MannyIsle 3 Posted November 10, 2021 Hi, just purchased my first ATV (an oldy) for some snowplowing. I've taken it for a few short runs and I've noticed that the top end of the motor (cylinder) begins to smoke (whitish smoke) after riding for 5-10 minutes. There is no smoke coming from the exhaust, and it doesn't smoke on startup. Also, the overheating light doesn't come on to indicate any issues with heat. Trying to figure out if it's just burning off water or old oil from the exterior of the motor, or if there is a bigger problem I may need to address. Thanks! Share this post Link to post Share on other sites
Goober 1,555 Posted November 10, 2021 you need a service manual Possibly oil leak from the rocker box cover or valve cover. Note: do not over torque any of those bolts or you’ll strip the threads. possibly overheating and burning off old oil; is the engine really hot? If your oil light is not coming on you need to replace the oil temp sensor and/or the alarm box you’re going to have to figure out where the smoke is originating. Share this post Link to post Share on other sites
AKATV 850 Posted November 10, 2021 Welcome to the forum! Great little machine will last forever with a bit of maintenance It may have a small leak at the valve cover? check with flashlight-its pretty common Need to determine if it looks/smells more like steam from water or smoke from oil If you just bought it, the owner could have pressure washed it and might have a bit of water up top boiling off If it is valve cover, a great time to adjust valves and seal up valve/rocker cover Share this post Link to post Share on other sites
Fishfiles 20,147 Posted November 10, 2021 11 hours ago, MannyIsle said: Hi, just purchased my first ATV (an oldy) for some snowplowing. I've taken it for a few short runs and I've noticed that the top end of the motor (cylinder) begins to smoke (whitish smoke) after riding for 5-10 minutes. There is no smoke coming from the exhaust, and it doesn't smoke on startup. Also, the overheating light doesn't come on to indicate any issues with heat. Trying to figure out if it's just burning off water or old oil from the exterior of the motor, or if there is a bigger problem I may need to address. Thanks! welcome to the forums , there is a sealing washer on one of the bolts of the rocker box of the 300 , it is located at #19 on this print , it may be missing from some previous work ------------ could also be leaking from the decompression lever shaft seal , or the rubber cam end cover or a few other spots around the rocker box Share this post Link to post Share on other sites
Goober 1,555 Posted November 10, 2021 Check also for leak or puddled fuel on the rocker cover—from fuel tank. White smoke isn’t usually oil, but it can be in small amounts. Share this post Link to post Share on other sites
MannyIsle 3 Posted November 10, 2021 Thank you so much for all of the input. The oil light does work, as it comes on for 1-2 secs when I turn the key to the on position. I'm going to try and let it run for awhile this afternoon and see if I can pinpoint where the smoke is coming from. I took a few photos and it does look a bit oily at the top end, and this might be the culprit as the oil burns off. Share this post Link to post Share on other sites
MannyIsle 3 Posted November 10, 2021 For service manuals, does anyone have a preference between the one from Haynes or Clymer? Share this post Link to post Share on other sites
AKATV 850 Posted November 10, 2021 (edited) Don’t use either of them they’re so abbreviated and a lot of the information it’s just combined and jammed together You can go to the service manual area here on the Forum and download the actual Model specific Honda factory service manual, they are superb and cover everything from basic maintenance all the way up to a complete engine tear down and rebuild Here is the link to the TRX300FW manuals https://drive.google.com/drive/mobile/folders/1GcqS65GYd3yFmEAGsI7LP-eZp2jMRVJU/1eqVb5JW5em4PBbDrgHsRbhFKH5rFr75l/1vG2Up48bgvpVgopy-jLg5p1AKUWQnypf/1xPtIRTon47rnmYmqflFS5d8LqLeuZlql?usp=drive_open&sort=13&direction=a (Man I don’t know why that link is so long…) Edited November 10, 2021 by AKATV 2 Share this post Link to post Share on other sites
Goober 1,555 Posted November 10, 2021 (edited) Yeah I don’t like either clymer or Haynes. i got the Honda ecopy and then bought printed copy off fleabay. you’ll want the 88-94 honda trx300 manual sometimes you see 88-90 or 88-91, etc. these manuals printed before intro of later models. These OK too but latest revisions are better wow that thing looks oily!!! Edited November 10, 2021 by Goober Share this post Link to post Share on other sites
MannyIsle 3 Posted November 10, 2021 The Honda factory service manual is amazing! Thank you for providing the link. Just want to say that this forum has been such a great help, thank you! 45 minutes ago, Goober said: Yeah I don’t like either clymer or Haynes. i got the Honda ecopy and then bought printed copy off fleabay. you’ll want the 88-94 honda trx300 manual sometimes you see 88-90 or 88-91, etc. these manuals printed before intro of later models. These OK too but latest revisions are better wow that thing looks oily!!! Ya I'm going to clean off all that oil and see if it helps me identify where the leak is coming from. 3 Share this post Link to post Share on other sites
Goober 1,555 Posted November 10, 2021 Very good. To inspect and clean You’ll have the remove the fuel tank. Two plastic tabs, 1 bolt and a fuel line. i usually drain it first (but you don’t have to) by using a tall funnel and fuel can: close the petcock disco the fuel line from the carb or petcock drain the tank Remove the kick start cover Disconnect the plastic fender tab (left side) from the tank. Very important or you’ll break the fender. remove rear tank mount bolt. ensure rear of tank will rotate slightly upwards easily. Grasp front of tank forward of fuel cap Tank rotates rearward and upward from two frame rubbers (see diagram) clean off oil using penetrating oil, brushes and rags. Don’t want you using strong solvents on anything exposed, like gaskets plugs paintwork and aluminum 1 Share this post Link to post Share on other sites
shadetree 5,977 Posted November 10, 2021 1 hour ago, MannyIsle said: The Honda factory service manual is amazing! Thank you for providing the link. Just want to say that this forum has been such a great help, thank you! Ya I'm going to clean off all that oil and see if it helps me identify where the leak is coming from. i'll save you the trouble. clean it all off the top of the engine, go buy a tube of yamabond or hondabond ( DO NOT USE RTV SEALANT ! ), get yer hands on the oil seal for the decompression release lever, the o-rings that go in the valve inspection caps ( 2 ), and there is two small o-rings that are around the rocker shafts ( slotted ends on spark plug side ) that will need replacing ( very common to leak oil ). the hardest part you will face is getting the rocker shafts out of the rocker box, reason : they are held in place by dowel pins ( or used to be ?), and can be tricky to remove. what i do is clamp these pins in my bench vise, slowly turn the rocker box back and forth, while i pull up on the rocker box, this allows me to remove the pins. once the pins are out of the rocker box, then you can pull the rocker shafts out of the rocker box, PAY CLOSE ATTENTION TO WHICH ROCKER GOES WHERE !. 1 Share this post Link to post Share on other sites
AKATV 850 Posted November 10, 2021 8 hours ago, MannyIsle said: The Honda factory service manual is amazing! Thank you for providing the link. Just want to say that this forum has been such a great help, thank you! Ya I'm going to clean off all that oil and see if it helps me identify where the leak is coming from. You are welcome, this is the a great place for help and advice Let us know what you find and how you make out See you around! Share this post Link to post Share on other sites
