Heres what I did- Don’t forget to hone the cylinder. Use lots of assembly lube. Before first start take out spark plug and turn engine over a few seconds to get oil flowing around a bit. Start it and let it idle for 30ish seconds, then rev it keep the rmps varying but not too high. This is so that the rings seat properly. And you need the variations to mimic the kind of conditions it will be facing while you ride- constantly changing rpms. Once it seems to be pretty well warmed up to regular operating temperature or you feel it has run long enough, let it cool down completely. Repeat the rev/cooling process 2 more times. Once you are ready to ride take it easy for the first 10 miles or so. Check all nuts/bolts periodically through this process. Hope this helps. The kit may come with recommended instructions also.

My own quad is a 1991 Honda Fourtrax 300FW, bought used 6 years ago. Only major repair I've done on it is replaced the rear axle and wheel hubs 2 years ago due to the splines on the axle ends and the wheel hubs wearing out ( a common problem on many of the older solid rear axle machines). I replaced the battery a couple of years ago and replaced the brushes in the starter this year. That's it for repairs. A friend bought a 1988 2 wheel drive Honda Fourtax 250 that had really been rode hard. The rear axle swing arm and torque tube was all cracked up.. Some welding and gusseting with my wirefeed and the machine has been good to go since. In my opinion, you can't beat a Honda for reliability and longevity.

Thanks, that's a lot better price than the rebuild kit I looking at for $140. Thanks. So, I will check the compression, replace the sp, and get this kit for the valves. I will attach a picture of my carb- It doesn't look like the one the YouTube vid..maybe the former owner put in the wrong carb? I dunno..

Back to the topic, I,ll be a Honda fan until I die. I went to work as a mechanic at a Honda shop in Oak Ridge Tn in the fall of 69. The owner sent me to the Honda training center in Atlanta several times. Since then I have worked at a lot of motorcycle and car dealers and none have impressed as much as Honda. I remember when Japanese bikes were considered to be cheap imports. We've learned a lot since then.

In BC, other than the cheapie smaller Mainland Chinese offerings , the Polaris is likely the least popular. I don't know about newer models , but the older ones gained the nickname "Pullhairis". It would be hard to go wrong with any Honda , Yamaha, Kawasaki or Suzuki if it was kept reasonably well maintained. One machine that far too many dismiss as " Chinese junk" but actually is one of the best is the Kymco... built in Taiwan.. Kawasaki , Yamaha and most likely Honda still have ties with Kymco. Kymco originally built parts for Honda before branching out on its own. It now is one of the largest manufacturers world wide for scooters, and supplies motors and other parts for some of the big name Japanese quads .. BMW ( yes , that BMW) has close dealings with Kymco. I am not familiar with any of the larger mainland Chinese made ATVs, but I've seen some that look very good. Don't kid yourself . The Chinese can make some cheap junk, but they can also make some products that can compete on the same level as the best of the world.

A manual is at the top of my list,but I need a few more post for that. I've got to get the plastic all off and give it a good cleaning. Put a winch on last weekend and saw there is a lot of dust buildup under the covers from sitting. I'll send some pics soon.

I've always had either Kawasaki or Yamaha in my garage. 2 strokes imo are easier to work on but comes with repairs quicker and maintenance and jetting and blah blah blah. I like the "edge of the seat" feeling. But I choose these to particular brands because Yamaha has sleek lines in the plastics and haven't changed alot over the years. And Kawasaki just because green is my favorite color. Lol. Sent from my SM-N920V using Tapatalk

Most of the smaller ATVs I believe have throttle limiters and not speed adjusters exactly, but it will allow you to keep them below a certain speed if they can't give it more gas. * Topic moved to General ATV Discussion Forum and adjusted topic title

You would definitely want to look through the manual but here's a good video to give you some idea on the process of air/fuel mixture.

I would agree with @Frank Angerano, look on ebay for used. I changed your topic title to be more descriptive of what you are looking for on your Honda 400ex.

Athena (P400250600300) Top End Gasket Kit https://www.amazon.com/dp/B00PLS6ZXW/ref=cm_sw_r_cp_api_77R6BbVRTF3VG Carb cleaner is great but sometime you have to run a small wire through the jets to be sure they are clear. I also like to blow air through the jets to be sure they are clear. I like to use a piece of wire from a bicycle brake cable, one strand of that. There are also small brush kits for cleaning carburetors on amazon as well.

Look on eBay. It will be a used pipe but most likely in good shape. I’ve picked up a few used exhaust pipes, silencers etc. factory parts that bolted right up. Just make sure of the year and keyword used.

go off the specs in the service manual to start with

You are not wrong just not aware. I have attached a pic for you to see. This is an adjustment to the needle hight inside the carb. To high the carb will result in too much fuel being delivered. So take a look and see. Maybe a long shot but def worth looking into. Put the clip at the second to last high spot on the needle and try that. Most common spot is in the middle or second to top. Also Manley sure all the meats are clean. After that I would go with a fresh plug and check the spark. Just to be sure it’s a good clean spark. https://youtu.be/7lnURLsBIHg Sorry make sure all jeys are clean . *** Jets* dam spell check!

Welcome to Quadcrazy! Nice looking bike. I’m not sure how mechanically inclined you are but if so then I would keep the bike! My guess is since you see blue smoke it’s most likely bad valve seals if the smoke goes away after it’s been running. It’s a valve seal kit you can buy and install. If your not familiar then we can help as well as you tube. If the blue smoke is constant then maybe a piston and rings may be in order. As far as the carb goes and if someone had tinkered with it before then my guess is the needle on the carburetor is set wrong. This can be adjusted very easily by following the throttle cable down to the carburetor and unscrewing the slide from the carburetor and making the adjustment on the needle. Its a clip on the main needle in the carburetor Go to YouTube and you will see how this is done. As well as Quadcrazy helping you along. Looks like a good bike but don’t feel obligated as I have a live for old bikes especially since yours is in such good shape

Well. Blue smoke is burning oil. Could be bad seals. Flooding is a float issue adjust to spec. Sent from my SM-N920V using Tapatalk

I agree! First things first; oil,lube and filter. Fresh spark plug and some clean petro. Get familiar with the bike and be safe. Good luck and send some pics. We love pics!

Welcome,sounds like a nice quad. I would start with a manual,you can find them here. I would start with fluid check and grease it up.. Good luck and have fun.

Age - got to the age where I needed something for hunting coues whitetail deer in some rough country in southwest AZ. Getting to them is difficult. Spent 25 - 30 years walking; glassing and stalking them and body just wants to do it a little easier. Used to ride bikes in my early youth, love all things mechanical - worked on heavy equipment for 42 years, so ATV's are a nice break to work on; ride and just enjoy in the outdoors!

Cool, I had a buddy that had a king quad with the shifters like that. The closest manual is a 1987 Topic moved to Suzuki forum.