Legal engine size for Nationals??

[stever250r]

What is the legal engine size to race nationals?

I was wanting to put an ESR 310 PV cylinder on my project R?

Could I still race with this engine? If so, exactly what class would it be considered?

Can anyone tell me?

Thanks

[Prey]

any size, 250r cant run production class but, they have a 265 class (265cc 2 stroke and 450 4 stroke) and an open class, the open class is where i race my 310R

[stever250r]

Thanks Prey,

Will a ESR 265 PV run with the new 450s?

Which would you recommend?

[addictedtomud]

I've got a PC2000 265pv for sale on ebay, ends tonight, check it out...


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=4557524356&ssPageName=ADME:B:LC:MT:1


Kyle

[Iliketogofast]

A modded 265 powervalve motor will destroy a 450. Just think of a bulldog let loose on a couch cushion. :scary:

[Prey]

Originally posted by stever250r
Thanks Prey,

Will a ESR 265 PV run with the new 450s?

Which would you recommend?

i chose the 310, and if i had the long rod i would have gone with the 330 (310 is bolt on for short rod and 330 is bolt on for long rod, after that there is machining the cases involved)

in a real racing scenerio, you are not going to be racing stock 450s (there will be some, there will also be a lot of modd'd ones too), you will be racing 450s set up like mine and the 265 will not keep up with it (it wont get killed but its definately not letting a dog loose on a couch cushion). my 310R is not any quicker than my 450, before anyone tells me the 310 is not setup right.....its an esr kit that was just reworked by tony kellner, look him up before you blast my comment.

my 265 kit (i took this off to put on the 310 kit) was 38.9 rwhp, i have not dyno'd the 310 kit but i speculate it around 45-48 rwhp, and the 450 is around 50rwhp

thing that kinda hurts the 250R IMO, is the gearing, i am running 14-38, that is the best combo i have found to put power to the ground and not having to make 3rd gear starts. with the taller 1st gear in the 450, you have a lot more flexability in gearing. what i am trying to say here is this, my 450 is geared lower and rips like hell up to maybe 65mph, my 310 runs well into the 70s and i cannot effectively gear it lower.

note that i have the trx7 port, probably not the best port for mx (its really and xc port) but budds creek (my local track) is full of sharp turns/switchbacks/uphills so i wanted my power to build at lower rpm's. maybe the gearing is not such an issue with the trx9 port, i havent ridden one.

one other thing, right before the atv nationals at budds i blew my 310 (thats why it is kellner re-built). i put back on the 265 top end, the hills at budds are very steep and the 265 would only pull 4th up the hills (ended up blowing that engine at practice and riding my mostly stock predator ... YIKES.... thats why i bought the 450). the 310 would strongly pull all 6 gears up the same hills

sorry for the novel, wanted to give you all the info i knew, remember, these are my opinions

[stever250r]

Thanks for being thorough. You answered many of my questions.

I am mostly a local track rider... bunch of amateur B class riders... but I live close to Loretta Lynn and sometimes a few of us get together just to try our luck. Thats why I was inquiring about the nationals.

I think I will also go with the ESR 310 kit. Do you have the PV?

Is the PV cylinder really worth the extra $600.00?

[Prey]

no, i dont have the PV, i have been riding 2 strokes since 86 and thought i was familiar enough with em to handle the sudden power surge........ and i am not sorry i did, i am sure the PVs are awsome, but i love the feeling of having my arms ripped off :devil:

[stever250r]

So by what you are saying the PV motors dont really increase HP, they just smooth out the powerband.

If thats the case... I agree with you... I like that sudden burst and hang the &^%$ on feeling too!!!! :eek2:

[gimp419]

If you do any racing at all then get the PV, the smoother delivery will give you another lap. That light switch powerband is nice but it can really wear you out!

Oh and the 265 may be a little out powered against the 450s but if you know how to ride it you can still win. To prove my point look at the 265A class at the High Point GNC, it was won by a 265PV R!

I would say that my 270R motor would run with any 450 out there and my 350PV would really put em to shame.

[TRX_250r18]

Originally posted by Iliketogofast
A modded 265 powervalve motor will destroy a 450. Just think of a bulldog let loose on a couch cushion. :scary:
ah ahahahahhaaha that funny ****

[hollywood250r]

Originally posted by addictedtomud
I've got a PC2000 265pv for sale on ebay, ends tonight, check it out...


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=4557524356&ssPageName=ADME:B:LC:MT:1


Kyle

Man that piston looks rough on the corners of the port. Did you check the bore/piston clearance and do warm ups?

[beerock]

umm prey, i beg to differ. a good ported 265 will keep up with a moded 450 and a 310 and 33 will beat a worked 450. PERIOD.

[Prey]

well, i have one of each......and im telling you that my 310 will not beat my 450 through 3rd gear (on the 450 which is high as i get on a mx track)

[nacs400ex]

Originally posted by beerock
umm prey, i beg to differ. a good ported 265 will keep up with a moded 450 and a 310 and 33 will beat a worked 450. PERIOD.

Couldn't agree more. The setup on the R is key, if your combination isn't proper your not getting your potentional power.

If your port job just isn't there, forget it.