Got my 350x back but it smokes worse then a 2 stroke! HELP

**TimSr** · 05-30-2006, 07:50 PM

Im in teh minority, but I have no problem using a used piston in good condition, and they are quite expensive. My Z just got new rings, but I saw no need to put a new piston in. I would never ever put used rings in a machine though, especially coming out of a different cylinder. They wear to match the cylinder (thats what break-in is) and shouldnt be swapped.

**cragster** · 05-30-2006, 07:56 PM

Originally Posted by TimSr

Im in teh minority, but I have no problem using a used piston in good condition, and they are quite expensive. My Z just got new rings, but I saw no need to put a new piston in. I would never ever put used rings in a machine though, especially coming out of a different cylinder. They wear to match the cylinder (thats what break-in is) and shouldnt be swapped.

He used the pother complete topend basicly. He used the other cyl. piston. rings. head. valve cover and everything..

**Howdy** · 05-30-2006, 08:02 PM

Originally Posted by TimSr

Im in teh minority, but I have no problem using a used piston in good condition, and they are quite expensive. My Z just got new rings, but I saw no need to put a new piston in. I would never ever put used rings in a machine though, especially coming out of a different cylinder. They wear to match the cylinder (thats what break-in is) and shouldnt be swapped.

This is exactly why the wrecker smokes so bad. It's a pure beater so not many new parts ever get put on it ( including gaskets ).
Howdy

**kb200x** · 05-31-2006, 11:16 AM

Originally Posted by TimSr

Im in teh minority, but I have no problem using a used piston in good condition, and they are quite expensive. My Z just got new rings, but I saw no need to put a new piston in. I would never ever put used rings in a machine though, especially coming out of a different cylinder. They wear to match the cylinder (thats what break-in is) and shouldnt be swapped.

I just rebuilt the topend on my 350x and used the stock 20 year old piston with new oem rings. I am no expert by any means but I dont see the logic behind only using a new piston. I measured my piston it was in spec. It looked fine appearance wise. why not use it? Hey Timsr maybe you are in the minority or maybe its more like you just dont believe everything you hear?

If my piston blows up at trike fest i will change my tune.

**random-strike** · 05-31-2006, 12:51 PM

its ok to reuse a piston, but not that good of an idea to reuse rings

should always put new rings when you hone.

the only way you could reuse rings, is in the cylinder it came from, and without honing it at all.

the rings break themselves into the cylinder they are in.

my guess is that the old ring did not seat properly into the newely honed cylinder, its possible over time you could see the smoke get less and less as the rings seat themselves

**kb200x** · 05-31-2006, 02:45 PM

The more I have thought about it I can understand if you where rebuilding a car or truck that you would want to use all new pistons ect.. just in case because its a pretty big job time wise to pull the motor and tear it all down. But with a trike that you can tear down and rebuild in a few hours I still dont see the logic behind only using a new piston. It seems you have just as much of a chance if not more with a new piston going south on you as an old piston. The new piston may be flawed to start with. If you use the old one that has works fine for 20 years I would think it would be a pretty good guess its going to continue to do what its suppose to do. Im not trying to step on anyones toes here this just interest me because I thought alot about this before rebuilding my top end. I went with my stock piston and new rings. Money was not the only reason but it always plays a part in any decesion. I just felt like i had a 350x that was still on the stock bore and nothing was wrong with my cylinder or piston so why change whats been working for 20 years. A light hone and rings and cleaned up some carbon new gaskets and seals and lapped the valves and i am good as new for less than what a new piston cost and I am still on the stock bore. I guess i am just trying to see the logic in always changing the piston for a rebuild.

