jdlmodelt

Halleluja!

Read this link about a guy with an 06 that turned out being jetting in the carburetor. https://www.trx450r.org/threads/wont-start-hot.177264/

Going out on a limb here. Ignition coil or spark controller, or crank pickup sensor? I wish you were my next door neighbor. We would have this figured out. I've seen some engines make a spark but not enough of a spark to get the engine to fire over. I would think if you were getting a weaker spark after 2 hours of riding, you'd notice a loss in power before shutting it off but maybe not. I had an old TRX250 that ran super rich and I had to change the spark plug on it everytime I took it out to ride. After driving it, later that day or the next day, it would not start again until I cleaned the spark plug. The spark plug would carbon up that fast. Running WAY too rich. I never got that carburetor tuned in. Your air mixture screw, if like most carbs, should only be about 1 1/4 turns out from completely closed if you are at a higher altitude. I'm at 6400 feet.

Freebo, I don't recall, is the rubber boot between the carburetor and the cylinder in great shape with no cracks? This would vary between a cold engine and a hot engine.

Freebo, when the spark plug has the black carbon build up on it and then gets exposed to a rich fuel mixture, it's most likely it will foul out, in my experience. I'm not sure why it seems to have more propensity to do that when hot as opposed to cold with your engine/carburetor. I don't recall if you installed a new, fresh out of the box spark plug when it's hot and won't start on the old plug yet?

I paid $900 for mine, 88 TRX350D Foreman. Sold the snow plow that cam with it for $200. So, $700 starting. Then the spending began. Lol. engine top end overhaul including bore and new piston, rockers, chain, gaskets, carb kit, front tires, some missing plastic, oil filters, handle grips, led headlight, both clutches, intake valves, seat, seat cover, totaled another $1028.56. So I'm in mine for $1728.56.

So, I finally got the nerve to pull the fuel tank and see if there was anything I could do to fixe the fuel level indicator/sending unit as it would occassionally flash 1 to 2 bars only when full and then no bars. I pulled the tank. removed the sending unit and discovered the pivot shaft was pretty floppy from 33 years of wear. I shimmed it up with some stainless steel shim material and got it to start showing level again. Cleaned out some rust and water in the fuel tank and put it all back together and now it's happy. I decided I needed to pull the fuel tank when I look inside and the color of the gas was opaque. foggy. Not right. Now it's clear after getting some crud out of there. I also added a heal shifter lever as my upper foot hurts when I shift with the toe shifter.

well done freebo86! I'm glad you stuck with it and now you have a fun machine with a healthy engine that you can enjoy!

totally unrelated but we popped the hood of my daily driver and the battery has a sticker on it from 2/2012 and the battery is still super healthy! That's like nine years!

we are doing Rotella in ours as well now.

and make sure you rinse the soap and dry the water off and oil the cylinder pronto so you don't get any rust.

Lol! This posting has been a constant whirlwind! I went back and read them all just to make sure I was caught up. He will have a good runner when He's done. I was dissapointed in how much I had to replace on my old 88 TRX350D after purchasing from the orriginal owner. Made me wonder what service he even had done on it over 33 years. It runs great now, but, I was getting pretty concerned when certain parts were not even available new for it anymore. No more ATV's over 20 years old from now on.

He's already sourcing a replacement head so, yep, read a few posts back to get caught up. lol! I know, it sucks to read back through them when it is this long after roughly a month of dialog. But half of what you spent time writing was old news. I'm giving you some joking Mr. Moderator. 🙂

just make sure you release that tensioner when you get the cam/chain installed. would be a bummer to forget. 🙂

Or have a machinist install a new seat. I wish you were out here. my guy does stuff for way too cheap.

aha! chain driven cam that drives pushrods. So cam isn't an overhead configuration. I missed that.

good deal. I thought he had already disassembled the top end.

It's your centrifugal clutch.

TDC on compression stroke. both cam lobes should be pointed down and both intake and exhaust should be closed. How were you planning to check with with your top end disassembled?

Aha! The 450 was the redesign when they started mounting the engines sidways. Yes, mine is an 88 TRX350D.

Is his crank shot? I wouldn't split the case unless it was necessary.

It's accessible from the right hand side by removing the right case cover. You don't have to split the case. At least that's how it was set up on the 350. It is recessed into the center cases in a small sump area that as I mentioned is accessible by only removing the right hand clutch cover case.

I hear ya regarding the time/money/value. I purchased my 88 350D Foreman for $900, sold the snow plow for $200. So started at $700. had to replace the rockers (used and nearly impossible to find), piston/rings/gaskets, had cylinder bored out to eliminate scoring from lack of oil or overheated (that made me nervous about other engine internal damage), two new front tires, replaced all lubes, purchased a seat pan (PO made one out of metal that didn't fit quite right), new foam, new seat cover, I probably have total of $1400 including the original purchase price. It's a Honda. They run forever if you take care of them. the PO who also purchased it new didn't maintain the engine oil as well as he should have I suspect. But, the engine runs like a champ now and the suspension and drive train are super tight. It's a solid ATV now. It would be about $8k for a new equivalent. Which is still tempting but I don't need it. so...

top end overhaul. not that bad. I did it to my 88 Foreman 350. Overhauling my Dad's 500UTV Hisun now.