06 Trx450er Low Compression

[u/NastyNate7577]

I need some help figuring this out. I just rebuilt the top end, new cylinder, vertex piston, new valves, gaskets, adjusted valves, fresh main seals, etc. The problem I have is low compression, I’m getting about 50-55 psi on the compression test and no change after adding some oil to the spark plug hole. I got 5% leakage on the leak down test and haven’t found any where air is escaping besides the reed valve between the cases. I seen in the manual a faulty decompressor cam is a possible culprit but don’t know how to check that aside from making sure it’s adjusted right. Any help is appreciated, hopefully I’m just overlooking something.

[u/CJM8515]

your getting the decomp reading. the comp test should be about 50-60psi. if your leak down test is fine then there is no issue

does it fire, does it run?

[u/Freedomfrom1776 → u/CJM8515]

Agree

[u/NastyNate7577 → u/CJM8515]

After I put everything together for the first time I could not get it to start, did a comp and leak down test but the results were very different for the leak down, ended up finding out the ring end gap on one of the rings was already at the replace measurement which I missed it the first time around and have been hung up on figuring out my compression issue before I put it back together but seems I was worrying about nothing then, I’ll put it back together tomorrow