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86 TRX350 advice and help

1541 Views 6 Replies 5 Participants Last post by  attitudeofgratitude
Hello I just finally registered after lurking around and reading for a month or 2. This is a great forum!!
I'm hoping for some insight or advice on my 86 TRX350. I was given this bike after it sat inside at my work for a year. Story is that it ran, but shut off. I figured out the ignition switch was bad. Ordered a new one (Honda OE) and replaced it. Got it running off carb cleaner and decided to get a carb kit and drain the old gas. The carb had been replaced with what I believe to be a newer model one since the throttle cable wouldn't thread into the body. I found the OE carb in a box of spare parts (never a good sign) and rebuilt it. Fresh gas, couple new fuel lines, proper vacuum line routing and it runs semi decent. No death rattles or mosquito killing smoke coming from it. But I did check the compression and it's at 126psi. Really low from spec. I've checked the valve clearance and set them. My question is should I keep going or scrap this project? Parts availability or being relatively affordable is not real good from what I'm seeing. Is there a good aftermarket supplier for this old model? Are newer models compatible with some parts? I'm of the belief that if I'm going to tear this thing apart and rebuild it then I'm going to go ahead and replace everything that is accessible while it's apart. I just don't want a ton of moola wrapped up in it. Any help, advice or criticism is appreciated!!
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Wiseco has 10.25:1 pistons and piston kits for the TRX350s from stock 68mm bore through 2mm (in .5mm increments) bore oversizes. You'll have to measure the bore before buying as shadetree advised. You can either find a reputable machine shop in your area to do the job or send the cylinder out to someone like G&H who will measure, bore to next oversize and final hone your cylinder to proper clearance for a Wiseco piston kit and sent it all back to you (including topend gaskets) ready to scrub clean & install. G&H also offers a reman service for your TRX350 head. Give them a call if interested.

No matter who does the machine work for you they must have the desired piston oversize in hand during final honing to properly clearance the piston in the new bore. If they say nah... we can do it without the piston... run away from that shop as fast as you can!

Welcome to the forums!
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You can still get OEM pistons too, in a few oversizes. If a parts outfit doesn't have them in stock you might find NOS pistons and ring sets on the fLeebay, though you'd likely have to pay more... Wiseco piston kits are better quality than OEM, are a compression ratio upgrade, not discontinued and a cheaper solution overall though.

As you might have guessed you'll probably need a new timing chain minimum... and a new cam sprocket if you can get lucky enough to find an NOS (not likely) at a fair price. An alternative 14321-428-000 cam sprocket may also be installed in the TRX350s, so there is hope... :)

Look the rockers, camshaft and cam journals in the head over real good during topend disassembly. If you need any of those parts your rebuild costs will go up.
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