atc250r Hp?

[william16339]

sorry for all the questions guys haha. what do do you think HP wize, i would get out of my fully rebuilt 1986 honda atc 250r. Ported mid to topend cylinder, vforce reeds, PJ 38 mm carb ( not the air stryker ) cr250 head gasket, and a PT high rev pipe? gearing is 14 37 if that makes a difference lol

[El Camexican]

More than 25 and less than 60 would be a safe guess

[william16339]

oh lol that narrows it down, i suppose

[250rRoostmaster]

Well.. My 86 motor put out 54 hp on LED's dyno. My motor is an 86 with 4mm stroker crank, dune port, handbuilt LED expansion chamber, 38mm A/S carb, Boyesen CF reeds, stock ignition, Uni filter- no airbox lid, straight race gas w/ amsoil interceptor @ 44:1. That will give you a ball park..

[pcs]

porting is the major factor, 30s maybe low 40s, but the port job will be a major factor. also, if the port job was made for that specific carb and pipe combo. mix and match set up rarely perform as well as a matched set up.

[pcs]

my other 85 250r was a long rod engine, ftz ported atc cylinder and chambered head, pwk 39 with a taper bore, esr reeds, fmf fatty made 49whp on 2 different dynos

[atc300r]

The 85-86 250r was rated at 38 stock according to Dirtwheels when they came out.

[250rRoostmaster]

my other 85 250r was a long rod engine, ftz ported atc cylinder and chambered head, pwk 39 with a taper bore, esr reeds, fmf fatty made 49whp on 2 different dynos

We should race!

[slashfan7964]

Factory rated was 38 according to the manuals. So probably just north of that. I'd say 43-45-ish is a safe estimate. These engines respond well to mods.

[pcs]

We should race!

i was thinking the same thing...u coming down for the invasion ride

the 2 dynos i used in phx had all bolt in atc/trx 250r in the mid 30 range at the wheel with various pipe/reeds/carb combinations. i do agree with slashfan that they do respond will to mods, my set once dial picked up almost 3 whp from doubling the air filter size. didnt have a chance to try a 41mm carb but with one i believe that combination would have broke 50whp.