total newb ? but need help

[brandonpeake]

I am new to the 250R's by thge time i earned enough to get something it was a built 250x then I mooved on up to the 450's so I kinda did this backwards but i love the 2 strokes i had a banshee and it hooked me in the 2 stroke so here is my question,

I see on ebay all these people with ported cylinders for sale for example
trx 250r ported jug cylinder (http://cgi.ebay.com/ebaymotors/TRX-HONDA-250R-PORTED-87-89-JUG-CYLINDER-250-R-TRX250R_W0QQitemZ220218024648QQcmdZViewItemQQptZMo tors_ATV_Parts_Accessories?hash=item220218024648&_trksid=p3911.c0.m14&_trkparms=66%3A2%7C65%3A1%7C39%3A1%7C240%3A1318)

So i am correct if you had a stock cylinder as in non ported you would bolt this up for more power or power in a different place?

I also see bottom ends for sale on ebay so is the cylinder and the bottom end the main parts of the engine,

again please forgive i know about 4 strokes so this is new i me and I am trying to learn, I am sure some others dont know either
Thanks in advance for the help and try notnto laugh to hard

[1promodfan]

Brandon, I'm no expert but I'll do my best to help. There are plenty more guys up here with more knowledge than me. But, I have to say yes, you can bolt on a new cylinder and get more power. You can also get your stock cylinder ported for whatever riding style you have. I would say the cylinder is one of the main parts of the motor for getting power. But the top is no good without a good bottom end.

There are plenty of cylinders and port jobs out there that will suit anyones riding style. Hope this helps, but like I said before someone else will chime in with a WHOLE lot more knowledge.

[g9901920]

First you need to make sure that the bore of you cylinder and and the bore of the cylinder you want are the same. thats if you are planning on using your piston.

and besides that they will match up.

[rustyATV]

First off, $350 is wayyyyy too much for a ported 250R jug.

If I remember A. Graham Bell's writing correctly, the exhaust pipe determines the TYPE of power, while the cylinder porting determines WHERE the power is, in simplified terms.

Now, on the 250R's ancient castings, there is some power to be made in the cylinder by improving the flow in the area on the underside, called the "transfers", but with a port job you're mainly moving the power around.

While the bottom end does influence the motor and lots of people spend time trying to make something happen there, it's purpose is pretty much just to hold the next charge that's going into the engine.

[atvmxr]

a ported cylinder without the proper exhaust will run poorly. but the cylinders/pistons will swap... its much easier than a 4 stroke cylinder swap. There is no cam chain/valves/etc. to line up. just bolt on, heat cycle/retorque, and ride :)

[regg187]

Originally posted by g9901920
First you need to make sure that the bore of you cylinder and and the bore of the cylinder you want are the same. thats if you are planning on using your piston.

and besides that they will match up. It's definetly a little deeper than this. Really a jug should come with a piston, as bore jobs are really the size of the piston +clearence needed for expansion. Pistons all vary in size within there "size". first over pistons are first over pistons, but due to the casting process they will vary slightly in actual size. were talkin .001 stuff, but a "big" piston in a "small" bore can be a instant seiszure.

The amount of clearence needed is also different, with type of piston. There are Forged pistons and cast pistions, 2 ways to make piston, and I type needs more clearence than the other, because it expands more when heated than the other type. hence the need for a piston to come with the cylinder.
but if no piston comes , you will have a shop measure the clearences from your piston to the cylinder wall, then if it is in spec have it honed and put on a new set of rings. that shouild be the bare minimum of bolting on a new cylinder.
you could buy the cylinder, have it miked, buy the next size up piston and have the cylinder bored for the new piston, and you'll have a fresh top end.

[norcalduner]

Originally posted by rustyATV
First off, $350 is wayyyyy too much for a ported 250R jug.

If I remember A. Graham Bell's writing correctly, the exhaust pipe determines the TYPE of power, while the cylinder porting determines WHERE the power is, in simplified terms.

Now, on the 250R's ancient castings, there is some power to be made in the cylinder by improving the flow in the area on the underside, called the "transfers", but with a port job you're mainly moving the power around.

While the bottom end does influence the motor and lots of people spend time trying to make something happen there, it's purpose is pretty much just to hold the next charge that's going into the engine.

Very well said bro :macho