Time for a bore?

[kilabeez0]

It are cause I gots the amazing psychic powers. And stuff. Actually I was just referring to what he should do generally. I'm not giving him instructions.

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[jenndnn3]

Tim is right! Only the proper tools will tell if you need the bore. The cylinder wears in different areas, usually top faster, bottom slower. You can feeler it but to truley test for bore you need to measure the difference between the top and bottom of the cylinder itself. Use a feeler to see how far off the piston is from the cylinder. If we have alot of wear yes your looking to prob bore. BUT you are aware the piston wears just as well? what if the piston wore first, then the feeler is not good.

I am with Tim in the sarcasm I am truley amazed that we can answer yes we need to bore, over the internet... I want those powers too!

Opinions or suggestions are for what oil, what gas, what color, and how do I make it faster. When it comes to the major componets of your engine and how to fix, especially in this form of a question, the numbers do not lie.

Now if he asked should I bore my engine myself, why lets start debating or giving opinions on that.

[Howdy]

First lets directly answer the questions from the original post:

I've got my cylinder apart on my YTM200. I'm getting mixed opinions on if I should bore it out. Some say do it, others say hone it. Its burning a lot of oil, The cylinder walls to not seem like they are scored.
What else causes it to burn a lot of oil?
What should I check?

What else causes it to burn a lot of oil?

On 4 stroke motors:
Bad valve seals / guides.
Bad rings
Bad piston
Bad Cylinder ( un even wear: out of round, tapered, scratches, ect ).

Next Question:

What should I check?

I would do a compression check on the cylinder first. But since you already have the motor apart we can skip this step.

So start with checking the Cylinder to see if it is within the wear limits ( via specifications ). You can probably have a local auto parts store check this for you ( if you don't have the tools ). Be sure to check for Taper, out of round, uneven wear, scratches, ect.
NOTE: If there are ANY scratches will need to be honed or bored out so that they do not cause premature wear on the piston & rings. Even the smallest of scratches can cause oil to bypass the rings thus you would still be burning oil.

If it checks bad it's time for it to be bored or replaced.

If the Cylinder checks good then check the Piston for any wear. If the piston checks good then check the piston to cylinder clearance. It is possible for the cylinder and the piston to both check good, but still be bad when put together. How this can happen is if the cylinder is at the very upper of the wear limits, and the piston is at the very lower wear limits. This would result in too much piston to cylinder clearance. Thus it would be bad. If this is the case you may need to buy a new piston.

Lets say this is what the problem is. Being as you have too much piston to cylinder clearance you would need to buy a new piston at the least. Since the cylinder is at the upper wear limits it won't be long before you would need to have it bored anyway. Add the fact that your already going to be getting a new piston, it would be very wise to go ahead and have the cylinder bored now rather than later. Does this make sence?

Now if the cylinder, the piston and the piston to cylinder clearance all check good, then procceed to check the rings ( check the ring end gap per spec's ).

If only the rings are bad then you can get by with just honing the cylinder and replacing the rings.

Now for the valve seals: Most top end gasket kits come with new valve seals. Unless you have just replaced these seals it is VERY wise to replace them while the head is off. To define "just replaced them", by this I mean if you have replaced them within 90 days and within 20-30 hours of run time ( which ever is less ). If you replaced them 1 year ago but only ran the machine 5-10 hours I would still replace them. The valve seals can and will go bad from just sitting.
Note: Some times they can be a pain to change. But normally they aren't too bad at all.

yes, listen to king tim. he is the grand master of sarcastic posts. he is always right. no one should even bother posting, just pm him and he'll give you the answer. here comes my debate of taking suggestions from other members rather than just taking tims answer.

WTF is this? TimSr has given more correct and helpful information than most of the users on this site. If you open your mind and "think outside the box" ( borrowed from Taco Bell ) you will see more correct information from TimSr than anything else. Yea, he does like to use some sarcasim in a lot of his post. A lot of it actually works to make you think for a moment. It's too bad some users can't define the difference from sarcasim and actuality.
To do a top end correctly and to make it last for the maximum amount of time you MUST measure the cylinder, piston, and rings to see if they are wore.
Yea, you could just do as KayodicWeazel said and put new rings in there. It may or may not take care of the smoking problem ( most likely it won't last very long ). Do you really want to take a chance and more than likely have to do this all again in a couple weeks / months down the road?

