To bore or not

[sdmyers13]

So got the engine pulled apart and the piston is definitely shot. Cylinder wall is scored but not as bad as the piston. If I bore the cylinder do I need to have the combustion chamber cut bigger too? If I go bigger bore do I need to swap for a bigger carb?

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[big specht]

Bore it. You never said what it was. And you don’t need to open the combustion chamber on 4 strokes.

[sdmyers13]

It's a 200x. Is there a pretty noticeable difference in power from stock to say .030 over? Any other components that should be swapped to accommodate the bigger displacement?

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[atctim]

Boring is not for performance gains - it's to get things back in spec and round (so to speak). People always confuse "Boring out" with "Big Bore" - two different animals. Big bore is significantly larger piston and generally a hogged out cylinder with a new larger sleeve. Boring out is just cleaning up the existing cylinder sleeve to true it up and make it round again. Have a machine shop measure it to see if it needs bored. You want to keep the bore as small as possible, for future boring.

For example - if this is a 200X - stock bore is: bore 65mm x stroke 57.8 = 191.798 CCs. Now say you bore it .030" over - now your piston has a bore size of 65.75mm, thus going from 192CCs to 196.249CCs. So essentially you are only gaining 4CCs - not very much. A big bore 200X kit will take you to 250CCs or so - depending on what you can find.

Telling people you have a bored out motor, and thinking that is a performance mod is something I hear people talking about and it makes them sound like they don't know what they are talking about. Big Bore is totally different - and about 5 times more expensive.

[Homeless Dave]

a bore out will not net you much for performance. I have a 250es that i just put back together a week ago, its bored 20 over, There is no noticeable gain. I did not change any jetting or the exhaust, completely stock just bored out. If you want power go with a big bore, high performance cam, carb and exhaust. If you want stock power and a fresh engine, just bore it out. You definitely will need a new piston. What happened to the engine for it to end up like that?

[sdmyers13]

Thank you for educating me. Growing up I always heard guys talking about their bored engines, now it makes me wonder if they actually did big bore kits lol.

Bought the bike about a week ago and I can only assume the previous owner ran this thing with little to no oil. He was the questionably sober type, and I dont mean booze. Looked like he's chased a few white dragons if you know what I mean.

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[Shep1970]

If this is for the 86/87 Honda 200x be sure to get (when your ready) a-
86/87 piston
Or Honda fatcat
Or 86-88 Honda trx200sx piston/ rings

While your in there:
Timing chain/ possibly guides
Atleast change out the valve seals

Do not use any silicone- try to get ahold of oem gaskets again the above bikes top end gasket kit will fit yours

Shep

[atctim]

Growing up I always heard guys talking about their bored engines, now it makes me wonder if they actually did big bore kits

I hear people talking about "bored out motors" as a performance mod constantly. It is a pet peeve of mine. When I hear them talking about it, I normally stop listening right afterwards.