Reply To: Carby 250 dies when choke turned off
Compression tester showed up yesterday. I got the below results on a hot engine with both plugs out when testing.
Front = 125 psi
Rear = 132.5 psi
Is that good or bad?
While I was waiting for the tester, I took out the jets for a 3rd time to triple check they were clear – they were. But I found that I missed the fuel inlet filter/gauze above the float stopper thingy. I took each of them out and one was semi-blocked with debris, the other was clear. Gave them a clean out, put the compressor blow gun on all holes and reassembled. Also made an auxiliary tank from a stainless steel water bottle so I can get the engine running without having to take the tank on and off everytime. This bypasses the ‘pump’ and goes straight to the carb inlet hose.
Few things I noticed:
- Good news is the bike will now rev to the limiter and everywhere inbetween as long as I keep the revs up, but it still dies at resting idle if I turn the choke off.
- It is also slow to decelerate when I release the throttle which I’m gussing is sticky slides/diaphragm? Odd as I cleaned all the sticky fuel residue off of them when I stripped the carbs. The throttle cable returns fine.
- As I bypassed the fuel pumps, I noticed the hoses from the inlet boots that create the vacuum for the fuel pump and the tank-tap pump had to be plugged well. They caused the motor to pop and cackle irregulary and the engine tune would improve when I blocked the hoses.
I’m not sure if it is running now due to the fuel inlet gauze being cleaned out in one of the carbs or it is because the fuel is gravity fed strainht into the carb hose. I need to hook the tank back up and see if the engine will still rev up. If it doesn’t, I think the pumps are the issue or the old vacuum hose’s have a leak in them (this is my pick).