1986 250 sx ticking and loses power

[Bfoco]

Hey, I just purchased a 1986 atc 250sx and it starts first or second kick and idles great. The problem is it has a slight ticking noise until it warms up. In first it takes off great but it bogs down when you shift into second third but in fourth it seems to run great as long as you dont slow down. Anyone knows what it could be? Thanks

[knappyfeet]

A lot of my things "tick" until they warm up but it's probably not related to your running issues. Never the less.......check the compression for piece of mind

Over the years I have found that 90% of running/performance issues are related to the fuel system.......more often the carburetor.

Has the 250 sat for awhile?

[Bfoco]

Yes it has been sitting for a few years. I have cleaned the carb. The one way bearing is bad also. When i kick start it, it free spins. I will be chaning that soon. The compression is a little over 100. I was thinking the timing chain is whats ticking or knocking but after idling for a few mins it stops. I cracked open the oil line and its pumping oil so I ruled that out. The power loss is mostly on take off. If its in netural it revs up no problem just in gear it bogs down until you get to a decent speed.

[yaegerb]

Yes it has been sitting for a few years. I have cleaned the carb. The one way bearing is bad also. When i kick start it, it free spins. I will be chaning that soon. The compression is a little over 100. I was thinking the timing chain is whats ticking or knocking but after idling for a few mins it stops. I cracked open the oil line and its pumping oil so I ruled that out. The power loss is mostly on take off. If its in netural it revs up no problem just in gear it bogs down until you get to a decent speed.


100 PSI is really low. To see if its rings, pour a little oil through the spark plug hole and recheck compression. If you get a higher compression reading its time for rings/bore/piston. I would also check valve lash if you haven't already.

[knappyfeet]

Yeah that's low compression and it's robbing your power.

Oil in the cylinder can give you an indication of rings but my thought has always been this...............since your going to have to get into the motor to do the rings or the valves I would do the other at the same time........get the whole done proper. I mean if I was doing a Honda CBX I might just address the problem but since it's a thumper I would attack everything.

[Bfoco]

I have 2 big red 250es a 1985 and a 1986. I used the same guage on those and got about the same compression 105. I dont know if the guage is worth a darn. They both run great no issues. It is a guage from harbor freight tools. I will try to put a little oil in the head to see if it helps. I always thought if rings were bad it would smoke? I doesnt smoke at all.