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I have a 100 gal compressor and it didnt kick on. I dont understand why they would make the gauge not even make it on the scale... I mean it never even budged off of the pin once it pegged. I had it on for 30 sec at 100psi. So I'm guessing its holding compression.
I have a 2 normal compression gauges. One of them holds the pressure inside until the cranking is over and can be released afterwards and it only gives me about 30psi. But I have one that bounces every stroke and it gives me about 72psi wot cold. That's with the exhaust cam shimmed at .14mm. With it shimmed at .20mm it was about 60psi.
Keep in mind that the last time it ran I rode it one day and the next it wouldnt start. I had low compression and couldn't figure it out so I replaced everything new except the head and cams. I had it decked and a valve job with new oem valves and springs. Now I am still having issues with compression. I'm around 13.5:1 and shimmed properly I'm only around 60psi.


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Did you properly gap the piston rings before you installed the piston...???

Also, The leak down test is two stages...

First stage is to determine the % of air leaking indicated on the red.yellow & green gauge...The video shows the procedure starting at 2:00...

Second stage is to turn up the PSI on the regulator to better hear where the greater air loss is coming from...why you need 100 + psi air compressor to better hear the air leaking...!!

intake, exhaust valves=leaking out the throttle body or exhaust pipe. head gasket= air bubbling in the radiator...piston rings=air leaking out the motor vent...

(Note) the motor vent hose in connected to the intake tube...might give a false reading if left connected...!!!

 

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Discussion Starter #142
I have my crankcase vent ran to a separate filter. I am going to put that base gasket on and measure everything there is from gap to compression and post it and hopefully you can catch something I'm doing wrong.

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Discussion Starter #143
My ring gap was incorrect. I must have gapped them in the old jug because they wouldnt even completely fit the piston with them shoved against the piston gap back. It's a je piston and I have the gap size sheet.
Which option would I choose though. It goes from street /strip to race blown?



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I saved this from my buddy
 

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Discussion Starter #145
The rings are done and I assembled the head and cams. I bought a new leak down tester because I thought the old one wasnt giving a correct reading. It was tho.
I have 100% leakage. Watched the video posted here and 3 more to be sure I'm doing it right. Unfortunately I am.
I turned the air up to hear it better and its pooring air out around both the intake and exhaust. Brand new valves and supposedly valve job from Dasa but it's not holding compression at all. I can see around 60psi on a bouncing compression gauge, and about 25psi on a stored compression gauge. The bike wont start and the shims are .14mm intake and .20mm exhaust. I've checked the timing 3 times, it's right.
I'm guessing I have to send this head to a professional racing shop again to have them checked?

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Discussion Starter #146
Never mind my last comment! Gauge was leaking.... I am getting right on the line between green and yellow. Which is still not good, and with the air turned up to hear it better....its still the valves leaking, both intake and exhaust.

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They cut the seats?

The seats should be good, and the valves should be flat.

Is timing 180* out?
 

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They cut the seats?

The seats should be good, and the valves should be flat.

Is timing 180* out?
I thinking the same...check if the valve timing is 180 degrees off...Check if the valve lobes are facing away...exhaust too the front of the motor & intake to the rear of the motor @ TDC

Like in picture shown...!

Is the piston 1-compression ring or 2-compression rings..??
 

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Discussion Starter #149
Heres where the cams were when I tested.
2 compression rings and 1 oil ring. It's a je 12.8.
I'm going to swap it out with my old piston and see if anything changes... (old piston is a wiseco 12.4) only about 10hrs on it) both 96mm


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Discussion Starter #150
Heres the wiseco... top ring gapped to .015" and second gapped to .018" as directed on the paper that came with the piston.


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Discussion Starter #151
They were supposed to cut the seats. I feel like they did but I cant tell for sure. I see one of the exhaust valves has an offset ring around it that appears to be shiny like it's new metal, but its offset to the valve seat. I tried to capture it the best i could. If you cant make it out I'll try again.
Intake shims are at .13mm and exhaust at..18mm and .20mm.


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Discussion Starter #152
Question?
I believe that when I put these kx450 cams in here someone said to make sure I switch the sprockets so that I kept the kfx450r sprockets instead of using the kx450f sprockets.
Why is this? They look the same. The spring size is all I see.
Previously the engine turned over fine but just didnt have good compression. I just started to wonder about the compression release. It all seems to be fine though


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Discussion Starter #153
Here is the first compression test after I have it back together.... this gauge holds the compression in until released and gave me about the same reading before. All tests are cold and wot.


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The exhaust cam mechanism has different parts.

The pin is shorter

If you didn’t change the gear and mechanism that’s part of the problem.
Also, you can’t use exhaust cams from a kx past 09
 

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I saved this from my friend tony regarding ring specs for the JE 12.8

He installed a 2 ring 12.8
 

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Discussion Starter #156
I have the kfx cam sprocket on there... it's the same one that I've always used.
I've never had a problem with an engine like this in my life. The only parts of the old engine left are the head and cams....

the issue has to be with one of them.

Considering the head just got re-done and ported I'll start by replacing the exhaust cam first.


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Discussion Starter #157
What I can say is i removed the spring from the exhaust cam and turned it over and even with a strong battery it couldnt turn the engine over because of too much compression so I couldnt even get a reading on that.

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Discussion Starter #158
I have kx cams in my bike now...if I want to just replace the exhaust cam, can I get stage2 hot cam to replace it with, or does it have to be a kxf cam?

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I have kx cams in my bike now...if I want to just replace the exhaust cam, can I get stage2 hot cam to replace it with, or does it have to be a kxf cam?

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No! it just has to be within the years of 2006~2008 KX450F...I recommend KFX450r hotcams stg 2...I have stg 3s in mine...!
 

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Discussion Starter #160
Just gonna buy new hot cams. I'm seriously considering using stage 3 instead of stage 2. I realize that it moves the curve higher. Just wondering if there are any real drawbacks?

It seems that if I have a +3 rod and valves that open further from taller lobes then it makes contact seem more likely...

However since it will be getting more air and stay cooler it may lower octane requirements right?


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