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Discussion Starter · #1 ·
I just traded for a 75' Honda Z50A K6 a few days ago, and today I got it running but it has white smoke coming from the exhaust and the carburetor after its shut off for a second. I have a video showing what looks to me, to be white smoke, I've heard when a bike burns oil its a blueish white, I figure some people here could help me figure out the issue it's having. Also, I will note that the gasoline I put in the temporary tank smells acrid for some reason so I'm not sure if that matters or not.

Honda Z50A
 

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White smoke is rings, blue smoke is valves. It could be your rings are gummed up and will clear out after some riding. A compression test will help determine if they need changing. Other possibilities are contaminated gas (that stink is a sure sign it has gone bad,) water in your oil (this one will only produce the smoke after the oil heats up,) or another possibility I have dealt with a couple times, oil inside the muffler. If the oil is from bad rings, they will have to be changed, and the smoking will continue even after an engine rebuild, until you heat the muffler enough to burn it out (this would have to be done with a torch.)
 

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White smoke is rings, blue smoke is valves. It could be your rings are gummed up and will clear out after some riding. A compression test will help determine if they need changing. Other possibilities are contaminated gas (that stink is a sure sign it has gone bad,) water in your oil (this one will only produce the smoke after the oil heats up,) or another possibility I have dealt with a couple times, oil inside the muffler. If the oil is from bad rings, they will have to be changed, and the smoking will continue even after an engine rebuild, until you heat the muffler enough to burn it out (this would have to be done with a torch.)
Excellent! ^^^

This is one of those gold nuggets that I like to print, and nail to my garage wall.
 

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Discussion Starter · #8 ·
Okay so I haven't been able to do much to it until now, I just tested the compression took me about 10 kicks maybe a couple more until it wouldn't go any further on the Guage and it looks like it's at 115 PSI so I think that means my piston and rings and piston jug are fine if I'm not mistaken. I'll post a pic so you all can see.

Clock Measuring instrument Gauge Font Auto part
 

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Discussion Starter · #12 · (Edited)
Optimally, the PSI reading should be between 165 to 180. These engines will run with 115 PSI....barely.
Very interesting, it seemed like it has power the back tire is completely flat has a gash in it, and it was able to drive me in a circle at 250lbs.

I should also mention, I changed the points out set the gap to .003 and a new spark plug in, and it starts on the first kick but when it gets warm it starts smoking. Also upon checking the spark plug tip it's turning black on the curved end piece.

So I do need to change the rings then?
 

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IMO, it never hurts to freshen up an older engine, while apart it gives you the chance to use all new gaskets and o-rings, clean up the valves and head, and replace the exhaust valve guide seal. That way, you know what you have as far as new parts, and you might want to consider this rebuild kit, well worth the price.

Also, the points gap is supposed to be .016" at TDC.
 

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Discussion Starter · #14 ·
IMO, it never hurts to freshen up an older engine, while apart it gives you the chance to use all new gaskets and o-rings, clean up the valves and head, and replace the exhaust valve guide seal. That way, you know what you have as far as new parts, and you might want to consider this rebuild kit, well worth the price.

Also, the points gap is supposed to be .016" at TDC.
I did buy a kit already it came with a piston jug in case I need it, but perhaps I should just change that out while I have it tore down, and a piston and the rings and the two gaskets, what does the valve guide seal look like and can I get it by itself so I don't have to buy another kit?

Good to know on the points gap, I must have been thinking of the number for the valves, I'll have to adjust that.
 

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Discussion Starter · #16 ·
Would I need to remove the spring and all those other parts to get to the oil seal? Also I don't have one of those valve compression tools to remove the little magnetic pieces, if I have to buy that which is like $25 and a seal or two, would it be better for me to just buy a whole new Cylinder Head for $48 or?
 

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No a 48 dollar head won't even make a good boat anchor. Stay away from no name Amazon and ebay engine parts. You can make a valve spring compressor with a piece of the right size conduit with "windows" cut into the sides to remove/install the keepers and a large C clamp
 

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Discussion Starter · #18 ·
No a 48 dollar head won't even make a good boat anchor. Stay away from no name Amazon and ebay engine parts. You can make a valve spring compressor with a piece of the right size conduit with "windows" cut into the sides to remove/install the keepers and a large C clamp
I think you're right, besides I want to keep it as original as possible, my OCD just gets the best of me and I get frustrated and then it makes me want to just start replacing things that may not need replacing. I've ordered two valve stem seals and I shall replace both of them. So far I have bought a tire for the back, a piston jug kit, oil seals a points and condenser kit and a quart of oil.
 

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If your engine is bone stock, you should only have one valve seal, on the exhaust side, under the valve stem seal cap. Part #7 in the diagram above.
 
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