Gear shifting issue

[Andy2157]

Hey all,
I have keysto ks777 21 speed mountain bike. I'm not able to shift the front gear to third level (highest level)
After shifting first two levels my shifter doesn't work at all
Can anyone help me?

 

[raleighnut]

Select gear 2 on the front shifter lever then adjust the cable tension so that the front mechanism is central on the middle cog, if that doesn't work post again.

 

[PpPete]

Try adjusting the 'H' limiting screw (usually the outer screw on top of the front derailleur.)

I would suggest that anyone who does not know what they are doing does NOT adjust the limit screws.
This is far more likely to be a cable tension problem.
Obviously difficult to diagnose at a distance but try this first:
Move the chain on the smallest cog at the front. Check for any slack in the cable (where it is bare wire - not in the housing)
Is there a cable adjuster anywhere? if so, wind it anti-clockwise a half turn at a time until it works.
if not, undo the bolt that holds the wire into the front derailleur. Remove any slack - pull it with pliers if necessary. Retighten the bolt.

 

[PpPete]

Move the chain on the smallest cog at the front. Check for any slack in the cable (where it is bare wire - not in the housing)
Is there a cable adjuster anywhere? if so, wind it anti-clockwise a half turn at a time until it works.
if not, undo the bolt that holds the wire into the front derailleur. Remove any slack - pull it with pliers if necessary. Retighten the bolt.

Spooky !
I had to do this myself mid-ride this moring.