1981 Seca 750 bogging problem

Hello all,
First off thanks for all the info you guys have given over the past week as I revive my bike after approximately 12yrs of storage.
She's up and running after extensive tune-up mostly by me but the after the 5th carb cleaning I took them in to a pro...
All was well for a few days until it started bogging a bit on start up when cold but would kick in after a few seconds of idle.
It worsened ever start up and now stays "bogged" all the time.
I think the issue is with the leads to my plugs.
If I disconnect #1 lead the bike runs no different on or off.
Would this explain my problem?
Thanks for any insight you may have...

 

It indicates there's some type of problem with that cylinder, but it doesn't necessarily mean it's a spark problem. It could be mixture, fuel starvation (stuck float maybe), or other problem.

Have you tried swapping plugs around in case the #1 is bad or fouled? Have you visually checked for a spark on that lead - connect a loose plug to the lead, ground the thread area against the engine, crank the starter and look for a spark at the gap - do this safely away from any combustible material and don't hang on to the metal You can't really tell anything from the intensity of the spark, but you'll at least know if there is or isn't one there.

I'm out of ideas, but I know some of the pros here should have more for you.

 

Welcome to you HedgeHog, Oblivion's observations are correct, it may not be the spark plug that is the issue. I would venture to say that you may have crud from your fuel tank (did you flush it throughly?) now washed down into the carbs. Did you install an inline fuel filter? Was the tank previously lined? I'd pull your carbs again and have a good look at what all is floating around in the bowls.

 

I believe I had a similar problem on my 650. It would fire on 3 cylinders untill revved/warmed up... Then 2 cylinders... And was very boggy (felt like it was running out of gas) on take off or up hills. Also it became a COMPLETE NUSANCE to start. The problem got worse after the bike was sitting for the winter.

In my case I had the carbs re-done, BUT at the same time, the mechanic that did the work noticed that I still had old (metal) plug boots.
So combined with a quick cleaning and a sync of the carbs, he installed new (actually they weren't exactly new, just a set he had lying around) plug boots. The bike is now stronger than ever and never bogs down under a load... But it was probably not one or the other that was causing the problem. More likely it was both.

I spent a good bit of time trying to figure out the easy solution to what was wrong with the bike... but of course it's always the obvious, it seems, on these older bikes... Carbs. Cost me $180.

 

Thanks guys, you are probably bang on with the diagnosis.
The spark is fine, a cyclinder wasn't firing as indicated by cold exhaust pipes. I need to flush my tank. I think its a little rusty in there.
Is there a recipe for a DIY tank flush around?
Thanks again for the input...

 

Determine if the problem is Fuel Starvation or Ignition Break-down.

Remove Air Cleaner.
Start and Run Bike.

When "Bogging" happens ...
Spray a shot of "Starting Fluid" into the exposed Intake Boots.

If bike's performance improves ~~> Immediately! ... upon the introduction of the Starting Fluid (or Propane Gas form your Torch Bottle) ... the problem is Fuel Starvation.

The Carbs need to be cleaned; again. Paying attention to the Top-end feed circuit.
Siphon Tube.
Siphon Tube Well.
Metering Ports feeding Well.

NO Improvement: Ignition Breakdown.

 

Keep a fire extinguisher within reach. Trust me on this. :roll: 8O
Or better yet, when he says 'shot' he means just that, not a soaking.

 

Eblo ..

Good call ...
Nice "lookin'-out" ...

I'm always presuming that they'll do it safely ... maybe the propane -- although not as effective an agent ... would be the better choise.

Fire extinguisher
Big blanket.
Be safe.

 

Well, I almost burned down my bike/garage last year trying to start the beast with way too much starter fluid. With no filter in place, one backfire was all it took to elevate my cardiovascular response. I was lucky enough to have the extinguisher handy and deploy it before the fire got beyond the airbox. Cleanup was a BEAR!

So yeah, sometimes things that 'go without saying' need to be said Like it says on the can, actually.

 

Been there done that. On the second day of trying to start my bike after I bought it, I was spraying a bunch of starting fluid in there when it backfired out the carbs and started the airbox on fire. Little did I realize that my #2 and #3 boots had come off, so there was starting fluid dribbling down the outside of the airbox, and onto the starter. I quickly blew out the fire that had started in the airbox, only to ignite the fluid that was all over the starter. When I blew that out, the airbox lit up again! It went back and forth 3 or 4 times before the fire stopped. Boy was that scary! Especially when there was no extinguisher anywhere to be found.

Needless to say, I bought an extinguisher the next day.

 

It don't seem to work all that well for what it says on the sides of cigarette packs.

I guess before you try it ... you should call-up the Fire Department and have them send-over an Engine Company.

Wait 'til you see water dripping from the nozzle of the attack line before spritzing the starter fluid in there ...