Won't advance past 3000rpm

[JohnnyAction]

Hey guys, I've been fighting with this problem for a while now on my '83. The bike fires up perfectly, idle great, but when you turn the throttle the bike doesn't advance past 3000rpms. It hits a rev limiter type feeling. My engine guy said he's seen this problem and it was the TCI, so I've bought two others and it didn't fix the problem. My carbs are the 'XS Performance Keihin Carb Kit' off Mike's, bolt on.

Here's a vid:

 

[jmink427]

Mine was acting stupid yesterday and would idle fine but when I would throttle it it would spew black smoke out the right pipe.... Found the main jet needle had come out of the jet.... It was pulling way to much fuel and choking the engine down... May be something to look at...

 

[jmink427]

Good lookin' bike by the way.......

 

[Dennis]

weak magnet on rotor has caused similar issues

 

[XSLeo]

Low voltage output of the alternator. The TCI box is very voltage sensitive. low voltage and it won't advance.
Leo

 

[JohnnyAction]

jmink427 - thanks, I'll take a peak into my carbs.
Dennis - how can I check that?
XSLeo - I think I'm going to check out the low voltage first. What's normal ranges, and what's too low?

 

[Gordon]

First off, re-route your plug wires, resting on the headers will fry them. Ok, now to check the charging system, attach a digital voltmeter to the battery. Start the bike and hold the rev's at 2000-2300 rpm. You should have at least 13.7 volts. If not, now comes the fun part of trouble shooting the charging system. If you do have good voltage, then check the magnet on the charging rotor, just use a .0025 feeler guage and see if it stick's to the magnet without falling off. That thin of a feeler guage should stay on the magnet, mine does. If it's falling off, there are a couple threads here recently that are doing the repair for the weak magnet's.

 

[XSLeo]

As Gordon says at 2-2300 rpms your alternator should be putting out the required 14.5 volts. If it is as low as 13.7 volts the alternator isn't working well.
At a charge voltage of 13.7 or less will only keep the battery charged to about 12 volts, maybe a bit less. At this voltage the electrical draw of the bike can draw the voltage as low as 10 volts at the TCI. At this point the TCI isn'tgetting enough voltage to function correctly. Some of it's functions will quit working, such as the advance.
It can also start to run rough, won't idle, no power.
Lot's of the trouble on these bikes can be traced to weak batteries and charging systems. Poor connections and grounds are right up there too.
I would reccomend that any one who gets one of these, or any older bike, the first thing to do is start at one end of the bike and work to the other end, checking each connection for clean and tight. If an older battery get it load tested or replace with a known good one.
After you get all that done you will have fixed most of your electrical problems before they can give you trouble.
Leo

 

[JohnnyAction]

Leo, I'm finally testing my voltage. At idle, it sits at 13.1 and when it throttle it goes up as high at 16 until it hits a 'rev limiter' type feeling. Any ideas? Is my reg/rec working right?

 

[XSLeo]

The voltage regulator should not let the voltage go over 14.5 volts. If your voltage goes over that then the regulator is not working right.
I would as i suggested in the previous post go through the wiring, checking ALL the connections from the front to the rear of the bike.
Pay particular attention to the wiring on the charging system.
The battery supplies voltage to the reg/rec on the brown wire. If the voltage on the brown wire at the reg/rec then the reg/rec is going to think the battery is low and boost the charge voltage till it gets the right reading on the brown wire.
If you find battery voltage on the brown wire at the reg/rec then the reg/rec is bad. If not trace it back till you find the problem. Often the key switch needs cleaning.
This over voltage can be the running trouble. The TCI has a circuit that protects it from damage by turning the power off till the voltage drops to the right voltage. This might be your rev limiter.
Leo