'86 Spree runs then dies

[Burl_GT]

It starts up, runs for a couple minutes, then dies. After a few minutes it will start again but will run a shorter amount of time. Seems to die once it gets hot. Idle jet screw has negligible effect.No apparent vacuum leaks. Carb has been gone over. Starting to lose my mind on this one..

[martynkim]

Several potential issues here. Have you read the manual? Without details on things like was it running? What is the condition of spark plug filter petcock exhaust? More detail prehaps one of us can help.

[Burl_GT]

Several potential issues here. Have you read the manual? Without details on things like was it running? What is the condition of spark plug filter petcock exhaust? More detail prehaps one of us can help.

700 original miles. Airbox leak-tight. Carb-manifold leak tight. Carb dipped, cleaned, float polished, jets blown out and clear. Mix screw turned out 1 7/8 turns. Petcock is supposed to be brand new according to previous owner. Plug looks fairly rich. Adjusting the mix screw lean, only lengthens the amount of time it will run. Has good spark. New plug, good wire and boot.

A couple of thoughts:

Compression? Seems low on the miles and very clean to have issues here. I will check but, not expecting to find a problem. Maybe torquing the head bolts is necessary?
Clogged exhaust? Also seems unlikely given the mileage but worth a look.

The bike is so simple which is what I think complicates it. I'm guessing it is something minor that I am overthinking.

[martynkim]

Check vacum hose to petcock and bystarter

[Wheelman-111]

Greetings:

If it starts easily and runs reasonably well for a few minutes, it isn't likely to be compression or spark.

Particularly since the plug looks rich I think it's probably running on the open Bystarter. That's about the time it takes for that circuit to close. Once it does, if the Pilot is still obstructed, your symptoms would be expected.

The other possibility is a float bowl that isn't being filled quickly enough. Insufficient vacuum with the throttle open due to a crack in the vac line or loose connection would close the petcock and stop the flow. Obstruction between the petcock and carb - including the petcock itself - is another possible cause. Martinkim's suggestion covers that angle.

[Trafficjamz]

Greetings:

Insufficient vacuum with the throttle open due to a crack in the vac line or loose connection would close the petcock and stop the flow. Obstruction between the petcock and carb - including the petcock itself - is another possible cause. Martinkim's suggestion covers that angle.

Fine rust particles can block the in tank filter after a few minutes of running too.

[Burl_GT]

What controls the bystarter electronically? I have 2 bystarters and it seems that neither do anything. If I unplug the one in the carb and plug in the spare, nothing happens to the spare and the bike does the same thing.

[Wheelman-111]

Greetings:

The bystarter receives current to heat up its element only with the engine running. Several threads describe how to test it. It does not "move" to the naked eye, but it's micro-erection takes place over about 2-3 minutes of receiving current. Once the bystarter closes the enrichener circuit, the carb operates on its Pilot circuit - or Fails to. The fault usually isn't the bystarter circuit itself, but a still-plugged Pilot. Search "Tiny Pin-* O'Light".

[patthesoundguy]

Greetings:

Insufficient vacuum with the throttle open due to a crack in the vac line or loose connection would close the petcock and stop the flow. Obstruction between the petcock and carb - including the petcock itself - is another possible cause. Martinkim's suggestion covers that angle.

Fine rust particles can block the in tank filter after a few minutes of running too.

The screen in the tank can also be clogged by varnish from old fuel and rust and who knows what else

Sent from my Nexus 7 using Tapatalk 2

[Burl_GT]

I tested the petcock with a vacuum pump. Flows freely. No gas in the vacuum line. What I did find was a bent carb needle. I straightened it out the best I could. I cleaned the pilot jet again.

Runs and idles pretty well. Seems to lack power overall. I think the bend in the needle had a negative effect on the taper. Especially above 3/4 throttle. Looks like I need to find a new needle.

[Burl_GT]

Anybody know where I can get a needle without buying A whole rebuild kit?

[mousewheels]

Take care to get the correct needle for your scooter.

1) Even the OEM Spree had unique part numbers depending upon year and if the Spree were restricted or not -- see info at this link
2) The only carb rebuild kits I've seen are for clone carbs, and they have only one needle. That does not match up with info above showing unique parts for some Sprees

[Burl_GT]

Take care to get the correct needle for your scooter.

1) Even the OEM Spree had unique part numbers depending upon year and if the Spree were restricted or not -- see info at this link
2) The only carb rebuild kits I've seen are for clone carbs, and they have only one needle. That does not match up with info above showing unique parts for some Sprees

Excellent info.. All I've seen on ebay are cheap rebuild kits with aluminum needles. With the info above I can search actual part numbers... Thanks!

[mousewheels]

Could you post the numbers stamped on your needle? That will help folks find an exact part for your carb

[Burl_GT]

I'll yank it back out tomorrow and take a pic