Just got my compression tested :)

[blaster2006]

heya, i tested my compression with a somewhat decent tester, but the thing which go's in the spark plug was about 3 or 4 times shorter (the threads) then the br8es spark plug... ( i have an adaptor to make it bigger, but it wont fit cause its too big and no place to get it inside the damn banshee chasis in the way.

 

but yeah, i tested it with the adapter being pretty small, i got 125 psi on the left cylinder and 120psi on the right one.

 

i hope thats pretty good being the threads were also pretty small?

 

also one stupid thing i may not have to mention but... im running a stock foam filter with airbox and lid, i DID push the throttle all the way in for unlimited air flow... but i dont know if it like.. even with the full throttle if it would get much air in it? or it does not make a difference about the filter...?

 

i would like to know till about what compression is it time for a rebuild? im thinking like about 100-110 psi right?

 

thanks.

Edited January 27, 2009 by blaster2006

[blowit]

heya, i tested my compression with a somewhat decent tester, but the thing which go's in the spark plug was about 3 or 4 times shorter (the threads) then the br8es spark plug... ( i have an adaptor to make it bigger, but it wont fit cause its too big and no place to get it inside the damn banshee chasis in the way.

 

but yeah, i tested it with the adapter being pretty small, i got 125 psi on the left cylinder and 120psi on the right one.

 

i hope thats pretty good being the threads were also pretty small?

 

also one stupid thing i may not have to mention but... im running a stock foam filter with airbox and lid, i DID push the throttle all the way in for unlimited air flow... but i dont know if it like.. even with the full throttle if it would get much air in it? or it does not make a difference about the filter...?

 

i would like to know till about what compression is it time for a rebuild? im thinking like about 100-110 psi right?

 

thanks.

 

 

 

NOPE. You will base your rebuild totally on hours and use. NOT, on compression. That is the easiest way to a new engine. You can easily break a piston skirt while still pumping new compression numbers. See it all the time.

 

 

Brandon

[magz]

if your motors all stock then your compression sounds fine.

 

 

 

90-100 psi is rebuild time, i think i remember hearing anything 10-15psi lower then what your originally supposed to have is rebuild time.

[blaster2006]

NOPE. You will base your rebuild totally on hours and use. NOT, on compression. That is the easiest way to a new engine. You can easily break a piston skirt while still pumping new compression numbers. See it all the time.

 

 

Brandon

 

problem is i bought it used, he tells me he ddnt use it much etc.

 

but by looking at the front tires, (stock) he never replaced them, they have like 10% tread, i should replace them asap. they are really worn out.

 

which means he rode it alot etc, but its very clean and he kept telling me it has low hours on it.

 

so god knows how many hours its got.

[blowit]

problem is i bought it used, he tells me he ddnt use it much etc.

 

but by looking at the front tires, (stock) he never replaced them, they have like 10% tread, i should replace them asap. they are really worn out.

 

which means he rode it alot etc, but its very clean and he kept telling me it has low hours on it.

 

so god knows how many hours its got.

 

 

If you plan to keep it, be smart about it and open the engine and have it mic'd so you know. I and some other very experienced builders could probably give you a god idea just by turning the engine over but that is still a best guess. You call. 30 bucks in gaskets and a few hours of your time.

 

 

Brandon

Edited January 27, 2009 by blowit

[blaster2006]

If you plan to keep it, be smart about it and open the engine and have it mic'd so you know. I and some other very experienced builders could probably give you a god idea just by turning the engine over but that is still a best guess. You call. 30 bucks in gaskets and a few hours of your time.

 

 

Brandon

 

yeah, changing top end gaskets are pretty easy imo.

 

i will do it eventually.

 

i plan on keeping it running good for abit longer than 1 year from now, cause then im selling it because im moving out of the country.

 

the problem is re-ringing and replacing pistons and expecially those rings, i dont even know how to put the rings or compress or make that clearance between the rings and cylinder lol.

 

it seems too complicated for me. taking the cylinders off and back on is more than enough to do myself.

 

i live on an island, in the middle east, so yeah, we just got the yamaha dealer and service center here.

 

no like proffessional motor builders for bikes

 

thats why things are bit tough for me.

