‘03 Arctic Cat 250 4x4 valve adjustments

[Breita]

Yes, I’m a Newbie to this forum, (so be kind… lol).  I’ve owned my ‘03 250 4x4 for 2 years… had to do a top end rebuild when first acquired.  I’ve also had to adjust the valves twice already and they need adjusting again.  I only ride periodically because the ATV is at a vacation home and not used year round.  My question:  Is it normal to have to adjust the valves every year?  I recently adjusted the valves this past summer and now the compression is 35psi (with no start).  I just started riding off road and am “self teaching” repairs from YouTube.  Any advice is greatly appreciated!

[Mech]

No, valves should not need adjusting every year. The most common reason they need readjusting is because they weren't set to the right setting to start with.

If you are adjusting them with feeler gauges you need to be sure there is no wear on the valve end or the rocker that's upsetting the measurement. It might be better to use a dial gauge that measures in thou, or calculate how much of a turn it will take of the screw to give the right gap, and then back the screw out from zero gap to get the required gap. It's important that you end up with as much clearance as possible, without noise, hot or cold.

Some old bikes with worn rockers and valves need a bit of trial and error to get them adjusted and stable. The apparent gap isn't always the only play. Sometimes we need them to have a slightly bigger than recommended gap, and sometimes slightly less. First up check the gap cold and then hot and see whether they gain or loose clearance when they warm up. Then factor that in as you are calculating/adjusting the clearance.  Always start with a little too much gap, and then if they are noisy, reduce it till they are just quiet hot and cold and then they should be stable.