Yea, TimSr is a friend of mine. But even though we are friends we don't always see things the same way. I'm not sticking up for him in this thread because we are friends, I doing it because he is correct in his original post. His second post was directed towards the Bad information given ( IMO ).

Do it correctly the first time!! It will last a lot longer than doing a half-arse job.
Howdy

[TimSr]

Interesting how we got here. Yes, I do answer a lot of tech questions via PM. They usually start out with something like "I am sending you a PM and not posting this because I dont want every postwhoring buttwipe who has never seen a bike like mine before throwing out a wild guess on the off chance that they might guess right, and make everybody else think they are a genius, while I am spending all the money to cover their guesses".

Quite frankly, I dont care if anybody takes my advice or not. I just feel a need to give advice when I see people steering somebody in a very expensive bogus direction. Let me be plain. Anybody who claims to be able to determine whether a cylinder needs bored over the internet without any measurements or personal examination is not somebody I recommend taking advice from, but if you wish to do so, go for it. If you new piston kit is toast a couple weeks from now, or your machine runs like crap because you didnt have it measured and do the correct fix the first time, Ill be chuckling to myself when I read the next thread you make crying about it. I gave the information. Take it or leave it.
See ya at Trikefest! Ill be the guy whose equipment all runs good!

[bigredhead]

HEy.. if one of tim's machines breaks down during trikefest.. someone get a picture !!! LOL...

[TimSr]

Bigredhead, Measuring ring gap is not very precise but I do use it as a general check. Cylinders wear egg shaped, which means youll get a larger ring gap in the center of the cylinder than near the top or bottom. This is not precise enough to tell for sure, but, if there is a measurable difference it definately needs bored. If the difference is not measureable, you need to have it measured to know for sure. Same deal with the feeler guage and piston clearance. Too much clearance it needs bored for sure. Clearance okay, have it checked measured with a mic to know for sure.

[TimSr]

or I could do it myself, saving maybe $150 in labour......
It's not too hard to do....

Most shops will check it free. If they do charge, its a very small amount.

An actual bore job from Wiseco is $50.00. Its teh new parts that cost all the money, which is why you want good bore job if needed to install them in.

[Yamahauler]

thanks for the reply's. I'm taking the piston and cylinder to a cylinder shop to get them to measure it. I'm going to replace valve seals too.
Now where should I get all the new things for the engine? the dealer? so far I need, piston (maybe), valve seals, cam chain, cam chain guides, wrist pin, clips, gaskets

[kilabeez0]

I bought a one over piston, rings, valve seals, cam, and a bunch of other parts from honda. It wasn't too much. Or you can shop around on ebay, but you usually get what you pay for if you try and buy cheap stuff. Like they said which I should've backed up rather than flame, do it right the first time.

Lets say this is what the problem is. Being as you have too much piston to cylinder clearance you would need to buy a new piston at the least. Since the cylinder is at the upper wear limits it won't be long before you would need to have it bored anyway. Add the fact that your already going to be getting a new piston, it would be very wise to go ahead and have the cylinder bored now rather than later. Does this make sence?

Also with what Howdy said, if your buying a new piston anyway, why not go one bigger and pay the $50 and have it bored .

[Howdy]

You might be able to get a Pro-X piston kit for it. They make the pistons to the OEM spec's so the rings will inner change. Dennis Kirk has a bunch for Honda machines, but I haven't check on ant Yamaha's.
Howdy

[Yamahauler]

Ok, I'm trying to to take these valves out to get to the seals, and I have got to the part where you are supposed to thread a bolt into the rocker arm shaft to pull it out. I cant get the bolt to thread in on the intake side but the exhaust side is fine, I think it maybe be cross threaded a bit.
Can I clean that up with a tap?
How are is it to pull them out?
Is there a tool to do this?

Thanks for the help.

[Yamahauler]

Well, I finally got into the city to get the cylinder measured. Turns out it really needed a bore! Specs say .001" to .0018" piston to cylinder clearance. Mine measured .006".

I think it was well due for a bore!

[Yamahauler]

Most shops will check it free. If they do charge, its a very small amount.

An actual bore job from Wiseco is $50.00. Its teh new parts that cost all the money, which is why you want good bore job if needed to install them in.

I just noticed this reply now, but when that Weazle guy said to take it to a shop and let professionals do it, I thought he was talking about letting them do the whole top end job. I knew that most shops will measure it for free.
Just thought I'd clear that up.