pics of bad comp
- Thread starter 2stroke4life
- Start date
hes getting 90 psi and i told him to check his rings and stuff.he put pics but i dont really see anything wrong with sleeve atleast in pics maybe u can give him advice pittboss ur the tec....
i do believe between 120-150psi dont hold me to that but i also heard they will run fine at 100 so
Around 125-135. Check the clearance between the piston skirt and the cylinder, if greater than .004 it needs bored.
instead of bore can i get a std or bigger piston. they have a top end rebuild kit on ebay, piston, rings, bearing and gasket, would that fix it. i dont want to spend a lot of money, i want to spend least as possible.
If the bore of the cylinder is too big, out of spec for Std piston size, then you must bore to the next size piston. You bore the cylinder using measurements from the new piston.
If the cylinder is out of spec, just bore it and put the new piston kit in it. Better to do it now and it's fresh. Also be sure to run good oil. If a ring sticks due to carbon build-up say hello to wall scoring.
Also if you removed the oil injection, due to it being air cooled, run a little richer oil to gas ratio...I would say no less than 32:1
If the cylinder is out of spec, just bore it and put the new piston kit in it. Better to do it now and it's fresh. Also be sure to run good oil. If a ring sticks due to carbon build-up say hello to wall scoring.
Also if you removed the oil injection, due to it being air cooled, run a little richer oil to gas ratio...I would say no less than 32:1
u have to order the piston kit first because the shop has to have it to do the measurements on the boring..so u kinda have to figure how bad your sleeve is but if u can get away with one piston size do that rather than going more....32:1 going richer than that ur gonna foul plugs like crazy i run 40:1 to 48:1 and never had a problem thats just my opinion pc
just for my own personnel knowledge, can i ask what in hell the temperature outside and hight above see level would have anything to do with how much compression a cylinder and head would have?
Effective or dynamic compression is the amount of pressure that is actually made by the piston and cylinder during the compression stroke. The effective compression will decrease when you go to higher altidudes from lower ones. Less Dense air at higher altitude = lower compression than sea level.
Also the colder the air the more dense it is.
Also the colder the air the more dense it is.
Please don't take my post as saying you didn't know what you are talking about.
Also Daniel, what octane gas are you running with your mods? I was thinking of milling the head .010 on this blaster I'm rebuilding but not sure if it's worth the gain. Are you running a Vito's advance timing key?
Also Daniel, what octane gas are you running with your mods? I was thinking of milling the head .010 on this blaster I'm rebuilding but not sure if it's worth the gain. Are you running a Vito's advance timing key?
could you explain that a little more? from my experence It shouldn't matter what elevation you are. compression will be the same at 5,000 and 0 FT. because your just compressing the air and fuel your not changing the internals of the motor. example shaving the head will give you more compression. elevation will need a jetting change cause the higher you go less air. by what I got out of your post if I have 130 psi at 5,000 ft then at sea level I should have 170 psi I don't see that happing. engines do run better the lower the elevation, you lose power the higher you go. I ride snomobiles and they said the engine loses a certain amount of power for ever elevation change up. but its only a couple of ponies enless your at 10,000 ft plus. Maybe I'am wrong.
hi joepa....
i really didnt know much about altitudes and the effects on the way an engine runs, so dont worry bout me taking your post in the wrong way, i learn something new everyday i log into these forums. thats why i come on here.
I run cam two race fuel in my blaster. its convent for me because there is a gas station about 2 miles down the street from my house that sells it. i live in upstate ny where its snowmobile country half the year, race fuel around here is easy to come by and not too expensive. i milled my head down .020 and thats getting down there pretty good ! i had bristol do most my work and they said they recommend race fuel for any head milling greater than .015 . they also said i may be able to run 94 if i wanted to try it but i may get allot of erratic spark and allot of fowled plugs. (may run like sh*t but it may not) .
also i haven't done anything with the timing yet, i had a certain amount of money put away last fall for my blaster project and have already spent most of it. building are blasters sure is freaking expensive isn't it !
i already have a new cdi box i would like to get hooked up , and over the next few months i wanna get my timing done and a new race carb from project blaster on it. THATS THE GOAL ...lol
i really didnt know much about altitudes and the effects on the way an engine runs, so dont worry bout me taking your post in the wrong way, i learn something new everyday i log into these forums. thats why i come on here.
I run cam two race fuel in my blaster. its convent for me because there is a gas station about 2 miles down the street from my house that sells it. i live in upstate ny where its snowmobile country half the year, race fuel around here is easy to come by and not too expensive. i milled my head down .020 and thats getting down there pretty good ! i had bristol do most my work and they said they recommend race fuel for any head milling greater than .015 . they also said i may be able to run 94 if i wanted to try it but i may get allot of erratic spark and allot of fowled plugs. (may run like sh*t but it may not) .
also i haven't done anything with the timing yet, i had a certain amount of money put away last fall for my blaster project and have already spent most of it. building are blasters sure is freaking expensive isn't it !
i already have a new cdi box i would like to get hooked up , and over the next few months i wanna get my timing done and a new race carb from project blaster on it. THATS THE GOAL ...lol
DBlaster
Ok, the compression ratio for an engine is say..10:1. That's not going to change no matter what because it is a formula of cyl volume, stroke, cylinder head dome size etc.
As far as effective or dynamic compression it is how much air can you get in that given amount of space then compress it. If air at sea level is X dense and then you climb higher in altitude the air will be lest dense. Meaning less amount of air in the cylinder to be compressed...less compression (psi). I dont think the change is that dramatic but enough to notice a differance if the carb isn't jetted properly.
Daniel,
Since you run race gas I would recommend trying a vitos key. I believe it's $20 and I'll let you borrow my flywheel puller to install it. really easy to install and from what I noticed on the Blaster is the most bang for your buck. Where are you located in NY. We head up to Pulaski all the time to go fishing..looking into purchasing land up that way soon too! Maybe we'll have to meet up some time to do some riding.
Ok, the compression ratio for an engine is say..10:1. That's not going to change no matter what because it is a formula of cyl volume, stroke, cylinder head dome size etc.
As far as effective or dynamic compression it is how much air can you get in that given amount of space then compress it. If air at sea level is X dense and then you climb higher in altitude the air will be lest dense. Meaning less amount of air in the cylinder to be compressed...less compression (psi). I dont think the change is that dramatic but enough to notice a differance if the carb isn't jetted properly.
Daniel,
Since you run race gas I would recommend trying a vitos key. I believe it's $20 and I'll let you borrow my flywheel puller to install it. really easy to install and from what I noticed on the Blaster is the most bang for your buck. Where are you located in NY. We head up to Pulaski all the time to go fishing..looking into purchasing land up that way soon too! Maybe we'll have to meet up some time to do some riding.
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thanks for the explaination didn't know the fancy word for it I work in a machine shop and my boss drag races and has a specail tool to read it and change for elevation and temperature has to compsate for it on his time to run down the track. does this sound right.
