runs terrible

[pahako]

I'm working on an 80 special and not sure if my problem is electrical or a fuel problem. It starts easily, and idles smooth, but when I try to rev it up, it becomes very rough and won't rev up higher than about 2500 rpm's. I have had the carbs off and all the jets and passages are clean on the bottom side, but I didn't take the tops off or do anything with the slides. It's getting fuel ok, I just put on a new petcock, inline filter, and clear fuel line.
Thought maybe it had something to do with the timing because someone recently put on a new rotor, but it starts very easy, so I don't think it's the timing, but I don't know. I also adjusted the cam chain, valves, and put new plugs in, but I am not sure what to check next. Thanks for any help.

 

[pamcopete]

pahako,

Well, I assume that you have the stock TCI ignition system because you didn't say other wise. If so, then having a new rotor installed could be the problem if the trigger magnet is weak in the new rotor. To test for this condition, unplug your rect / regulator temporally and see if the problem goes away.

 

[5twins]

If that doesn't do it, check the condition of your carb diaphragms. If they have holes in them, you won't get proper slide lift, maybe no lift at all if they're bad enough, which means no revving up.

 

[pahako]

It's all stock pamcopete. Do I unplug the reg/rec while it is running?

 

[pamcopete]

It's all stock pamcopete. Do I unplug the reg/rec while it is running?

No. Unplug the reg / rect before you start the engine. The ignition does not need the reg / rect to run. The reg / rect is there to charge up the battery, so you could run for a couple of hours without it. This is just for a test.

 

[pahako]

So I unplugged the reg and it revs fine. I found another thread where you (Pete) recommend using a magnet from radio shack to epoxy other one. I assume this fix may work or you wouldn't have suggested it, but what kind of magnet should I be looking for? Just something similar to what is on there?

 

[Dennis]

the magnet is one of the easiest things to do and has been my fix to a very similar problem
do a search and you will find the info you need
they come in a pack of two

 

[pamcopete]

So I unplugged the reg and it revs fine. I found another thread where you (Pete) recommend using a magnet from radio shack to epoxy other one. I assume this fix may work or you wouldn't have suggested it, but what kind of magnet should I be looking for? Just something similar to what is on there?

Yes, something similar. You do not want the magnet to be too strong as some have used a very strong rare earth magnet and made things worse. Use something metal to judge the strength of the magnet that is in the rotor and find something about two times stronger. You must also observe polarity, which takes care of itself because the new magnet with stick to the old one and assume the correct polarity, but just to be sure, use a compass to determine the polarity of the magnet on the rotor.

The replacement magnet also has to clear the stator housing as it rotates.

I think that my earlier recommendation to use the Radio Shack magnets may be incorrect as I think they only carry the very strong rare earth magnets. Find something not so strong.

By the way, I am not the one who came up with this fix originally. I wish I could remember who it was so I could give credit where credit is due.