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Checked my compression
Posted: January 11th, 2011, 1:18 pm
by robfromga
Faack! 100-105psi
Bike runs fine
Time for a topend? Unknown hours on the motor
Posted: January 11th, 2011, 1:28 pm
by Tharrell
Throttle wide open while kicking?
Makes a big difference.
Posted: January 11th, 2011, 1:33 pm
by robfromga
Tharrell wrote:Throttle wide open while kicking?
Makes a big difference.
Yep...wide open, thumb on the kill switch. Kicked the piss out of it maybe 10 times. I dont want to believe it, but I dont wanna go pull all that crap off again
Posted: January 11th, 2011, 1:39 pm
by lewisclan
if its a trail bike Id run it, it can stay right there for years
Posted: January 11th, 2011, 1:43 pm
by britincali
+1 My AF has shit compression and runs awsome, just means its easier to kick

Posted: January 11th, 2011, 1:46 pm
by robfromga
Really? Some Im not facked?

Im not getting at all full power am I? Not that I can handle full power...ya know what I be saying. I just have this thing about things running right.
Posted: January 11th, 2011, 1:50 pm
by AlisoBob
Look down its throat ( reed block out) and up its ass ( pipe flange) and if nothing is scored or cracked, follow Jays advice.
Posted: January 11th, 2011, 1:53 pm
by south central hoon
just ride it.
anything below 100 start looking at a rebuild. jay lewis is right they'll run for a long time right around 100psi.
also, what is your elevation? temperature? these things will affect the reading as well.
Posted: January 11th, 2011, 2:50 pm
by robfromga
south central hoon wrote:just ride it.
anything below 100 start looking at a rebuild. jay lewis is right they'll run for a long time right around 100psi.
also, what is your elevation? temperature? these things will affect the reading as well.
Im at about 300-400' it was very humid,id guess atleast 70%-80% temp was no more than 40f maybe even 35
Bob, I posted some pics in another thread, the intake is clean. I put a pipe on it a few weeks back, thought the exhaust was clean too. I need to reaseal the flange ill check it, but again I thought it was clean.
Im just kinda bummed, I want all my bikes to be at a certain level of repair and didn't want to break this one open yet.
Posted: January 11th, 2011, 4:19 pm
by robfromga
intake
see that scratch at 11 oclock?
Posted: January 11th, 2011, 4:46 pm
by AlisoBob
Looks fine to me, check it in another 50 gallons of gas.
Run some 927' @ 32:1
That will help seal things up....
Posted: January 11th, 2011, 4:55 pm
by south central hoon
just ride it!
Posted: January 11th, 2011, 4:59 pm
by lewisclan
south central hoon wrote:just ride it!
x2
Posted: January 11th, 2011, 5:02 pm
by robfromga
Bob, Ive been running Honda HP2 at 40:1 Ive got a couple cr125's and a 250 and they all get the same mix.... I cant tell if your pulling my leg about "tighting things up"?
What I dont wanna do is screw the bottom end, as in crack the piston, piston bits into the case....

Posted: January 11th, 2011, 5:05 pm
by south central hoon
JUST RIDE IT!
927 @ 32:1 PERIOD.
Posted: January 11th, 2011, 5:42 pm
by robfromga
south central hoon wrote:JUST RIDE IT!
927 @ 32:1 PERIOD.
OK!
thanks

Posted: January 11th, 2011, 10:52 pm
by Kuma
How do the scallips effect a compression check? don't they act like a compression release at slow kick start speeds and then don't play as much a role in the higher rpms?
if two equal motors, in port timing and calculated compression, what would the measured difference be between a scalliped motor and one without?
What are the advantages of running without scalliped bore?
Posted: January 11th, 2011, 11:06 pm
by AlisoBob
Kuma wrote:What are the advantages of running without scalliped bore?

Posted: January 31st, 2011, 7:40 pm
by robfromga
All this still has me thinking of a top end. Im gunna pull off the pipe and cycle it through to check the bore, is there anything stopping me from just ordering a flex hone? It looks pretty simple?
Ehhh?

Posted: February 1st, 2011, 12:34 pm
by nmdesertrider
Mine was 2 over and had a crack completely through one side of the liner on the intake side- if I didn't take the head off and check it I could have blown the motor- piston looked fine.
I think 'it depends'
Posted: February 1st, 2011, 7:04 pm
by robfromga
I pulled the pipe of tonight and checked out the cylinder, as best as possible through the exhaust. Looks good, no grooves on the exhaust side of the piston or no groves in the bore.
I did notices some lines running up and down in the cylinder, but the were smooth when I got my finger in there.... so am I cool? Can I flex hone it?
Posted: February 1st, 2011, 8:35 pm
by 100hp honda
i been lost from the beggining. your concearned with compression so you want to run a ball hone through it ? what good will that do if your planing to re-use the old piston

. if your that concearned just take the jug off and measure what you got. put it back together if everything specs ok. if not then put pc9 on there, its only $60. or get bore job and all new piston. 100psi aint ideal but the bike will still run fine and if the piston aint slopping then who gives a shit. like i said im pretty lost what your trying to do
Posted: February 1st, 2011, 9:40 pm
by mr500
The only thing you can't check by looking in the exhaust port is if the bridge is pinching/scoring the piston.Every 500 that I'v pulled the cylinder off that has been worked on by someone else, has not had the bridge relieved.
Lots of bike shops don't even know that 500 cylinders need this mod.
Pull off the cylinder and measure everything so you know where your at.
Posted: February 2nd, 2011, 4:45 am
by Tharrell
Pull the topend.
Check your ring end gap.
It may be that simple.
They're supposed to wear.
Posted: February 2nd, 2011, 4:46 am
by robfromga
100hp honda wrote:i been lost from the beggining. your concearned with compression so you want to run a ball hone through it ? what good will that do if your planing to re-use the old piston

. if your that concearned just take the jug off and measure what you got. put it back together if everything specs ok. if not then put pc9 on there, its only $60. or get bore job and all new piston. 100psi aint ideal but the bike will still run fine and if the piston aint slopping then who gives a shit. like i said im pretty lost what your trying to do
I never said a thing about reusing anything. Im just trying to redo the topend with out sending the jug out and missing a weekend of riding. I don't trust any of the local shops. So if the bore was clean, ie not scoredy plan was to pull the head on sunday, order a new piston rings gaskets etc, have that stuff Wednesday, hone it and pop it all back together.
Im slightly concerned with the 100 psi, id rather rebuild it and know what's what. The bike has a unknown history. I've rebuilt several topends but always sent away the jug, for nearly the cost of shipping I can get a 50 flex hone. My question was if that's kosher, not if I can reuse the stuff, im cheap ....but im not britt
