high compression help

[woodsracer144]

hello,

i have a pro-x La sleeve 265 topend with a pro cross head with the changeable domes... i called pro cross today and i was on hold for 5 min.s so i hung up the phone... i think it might of been la sleeve that i called... anyway i did a compression test and the first time it was 151PSI and the second time i did it it was 175... the 151 i did yesterday on a motor that was wormed up and the 175 was a cold motor...

i would like to run on pump gas... not on 110... any help would help.. i also have the stock 250 jug but it needs work and i thought if i could get this one goin it would be cheaper... thanks for reading and helping me.

[woodsracer144]

i took the dome out of the head and teh numbers on the dome are 660220

can anyone make anything out of this... thanks

[Dave83]

You should check the compression on a warm motor.Warm it up then hook up the compression tester,hold the throttle wide open and kick it over until the guage stops moving.If you get less than 190psi,then your good on pump gas.If its down in the 150 range,your not far from needing to re-ring.

ive never seen the comp numbers lower on a warm motor then a cold :confused: maybe you need new rings

[woodsracer144]

cold its 175 worm its 151 i talked with pro x and they said i was good tu run pump (91)

[C-LEIGH RACING]

I would say that dome to be a 20cc & your compression amount is ok to run pump gas.
Without high compression though & it being a 265cc, you'll need to spin it some right high rpms for it to produce fairly good HP.
Neil

[woodsracer144]

i dont get the
it being a 265cc, you'll need to spin it some right high rpms for it to produce fairly good HP

this thing flys to me... i moved from a blaster and this thing has more than enough motor for me....

whats the most HP i could get? its the fasted quad i've ever rode on...

[C-LEIGH RACING]

Originally posted by woodsracer144
i dont get the

this thing flys to me... i moved from a blaster and this thing has more than enough motor for me....

whats the most HP i could get? its the fasted quad i've ever rode on...

You being so new to a 250R engine & comming off a blaster, you probably cant feel or tell the difference right now in hp amount from a 265cc cylinder ported for bottom end or high rpm output, so what I'm saying, most 265cc 250R engines are ported for upper rpm output because of the piston size, most, not all though.
In time though, you'll sort the 250R engine out, its functions & be able to feel just how it reacts.

There are some porters, that will build a 265cc engine with high compression so the output of the engine will produce power in the lower rpm ranges where you dont have to turn it high rpms for it to pull good.
A good pulling high compression 265, is an easy handling bike to ride, one that wont beat the rider up so much.
High rpm 265s can be a handfull to ride, about the time you think your doing good riding it & then comming out of a corner the engine jumps up on the pipe & BAM, your out of control & probably heading in a direction you hadnt intended the bike to go in, so now you got to control it.

In time, you'll understand what I'm saying & be able to see the importance of the cylinder porting & engine output matching the riders riding level.
When those things all come together, bike, engine, rider, match each other, normally that rider is the first to see the checkered flag in each race.
Have a good day.
Neil

[woodsracer144]

im a fairly good rider... this things weight to power is alot lower than the blaster... the blaster was stock and this thing is all aftermarket but the frame... and i can feel the powerband alot better.. and its alot more smooth of a ride... i can feel the power in the R motor when i come to the hills and i have it pinned out becuase i scoot right along up them... i havent noticed haveing to get the more Hp out of the Higher RPM's yet.... i've rode on 400ex's 450r's 300ex/250x's blasters... and alot of other sport quads and the 250r i have now has to he the funnest one i've ever rode...

[wilkin250r]

Let me see if I can translate.

Most engine packages are designed around racing, so the definition of "good" horsepower is really any amount that will compete with or beat other machines on the track.

Almost anything has a "price". If you want good low-end power, you're going to pay the price in top-end power. Or vice-versa, an engine with strong high-rev power (like a drag-racer) has very poor low-end performance.

High-compression is one of the few things that are almost "free". It gives you a good low-end boost without significantly sacrificing the top-end horsepower. This strong low-end power makes the powerband easier to manage, improves traction coming out of corners, and makes the bike less exhausting to ride. For this reason, most engine packages use high-end porting to give you good peak power, and high-compression to boost your low end.

However, if you don't have that high compression, then (as Neil stated), you'll need to be running high RPMs in order to get good power out of it.