New to 4 stroke tuning

2strokesteve89

2strokesteve89

ossagp:
What I was talking about was the pressure that combustion produces. Typically max about 8-12 times what you get without ignition. I am confused by what you are saying.
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All I was saying is if say you have 150 psi cranking compression, then you should expect to see about 75 psi compression while the engine is running. Maybe I didn't understand what you where getting at but that was what I was trying to say.
 
O

ossagp

Well you still lost me there Steve. It sounds to me like you are saying that the motor while running is making about 75 psi. I know that cant be what you mean as far as combution pressure goes. (If it was your car would run better off it's starter.)
 
2strokesteve89

2strokesteve89

ossagp:
Well you still lost me there Steve. It sounds to me like you are saying that the motor while running is making about 75 psi. I know that cant be what you mean as far as combution pressure goes. (If it was your car would run better off it's starter.)
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Thats ok.....however in my 30 years as an auto mechanic, I've never seen a naturally asperated engine have more compression running, than cranking, just tested a chevy 350 last week, (150 psi cranking 55psi running) and it ran well, however none of this really has anything to do with this thread, and thats my fault, so if you want to continue this conversation I will either pm or another more appropriate thread....thats all folks
 
YZcarver

YZcarver

To be fair, I did take it all apart and put it back together. There could have been an air leak or something. It seems relatively happy now. I just wanted to say that that was all I did. No jetting changes, no valve adjustments, just the simple things, disassemble, reassemble, new gas.
 
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YZcarver

YZcarver

Got a ZipTy fuel screw. Took the stock one out and found that the washer and oring were flopped. It's much happier now. Starts easy. Runs good. Still pumps out a ton of heat, but hasn't boiled over on me yet. Got a trail Tech Voyager. It tells me I've hit 226 degrees on a casual ride. That seem normal?
 
hondacr500af

hondacr500af

2strokesteve89:
Thats ok.....however in my 30 years as an auto mechanic, I've never seen a naturally asperated engine have more compression running, than cranking, just tested a chevy 350 last week, (150 psi cranking 55psi running) and it ran well, however none of this really has anything to do with this thread, and thats my fault, so if you want to continue this conversation I will either pm or another more appropriate thread....thats all folks
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that is not right at all. The compression will not be lower while running. Especially when the pistons expand at running temps.
 
2strokesteve89

2strokesteve89

hondacr500af:
that is not right at all. The compression will not be lower while running. Especially when the pistons expand at running temps.
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I see what I see, you believe what you wanna believe.do a running comp test and tell me what you get, you need to pull the valve core from the tester, but try it for yourself.
 
O

ossagp

2strokesteve89:
Thats ok.....however in my 30 years as an auto mechanic, I've never seen a naturally asperated engine have more compression running, than cranking, just tested a chevy 350 last week, (150 psi cranking 55psi running) and it ran well, however none of this really has anything to do with this thread, and thats my fault, so if you want to continue this conversation I will either pm or another more appropriate thread....thats all folks
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Didn't we establish that we were talking apples and oranges in the type if test? Avg cyl pressure etc?
 
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