Honda ATV Engine Repair Q&A

When you have questions about Honda ATV engine repair, our resident powersports pro John Talley has answers. From an engine that smokes and burns oil to a blown cylinder gasket, John addresses several engine repair issues with Honda ATVs.

John does live Q&As every Friday at 3pm Eastern on our YouTube channel, and in this session, quite a few questions came up regarding Honda ATV maintenance and repairs. Here are John's answers to several Honda ATV engine repair questions. 

Honda ATV engine repair

Honda ATV Engine Repair

When my 400 EX sits for a while and I go to start it, it will smoke, then stop and it burns oil. What’s the issue?

John Talley: It sounds to me like either your valve guides or your valve seals are starting to fail or have already failed. Because when the machine sits still and it’s got oil on top of the galley ways up under the camshaft, it’ll just run down past those seals down the valve guides and kind of pulls up in the cylinder and when you first fire it up, it burns off that oil. The only other possibility is that it’s maybe getting a little too much blow-by and it’s blowing it into your intake, and maybe it’s pulling in there. So check in your air filter box and make sure that doesn’t have any oil up inside the intake anywhere. If it’s not that, it’s probably going to be your guides or your valve seals, one of the two. 

Watch the video above to see how to clean and oil a Honda ATV air filter.

Buy ATV air filters

Buy ATV valve train parts

I recently noticed a blown cylinder gasket on my 400 EX. I’ve been riding it like that for a while, but I’ve got new gaskets now. Is it necessary to replace the top end as well?

John Talley: No, you shouldn’t have to. Just be very careful that you get everything back exactly where it was, to even try to keep the rings, wherever they decided to seat. I know they still rotate on the piston somewhat, but just make sure you get it back together. But that would be the best time, if you have to pull it down, to maybe pop in a new set of rings. Just look at the clearance and look at the wear patterns inside the cylinder and see what kind of shape they’re in.

Watch the playlist above to see how to rebuild the top end of a Honda ATV.

I have a 2008 Honda TRX 450 and I can’t figure out if I'm doing the valves right. I know that you should check on compression stroke, but I can't get it to start and it backfires. Any thoughts?

John Talley: It sounds like you’re going in the right direction. If it’s backfiring, that tells me that the valves aren’t shutting or closing completely and they’re probably out of adjustment. Yes, you do want to take it to the timing mark and put a feeler gauge on them to see where those lifters are set.

Watch the video above to see how to do a valve clearanace adjustment on a Honda ATV.

Want to see more live repair questions answered? See more motorcycle and ATV repair questions answered here.  



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