First bike, starting steps.

[Sourmilk]

Hello first posting here about my first bike. Just bought one XS400 for 2 hundo. It needs some love which is fine cause its chilly out. I have experience building mopeds so I'm not a total newb. Also have repair manuals.
So currently the bike starts and idles. When you give it some throttle it bogs down. I figured the carbs need a tuning. While putting in new spark plugs I tested the cylinders compression. lefts at 90psi and rights 100psi. I assume it should be around 140psi. While checking the forum earlier someone mentioned cleaning the values?
I assume its the rings. Should I first plan to replacing the rings and seals, see if that improves the compress, if not dig deeper?
Thanks. I look forward to getting some feedback now and with future questions.

 

[xschris]

Put a little (like a teaspoon) of oil down each plug hole then do a compression test. If they go up a lot say to 140-150psi then its your rings. If it only goes up a little say 100 -120 then its your valves.

 

[Sourmilk]

Awesome, thanks Chris. Yeah I had read that and wanted to do that be before I did anything like tear everything apart. I dont know the history of the bike. As of now it needs brake work, and this ring/value issue. After that I was just going to re-oil and re-grease it and make sure everything is nice and tight. Anything else that would be advisable?

 

[xschris]

Make sure your carbs are clean.

 

[Sourmilk]

Totally.