Topic: Trail 90 issues

[Shenanigans]

1974 trail 90. Last ran 1980, All I have done so far is clean out the carb and put new fuel lines and a new battery. I have good spark and fuel in the bowl.

I kick and kick and after about 15 mins and she finally starts with the choke on. Only runs with the throttle open but seems to have good throttle response, so I am thinking the idle jet might be blocked? double checked and it seemed alright. Came back an hour later and could not get it to start. The air box is off so the carb is just open.

Sound like any know symptoms to anyone? Just wondering where to start...

[OakBehringer]

The air box is off so the carb is just open.

If your idle jet isn't clogged, it's running too lean to idle. If the trail 90 airbox is anything like my '72 Trail 70 airbox, it's very restrictive... your bike will not run well without it. If you're going to put an aftermarket filter on you will need to re-jet it. Obviously you would never even think about running it without a filter...

[Shenanigans]

The air box is off so the carb is just open.

If your idle jet isn't clogged, it's running too lean to idle. If the trail 90 airbox is anything like my '72 Trail 70 airbox, it's very restrictive... your bike will not run well without it. If you're going to put an aftermarket filter on you will need to re-jet it. Obviously you would never even think about running it without a filter...

Hah, I have a scan of that same ad.


The problem turned out to be the gas cap completely sealing, creating a vacuum when fuel tried to flow. I cracked the fuel cap and now she runs perfect. But thanks anyways!