Ok, So I got the service manual, read through it and it doesn't seem to be a hard job. Can I have some input from you guys that have done this before? I have never adjusted valves before, but it seems like all the pain is in GETTING TO the valve cover caps and the timing caps. Is there something I'm missing? Thanks

 

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any recommendations on where to buy the shop manual? I'm picking up a new 420 tomorrow! :-)

 

I bought mine from www.helminc.com. The price was $56.00 with shipping?! You may can find it cheaper if you look hard. The book is well worth the price though. The info is very detailed and has pictures and diagrams of every aspect of the atv. The link is below. Oh, and congrats on the purchase! It's an awesome machine!

www.helminc.com

 

just remember to have the engine on top dead center on the compression stroke. having it on top dead center after the exhaust stroke will cause you lots of problems.

 

and how can u tell if its tdc when i did my valves on my 350 i just looked when the valves were both closed and got the piston close to high as it can get where is a timing mark like a car ? mine is a fresh rebuild with 60 pounds compression and oil doesnt make it go n e higher

 

what tools are necessary for a valve adjustment on the 420?

 

I did mine last night. It took no longer than 1-1/2 hours. Before the valves were tapping really loud and after completion you could hardly hear them. I could still tell they were hitting, but nothing like before. The hardest part was taking all of the plastic and the gas tank off. One thing to remember is not to loose the little black clips that hold the plastic on. Also, make sure to turn the gas to "off" before taking the gas line off. I did take pictures and will try to post them at some point.

The tools that are needed (probably not a complete list) are 8mm, 10mm, 12mm and 17mm socket and a set of allen wrenches (I don't remember the sizes). The 17mm is for turning the crankshaft to TDC (which was easier to find than I thought). Other tools required are a feeler gauge (.006" intake and .009" exhaust), a phillipshead screwdriver (for the fuel "on/off" ****), a flathead screwdriver (for making the adjustment) and a 7/8" or 1" (don't remember) for taking the valve adjustment caps off the block.

TDC is marked by a line with a "T" on top. The line matches a notch in the block. You know you hit TDC on the compression stroke when you line up the "T" and there is "some", not much, play in the rocker arm. After that it is a matter of getting the feeler between the top of the valve and the adjustment screw. In doing mine, the exhaust side felt really tight and not much adjustment was required. However, on the intake side, it felt like I could have slid a penny between there. Like I said, my atv was really tapping loud after 27 hours. I've heard from others and on the web that you want to tighten the adjustment screw down until you feel a drag on the feeler gauge. Then tighen the nut down. I used an open face wrench (10mm I think) so that I could see if the nut was turning the screw and making it too tight.

I hope all this makes since. I have never done this before, so I hope some experienced mechanics can weigh in and describe this process in more detail.

If you want the page from the manual emailed, pm me. I Hope this info is helpful.

 

it says in my honda manual .06 for both intake and exhaust but that bit of difference wont hurt mine befor i set them were at .20 and knocking real bad theres this bolt located to get it to tdc if you want to email that pagees to me you cann at zettelryan@hotmail.com

 

Yes, the .009 is for the 420's and the .006 is for the 350's. I will scan the shop book in tonight and email it, though I don't know how helpful it will be because it is for the 420.