Newly rebuilt Carbs... Lots of WHITE smoke!

[Gumbo76]

Did you hold the throttle wide open when you checked compression?

Actually, I did not. I will go back and recheck these numbers "PROPERLY" tonight. Unfortunately I forgot all about the WOT! I even looked up the correct procedure.

Your compression numbers are above the minimum but they are supposed to be within 10% of each other, so they are not good. Also, your high compression number (180) is above the high service limit (171). That doesn't happen by accident, and 130s are generally the highest normal numbers, so there's a good chance you have a high compression piston kit.

What is the effect of not having WOT while checking Compression? Would that skew my numbers UP or DOWN? I'd hate to find scarring. That would warrant a rebuild wouldn't it?

Your petcock may be good now, but it may have been fixed by the PO. It could be that cylinder is glazed. I like sea foam for trying to loosen rings. Try running it for a few short jaunts, see if any thing changes.

Good point! I'll do this.

The low compression may be due to tight valves. Did you check them?

This is on the list of things to do. I suppose I should start this little project tonight. I should have checked this while I had time the other day. I've got everything I need except the valve cover gasket, so I'll have to order one of those.

[Gumbo76]

Checked the Comression again...

...This time with WOT. These are the numbers.

#1- 150
#2- 125
#3- 150
#4- 150

#2 is still low, so I am going to check the valve clearances tonight. I'm hoping all the smoke is from a tight valve.

Also, I noticed that when I throttle up there is a lot of white smoke from both exhausts... (I think I'm pi55ing off my neighbors) I do not have the cross pipe in the exhaust, so I know it's coming from #3 and #4 as well. Running too rich perhaps? I've synced the carbs, but perhaps I need to get new needles and jets? Although I cleaned and polished them thoroughly. Thoughts?

[Adler]

did you try checking compression on #2 after pouring a bit of oil in the cylinder?

If the number goes up substantially then its losing compression past the rings.

[hampshirehog]

Choke plunger stuck / not sealing on #2? You might be lucky - I've seen that cause those symptoms.

[GS750]

Its definitely oil burning, probably fuel in the sump or stuck/broken rings from your updates.

If its stuck rings then I have previously and successfully soaked them with a mixture of kerosene and diesel. To do this I have simply left the old oil in the engine and squirted about 50ml -100ml into each cylinder through the spark plug hole, leave the plugs out and let it sit for an hour or so, then wind the bike over (MANUALLY, so no chance of a spark), repeat the diesel/ kero (50-100ml) and do that several times over a day or 2.

After you have done this, do an oil change, then try starting again.

You can expect some more white to grey smoke to chuff out the exhaust for a minute or 5 but that is normal after doing this.


Another thing, drop your exhaust/s and make sure that they do not have any water sitting in them. I have had that before, especially when the bike has been in the weather, the pipes hold water and will spit wet black stuff which is just the carbon from the exhaust mixing with the water.

[GS750]

and with compression test, you should just hold the throttle on full, do ALL cylinders dry, then squirt 25-30ml of clean engine oil into each cylinder (immediately before you re-do the compression test) and that will give you an indication of the condition of the rings.