1987 Honda TRX350D

15795 Views 156 Replies 9 Participants Last post by Goober, Oct 31, 2020

SnapTech

Discussion Starter · Oct 12, 2018

Hi all,
First post. Just got a 87 TRX350D for free from a guy who was gonna junk it. It hasn't been run for a couple years so wasn't disappointed when it didn't start, no spark. Took the CDI out and threw it in the freezer over night and reinstalled the next day. It started. WOOHOO! I let it run for about 15 min. At first it blew a little smoke but that stopped after a couple min and purred away. As it was running I looked it over and saw it was leaking oil between the head and the cover. Shut it off, then it wouldn't restart. No spark. CDI bad. Ordered a new one. While waiting for parts, took head cover off and no seal. Chain was tight. Checked valve lash before taking cover off and they were all in spec. Put the cover back on and rechecked lash, all good. Installed new CDI and it started right up, but is blowing smoke like crazy. What did I do wrong? It wasn't blowing smoke anywhere near what it's doing now.

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retro

· #5 · Oct 13, 2018

Have you changed the oil & filter? What do you have in it? Is it overfilled?

Also check the crankcase vent hose to make sure it isn't plugged up by mud daubers or something.

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retro

· #8 · Oct 13, 2018

Don't throw your original CDI away... those 87 350D CDIs are one of a kind and they can usually be repaired. Cold/cracked solder joints is what makes them fail.

Another question... what type of sealer did you use on the the rocker cover? Any chance you partially blocked the oil drains leading toward the chain/sprocket end of the cam with silicone sealant? If so, oil can get forced past the valve seals and make it smoke like a train.

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retro

· #12 · Oct 14, 2018

Unless you used OEM Honda carb parts or a genuine Shindy carb kit, you'll have to fix your carb too. Let us know how it goes with the compression test and bore measurement if you refresh the topend.

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retro

· #15 · Oct 21, 2018

Ya thats it! I suspect that the valve springs are sacked (you can have them checked on a spring scale) and the valve retainer smacked that guide, breaking it. Most of the original valve springs in TRX350 motors are sacked after 30+ years of service so this is not uncommon. Luckily it didn't drop a valve.

You can still buy an oversize valve guide from Honda but the OEM valve springs are NLA. Shindy sells all four valve spring sets though. Check those retainers out closely and replace any that are damaged by contact with the guides. And check each valve for a bent stem, especially the one that was in that busted guide. If anything looks questionable, replace it. Shindy sells valves too, I think...

If you decide to swap a used head on it rather than fix that one you'll need a new set of valve springs and seals and make sure the cam journals are in good condition... with no rolled out aluminum in the journal oil dam areas.

Keep us posted if you can.