Partzilla Live Q&A with John Talley – February 12, 2021

John Talley wraps up another edition of Partzilla Live Q&A, in which he answers your motorcycle and ATV repair questions every Friday afternoon. 

Quite the variety of topics were touched on in this session, including electrical problems (specifically regulator-rectifiers) and a handful of Yamaha ATV questions (specifically the YFZ450). However, ATV oil-related questions seemed to be the most popular this time around. Check out excerpts from Partzilla’s latest live Q&A session below, and tune into our YouTube and Facebook channels every Friday at 3pm Eastern for the next edition.

Partzilla Live Q&A 02-12-21

Partzilla Live Q&A – ATV Oil Questions and Answers

Honda ATV Oil 

How many hours until I need to change Honda TRX90 oil?

John Talley: Well, that one’s a little bit tricky because it doesn’t have any type of hour meter, so you’re pretty much going to have to log your time as to how much you’re riding it. … it’s only a quart, so I would say about every 40 to 50 hours. If you take it out for 10 weekends in a row, it’s probably time to go ahead and change the oil, and don’t forget to take care of the air filter as well. If you do those two things, those little TRX90s will run forever … 

What oil type is better for a TRX90, 10W-40 oil or 20W-50?

John Talley: That’s a bit of a loaded question. The different weights and viscosities of oil are usually targeted toward what the temperature is that you’re riding in. If it’s really cold, you want a little bit thinner oil so it circulates easier. If it’s really hot, you want something a little bit thicker, to where it doesn’t break down so much and actually lubricates as it should. So the question really should be “what’s the temperature outside?", to determine which one is the better oil. It depends. 

I have a 2013 TRX 400EX and it burns oil. What do I do if it has the correct compression?

John Talley: Your compression is not the end-all and be-all, especially if you’re burning oil. If anything, when you get oil inside of the combustion chamber, it gives you a false compression reading because it actually helps seal up the motor more than it should be in some aspects. So, the question is, is oil getting there through a failed gasket or is it getting in there through valve seals, or is it coming up through and around the piston? Or are the oil rings not sealing up as they should? I would suggest that if you’ve done the compression test, and it’s not telling you the information that you need, to do what they call a leakdown test. I’m sure we’ve done that on several machines, and if you go through that procedure, it’s going to point you in the right direction as to whether it’s a valve problem, a gasket problem or a piston ring problem. 

Yamaha ATV Oil

Is it normal for the oil in the reservoir of my 06 YFZ450 to drain back into the crankcase? It's been sitting for 2 weeks.

John Talley: Yes, over time it is going to drain down into the crankcase. That’s why it’s very specific when you’re actually checking the oil level in there. It has to run for X amount of time and sit for X amount of time and then you check. Because that’s just indigenous to a dry sump system. So yes, it’s quite common for that reservoir tank to empty down into the crankcase. Nothing going wrong, it’s just doing what it’s supposed to do. 

Want to see more live repair questions answered? See all of Partzilla’s Live Q&A sessions here.  


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