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how many of you guys have never had to adjust your valves. i checked mine after the first 2 rides, then a year later. they have never been out. i know with this motor they rarly do. my question is its getting time to check them and i hate doing it. should i skip it. how many of you have never had a valve come out of adjustment.

parx

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Hey Parx;

If'n you'd rather skip the valve check, one of the best ways to know if your valves are going tight or out of spec, is how your bike starts. If she starts well, most likely your valves are doing OK, and vis versa. It's not a horrible process to check them, so do it however often your comfortable with.

BTW, I'm doing mine once a year just to be sure.

Dodger :D🙂

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I am doing a top-end rebuild on my bike rightnow, and after 1 year of racing MX, my valves were WAY out of adjustment. I had to go to 1.45 shims on the exhaust side, and 1.45/1.50 shims on the Intake side. Stocks are 180/185's. My valves being out of adjustment seems to be from the falve faces beating the seats all to hell. The valves seal terrific after I put the correct shims in them, but the bike almost WOULDN'T start towards the end of the season. I got 2 DNF's because of the bike going down, and it not starting when hot. I was having very funny carburator problems towards the end of the season, which I equated to a messed up carbeurator, but it now seems that the intake valves were never completely sealing, so some pressure was being blown back up into the carbeurator when running. My case is probably on the extreme side, but checking your valves should only take you about 20 min. Take off the seat, tank and shrouds. Remove the upper motor mount, and then pull off the valve cover...it takes a bit of manipulating, but it WILL come out...have someone help you keep the wire harness out of the way. you can get a feeler gauge in to check the gauges from there...just make sure you do it when it's COLD. There is a handy-dandy chart in your book that shows you what shims you'll need if any of them are out of spec, so you don't have to have your bike down while you order new shims (watch out, they're around $6.00 EACH!). I am ordering my shims just a hare on the low side, to give myself room when the bike is hot, but this will give me more valve-seat wear at high-rev's. It's also going to cause some damage to my cam's as the cam will be encountering more of a 'slap' when the lobe encounters the bucket than if I had less gap....but I really want the bike to start when it's hot from now on...

The 'hopper'

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The valve clearances on my '99 WR400 had been pretty stable for about the last year and a half. They were all always within specs, on the tight side. I check them about every 6 months.

But the timing chain gave up the ghost a few weeks ago (stretched) and jumped a couple of teeth on the exhaust cam. Luckily, it ran for about only 10-15 seconds like that so no major damage was done to the valve train. I replaced the cam chain and guides and put the motor back together. One of the intake valves was a little tight when I was reassembling but not too far off so I figured I'd just ride and re-shim it in a couple of weeks. I ran it for about 250 miles in those two weeks, then I checked the valve clearance again. I did notice that starting had become more difficult than it used to. All the intake valves were too tight, and one of them had zero clearance and one exhaust valve was a little tight. Luckily, the local dealer keeps a large selection of shims in stock and he had exactly what I needed. I put it back together last night and it started first kick-much better! I had also been having some stalling problems so hopefully this will fix that. I thought it was my carb that was the culprit but now I'm pretty sure it was the valves. The spark plug looked perfect- a light coffee-colored insulator- so I'm not messin' with the carb for now.

If your valves don't need adjustment, don't sweat it because they will sooner or later.

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