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Discussion Starter · #1 ·
Hey guys, I just picked up a 1987 TRX 350 4x4 tonight, it's really nice, in really good shape, and I'm excited to get it on some local trails. It starts right up, and runs well, but there is a knocking noise while it's idling. As soon as I give it some throttle it goes away. It shifts great, and otherwise is perfect. Anyone have any thoughts on what it could be? I'm not all that mechanically inclined when it comes the motors, so I'm not sure if it's a valve adjustment issue or if it's a timing chain issue, or a cam chain (is that a thing?). Any help would be great!
 

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Cam chain and timing chain are the same thing. Can you post a video of the knocking?

Welcome to the forums!


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Discussion Starter · #3 · (Edited)
Thanks!! I'll try to grab a video of it tomorrow night, but it is pretty loud until you give it some throttle. There's no power loss, and it's not running bad, just making the noise while idling.


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welcome to the forums. knocking ?..or clicking ?, or clanking ?. there is a difference !. clicking tells me cam chain. ticking tells me valves. clanking..tells me piston, rod, crank.
 
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Congrats!! Good job on getting the 87!
When I needed a cam chain, I could hear the valves clacking but not a knocking sound.
Could be you just need the valves set but it sounds like lower end
If you're not mechanical you may want to take it to the shop and let them diagnose it.
At least download the service manual here
 

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Discussion Starter · #6 ·
Hmmm, I'll get a video and post it so you guys can hear it. Like I said, as soon as you give it throttle it stops and it starts easily/runs really well regardless. I can't believe how great of shape this thing is in, probably as clean as you will find for a 30 year old machine.

Here is a pic:



Just hoping it is nothing major and that I can ride it!!!


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Discussion Starter · #8 ·
Haha true!! Ummm... I traded a Kimber Ultracarry II for it... hahaha.

Could the decomp lever make noise? I think I read that somewhere...


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Discussion Starter · #9 ·
Also, is there any chance it could be something to do with the clutch? It just seems odd to me that the noise would happen ONLY at idle if it was something to do with the engine... literally give it some throttle and its gone.


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without tearing it down...AFTER YOU GET A SERVICE MANUAL !. there is no way for us to tell you one thing or another ?. all we can do is point you in the direction of what we may think it is going by what your telling us ?. no, it's not the decompression lever, reason: if it was ?, it would do it at all times. could it be the clutch ?, maybe ?, maybe not ?. you have a solid. great atv, the down side of owning that model ?, IS FINDING PARTS FOR IT ?!. as most are discontinued today. if you do find the part your after ?, YOUR GOING TO PAY TOP DOLLAR FOR IT IF ITS OEM,NOS ?!.
 
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Discussion Starter · #11 ·
Yeah, it looks like there are a ton of parts on eBay but there is a honda dealer near me that I think I could get some parts thru as a last resort. I'll have to take a video later and have you guys hear it.


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That is a great looking unit--easily worth $2k --- has a winch and plow mount.

If you're close to a Honda shop load it up and run her by there -- let the fellas get a peek. They would be excited to see this old rig and they could give at least a cursory appraisal on the knocking sound.

Most Honda shops will charge extra to work on older machines unless they are in great shape.

Get the service manual--download it here or buy an old paper copy--or both. Even if you're not mechanical now you can work to find your comfort zone.
 

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Discussion Starter · #15 ·
Hahaha it is nice looking, just gotta figure out the noise and it'll be golden!

Any idea how big of tire will fit with no lift? Does anyone even make a lift for these?


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No lift that I know of but I am an OEM guy there are members here who've tried it mebbe Tennessee Country Boy

I have a set of 25s on the rear of a shop atv and didn't realize it! I'm thinking front clearance might be tricky
 

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I noticed the plugs for your front brake drum inspection ports are on the wheel not the brake drum. This is a common misplacement I see this even on old Honda brochures. Just don't push it too hard into the port as you fit it into the port or you'll have to dig it out with a pair of needle nose pliers
 

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Discussion Starter · #19 ·
Anyone know what the plug on the right side of the headlamp is for? Also, when I turn the key on and the machine is in neutral and I'm not sitting on it the neutral light comes on and I can start it. If I do sit on it, the light won't come on and it won't allow me to start it. Is there something I can adjust to fix that? Noticed it today.

The winch doesn't work either, anyone have experience troubleshooting those?
 

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You probably have a loose connection on a green wire that goes down to the neutral switch by your right footpeg

The plug by the light is an accessory power plug; you can wire stuff to it and energize thru your ignition switch

That sounds like your piston is hammering on a valve I hope I'm wrong! At the least it needs a valve adjustment
 
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