi Gents,
I need some help here. Im working on the 73 I rebuilt last winter, and Im having a hell of a time with excessively smokey exhaust. I completely rebuilt the engine - new rings and lapped the valves. Everything was within tolerance when it went back together. I also just checked the valve clearance and that is good as well.

I have the Elektronik Sachse ignition, which Ive checked with a timing light and is firing as expected.

I have modified pipes (limited baffling) on it and K&N pods. I have 2.0 float valves (were 2.5 but changed to 2.0), 130 mains, 42.5 pilots and the z-6 jet and 4N8 needle pair with the needle clipped one above the center. The butterflys are 120s, and the slides are what came with the carbs when I got them - ebay purchase. Float height is at 22-23mm. Stock for the bike is 4GJ and Z-4 needle and jet, 125 main, 45 pilot, 2.0 float vlave, 115 butterfly.

Im banging my head because the bike starts and runs, idles out fine but holy hell is the exhause smokey. I have zero clue what the hell Im doing wrong or what to check. I could use any help you guys can give me.

Thanks.
Russell

[minnesota750]

I dont think my rings have seated properly, and I havent put any miles on it so far, which isnt helping my case. Do I just take it out blowing smoke and run it? Im going to haze the whole county the way it smokes right now - any fixes to get them to seat faster? I've read under load is the only way its going to happen. Any suggestions?

[jayteenz]

The advice I have always been given with new rings is to "ride it like you stole it". You need to be full throttle a much as you can. You only have a limited time for the rings to bed in (about 50 miles I believe) so that could be your issue.
However, if it's smoking really badly I would suspect something more serious like piston / bore clearance etc.
Is the smoke a blue haze or white haze ? Blue would mean you are burning oil so piston / rings / bore would be the suspects. White would indicate possible top end (valve) issues. Does it have new valve guides and seals ?
Just a few thoughts.
JT

[minnesota750]

Thanks for the info! The smoke is whiteish and there is oil blowby on the exhaust pipes, apparently the seals on my header pipes are not sealed very well.

When I rebuilt the engine I made sure all of the piston and ring tolerances were good, and I know the rings were very tight when I first put the pistons into the cylinders.

The valve seals are new, but the valve guides are not, although they also checked out for tolerance specs.

I'm going to just take the bike out tonight and run it and see what happens after I get it out and put about 50 miles on it at varying speeds.

I will also pick up a compression tester/bleed down tool tonight on my way home and report back numbers I get.

I can only hope it's not the guides and it's the pistons that need to seat properly, as I have put zero miles on the bike so far, and have not had the engine running total for more than an our on and off since the rebuild.

TxRp.

[bigskyforever]

Hey Minnesota, I chased this white smoke issue for quite a while. Does the smoke clear after it has warmed up?

Check the pins through your carb floats they can hang up, I had that issue with some new floats. For sure the white smoke is a sign of too much fuel and in my experience a float did not pivot, this caused constant fuel overflow and I chased the float height for a while.

Maybe you can put a light sheet of paper behind the carb holder to see if the issue is fuel flowing from your carbs even when shut off which can isolate float or needle valve issues.

Your carb height is plenty low which makes me think you have adjusted them to try to stop the white smoke demons.(go back to stock settings)

[bigskyforever]

I had the same issue of oil coming out of the exhaust header, don't hit the panic button on the rebuild, check your timing chain tension, then valve clearence before you do a compression read, and remember you probably washed down the cylinders with the excessive fuel, so compression will probably be down until you run it for a while after isolating the problem. Change oil if it smells like fuel after you isolate the issue, this will help clean things up. Hope this can help.

[bigskyforever]

Me again, looking at the first posting of this link, your float height setting should be between 24.5mm to 25.5 mm with the gasket.

[minnesota750]

Thanks Bigsky, this has been a frustrating project. I dropped the oil and remembered I had put synthetic in it, I think it was preventing the rings from seating properly. I had also used a synthetic assembly lube that was still pretty thick in the engine - I guess I was being overly cautious. After i dropped the oil i ran some gas through the cylinders to deglaze things. I was able to get it out and run it a couple of blocks, and the smoking was going away. Then the starter chain dropped off of the sprocket. Fml. I have the updated chain and sprockets in it and removed the tensioner like the service bulletin said, but I think I need a solution/solve for the tensioner. Any ideas on a solution for the tensioner - I havent dropped the side case off to look at it, but suspect this will need an innovative solution. Im going to start another post in the hope someone has a fix for this.
TxRp.

[bigskyforever]

Hey Guys;

I thought I might share an issue regarding smoking. I had installed some new rings, resurfaced valves installed new seals as guides where good. Bike would always smoke upon start up and when throttled up.

I fought with this engine a long time, so I finally tore down the engine out last week and found what I had suspected.

The previous owner had removed and reinstalled new exhaust guides without installing new viton o'rings at the base of the guides, allowing oil to move from the top of the head to the cylinder.

You never know what you will find with this old stuff.


If all else fails go back to the drawing board.

Cheers.

[pewe]

Hey Bigsky,

seems I have the same problem. Oil in exhaust left cylinder. Did you find a way to get the guides out without destroing them?

Cheers
Peter

[bigskyforever]

Peter

Without the o'rings oil gets baked up on the inside of the head(bored opening for guide) and they are a real b**ch to remove. I destroyed mine taking them out. No real option, I had already tore the head off after the initial rebuild and changed the new seals with another set of vitons so I knew something was up. If you get the engine hot and pull the plugs you may be able to see smoke coming out of the plug hole. Quite easy to determine it is oil and not fuel.

Cheers

Claude