This girl won't run for me

So I have an XJ550 SECA from 1982.

Right now this bike doesn't start, but it used to. The starter will crank it but nothing from the engine. Not even a sputter.

Since it ran I've added pod filters (yep!) and a new speedo and tach.

It's started and run well enough to sync the carbs with a vacuum gauge (after the bench sync). Now the bike won't start.

I've heard and seen a few things that are interesting. When I put some carb cleaner in the carbs, it will backfire a one or two puffs of smoke back out the carbs with a sharp crack, and maybe a pop out the tailpipe. Symptom? I smell gas with regular setup, so I think it's getting gas, I've seen the spark, it's getting air...

I've checked the valve clearances and a couple are a little out of spec by a .02mm or so, decided not a huge deal for now.

The electrics check out so far: the ignition coil and switch are right. The volts are dropping to around 9 to the coil when it cranks. Am I not getting enough? I can't find a leak.

Thanks for any help!

 

Soggy or flat battery. Fully charge or replace.

Fit a brand new set of NGK D8EA plugs, properly gapped.

Start the bike.

Then get your valves in spec so you can get it properly tuned.

 

So I put in new plugs which were a bit blackened and charged the battery and...fail!

Seriously, what's with the occasional blowback out of the carbs?

She has run with this same carb and filter setup earlier.

 

You're sure that all 4 are sparking? When I put my tank on, it bumped the harness for the right coil off so only 1 and 4 were firing. It would sputter a bit, nothing special. Plugged the other coil in and TADA!

 

The next day I recall that mine wouldn't start because of a kinked fuel hose, it was getting fuel, but not enough. I think Wirehairs had the same issue recently.

 

Why does my engine sometimes backfire when I first turn on the key (without attempting to start the engine)?:

- When you kill the engine, the intakes will still have some remaining (un-burned) air-fuel mixture remaining in them. Upon powering up the bike (turning the key on), the ignition system will apply 12 volts to the coils, thus charging them. Of course, that constant current is not good for the coils, so few seconds later (if the engine is not started) the TCI shuts down the coils by grounding them (to protect the coils from overheating) which cuts the current to the coils and thus triggers a spark to the plugs. If there is enough un-burned fuel in the intake manifolds or the combustion chambers, and if the valves are held open by the camshafts, a backfire thru the exhaust header and/or thru the intake manifolds/carbs/airbox can result.

 

I said "brand new." Plugs that are a bit blackened are NOT brand new.

The reason I specified BRAND NEW is because it's very easy for the plugs to become saturated with gas and quit firing consistently or altogether. There's no way to "dry them out" except letting them sit for a month.

Try a BRAND NEW set of plugs this time; re-charge the battery so it's fully charged, put the petcock on PRI to ensure the float bowls fill up, full "choke" and zero throttle and see what happens.

Put a meter across the battery and see what happens to the voltage when you crank it. Report back with those voltage readings.

 

Yeah, I had the problem of a new fuel line that was kinked just enough to cause fuel flow problems.

My differential thinking goes like this: your engine cranks, you've got spark, then the issue is around fuel. If you know fuel is being delivered to your carbs, you can eliminate the petcock, vacuum line issues, or the fuel line itself. So we are back to the carbs. I'd yank 'em and look inside and check the floats and jets and the fuel passages. It's my understanding that carb cleaner will ruin rubber, so if you've sprayed some into your carbs to try and get it to run, check your diaphragm for any damage.

I'll add that for a few bucks, one of these is worth having: http://www.ebay.com/itm/231008372924 You can see how they are used here: http://www.youtube.com/watch?v=eQBtzk-dGYM

 

In retrospect my earlier post made no sense. That's what I get when I post just before bed.

SO, I got rid of the old black plugs and put some new ones in. Ten bucks well spent.

When I'm cranking this bike the volts across the battery drop from 12.5 to 11.5 fully charged. I'm getting about 9.5 to coil itself.

I know I'm getting spark in both coil circuits because 1 and 2 are sparking. I'll be checking all plugs tonight just to cover the case of something screwy.
I'm getting the right levels in the bowls so the hose isn't the issue. Fuel smell in exhaust and backfires confirm this. Extra gas on the filters will cause the bike to pop, but not sputter or give any indication of wanting to run.

At this point I'm interested in my air screw/ pilot jet condition or the TCI unit which I'll admit I don't know much about yet. I'll have another look at carbs tonight as well.

 

One and two share a coil. Three and four share the other coil. Check the 3/4 coil.

 

Close, k-moe, oh so close!

Coil "A" fires cylinders # 1 and #4, and coil "B" fires cylinders # 2 and #3.

 

We'll darn me for trying to post at my lunch break. Prftth.. Wrong again.

 

Does anyone know if I'm supposed to see a spark arcing across the points, at the pickup coil underneath the left side cover?

The manual lists testing the points by checking resistance between four wires going to the pickup, but I only see three.

 

NO, there should not be any sparks.

The black wire is a common ground and serves both pick-up coils:

IGNITION PICK-UP COILS:

One of the nice things about the stock XJ electrical systems is the transistorized (maintenance free) ignition systems.......no points to set or timing to adjust (except on 1986 XJ700-X models). All of those dreadful chores are handled for you, automatically, via the IGNITION PICK-UP COILS SYSTEM, and further down the line, via the TCI CONTROL MODULE. These components are generally very reliable, almost to the point of being bulletproof, and as mentioned, are truly "plug-and-play" devices that need no periodic maintenance once installed. However, they are quite susceptible to damage via electrical shorts or voltage surges (i.e. if you jumper the battery incorrectly, etc.).

Checking pick-up coils: the resistance across each pair of lead wires (at the TCI) should be as follows. NOTE: if both coils are out of specifications, suspect a pinched or shorted black ground wire, which is a shared ground for both of the pick-up coils on most models. It is very unlikely (although not impossible, especially in a case of improper jump-starting, etc.) that BOTH pick-up coils would expire at the same time!

A simple test to see if the coils are working, at all is to place a voltmeter (preferably an analog unit) across the Grey or the Orange wire to the Black wire. Energize the system and watch for voltage pulses as you rotate the reluctor past the pickup. This can be done by hand or with the starter.......we'd recommend using the hand method so that the pulses are slow enough to see. These "pulses" are what the TCI "black box" counts and interprets when "deciding" when to fire the ignition coils.

NOTE: the orange lead wire is the trigger wire for the #1/#4 ignition coils, while the grey lead wire is the trigger for the #2/#3 ignition coils.


120 ohms +/- 10% for all XJ650 Turbo models, XJ700 all models and XJ750-X models, XJ900RK, RL, N/FN, and F models, and XJ1100 models.

650 ohms +/- 20% for all XJ550 models, 1982-84 XJ650 Maxim, 1982 XJ650RJC Seca (Canadian, yics-engine), and all XJ750 models.

700 ohms +/- 20% for all 1980-81 XJ650 models and 1982 XJ650RJ (non-yics engine) models.