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By Dwight Williams
Ok, so I bought a 2006 bayou 250 for 200 bucks, kid couldn't start it and had no idea why it wouldn't run, I pulled the rope and felt what I thought was valve to piston contact, he wanted 500 and I talked him down to 200 and brought it home. Sure enough, timing was way far out, timing chain incredibly loose. So for fun I re-tensioned the timing chain and re timed it, got about 120lbs of compression, pretty low. I cannot get the chain very tight but the the tensioner seems to work fine, the chain guides don't look very worn. Also, when I took the head off the valves don't look bent and the piston has no discernible marks on it. Is this an interference engine? I sure thought I felt some contact with the pull rope but maybe no permanent damage was done? Anyway, I plan on doing a full top end job as well as timing chain tensioners and hopefully that'll cure it. Is there any reason other than chain stretch (I measured it and it's ok) or guide wear that would cause the chain to be so loose? Thanks!
I've never done this before but after reading a few thread I decided to check my valves for the first time and to my surprise it was much easier than I thought.
My bike is a 2005 Sp 500 HO.
I first pulled the seat and the right side panel off, and that's it! It wasn't too bad to get at.
Next I pulled the spark plug out and removed both the head cover ( 8-8mm bolts)
then the side cam cover (5-8mm bolts).
Also remove the plug in the recoil cover (14mm bolt) to see the timming marks.
Next I turned the engine over with the pull cord untill it was at TDC of the compression stroke.
The best was to tell that your at TDC of the compression stroke is to rotate the engine until the
timing marks are parallel to rocker cover gasket surface.
The cam sprocket locating pin will be facing upward directly in line with the crankshaft to camshaft center line.
Now fine adjust by looking into the timing hole in the recoil cover and line up the upside down "T" on
the flywheel into the center of the hole.
Now using a feeler gauge, slide the .006" (.15mm)blade between the top of the valve and the bottom of the adjuster and adjust accordingly
To adjust, Loosen the locknut (10mm) and check clearance with a feeler guage. Clearance should be .006" (.15mm) for both, intake and exhaust valves. Turn the adjuster with a stubby flat blade screwdriver untill the proper clearance is achieved then tighten the locknut (5.8-7.2 ft. lbs) while holding the adjuster in place with the screwdriver. Re-check the clearance with the feeler guage one last time and re-assemble the covers (72 in.lbs) and plugs.
The only thing that i noticed was that I had to clean and silicone the side cam cover other than that I found the whole process rather simple.
I'd give it a 4 out of 10 on the skill level scale.
I hope this helps!
By Brian Simmons
I have a 2003 Polaris Predator 500 . I know my valves need adjusted . Here recently I`ve had to bump start it . And i noticed a power differents . Now it won`t bump start . Did i mess anything up ? Or can I still just adjust the valves . By the way does anyone have a video of how to do a valve job on it ? Let me know ASAP !!!??? Thank you
I have an Outlander 800 XT with 480 hours on it. Very recently the engine power dropped significantly while riding. Soon thereafter the engine created much noise and stopped.
On opening the rear cylinder I found one inlet valve stem bent and the other broken. The valve head caused considerable damage inside the cylinder.
My reading is that the timing chain to the rear cylinder jumped at least one sprocket tooth to reduce the engine power, thereby compromising engine power, and then shortly thereafter jumped one or more teeth to allow the rear piston to contact the intake valves. On disassembly I did not notice that the timing chain was particularly slack, but neither was I looking for such things. The ATV has been serviced by agents according to requirements, in fact it was serviced very recently, by accredited agents.
Coincidently I met another 800 XT owner a couple of days ago who had had a similar incident a few years ago, which makes it likely that there are others out there who have had similar experiences. If there are I'd very much like to hear from you.
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Doing this for the first time on the old 2011 Grizz 700 and have a few q's?
I've found valve clearance specs as such...
Intake 0.09–0.13 mm (0.0035–0.0051 in)
Exhaust 0.16–0.20 mm (0.0063–0.0079 in)
If anyone can confirm that'd be great. I've been told to adjust the valve clearances to the top of the range in anticipation that they will tighten over time. This sound about right?
Are these the only two o-rings I'll need to replace? Both #18s in the schematic...
Yamaha ATV Parts 2011 GRIZZLY 700EPS 4WD HUNTER - YFM7FGPHA CYLINDER HEAD Diagram
And finally, which of those two valve covers are the intake and exhaust?
Also, was wondering about replacing my two gear box oil drain plugs and engine oil plug with the magnetic Gold Plugs. But at a price of $60 I'm wondering if they're actually worth it. Do people regularly find metal bits attached to these plugs?
A week ago I could not even get close to starting it. But now I adjusted the valves (exhaust valve was not closed). i got it running but would not run without choke. i adjusted the float because it was to low tried starting it up again and it would not even start. So i went back and looked at the valves and the valve was now open again so i adjusted it and it started right up and ran perfect without choke. So i put it all back together thinking it was ready to go. Started it up and let it run for a little bit. i turned it off and tried starting it again there was NOTHING. took it apart and there was 0 compression and the exhaust valve was open again. I am completely lost need help PLEASE!!!:aargh:
I have searched all over and can't find anything on how to adjust the valves on my sons 2007 Polaris sportsman 90. Has anyone done this? Anyone have a manual for the 90 showing how to do it? I need to get this done pretty quick, since he has a ride coming very soon. Thanks.
:aargh:I need a little help figuring out a vavle tightening problem im having with the bike. I adjust the valves with a feeler gauge, start the bike and ride for about 10 minutes then its starts to run really rough, check the valves and their now too tight, so i adjust them again run the bike for about 5 minutes and the bike starts to bearly drives now, check the valves and their too tight again...Now this happens to both intake and exhaust at the same time and approx the same amount of change. Also sometimes i go to start the bike after it starts to run rough (adjusting the valves back out because now thier to tight) after a couple pulls and it doesnt start i go to check the vavles again and they are wayy too loose, causing the bike to not start..Some how the valve timing/gap keeps changing..Could this be a cam or timing chain problem??They both looked good after visual inspection.Cant figure it out and need some help, any help is greatly appreciated, thanks.
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