[petey4]

Hi, I?m new here and I was wondering if anyone could help me out. I got an 1986 350 from a friend for free about a year ago. It obviously took some work, but I got it running after spending only a couple hundred bucks.

It ran great for a couple months. But one day I was riding it for about 5 minutes and it just died and I haven?t gotten it to start since then. It cranks and nothing more.

It gets a good spark, and fuel is getting to the carb. Everything I find online seems to point to the timing chain, but it seems to be in pretty good shape and isn?t very loose. I?m not ruling it out though. Let me know what you think. Thanks in advance.

 

[shadetree]

do a compression test !. these old girls require a lot of compression to run !. if that checks out good ?, then do a SHORT burst of starting fluid to the intake, give her a crank over, if it fires over after doing this ?, then you have fuel issues. if compression is good, and you know spark is good ?, it should fire over with a SHORT burst of starting fluid. STARTING FLUID SHOULD ONLY BE USED AS A TESTING METHOD !!!..DO NOT KEEP SPRAYING IT IN THE INTAKE TO KEEP IT RUNNING !!!!!!.

 

[petey4]

Thanks! Hopefully I?ll have time to do that before this weekend. I?ll let you know how it goes.

 

[shadetree]

Thanks! Hopefully I?ll have time to do that before this weekend. I?ll let you know how it goes.

your welcome. if I remember right ?, these old gals need a min of around 178 psi to run ?, anything over this is even better !.

 

[petey4]

I finally got a chance to do a compression test and it only got up to about 125 psi. I guess the issue is timing? What do you think?

 

[retro]

I don't care to take any guesses... I'd rather diagnose for the facts. And well, the service manual says the compression should be from 178 PSI to about 206 PSI I think... You were holding the throttle wide open while testing compression right?

Anyway, 125 PSI is low. If you are certain it has spark on a good spark plug and is getting fuel & carb is good and clean you'll need to find out why it suddenly quit running.

First thing to do would be to take the valve covers off and check the valve adjustment. That procedure is in the service manual and its quite simple to do. Basically you'll line up the "T" mark on the flywheel with both cam lobes facing down... that is the Top-Dead-Center on the compression stroke and that is where you check & adjust valve lash.

While its open snoop around inside the rocker cover with a small flashlight & mirror.... rotate the motor over a few times in the normal direction and watch the valves open & close to verify none are sticking open. Look at the cam lobes and rockers (rocker faces where they contact the cam lobes) to see whether they are worn bad or not.

If no problems are found under the rocker cover you'll be checking the timing chain wear next while you have it apart.

A quick explanation on how to do that on a TRX350 is HERE.

Update us if ya can... & enjoy your work!

 

[Goober]

You have the service manual right? Download it from link below. Check ignition troubleshooting guides. Check to see if your CDI has a crack in the sealant. I had a unit suddenly quit and it was this CDI and the sealant had exposed circuitry. Crazy thing it was running great the previous afternoon! Some folks say to tap on CDI while cranking I have never tried it.

You're supposed to hold the throttle wide open while cranking during compression test. I think otherwise the decomp lever actuates.