**random-strike** · 05-31-2006, 04:50 PM

Originally Posted by kb200x

The more I have thought about it I can understand if you where rebuilding a car or truck that you would want to use all new pistons ect.. just in case because its a pretty big job time wise to pull the motor and tear it all down. But with a trike that you can tear down and rebuild in a few hours I still dont see the logic behind only using a new piston. It seems you have just as much of a chance if not more with a new piston going south on you as an old piston. The new piston may be flawed to start with. If you use the old one that has works fine for 20 years I would think it would be a pretty good guess its going to continue to do what its suppose to do. Im not trying to step on anyones toes here this just interest me because I thought alot about this before rebuilding my top end. I went with my stock piston and new rings. Money was not the only reason but it always plays a part in any decesion. I just felt like i had a 350x that was still on the stock bore and nothing was wrong with my cylinder or piston so why change whats been working for 20 years. A light hone and rings and cleaned up some carbon new gaskets and seals and lapped the valves and i am good as new for less than what a new piston cost and I am still on the stock bore. I guess i am just trying to see the logic in always changing the piston for a rebuild.

do you have the tools to propertly check if a cylinder is true? or a piston?

thats why you use new parts.

20 year old piston might not be as true as it should be, and you may have oil control problems. especially if the motor was used and abused

reusing a piston is definatly do-able, its a tad of a risk if you dont spec the piston and cylinder...etc... but like you said, its just a trike motor

**kb200x** · 06-01-2006, 10:53 AM

Originally Posted by random-strike

do you have the tools to propertly check if a cylinder is true? or a piston?

thats why you use new parts.

20 year old piston might not be as true as it should be, and you may have oil control problems. especially if the motor was used and abused

reusing a piston is definatly do-able, its a tad of a risk if you dont spec the piston and cylinder...etc... but like you said, its just a trike motor

Well I think you just answered my question and something that never accured to me. I do have the tools to check everything. I have access to several coordinate measuring machines. So I have checked everything in my top end with in 5 microns of what it actually is. I have more accurate measurements than what the honda factory could have even dreamed of 20 years ago. So yes I see your point! If i didnt have the tools i think i would have went all new stuff also.

**slothminx** · 06-01-2006, 11:16 AM

Metal fatigue. All those exspansion and contraction cycles has to take its toll on the piston.

you dont want this happening. If you have the motor apart I think its worth the extra money to go new, especially if its a two stroke motor.

**kb200x** · 06-01-2006, 12:07 PM

Originally Posted by slothminx

Metal fatigue. All those exspansion and contraction cycles has to take its toll on the piston.

you dont want this happening. If you have the motor apart I think its worth the extra money to go new, especially if its a two stroke motor.

Very true I dont want that to happen I guess every case is different my piston looked like it didnt have a scratch on it just a little carbon on the dome. 2 stroke I think I would replace everytime also. I was just not seeing the logic behind " replace the piston everytime" But if i didnt have the tools to verify what i was dealing with then I can see the logic in just replacing. I was amazed at the very small amout of wear on my piston and cylinder. My head looked like carbon city. she ran rich for a long time I would guess.

**Kintore** · 06-01-2006, 03:19 PM

Im in the same boat, 20 year old piston nothing wrong. Figured while im here might as well do it right. Got it bored out, with a new piston and rings. Makes me sleep at night, I was told it was too old of bore to continue with new rings. So I went with a new one. Hope this helps!

**cragster** · 06-01-2006, 04:00 PM

Its ok i think. I live next to an engine shop. Boring is 44 dollars. .20 over wiseco 10.25 to 1 piston is 84 dollars shipped. Top end gaskets shipped are 26. Thats 154 dollars for a top end assuming the guy i had to the work fixes it free because of his fault

**random-strike** · 06-01-2006, 04:23 PM

Originally Posted by cragster

Its ok i think. I live next to an engine shop. Boring is 44 dollars. .20 over wiseco 10.25 to 1 piston is 84 dollars shipped. Top end gaskets shipped are 26. Thats 154 dollars for a top end assuming the guy i had to the work fixes it free because of his fault

82 shipped isnt that bad i suppose, even those you can get 8 HE pistons for a small block chevy for $140 lol

damn supply and demand

**cragster** · 06-01-2006, 04:41 PM

Yep i know. Now i just need 154 dollars lol.

**jason 32** · 06-02-2006, 04:06 AM

hummm
should have checked ring end gap!! yea you should have gotten new rings at least.is it over full of oil???? its just work to fix it right ,maby the oil ring collapsed
need new valve seals?

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