how to identify 83-84 atc250r 300 cylinder

[jason85atc250r]

my buddy has a cylinder,intake + head from a 83-84 atc250r. it does not have any cc marking anywhere. if i remember rite a guy brought it around to his shop years ago and we could not find a piston for it. the guy said it has a 300 kit but my friend dont remember for sure.

i want to check what exactly it is before i sell it. thanks for any help

[smyers33]

I think all of the cooling fins on the head are verticle, not slanted...I am almost posotive that is correct

Edit: Here is what it should look like http://www.3wheelerworldforums.com/attachment.php?attachmentid=36927&d=1165680368

[jason85atc250r]

it does not look like that. i know there was 2 models Mugen and factory honda one. what would the cylinder measure out to.

whats got me confused is theres no displacement stamping on the cylinder showing the cc's.

[Billy Golightly]

Measure the bore and see what it is, that'll tell you for sure.

[smyers33]

Does it look like the one in this thread? http://www.3wheelerworldforums.com/showthread.php?t=42366&highlight=mugen+300cc

I guess DG made a 300cc kit back then, so did Mugen. Best of luck finding out! :)

[jason85atc250r]

i just measured the bore size. it is about 2.75 inches when you multiply by 25 mm it = 68 to 69 ish mm bore. is that close to stock?

maybe it's was on it's last bore and that why we could not get piston for it.

the whole thing went down 10 years ago thats why it's hard to remember. plus no cc markings has me confused. which is easy sometimes.:lol:

the head was there. the intake, reed cage and exhaust flange are still bolted to the cylinder. if sombody needs that stuff

[Billy Golightly]

Yeah thats pretty close to stock. I can't remember the stroke of the 81-84 motors, but I know they hard a larger bore then the waterpumpers (66mm) did stock. It'd need to be in the 70mm+ range to be a big bore.

[jason85atc250r]

so maybe it's just a stock on with no bores left:cry:

so do all the older air cooled stock cylinders have no displacment markings?

[firefirefire90]

If you send it to me, I'll just pay for shipping. I need to mess around and learn how to do port work.

[jason85atc250r]

i would like to get a answer 1st and see if its good or not yet. if the 68 or 69 ish mm bore still has some life yet. the cylinder has not been ported.

i want to sell the intake and reed cage + i got the cylinder haed also.

[dufrain]

COunt the head studs the 300 has one more than the 250 .Im pretty sure its 7

[jason85atc250r]

it has 6 studs.

[firefirefire90]

I was just saying, I need something to practice on...so whatever. If you want to get rid of it, I will take it and pay shipping.

[Billy Golightly]

Might better check that measurement again. According to the specs page, 70mm was stock bore on the airfoolers. http://www.3wheelerworld.com/1984HondaSpecpage.shtml

[jason85atc250r]

it measures 2 13/16th which by times 25 mm = 70.3 mm.

i noticed some stuff is wrong in the spec page for the 85atc250r. maybe this is?

[jason85atc250r]

I was just saying, I need something to practice on...so whatever. If you want to get rid of it, I will take it and pay shipping.


i just want to make sure it's good 1st and i mite be able to sell it or trade something for it

sorry if it sounded like i was mad about what you said,

[Billy Golightly]

Yeah I'm not sure if that is accurate or not jason. Perhaps another airfooler owner can chime in?

[petesatc]

here's a pic of the 300r kit but the easiest way of telling is the 300 kit has 7 head bolts and the standard cylinder has 6 bolts

[jason85atc250r]

since the spec page and what i'm measuring dont match is what has me confused.

does wiseco make pistons for these? maybe that was why they could not get one or maybe the guy was cheap :wondering

[SYKO]

http://www.qande.com/

this place has everything to redo the old 300 hondaline cyls, sleeves/pistons/gaskets, everything, I got them saved so when mine goes down I dont have to go searching for parts.

[mustangmachanic]

a stock air fooler bore is found in the manual i belive it is 70mm

[sbjones73]

yes the bore is 70mm stock. you can do overbores out to about 72.00 i think that is the biggest i have seen. now that is with the stock cylinder.

and yes the 300 kits have the 7 studs on them, not the 6.