GT380 She Lives!

[miked914]

Evening All,

Just picked up a 1974 GT380. Did the usual clean-up before starting. Went through the carbs and installed new 80 mains, stock pilots and new float bowl gaskets. I cleaned the carbs to surgical clean (or as close as possible). Changed the oils, brand new fully charged battery, new plugs, fresh gas, fuel lines and fuel filter, etc...

I rebuilt the petcock and as ALWAYS with these old bike-it still leaks--more on that to follow.

So the bike came alive on the first kick! Smoked quite a bit. It ran on idle and all the way through the rev range but did end up cutting out and then not re-starting. Here is what I found.

1) The left cylinder did not appear to be firing (or at least not for long). The exhaust header (right at the exhaust exit) never got more than warm. I confirmed good spark at that cylinder and it is getting gas ( i loosened the float bowl drain screw and fuel did spill out). Any ideas?

2) The middle carb began pouring fuel out of the bottom vent tube. I'm guessing either a stuck needle or a float issue. (I did set the float on all three carbs per one of the manuals I found on this site)--any other thoughts here?

It smoked quite a bit, to the point where my garage was quite hazy. I know its a 2-stroke but I'm just not sure if that was due to initial start up or another issue--I guess I'll have a better idea once its running properly.

I was planning on ordering a petcock adapter plate and going to a new style (non-vacuum) petcock. Something that won't leak--anyone have any experience going that route?

All in all the bike is in beautiful shape. 5,000 original miles, yellow-gold paint in great shape, original exhaust with 8/10 chrome and ZERO holes, rust or pits anywhere, no tears in the seat--I got very lucky on this one (and only paid $150.00 for it--BUT no title....so I'll deal with that down the road). I plan to keep this one bone stock and enjoy riding it around town.

Thanks!

-Mike

[Craig380]

That sounds like a really sweet deal, $150 is peanuts! Good luck with her

Taking the questions one at a time:

1) The left cylinder problem is probably crud in the pilot jet, or possibly it flooded a little. Hard to say until you can actually run it on the road, but at least it fires. Could also be a plug cap problem, worth changing those too as they cost nothing.

2) The middle carb pouring fuel out of the bottom vent tube will be a stuck needle or a float problem -- could just be a bit of dirt too.

It smoked quite a bit: they all do that, sir, especially when starting from stone cold and running on choke . It will need to run fairly hard on the road to clear the residual oil from the cases, pipes etc.

Never tried an alternative petcock, but someone else may have.

[Coyote]

if you switch to a manual petcock, remember to cap the vacuum port on the carb. Otherwise you will have a massive air leak.