Top end of first gear haemorrhages?

[Staticam]

... did you clean out all the jets?

Well no. The thing was so clean it didn't seem justified. You think I should remove and inspect the main jet and sprayer? (I can't post a diagram at the mo').

[BoristheBiter]

Well no. The thing was so clean it didn't seem justified. You think I should remove and inspect the main jet and sprayer? (I can't post a diagram at the mo').

Yep, i would give it a go. mine was spotless as well but blocked.
What does it run like with the choke on?

[Taz]

Air filter good? Changed spark plug?

[idb]

Blockage in the fuel tank air breather maybe?

[Staticam]

Yep, i would give it a go. mine was spotless as well but blocked.
What does it run like with the choke on?

Fair enough, I'll try cleaning it properly next weekend. Choke is needed for start but runs rich if left on once warm. (I think I know where you are going with this - I'll try it before attemping the clean).

Air filter good? Changed spark plug?

Air filter clean, probably not plug, refer post 12

Blockage in the fuel tank air breather maybe?

Tank is clean. I doubt a tank or breather block could build up a vacuum so quick. If a clean doesn't get me anywhere I'll try with the lid open.

[Staticam]

Tonight's effort. Tank off, carb out, main jet and sprayer removed - spotless. Reassemble. Test - fail. Test with choke full on - fail. By fail I mean it won't rev properly above 3/4 rev range. All up about 40 minutes. Forgot to try with the tank lid open.

Tank is clean (plastic).
Fuel is clean and fresh.
Carb is a Mikuni SE BST 40 (a bit like an SU) and is clean.
Spark plug is used but looks acceptable (light brown coloured). Tried a different plug, also used but one step colder - no difference.

Down to the wire(s) now.

I have had the alternator cover off in the recent past so I have disturbed the wiring harness. From the alternator there are 3 wires to the regulator (all Ye/Bu) and 4 to the CDI (Rd, Bk, Wh and Gn). Can they be checked and how?

How can I test the output of the CDI to coil?
How can I test the coil and it's integral spark plug lead?

TIA, Luke

[idb]

Tonight's effort. Tank off, carb out, main jet and sprayer removed - spotless. Reassemble. Test - fail. Test with choke full on - fail. By fail I mean it won't rev properly above 3/4 rev range. All up about 40 minutes. Forgot to try with the tank lid open.

Tank is clean (plastic).
Fuel is clean and fresh.
Carb is a Mikuni SE BST 40 (a bit like an SU) and is clean.
Spark plug is used but looks acceptable (light brown coloured). Tried a different plug, also used but one step colder - no difference.

Down to the wire(s) now.

I have had the alternator cover off in the recent past so I have disturbed the wiring harness. From the alternator there are 3 wires to the regulator (all Ye/Bu) and 4 to the CDI (Rd, Bk, Wh and Gn). Can they be checked and how?

How can I test the output of the CDI to coil?
How can I test the coil and it's integral spark plug lead?

TIA, Luke

Plug out with lead attached, rest on motor, crank over, there should be a spark.

[Staticam]

Plug out with lead attached, rest on motor, crank over, there should be a spark.

Um, I can't use that method to test at near max rpm.

[idb]

Um, I can't use that method to test at near max rpm.

I'm not sure what that will tell you but if that's what you want I can't see why you couldn't do it one plug at a time.

[Staticam]

I'm not sure what that will tell you but if that's what you want I can't see why you couldn't do it one plug at a time.

A bit tricky cause it's only got one plug! It's a 600 single, four valve.

[idb]

A bit tricky cause it's only got one plug! It's a 600 single, four valve.

oh........

[BoristheBiter]

Tonight's effort. Tank off, carb out, main jet and sprayer removed - spotless. Reassemble. Test - fail. Test with choke full on - fail. By fail I mean it won't rev properly above 3/4 rev range. All up about 40 minutes. Forgot to try with the tank lid open.

Tank is clean (plastic).
Fuel is clean and fresh.
Carb is a Mikuni SE BST 40 (a bit like an SU) and is clean.
Spark plug is used but looks acceptable (light brown coloured). Tried a different plug, also used but one step colder - no difference.

Down to the wire(s) now.

I have had the alternator cover off in the recent past so I have disturbed the wiring harness. From the alternator there are 3 wires to the regulator (all Ye/Bu) and 4 to the CDI (Rd, Bk, Wh and Gn). Can they be checked and how?

How can I test the output of the CDI to coil?
How can I test the coil and it's integral spark plug lead?

TIA, Luke

If it was a car i would say its either the vacuum advance or the timing but i have no idea how your bike is set up.
It still sounds like the carb settings air/fuel mixture as it runs fine until you open the throttle up. 75% throttle is open quite far for a wiring fault and it would generally be picked up even when idling.
Can you run it with the air filter off? listen to noise change when it starts to die. try with choke on and off.
Does it run fine at 50%? what it the rev range for when it starts dieing? is it the same in all gears?

[Staticam]

If it was a car i would say its either the vacuum advance or the timing but i have no idea how your bike is set up.
It still sounds like the carb settings air/fuel mixture as it runs fine until you open the throttle up. 75% throttle is open quite far for a wiring fault and it would generally be picked up even when idling.
Can you run it with the air filter off? listen to noise change when it starts to die. try with choke on and off.
Does it run fine at 50%? what it the rev range for when it starts dieing? is it the same in all gears?

If it was a horse I'd shoot it!

Apart from my checking the carb settings should not be out. It did run fine. Between then and now the only thing that could have been disturbed is the wiring. I suspect that as the revs increase so does the pressure of the smoke in the wires. Because wiring has been pushed around maybe the insulation is breaking down, smoke escapes under pressure.

I can try with the air filter out but the exhaust, Ducati like, is loud, I doubt I'd be able to hear anything. The choke makes no difference. It idles and runs up to 50% maybe more happily in neutral or any gear. When full demand is asked for it's like it hitting a limiter at about 75%. It has no tacho. I built a kitset one but it won't work with the CDI, the trigger voltage is to high? I don't fully understand the alternator/CDI/coil setup to make it work. I wish I did.

[BoristheBiter]

If it was a horse I'd shoot it!

Apart from my checking the carb settings should not be out. It did run fine. Between then and now the only thing that could have been disturbed is the wiring. I suspect that as the revs increase so does the pressure of the smoke in the wires. Because wiring has been pushed around maybe the insulation is breaking down, smoke escapes under pressure.

I can try with the air filter out but the exhaust, Ducati like, is loud, I doubt I'd be able to hear anything. The choke makes no difference. It idles and runs up to 50% maybe more happily in neutral or any gear. When full demand is asked for it's like it hitting a limiter at about 75%. It has no tacho. I built a kitset one but it won't work with the CDI, the trigger voltage is to high? I don't fully understand the alternator/CDI/coil setup to make it work. I wish I did.

I agree just shoot it.

[Staticam]

I've tested for smoke leaking out of the wires, and there wasn't any. Time for a new approach.

The clattery rattle racket it makes while running, while possibly some valve noise, is most likely the timing chain. The tensioner is at full stretch.

If it jumps a tooth would it run, or run noticeably out of whack?
If the chain is flailing round and hitting things, could that be the problem?