Update. Need advice from a pro!

ok so I have been having this weird problem. It doesn't matter if the bike is warmed up or not. when the motor is running all of the sudden it just dies. the only way to get it to turn back on is to turn key off then on again. then runs fine.

But it gets worse. The biggest problem i am having now is some times the bike will be running and all of the sudden it boggges down then when your at a still I give it gas and it wont rev up. instead it just makes a weird popping noise maybe going up to 1800 rpm instead of its idol at 1200. now I can shift through all the gears while its doing this successfully reaching about 10mph in 5th gear, I know its very weird. then all of the sudden it will just boom start working great again.

So far I have replaced the ignition, rebuilt the petcock, replaced the fuse box, replaced the fuel line, and replaced the vacuum line.

I did pull off the TCI today and notice some corrosion on the metal things. )How do I clean those)? I also pulled of the spark plug wires and the black things those are connected to. I want to replace both of them. (what are they called and where can I get them?)

Anyway before I write you all a book Ill stop

Please let me know what you think!

 

First, if this is a new bike, anyone on here will tell you to check the rear brakes and check for delamination!

Second, Im sure other people can give better advice, but what condition are your carbs in? Do you have a good battery?

If you look up a member called "Chacal" he can help you with replacing the wires and boots (I think they are called). If you click on the top of the forums where it says XJ4ever, that will get you pointed in the right way.

Cleaning the terminals can be done with a light sanding or steel wool I believe? (Someone correct me if Im wrong!!!)

how long have you had the bike?

 

that was one of the first problems i had to fix on my yamaha. the carbs were clean but all 4 floats were different settings. anywhere from 19mm to 13 mm float height.

then i had a vacuum line to fuel petcock that was too big. air leak. the other 3 caps on the intakes were also to big. sucking more air. once that was all done the bike ran pretty good. albeit with a missfiring condition untill it hit that 4k rpm sweet spot. replacement tci box and all was golden.

 

I'm going to say TCI as well, when my 400 was all gimpy, a new TCI fixed everything.

You could have badly drifted caps in your tci which will show up as the issues your describing. I'm not going to say it will 100% fix it, it could still be carb related.

What do your plugs look like? White? Black? brown?

Let us know, Cyl's are numbered 1-4 left to right as you sit on the bike.

 

Bike was kinda doin the same thing to me before i cleaned the carbs for the winter. Sprayed out allll the enrichment circuits and every hole in the dang thing and then replaced my sooted up spark plugs with new ones and she runs like a dream.
I'd say do your carbs and plugs first then attack the TCI.
And like Snowy said, Check those floats too! Could be filling one up enough to idle but when you give it throttle it may be sucking it all out.
So!
Carbs. Its 90% of our runnin probs in these bikes. I clean my carbs 3 times a year to keep her runnin tip top
-Chris

 

I recommend using a miniature abrasive blaster (requires a compressor) to clean the contacts. http://www.harborfreight.com/air-eraser-kit-99636.html This is a cheap knock-off of my Pasche Air-Eraser. $20 isn't a bad price either.
I offer a TCI refresh service should you require it, but I don't have a means of testing the 400 models.