90 Sport runs perfect then dies?

[guzzisvt]

My 90 with 8k will run perfect, maybe a couple of times around the block and then dies. Got spark, got gas in the carb. I can get it started with the choke on but will not run well. When it dies it's like the ignition turned off, no sputtering, but it had a good spark and the plug looked dry. I checked the carb and jets, all clean as a whistle. Back around the block and it dies again. I'm getting tired!
Last time I took it for a long ride it seized, so I put a little oil in the gas. Now I'm chasing this problem.
Should I be looking at crank seals?
Any help?

[disc_valve]

Hi, Bill.

Sounds a bit like fuel starvation. You say you have gas in the tank, but is it reaching the carb? Check that the fuel cock is passing gas OK, and also, next time it dies, try taking off the fuel filler cap and see if the motor will then start. If t does, you've got a blocked breather hole in the filler cap. Is the carb float  or float valve sticking?

Graham

[guzzisvt]

As my father always said "if it feels like it's run out of gas, then it's running out of gas".
I was talking to my brother about this this morning and then it hit me, I think I had this problem before, maybe with this bike but for sure with my Moto Guzzi Lario. Yes you were correct it was the gas cap vent hole plugged. I put a suction on it and it was clogged up with rust. I cleared that out but also took of the carb to see why it left a pool of gas where I parked yesterday. After removing the float I saw the needle valve had come unscrewed almost all the way out. Two birds with one stone.

She's running clean and strong now. Thanks for your help!!!

[disc_valve]

I'm pleased to be of help, Bill.

The cap blockage doesn't happen very often, but it's a bugger when it does clog. I had the same problem on my Dual twin earlier this year - the first time in nearly 30 years of ownership. This one was my fault, though. The hole was clogged with chrome polish, as I'd recently given the top surface of the cap a treat to remove some light rust spots. Doh!!!

Graham