SOLVED bogs at low rpm revs over 2K. Ignition help. SOLVED!

Ok, the symptoms.
Bike will idle, but when you turn the throttle it sounds like it doesn't want to take the fuel, bogs.
With alittle feathering of the wrist you can get it to rev, once over 2 grand it revs up pretty good but not right.

History: two years ago this started.
I rode the bike back and forth to work for a whole season like that, while I tried to figure out where my problem was.
Fuel/electric?
Last year, beginning of the season I put a new battery in and the issues went away.
I thought damn, it could turn the bike over no problem but couldn't fire the plugs.
I rode all last year with no issues.
This year I went through the bike.
New battery.
Valves adjusted, carbs cleaned, synched, tuned.
Plugs a beautiful tan.
I was proud, the best this bike has ever run.
Then out of no where the same issue came back.
One day fine, started it the next and there it was.
Like I said you can ride it like that.
Twice the issue has cleared up for a day and then come back.

So this is definitely ignition but, with a twist.
I have spark on all four cylinders.
Hhmm.
So I moved on in the check list.

I had 13v which slowly dropped until it got to 11.8v where it stayed.
During cranking voltage dropped to 8.9v, so.

New fuse box beginning of last year, I went back and reflowed all connections at the box.
New battery, topped off.
Checked wires from TCI out to coils for continuity.
Did not go into ignition switch or run stop but tried jiggling both to get a reaction of any kind, there was none.

I decided to change my approach.
I did a power on test.
Where you ground a plug on the block and turn the key to on.
You should get a spark in a second or two.
So 2/3 spark, 1/4 no spark.
Ah ha we are getting somewhere.
I checked the pickup coils They both ohmed out in spec 683 and 685.
I checked the coils both primaries in spec at 2.6 ohms.
The secondary 2/3 in spec at 11.9K, 1/4 reads 7.9M, yes Meg.
So the coil is shot but, still sparks, Ok.

Not being happy with the results of the power on test I swapped the wires from the TCI to the coils.

With wires swapped 1/4 now sparks.

A coil that sparks but reads 7.9M.
Spark on all four when cranking.
When doing power on test spark follows the 2/3 side of the ignition.
I took the cover off the TCI and there is no visible damage on the back side.
Before I take the board out and replace capacitors or order new coils.
I thought I would see what you smart folks thought.
Thanks

 

Re: bogs at low rpm revs over 2K. Ignition help please.

I hate to say this, but the actual symptoms sound like a float level issue.

It MAY be ignition related though; don't mind me--- carry on.

 

Re: bogs at low rpm revs over 2K. Ignition help please.

There's something significant about it going away when you put a new battery in....that shouldn't correct a faulty TCI? See if you can "borrow" a coil to test

 

Re: bogs at low rpm revs over 2K. Ignition help please.

You could always check your boots too. Make sure it's not a bad boot that's giving you the extra impedance.

Cut 1/4" off the spark cable and re "Screw" in the boot, after checking it's resistance of course.

Are you using resistive caps? or no?

If these check out, i'd look to see if i could grab a coil from a bike graveyard for cheap and slap that on.

 

Re: bogs at low rpm revs over 2K. Ignition help please.

Upgrade to Dyna coils, no sense in keeping 30 year old ignition coils in play. XJ 4ever has the mounting brackets and all you'll need.
Rebuild the TCI while your waiting for the new coils.
Let us know how it turns out.

MN

 

Re: bogs at low rpm revs over 2K. Ignition help please.

Right that's were I'm at, ordering coils.
I know it's shot for sure.
Let you know what happens.

 

Re: bogs at low rpm revs over 2K. Ignition help please.

So I installed a set of Accel coils.
300 miles and all is well.
They gave the bike a deeper tone, no other noticeable improvements.
I'm still dialing in the carbs but, without a colortune it takes a little while.
It's good to have her back, jetting down the road.

The install was an adventure I'll start another thread about that and link it back here.
IN THE WIND again.

 

Did you end up overhauling the aTCI. Seems like that's the big thing right now , all the old electronics breaking down.

MN

 

Once she fired up and ran I put the cover back on the TCI.
We'll save that one for another day.