[peterlocal22]

heya, i tested my compression with a somewhat decent tester, but the thing which go's in the spark plug was about 3 or 4 times shorter (the threads) then the br8es spark plug... ( i have an adaptor to make it bigger, but it wont fit cause its too big and no place to get it inside the damn banshee chasis in the way.

 

but yeah, i tested it with the adapter being pretty small, i got 125 psi on the left cylinder and 120psi on the right one.

 

i hope thats pretty good being the threads were also pretty small?

 

also one stupid thing i may not have to mention but... im running a stock foam filter with airbox and lid, i DID push the throttle all the way in for unlimited air flow... but i dont know if it like.. even with the full throttle if it would get much air in it? or it does not make a difference about the filter...?

 

i would like to know till about what compression is it time for a rebuild? im thinking like about 100-110 psi right?

 

thanks.

sounds good

[AKheathen]

you ever open those carbs up and give them a good cleaning?

[blaster2006]

you ever open those carbs up and give them a good cleaning?

 

working on it.

[locogato11283]

whats your elevation? 120 psi seems a little low to me, and i can tell you if my bike hit 120 psi, it would be getting it rebuilt ASAP.

 

if youre gonna take the time to tear it down, why not just rebuild it anyway?

 

i see no point in tearing it down just to take some measurements.

 

if youre doubting it, just rebuild it.

[blaster2006]

whats your elevation? 120 psi seems a little low to me, and i can tell you if my bike hit 120 psi, it would be getting it rebuilt ASAP.

 

if youre gonna take the time to tear it down, why not just rebuild it anyway?

 

i see no point in tearing it down just to take some measurements.

 

if youre doubting it, just rebuild it.

 

hmm, sea level, 120 psi, and 125 on the left cylinder( with like threads of the compression tester going in the cylinder only like 1/3 of an inch or so)

 

i could try to use the adapter for the compression tester with the longer and bigger threads. although that one is abit too big.

 

it is maybe 2-3mm longer than the br8es threads (i dont know well about this) but i was also abit scared if i used that ... the piston might hit it since its abit bigger than the spark plug XD?

 

will it? or is it safe to use

Edited January 28, 2009 by blaster2006

[blowit]

hmm, sea level, 120 psi, and 125 on the left cylinder( with like threads of the compression tester going in the cylinder only like 1/3 of an inch or so)

 

i could try to use the adapter for the compression tester with the longer and bigger threads. although that one is abit too big.

 

it is maybe 2-3mm longer than the br8es threads (i dont know well about this) but i was also abit scared if i used that ... the piston might hit it since its abit bigger than the spark plug XD?

 

will it? or is it safe to use

 

 

VERY big difference in having the right compression tester adapter. You should pump up 135psi or so with the correct tester. That does not always means your motor is perfect, but sounds like you lack support there so run it till it blows!

 

Brandon

[locogato11283]

hmm, sea level, 120 psi, and 125 on the left cylinder( with like threads of the compression tester going in the cylinder only like 1/3 of an inch or so)

 

i could try to use the adapter for the compression tester with the longer and bigger threads. although that one is abit too big.

 

it is maybe 2-3mm longer than the br8es threads (i dont know well about this) but i was also abit scared if i used that ... the piston might hit it since its abit bigger than the spark plug XD?

 

will it? or is it safe to use

 

were you getting a good seal? is there an o-ring on the tester? was it down far enough to seal?

 

sounds like you might need a better tester. my comp tester fits really well into the dome and it seals with an o-ring.

[blowit]

were you getting a good seal? is there an o-ring on the tester? was it down far enough to seal?

 

sounds like you might need a better tester. my comp tester fits really well into the dome and it seals with an o-ring.

 

 

I know what he is talking about. The adapter just does not have the long reach threads like the spark plug because it is made for lawn mower type plugs. They also generally do not have a schrader vavle right at the tip and that is a big no no. The proper test adapter should show a nice bump in cranking compression.

 

 

 

Brandon

[locogato11283]

I know what he is talking about. The adapter just does not have the long reach threads like the spark plug because it is made for lawn mower type plugs. They also generally do not have a schrader vavle right at the tip and that is a big no no. The proper test adapter should show a nice bump in cranking compression.

 

 

 

Brandon

 

so basically his tester is junk? sounds like too many variables to me to be considered reliable.