I've been reading alot of posts about re-setting the valves every 20 hours of riding. I understand the concept of adjusting the valves after the engine breaks in. But I dont understand why they need to be adjusted so often. I wouldnt think the valves wear that quickly or spring become weak. Ether that or the materials that they are made from must be very soft. Once every year at the most should be more than enough. Even longer wouldnt hurt anything. Much better to be a larger gap than tighter. What say you gurus?

 

Dissimilar metals expand & contract & respond to heat in diffrent ways. They will strech & contract under normal conditions.
Also high RPMs do wear parts & a couple of thousands does make a diffrence.
Every time I've adjusted my valves (every 20 hours) the intakes has been tight, Too tight on the intakes will result in a loss of preformance & burnt valves.

It doesn't take long to do & if it makes my quad run better & last longer why not do it?

 

Thanks for the reply Moose,
I suspose if you wish to squeeze every last ounce out of an engine, then PERHAPS adjusting the valves may help. But I would think that unless something is wearing fairly rapidly it wouldn't be necessary and wont provide any substantial gain. I agree about the too tight valves. Not good. But it is sort of perplexinig how a valve gap can become smaller rather than larger with use. I guess I am just on the other end of the spectrum. Unless I hear em knocking at me, I leave them along. But I am a utility quad rider, which may make a difference.

 

If your valves arent adjusted fairly regularly, your quad may start to build up carbon on the valves and cylinder and you may end up spending alot more money in repairs. Also it may have problems with starting or idling, and your throttle response is going to get worse and worse.

 

This is certainly true. I think valves needed to adjusted periodically. But probably not needed as much as some think. It really takes alot to get the valves and cylinder in a carbon deposit situation and the large gap will do that along with uncombusted fuel or poor qualty of gas. Perhaps I should be thinking in terms of a high reving performance machine. I suspect these parts would wear excessively as compared to a utility machine where rpms and heat are less. Think I'll chalk it up to the excessive need for speed and performance which I am not really looking for. And like you imply a machine that has correctly adjusted valves will out perform one which is not therefore tweek what needs tweeking!

 

I set mine 2 times a year or when I have my tank off.Other than that if one of the 4 strokes get hard to start I set them then too.But on a Uttlity machine you dont expect the same performance as a sport machine.

 

Dormrat,
The problem is not that valves tend to be over spec but that they tend to be under spec, due to the continual pounding of the valve stems against the valve seats, causing the seats to be compressed, thus causing the valves to travel further in order to close fully. The time interval of course depends largely on the hours ridden and the degree of stress on the engine during that time. A general rule of thumb is about every six months unless raced or ridden hard. Less often if ridden very casually.