magg wrote: Sat Apr 23, 2022 12:04 am When you remove the plugs are they at all wet with fuel. Have you had the carbies off for a clean. Fuel in the float bowl is a plus but the air and fuel jets could still be blocked. No fuel tap vacuum hose with fuel flowe on reserve setting and none on main is odd. Ssounds like someone has played with the fuel tap to remove the vacuum diaphragm and got it wrong. Fuel should fuel freely in either reserve or main settings at all times.

Hi magg. I've been waiting for parts. The spark plugs finally arrived, but bummer, they did not solve the hard starting issue.

I cleaned the carbs agin and found th idle jets blocked. Cleared them out.

I changed out the fuel tap, the old one was definitely leaking fuel through the vacuum hose.The new one works, so it turns out the vacuum hose is not giving vacuum at start up. Cylinder 1 seems to be pushing out pulses of air instead of pulling vacuum.

The good news is that bump starts got it to start maybe five times, and all four cylinders were firing (maybe the new spark plugs?), but she was too eager to die out on low revs. After a while only two cylinders (1 and 4) got hot, and after a while again it wouldn't even bump start at all.

The valves are probably kaput, am I right? What should I be looking for if I must wrench off the engine covers?

Just out of interest, is your fuel fresh? Do you have bio fuel over there? Carbed bikes don't really like fuel with bio content.

Still sounds like fuel flow issue. Have you tried leaving the fuel tank cap open while starting/running the engine. If the vent system is blocked the carbies will be starved of fuel.

magg wrote: Tue May 17, 2022 10:39 pm Still sounds like fuel flow issue. Have you tried leaving the fuel tank cap open while starting/running the engine. If the vent system is blocked the carbies will be starved of fuel.

Good call, haven’t heard this one for a while

MadMotoUK wrote: Tue May 17, 2022 6:57 pm Just out of interest, is your fuel fresh? Do you have bio fuel over there? Carbed bikes don't really like fuel with bio content.

The hard starting has been a problem even from the beginning when I put the bike back together and put fresh fuel in. By now the fuel has sat in the tank about a month. There have been complaints many complaints about our fuel being adulterated by dealers here lately, but bio fuel is not commonly found.

magg wrote: Tue May 17, 2022 10:39 pm Still sounds like fuel flow issue. Have you tried leaving the fuel tank cap open while starting/running the engine. If the vent system is blocked the carbies will be starved of fuel.

I have tried leaving the fuel tank cap open, and it doesn't change my results.
On the fuel side the problem I have identified is definitely the vacuum port from cylinder 1. There is no vacuum there. If I disconnect the vacuum tube and suck, fuel flows from the tank to the carb.
Anyway, it doesn't seem like fuel delivery, because there have been instances where the carbs are confirmed full of fuel but the hard start persists.

Updates:
1. I've checked the (new) spark plugs. Their tips are blackened already. Probably from so much cranking. But they all still give good spark.
2. The battery is probably too weak from so many failed crank attempts. I'll have it charged (again) and come back with results. It's three years old, and sat for two years, and might need replacement ultimately.
3. It used to be able to jump start. Now that's just a waste of energy. No joy.
4. The cheap no-name eBay compression tester i bought and shipped failed straight out the box.
5. I want to check ignition timing and valve adjustment. I'm starting to think that's where the problem lies. 100,000+ kms and no service history.

THE PLAN: going by your suggestions, I'll start with the easy stuff first, trying at each step until hopefully I get at the fix and identify the problem.
1. Drain out the fuel and put in fresh.
2. Charge the battery (or replace?)
3. open fuel tank cap and attempt to start
4. Check valve gaps
5. Check timing marks
6. Check condition of valves

I'm probably overthinking this or overlooking something.

Plugs blackened but not wet and engine not running suggests no fuel. Have you tried spraying fuel into the carby throats while cranking the engine, or placing the palm of your hand over the throat of each carby in turn while cranking the engine (make sure the float bowls are full). Either action should provide enough fuel to get a response.

Ephasis on spraying FUEL not Easy Start into the carbs........

MadMotoUK wrote: Sun May 22, 2022 4:54 pm Ephasis on spraying FUEL not Easy Start into the carbs........

Good catch man, starting fluid was in the shopping list until I saw your post