Shifters on trek mountain track 800
 

I'm having problems with my shifters shimano, the front I can only shift through the smallest 2 cogs, the rear through the smallest 4 cogs. suggestions? I have reset the tension when on the smallest cogs. I can force gear shift by pulling the cable. should the softer be able to click through the gears if the cable is loose? I would put a picture of my shifters but can't figure out how.

Most of us would rather not have to search for your bike's specs to know which shifters it has. If a photo isn't possible a description will substitute.

If the shifters are Shimano lever types then the problem is likely that the lube has turned gummy and causes the ratchets (the little parts that make the click) to no longer freely rotate on their small pivot shafts. Short solution if this is the case is to spray a light weight lube into the shifter pod and work the levers until enough lube has gotten to the ratchet pawls and softened the gummy stuff. Long term is to use solvent, dry out and then use thin then thick lube. Andy.

I've serviced some of these older Shimano click shifters. The ratcheting disc is actually a plastic thing, and the tabs can break off. You need to remove the cover, put the bike up on a stand, and watch the shifter action while you crank and shift. Sometimes, as has been said, it's just gummed grease that is fouling up the ratcheting mechanism. This can be flushed with a small brush and some WD-40. You'll have to replace with a suitable grease, almost anything you find at your autoparts store will do.

The alternative is to replace the 3 x 7 shifters with Shimano ST-EF51 combination shifter/v-brake levers. They can be had on eBay from various far east sellers for about $20 shipped. I got my last set from Malaysia for under $20, took 10 days. They come with inner cables, too. So, there's that...

thank you, they are the lever style with brake levers on them, I have taken the covers off, they look grimy inside, will work on cleaning them up. What type of line? a past, spray, oil?

Cleaning worked! They are now shifting smoothly, still have a little tweaking in the cable tension on the rear, but that will be easy. I have spray bike lube, Teflon based, would that be good to spray the shifters?

If you flushed them with WD-40, no need to really use anything else unless you want.
You know what to do next time.