Won't rev past 6k
Posted: Sat May 09, 2015 7:06 pm
The 3EN1 is giving me a hard time, as it will not tach up past 6k and won't hold an idle. The bike starts up pretty easy, give it at least half choke when stone cold and it fires right up.
When I bought it, the chap said the motor had been rebuilt recently, which I can see that it has a few new parts and fresh RTV, so I had reason to believe him. He thought the stator might be bad as the battery goes flat after riding for a while, and he replaced the R&R hoping that would solve the problem. I tested the stator itself for continuity and it seems just fine, no shorts, and after firing the bike up and putting a meter across the battery terminals, it reads about 13.8 V at idle (what I can get close to anyways) and only raises to 13.9 at about 5k. I always thought it was supposed to be generating above 14 V running, so I think there might just be a draw somewhere in the electrical system.
The carb settings when I opened it up were the needles all in the position second from the top and float heights of 25.0mm, 25.0mm, 24.5mm, and 24.2mm, idle air screws at 1&1/8 turns out, 1&1/2 turns out, 3&1/2 turns out, and 3&1/2 turns out going from cylinders 1-4. The diaphragms seem to be in good enough shape, no holes that I could see.
Taking the plugs out, cylinders 1-3 all looked like it was running rich, with cylinder 4 looking much leaner. It turns out that plug #4 was only turned in about 1/4 of the way in due to mangled thread, which I have since fixed. I just put brand new plugs in to see if it makes a difference, which it hasn't.
I've had the carbs off and hosed down the innards with carb cleaner and resent the float heights to 22mm (that's what I've read somewhere on the forum before, please correct me if I'm wrong) turned the idle air screws to 2&1/2 turns out and that made no difference whatsoever.
To the best of my knowledge, the bike is completely stock. If I can get it to hold an idle, I'll give the carbs a balance and see if that affects anything. I don't know if the issue is electrical or just carburation, but it's been driving nuts because the weather is perfect and I'm stuck staring at a bike in pieces because I can't figure out what is probably a simple problem.
Any ideas? Thanks
When I bought it, the chap said the motor had been rebuilt recently, which I can see that it has a few new parts and fresh RTV, so I had reason to believe him. He thought the stator might be bad as the battery goes flat after riding for a while, and he replaced the R&R hoping that would solve the problem. I tested the stator itself for continuity and it seems just fine, no shorts, and after firing the bike up and putting a meter across the battery terminals, it reads about 13.8 V at idle (what I can get close to anyways) and only raises to 13.9 at about 5k. I always thought it was supposed to be generating above 14 V running, so I think there might just be a draw somewhere in the electrical system.
The carb settings when I opened it up were the needles all in the position second from the top and float heights of 25.0mm, 25.0mm, 24.5mm, and 24.2mm, idle air screws at 1&1/8 turns out, 1&1/2 turns out, 3&1/2 turns out, and 3&1/2 turns out going from cylinders 1-4. The diaphragms seem to be in good enough shape, no holes that I could see.
Taking the plugs out, cylinders 1-3 all looked like it was running rich, with cylinder 4 looking much leaner. It turns out that plug #4 was only turned in about 1/4 of the way in due to mangled thread, which I have since fixed. I just put brand new plugs in to see if it makes a difference, which it hasn't.
I've had the carbs off and hosed down the innards with carb cleaner and resent the float heights to 22mm (that's what I've read somewhere on the forum before, please correct me if I'm wrong) turned the idle air screws to 2&1/2 turns out and that made no difference whatsoever.
To the best of my knowledge, the bike is completely stock. If I can get it to hold an idle, I'll give the carbs a balance and see if that affects anything. I don't know if the issue is electrical or just carburation, but it's been driving nuts because the weather is perfect and I'm stuck staring at a bike in pieces because I can't figure out what is probably a simple problem.
Any ideas? Thanks