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View Full Version : learned something know today



junkyardjon
10-01-2012, 12:12 AM
when your intake valves are adjusted too tight, you lose compression and it won't start.

been working on a customers KFX 700 quad over the weekend, all he told me is it was running slow and now it won't start.. so after checking spark & fuel i pull the carbs & clean them, 1 pilot jet was plugged. i figure that can't be the problem for the no start. so slapped it back together and still nothing... so i pull the cover's to see if a valve is bent or something, figure i'll check the valve clearance. pull the plugs to find top dead center and it don't have any compression. i told him i'd check the valve clearance anyways.. so now i'm thinking the engine needs a top end, it had zero compression !!
i figure i'll set the valves and let him know his motor is toasted tomorrow lol. so i pull up the factory manual and set the valves, slap it back together for the hell of it and hit the starter button. to my surprise it fired right now but made alot of valve noise, figure i adjusted them too wide. so i go through it again and same thing, valves way too loose. now i'm getting pissed cause i'm following the manual to a T but it has compression now !!! so i watch the valves move and find the widest gap and set gap, which is about 30 degrees or so past the mark the manual said to set them at. spin the motor over a few time and check the gaps again and there all spot on now.

so i learned the valve adjusters of kfx700 like to tighten up and lose compression(first i've seen this happen) and the factory service is flawed when it come to setting the valve adjusters. also learned it's a torgue monster that has to problem lifting the frontend and gets up to speed real quick lol
next up is a honda 400ex that likes to over heat...

Caveman
10-01-2012, 02:43 PM
well if intakes are too tight, then no air or not enough air in there to compress. I get it sounds weird at first, but if you work it out, it makes sense. Cool find Jon.

Gas Man
10-01-2012, 03:25 PM
Those times when the world is out to get you... :wtf:

:lol: glad you got it all figured out.