upgrading the piston size

[bigdady536]

if i upgrade to a 87mm piston from the stock piston i have to get the cylinder bored right. Now when i get the cylinder bored what happens to the sleeve that was in there originally and how come no one ever mentions anything about the sleeve. do i need to get a new sleeve. what is required when upgrading to a larger piston please let me know thanks Mike. Also would blue smoke or white smoke coming out of my exhaust along with some black oil be a result of a bad piston or O rings. How can i check if my piston actually needs to be replaced. Thanks for any responses.

[dariusld]

Start by taking it apart. Look at the piston and the cylinder. Look for signs of wear, they are obvious. I don't understand the sleeve question. Do you know what boring is? You don't have to replace the sleeve until you have no more bores left, 426 is the biggest you can go on the stock sleeve. The best thing to do if your cylinder has deep wear marks is to take it to a mechanic to see what the next smallest bore would be. It might not be the next size up because of excessive wear.

Smoke is also a sign of bad valve seals. But if your getting oil, then your rings are probably bad. But when you do all this work, you might as well replace the valve seals.

[bigdady536]

would a compression test tell me if there is any leak within the cylinder regarding the piston. I just want to get me 400ex running without smoking like a chimney. I don't feel like spending a lot of money but if i have to replace the piston then i will. I just hate riding around with tons of smoke hitting my fiance in the face when I'm in front or black oil spitting out the exhaust resulting in small specks of oil on her shirt or face. Any ideas on what to replace at the least cost.

[dariusld]

The least amount would be about $120. About $40 - $60 for the bore job. And a cheap piston and gaskets on Ebay about$80-$100. But if you spend about $120 more for a cam and get a high compresion piston instead of stock , you will be alot faster:D If you have a stock exhaust, I would just go the cheapest route.

These prices are based if you do all the work and there is nothing else wrong.

[Zeb400EX]

Whenever my started to smoke. I just took apart the piston,and the piston and cyl. looked pretty good so I bought new std. bore rings. Put the new rings on the stock piston and it stop the smoking. I didn't have to bore or hone out the cyl. In your case. I would do the same as long as everything looks ok. You can get new rings from honda pretty cheap on cheapcycleparts.com When you get it apart just look for any deep scratches on the piston skirt and the cyl. walls. Also look to see if there is a ring around the top of the cyl.

[Zeb400EX]

Also could be the valve seals. Most of the time if the valve seals are bad it will smoke pretty bad at idle.

[dariusld]

Its like dejavue. I usually read a thread before I respond;)

[Zeb400EX]

Originally posted by dariusld
Its like dejavue. I usually read a thread before I respond;)

sorry man. just trying to help out.