XS650 BigFin KIt

Got the regulator/rectifier installed and my charging issue is resolved. In neutral the bike rev's to 6k with the regulator/rectifier connected or not connected. Under a load it is a different story! The bike tops out around 65 in 5th with the regulator/rectifier plugged in. With the regulator/rectifier not connected the bike tops out around 75 and it starts to surge a little bit acts like it is starving for fuel. Very strange... I am going to replace the rotor with the rebuilt from 650 Central. Decided not to go with the rare earth magnet fix. I am not sure where this is heading.. I am looking inside my tank and this is what i see.

Tank_Rust.jpg
I suppose i will be taking off my float bowls to check things out. This bike accelerate fine before the Big Fin 650 kit install. Very frustrating!
 
You have done tests that point at a weak magnet being an issue but you aren't going to do a simple cheap fix to see if that cures the problem. I don't think I understand. It takes a stronger spark to properly fire a cylinder that's under load compared to one that's loafing........... A barely cracked throttle is kinda like having low compression pistons.
 
gggGary: Here is my thinking.. Say that the rare earth magnet resolves my revving under load. Where does that leave me? Do i trust the bike farther than my 100 mile AAA towing range? Everything i read on this site basically states that the rotor is practically a wear item. The rectifier/regulator was defective and it looks like the magnet on the rotor is weak. I am having a hard time convincing myself that this is all a coincidence. This bike has been solid for the last 25 years with maintenance done on a regular basis. I can not keep this bike if i do not trust it!
 
The magnet is completely separate from the charging function of the rotor. Can you trust ANYTHING on a 40 year old motorcycle? Heck plenty of machines puke just miles after leaving the showroom floor. Yes periodic maintenance, replacements are part of the package of anything with a few years under it's belt. Have you replaced the front brake lines? Now that's an item to REALLY worry about. :(
 
Before replacing the cam seal, make sure the one in there is seated in the housing deep enough. It needs to be pushed in as far as it will go, so it's flush with the back side of the housing .....

BZEmwYq.jpg


There are a couple other "gotchas" in this area, especially if the cam has been out like yours was for the big fin kit install. The cam bearings must be pushed onto the ends of the cam as far as they will go. This will have them sitting inset into the head a little on each side .....

i1iiEYS.jpg


Then the cam needs to be centered in the head. If it's not, besides the obvious chain alignment problems, one end of the cam may not protrude out far enough for the seal lip to get on it. To center the cam, you measure that bearing inset on each side and make sure they are the same.
 
5twins: Both my cam seals are seeping but i am putting them on the back burner for the moment.

gggGary, TwoManyXS1BS, retiredgentleman: I am at a crossroads because the magnet on the rotor is very strong it does not appear weak at all.

20170926_184703.jpg

Maybe a better question is how strong does it have too be?
 
Good question! I kinda tried to quantify that with rotors from the tub, a larger lets say 8mm hex key should stay stuck on the magnet even when held by the short arm so the weight of the long arm is supported by the magnet out to about 45 degrees from vertical? yeah not super scientific but it thee were a few weak magnets from my sample pile that were REALLY weak. :umm: some would barely attract a hex key.
 
Well,, the rare earth magnet is curing... i have my fingers crossed that there is clearance for the pickup coil!
20171002_093119.jpg
Does anybody know if cutting the wires at the pickup coil near the stator is the same as unplugging the pickup connector in the frame? If i have to go Pamco, i really do not want to remove the stock air boxes to access one connector plug.
 
The good news is the rare earth magnet clears the pickup coil.

20171003_171353.jpg

The bad news is the same old issue, revs out in first but will not rev past 3k in the other gears. Going to pull out the air box so that i can access the connectors to the pickup coil and TCI unit.
 
Well, this is just a terrible mystery. Was there any carb work done? Could it be as simple as the throttle not opening all the way?
Grasping at straws.
Tom
 
Look I'm late to the party so feel free to ignore me . Have you verified that the engine is advancing ?
I have seen many of the pickups fail on one side and still be good on the other.
Remember if testing out of the bike to stress the pickup pretty good. I warm them up in oil , 260 degrees or so .
If it won't advance it won't rev ....

kop
 
kop why would it be selective or gear determined? If the advance works in first but not other gears?
 
Tomterrific: These carbs were not touched to the best of my knowledge. I am going to exhaust all my options on the ignition before looking at the VM34.

Kopcicle, weekendrider: I have checked the advance and it is fine. However this was not done under load.

Do i need to unplug the TCI connector or can i disconnect the orange wire at the coil to isolate the TCI on this bike?
 
Hey kop has something. Did you put a timing light on the engine to see if the timing advances when it revs?

The pickup is two sided. One is timed for idle and the other is at full advance. As the engine rpms increase the voodoo electronics in the TCI box adjusts the timing between the two.

Use of a timing light will quickly and easily show the proper advance function, or not.

Tom
 
yes, post 19.. timing is spot on at idle.. timing full advance when revved is spot on.. I am going to replace the coil, wires, spark plugs and NGK ends. I may have to go pamco and i want to replace all the components from the TCI ignition.
 

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