Bike won't rev above 5000rpm

[Bushyeyed1]

http://www.xs650.com/threads/1981-650-miscellaneous-parts.57338/#post-645141

If I was you before buying anything for the TCI I would run through the resistance checks of the system in the manual. If you don't have a manual go to the tech section and download that one or biker.net has one as well. If it is the TCI box bad you can buy the four diodes on ebay for cheap and/ or resolder the joints. I actually have some of the diodes if you want to get some from me, but still do the resistance check and read the ohms on the tci box. I almost bet that may be your problem.

If everything checks out then check your ignition coils next. If it is the stock coil it almost should be replaced anyways, but check the end caps too that plug into the spark plug for corrosion by pulling them off the wire. It is also likely they may be loose in the first place too.

 

[sleddog83]

Check the classified on this forum. There was one for sale the other day. It is always a good idea to have a spare TCI if you can get it cheap. It helps you troubleshoot problems like this. They can be repaired as well. So if you want help with that let us know. I have some schematics and can recommend replacements for some of the components.

 

[bakerman24]

To me, that sounds like some more carb tuning will help clear up the low end a little bit.
If it gets up past 5k smoothly now, and idles well, but bogs when trying to accelerate at low rpm, i think you can play with needle height and maybe different slides to help with this. I’m no carb expert tho.
Also, my buddy has always told me not to use cv carbs because of the tuneability issues. I just took his advice and got some Mikuni VM carbs to play with. They are simple carbs that work really well for me. I personally use the Vm32’s on my 81, where other people use 34 or even 38s i believe. If you find that the ignition is not the problem, then i would change out the stock carbs.