won't start. Can lack of rubber airbox boots be a factor?

background: showroom-clean 82 seca 650 just out of mothballs, currently being resurrected. 14k kms / 9K miles. On Sunday, I did a lazy partial carb cleaning and it immediately sprang to life, on cylinders 1, 2 & 4 only. Very encouraging. After 2nd, more thorough cleaning, now I just get backfires


the only difference between Sunday and today is I didn't install the rubber boots between the airbox and the carbs. I thought I'd leave them off until it's running properly (since they're a PITA).

Could that change in airflow make such a big difference as to make it much harder to start?

 

when i had pods on my 550 i would sit there and crank the bike sometimes for a good 20-30 seconds before it would start at full choke. when i put the stock airbox back in the bike starts when i breathe on the start button.

 

bummer
I reinstalled boots and breathed on the starter. Still nothing

thanks anyway

 

choke on or off is it cranking at all?

 

Re: won't start. Can lack of rubber airbox boots be a factor

I know this is obvious, but........................
petrol?
spark?
battery giving out at least 12 volts?

Have you tried turning up the idle screw, because playing about with the carbs and rubbers can make a change in how it used to run. It may be worth a shot.

Another option (although I've never actually needed to try it is, a spray called Start or something like that (perhaps someone on here could fill in this blank).

Good luck

Just an after thought, have you got the leads going to the right plugs?

 

Re: won't start. Can lack of rubber airbox boots be a factor

Easy (Start) Spray into the air inlet - under the seat.

 

Re: won't start. Can lack of rubber airbox boots be a factor

Yep that's the baby, cheers Markie.

 

Yes - I think that the boots DO make a difference. I was struggling with mine and two have come away from the carbs = hard to start!

 

choke was on, turning over strongly (battery charger attached to assist and avoid low voltage issues)
Also, all 4 cylinders get fuel and spark.
And airbox-carb boots back in place

It came back to life again, more or less. This time on 2 cylinders (2 & 3).

Hmmm.... #3 wasn't working on sunday. That's interesting.

Prior to starting this round of attempts, I had cleaned all the plugs nicely.
When it fired-up, I ran it for a good 90 seconds, then pulled the plugs. 2 & 3 were fouled all to hell in that short period.
1 & 4 were clean & wet, of course.

I ROTATED the plugs from 1&4 to 2&3 and repeated. This time, the #1 cylinder was firing and #2 was not.

Logically, I should go buy all new plugs and I'm thinking plug caps.

Any universally agreed-on plugs that are good for the seca 650?
And anyone know if there are generic spark plug caps that can be purchased at a local stealership? OR should i get something specific. This info would be very helpful.

Getting close. I'm a lot more relieved than this morning. I just want to avoid running the starter motor into the ground so I'll hold off until I have new plugs & caps.

thanks to all!

 

I will confirm the boots make a very big difference. The CV carb needs a measured amount of restrictive air inlet to work right. It sounds counter-intuitive but you will create more problems by opening up the back of the carbs to ambient atmosphere. It must be metered (ie the airbox restriction) to have the carbs work right.

 

Robert,
Mj Says Get back to work!!!

 

LeSkid

This is what I did in my work (I’m retired).
When I was working on something and someone walked up and said “what happen it was just working?”

I always said to myself
“what did I just do?”

99.9% of the time I had broken something.

Now for the big question, “what did you just work on?”

I suspect you need to revisit your Carbs, try checking the float levels first (fouled plugs), then double check that you got ALL the jets back in their RIGHT places (fouled plugs again).

Good luck
ab

 

hey there AB
for the sake of brevity, I didn't mention the curious inconsistencies in my testing results. I had an inexplicable & ever-changing variation in spark tests, which I attributed to the flooding / fouling. But I played a hunch and bought new plugs & caps to eliminate those as potential issues. My hunch was correct.

So now I have a running engine but with my amateur carb rebuild, I now have to seek the help of someone who knows these engines & carbs. There's a forum member not far from here with such skills..... now all I have to do is figure out the appropriate bribe so Ken will pop-up and say "come on by!" heh heh.

 

Before you can begin Fine Tuning, ...

The Carbs must be Cleaned like they are NEW.
Enrichment Circuit / Bowl Jets & Pickup Tube
Enrichment Passage
Main Jet & Emulsion Tube
Pilot Jet & Passage
Pilot Air Passage
Main Air Passage
Diaphragm Piston Bores Scrubbed & Polished

There is only one standard of clean. Perfect.

Once you are ready to Tune with Cleaned Carbs:
Bench Synced
Floats Set
Pilots Preset or ColorTuned

The rest is easy.

 

Ask him if he is warm enough... and send my condolences to his sweetheart, she sounded pretty sick on Saturday. I hope she and the kids will be up to pizza Thursday!

 

Rick
it's not mentioned in this post but after I did my lazy partial cleaning, it actually fired-up easily and I was happy until the next day, when I found your cleaning guide.

After reading it (seeing how much I missed), I started all over again. I followed your instructions to a T and am I ever glad I did. I can safely say they're all clean as a whistle now.

The pilot screws were untouched virgins so they were a breeze. The pilot jets were another story - I spent over an hour on just those.

thanks a pile Rick

 

LeSkid,
Thanks a bunch for the "what did you just work on" suggestion.
Im at my wits end. Ive been adjusting carbs all morning. ( had boggy starts from full stop)
I changed plugs adjusting the mixture and tracking info on a chart I made.
I was getting close to perfect when I ran outta gas. Flipped to Res and freaked out and choked the *)@&&#$ outta the bike... ran it for a quarter mile and it slowly died.
I tried to start it for a minute. Gave up and walked home.
Longer story short... its home and Im tinkering. Now I have somewhere to start.

 

Choking the crap out of it ... likely fouled the Plugs.

Get back in the Groove.
Prime the Empty Fuel Bowls
Get it running.
Idle it with as little Idle Rod as possible.
Adjust the Mixtures for Highest rpm's without Rich-side Fouling.

Keep the process going on 2, 3, 4
Tweak the Mix Screw Out obtaining the Highest Idle while Turning the Idlw Adjustment Rod OUT to put the Bike on the Pilot System for Idle.

Turn the Petcock to FUEL or ON after she fires up.