350x compression

[toyvette81]

well one of my questions is , is a 350x kind of quiet stock?? like a warrior or most other sport 4 strokes?
and i know the stock comp on the x wasnt all that high like 8 something? right,
well mine hits aweful hard to be stock compression the air coming out of the pipe hurts my hand and stings the leg through jeans, and its so loud it hurts the persons ears behind me and mine a little (no 1 wants to ride behind me), but thats besides the point, basicly i wish i had a stock 1 w/out a dg to see and feel the diff, mabye mine has a 10:25:1 or so in it? the guy said it was stock when i bought it about 6 months ago....
mabye this is why im running with & beating some quads that seem to not make sense to every1 on here.... im not 1 to lie and if it sounds that unbelieveable 4 a stock machine then it must be???

[hrc200x]

Yes, they should be fairly quiet, You might be able to look down the spark plug hole with a flashlight and see if the piston is domed.

[BIGCRIP28]

dont you have a gutted DG on it?
if so, thats why its loud. my DG is loud and it isnt gutted

[Blown 331]

If you have a 10.25 I'd say it would spark knock on 87 octane. What kind of gas do you run in it?

[fyi]

Stock C.R. is 8.5:1, as referenced from the factory service manual.

[toyvette81]

yeah i knew stock was around 8.5 i run 93otc in it, but have ran 87 and no real diff yeah i do have a gutted dg, but everything we have around here is built even my 89 polaris trailboss 250 hits hard lol, and the harleys, cars etc.. so i can pick a built motor out of a stock 1 and if i was not told that this X was stock i would for sure bet it had a high comp piston and a pretty steep cam but theres no real way of finding out unless it knocks with 87, take it apart which i dont plan on doing until it needs the rebuild, or put a high performance cam & high comp and piston in it or this winter when i Was going to rebuild it but if it has this stuff i wont be doing the cam and piston or i could ride a stock one if there was another 3 wheeler in nc besides my 2 lol

[toyvette81]

i have a compression tester.. what should that read for a stock 350x.? i know there not exactly accurate. and dont tell you #'s like 8.5:1 etc... but how many lbs should it read? does any1 know? if it reads something way over stock then i have 1 answer as to wether its high comp. or not.

[fyi]

178 psi. w/ a wide open throttle blade during cranking.

[toyvette81]

impressive fyi, i just went out there and tested it and it was about 178 on the money, ok well that helps me figure out wether my bike is in fact stock.... what would it read with a 10.5:1 piston? do you know? or does any1 else have a 10.5:1 or 10.25:1 piston in their X and what is your psi if so?

[fyi]

I'm not certain of what the cylinder pressure outcome would be with the pistons you list. There are really quite a lot of variables associated with compression and cylinder pressure relationships such as cam timing, duration, LSA, lift, ring condition, piston clearance, etc, etc, etc. Hence, there is no *real* accurate way I could say either way without guessing somewhat.

I can guesstimate for you however, based on some known math calcs I use here for auto engine build-ups, so only use these figures/data as a approx. reference point.

10.5:1 = 219-221 psi.
10.25:1 = 214-216 psi.

Hope that helps. :)

[toyvette81]

awesome, thats about where i guesstimated too, and were sure its stock now though right?
i want to build it this winter to 10.5:1 and the mid range cam but i did not want to do it if it was already built b/c it would be pointless, just wanted to make sure my compression was stock

[fyi]

and were sure its stock now though right?

That will be a call you'll have to make since you're right there with it. I would look for visual clues also like looking into the sparkplug hole to see if there is a dome on the piston, shiny corners on the head bolts where someone had a socket on them, new-looking gaskets, etc. etc. etc. ;)