Valve adjustment questions.

[Sweetwilliebrownjr]

I've read somewhere that the valves tend to tighten up when they go out of adjustment on these motors. Is that right? It would seem that if that's the case, the engine would pull more vacuum? If that happened, wouldn't it then pull the slides and needles out earlier? It seems my bike is doing just that, and going pig rich at low rpm wot.it seems like the needles are pulling early and dropping too much fuel too early. Any one have any insight or experience with this?

 

[dannymax]

Not sure about your conclusion but yes, the valves do tighten over time.

 

[Sweetwilliebrownjr]

I guess if they got tight enough, they might not seat properly, which would cause low vacuum, which makes my assumption wrong. Trying to eliminate any possible items I may have overlooked.

 

[jfeagins]

Valves getting 'tighter' and 'not seating properly' do not necessarily go hand in hand. Two separate valve issues.

Not seating properly would be when the valve seats were worn, or the valve itself gets worn where it seats in the seat, or a combination of both. Can even be caused by carbon buildup in between the two, I guess.

Getting tighter would be where a valve begins to wear a bit on its other end at the point it contacts the rest of the valve train, and/or the cam lobes get worn, causing the valve to no longer open up to their specified gap.

That's the way I understand valve function anyway.

 

[Sweetwilliebrownjr]

I was thinking the adjustment got tighter, not the valve itself, which would open the valve more, and potentially cause it to not close all the way. If its the valve itself actually getting tighter, then my theory potentially holds up.

 

[dannymax]

The valves 'burrow' into the head, effectively reducing the shim to cam dimension....this in turn keeps the valve from opening fully to get it's proper cooling and can result in burned valves.

 

[Sweetwilliebrownjr]

But can it create excessive vacuum and affect the slide operation on the carbs? This is my main concern, because I've been fighting a rich condition for awhile, and cannot explain it.

 

[dannymax]

But can it create excessive vacuum and affect the slide operation on the carbs? This is my main concern, because I've been fighting a rich condition for awhile, and cannot explain it.

:confused2: Never heard if that being a result of out of adjustment valves....but maybe?

Why not check the valves, eliminate them as a possibility?

 

[Sweetwilliebrownjr]

:confused2: Never heard if that being a result of out of adjustment valves....but maybe?

Why not check the valves, eliminate them as a possibility?

Hard to find the time. I've been fiddling with the carbs in between jobs at work and at night when I should be sleeping. I also just got to the point where I'm considering this as a possibility. I'd like to avoid any potential down time until winter hits.