First bike 81 xs650 bobber. Flat power at high rpm

[nj1639]

You need a battery to start these bikes with the stock charging systems, so it's important to know what you have there as in stock or aftermarket.
Consider adding the tach and speedo, many of us include a voltmeter to keep an eye on our charging systems.

 

[650Skull]

No..........the battery needs to have a good charge or the bike won't start, even with the Kicker...........

Need to identify your charging system.....And ignition system............The reason for ignition system ID is if the bike has factory Electronic Ignition, (TCI), then damage can be done to it if the wrong procedures are done while trouble shooting..............If your battery is going flat then it needs to be load tested and fully charged. The charging system needs to be checked.............

In the pics showing the Reg/Rect the wiring looks to have been modified..........Needs to be checked for proper installation. Again Pics of the parts/wiring.............Fuse box???? what do you have and is it factory or PO wired.........
.
Do you have a manual????

It would pay to do all the IDing of parts and systems before doing to much more other than getting your carbs jetted Synchronized and back on the bike.

Go to the "Tech menu", scroll down to "Maintenance and general Troubleshooting" read the 2 links "Bike wont start" and "Buying Guide" ..........These are a must read for someone with a new bike..........Probably raise a lot of questions but that's alright, just ask...........

 

[Gavin Mackenzie]

Don't have a manual, that tech menu is pretty awesome though I'll definitely learn a lot from that. Here's a few pictures of the bike, no fuse "box" more of a fuse and wire "hole" somewhat protected by metal plates. At work now. I'll check back in later!

 

[nj1639]

Remove the chrome cam end cover above the left spark plug and remove the Yamaha plate off of the lower left side of the engine.
If there's nothing but the end of the cam under the cam end cover and if there's a black oval plastic piece, roughly 2"X1" attached to the stator at, say, 2 o'clock position, then your running a stock TCI. Use your judgement to confirm or post some pics of what you find.

 

[Brassneck]

Interesting bike...there's a whole lot of modifications to it (based on the pictures). Hard to tell what's been done to it, but the good news is these bikes are pretty simple and based on the relocation of the battery and the fuses, the wiring is probably simplified to some extent. Fortunately/unfortunately, you'll soon be VERY familiar with the nuances of what was done to it...my guess is you'll be going through it all to figure out what's what. As others have said, start with the charging system and go from there.

 

[fredintoon]

Hi Gavin and welcome,
lotsa photos is a good thing, photos that show the complete bike will be a good thing too
so we can see what else the dreaded PO did to the poor thing.
From what I see in the close-ups:-
Good
Keeping the rear suspension (your spine will be grateful) Swapping in the earlier aluminum rim wire wheels (They look nice)
Iffy
Replacing the stock glass-tube fuse block with a dog's breakfast of individual blade fuses (OK if they're wired right but not otherwise)
Solo seat (HTF can you pick up a pretty girl if there's nowhere to put her?)
Bad
Pleated Cone carb air filters (They don't breathe right on stock carbs) Welded-in battery box ( The stocker was rubber mounted
to save the battery and the ignition module from death by vibration) Open Drain exhaust ( Street bikes need some back-pressure)
But WTF, it's all fixable, right?

 

[Gavin Mackenzie]

Not sure what I'm looking at here. But I think these are the pics you requested nj1639

 

[Jim]

That's what we wanted to see. You have a stock TCI ignition system and a stock charging system. You might wanna add that to your signature.

The timing sensor (oval shaped piece in top pic) has new screws. That means someone has re-timed it. If it were me, I'd double check timing. Too far advanced can cause detonation and hole a piston...

 

[650Skull]

JD........Early TCI Stators had the pic up riveted..........Yamaha changed to screws on the later pic up's...........


Normally these can't be moved. Some knowledgeable people have slotted the pic up bracket so the bikes advance is retarded. ................This shouldn't be done unless the person knows what they are doing.

There is a caution though. The timing mark plate on the bottom of the stater can be moved. This should be checked against a TDC of the piston to confirm it hasn't been moved.

 

[59Tebo]

Gavin, welcome! Yeah, get some 'pods on it and do whatever you gotta do to make it run right, but for the love of GOD keep those fishtails! Those pipes are the nuts! And when you get a chance, maybe give us a long-shot that shows the whole bike.

 

[perki48]

now another thread about the same thing with posts wasted.............Not wasting my time here

OOPS, thought I was back on the Harley forum for a second there.

 

[650Skull]

OOPS, thought I was back on the Harley forum for a second there.

Well newbie if you Read the thread ......And not just one post.........you would see i corrected and apologized.....

 

[Jim]

JD........Early TCI Stators had the pic up riveted..........Yamaha changed to screws on the later pic up's...........


Normally these can't be moved. Some knowledgeable people have slotted the pic up bracket so the bikes advance is retarded. ................This shouldn't be done unless the person knows what they are doing.

Mines an 80SG.... first year of the TCI. They used screws (and epoxy) to fasten the sensor. The screws they used had a head that sheered off when you torqued them. And the sensor is slotted for about (I'm guessin' here) 10-15 deg. of movement. That's from the factory. I used a cutoff wheel to cut a slot in my original sheared off heads and replaced 'em with allens. They never used rivets and as far as I know, Gavins 81 was done the same way. Those aren't factory screws on it.

 

[Gavin Mackenzie]

Ok, so what I've been reading is, if it runs, get a timing light to check timing ? Couldn't find anything else in tech section about checking timing. Also how to check TDC of piston to timing mark plate ?

If there is any info in the tech section about how to do this (and what I'm even looking for) I'll try to find it and read through.

Thanks guys! Skull, JimD, Tebo, Fred, Brassneck, NJ

 

[Jim]

The search box on this site works great. I just typed in "finding tdc" (check the search titles only box) and got lots of results... including a few videos.

 

[nj1639]

I've seen rivets (or were they unsloted screws?)and screws used in securing the TCI pickup......carry on.

 

[Jim]

I can only speak to my 80SG... but when I took it all apart, it did indeed look like rivets holding it in... 'till I looked on the inside and saw threaded shanks protruding through the stator....

 

[gggGary]

jim those do look like the later factory mounting screws (not disturbed?) looks nice and clean too. Otherwise carry on.

 

[Jim]

looks nice and clean too

Yeah, that's why I thought they were replacements. You guys know more than me about these bikes.... so I'll defer.

 

[nj1639]

The current charging system will become moot in the event of a re-phase.......