**UPDATE** My Seca Woes :( Need Advice guys.

Ok so i got the Seca on the road. Yesterday it ran really good, till i went to come home. I had filled the tank with half a bottle of seafoam added before filling, it ran good for 40 km. The Dez and me did some stuff (prolly 5 hours) but when i went to go home, the bike was stipping and missing on a couple cylinders, but evened out after 10 or so km. Then she ran like a dream the rest of the way home.

This morning i start the bike to goto work. Little choke and away she goes idling fairly nicely. When i go to actually take off, she starts to sputter and back fire, wouldn't idle without dieing.

**Little background info**

I've got a 4-1 supertrapp on her, but where the 4 pipes come together into 1, there is a hole in the collection (can't see how big).

**

So i could actually see the little flames jumping out of this hole when it backfired. 1k rpm 4k rpm it didn't matter, she backfired.

After 10km down the road on my way to work is my first stop sign. She was idling and running perfectly, ran good the rest of the way into work.

Tonight coming home was the same thing, had to baby her in the parking lot for 30 mins till i could even drive her. She spit and backfired for prolly 5km till i got out of town, then she ran perfect the rest of the way home.

i've gone just under 200km since filling her up and she's almost down to the last segment on the atari... not good...

I'm thinking that i may have a couple cylinder running SUPER rich, and a couple running SUPER lean. So the extra hot lean exhaust gas is igniting the not fully burned rich exhaust gas in the pipes.

Does that seem right, or am i way off base? Could the seafoam have done something (carbs were clean).

I'm running 6 plates in my supertrapp right now to compensate for the hole in the pipes, but maybe i went to far with that lol, should i out a few more plates back in?


I've run out of ideas right now, i can provide more info if needed, i've got a few hours tomorrow morning to play with it, i'll find out what the pilots are set for and report back. (i had them set for 4.5 turns out to get her to idle nice. Last time i checked plugs, none were pure white, but a couple had white tips with black around the last threads and way up in the plug.

Voltage measures over 13V when above 2k rpm, lights reflect this as well, BUT i did notice tonight, that when i come to a stop, they are probably half as bright as when i'm driving at speed.


Thanx guys for any help!, i really love this bike when she's runnin right

 

Re: My Seca Woes Need Advice guys.

And exactly how did you set your float levels? Sounds to me like you're absolutely dumping fuel into the cylinders--- sometimes.

Floats.

Dim lights at idle is normal unless you have a brand new battery and every connector and wire on the bike is perfect. Then they still dim, just not as much. You're ok there.

 

Re: My Seca Woes Need Advice guys.

Wouldn't that run good when cold and horrible when hot Fitz? When i got home tonight i could let her sit there idling at 1k and she ran as smooth as silk, no pops or backfires and didn't die out.

Honestly my drain screws are like part of the bowl right now, so no way to check it with clear tube method :/ Also, wouldn't my plugs be completely covered in soot if it was dumping on any cylinder?

Or am i off base here again lol

 

Re: My Seca Woes Need Advice guys.

Hmm i'm wondering if by me takin out plates (from 12 down to 6) that i've just got my pilots out WAAAY too far.

One thing i did forget to mention, the other day, when warm, i could unscrew my idle screw fully and it would idle fine at 1k rpm, i'm pretty sure she should have died if i backed it all the way off the butterfly's.

 

Re: My Seca Woes Need Advice guys.

You said you saw liquid fire in the headers. Raw fuel burning off does that.

Dude, I'm not trying to pee in your cornflakes, but you're shortcutting. Your symptoms point to float levels, you're trying to talk yourself out of it. You can't out-argue science.

Floats aren't set until you do it with the clear tube method; set them dry and check 'em and you'll be way off on at least a couple. That's because the difference between whacked and right on is so slight if you know you bent the tang you went too far.

I'm not making stuff up; I've been through this with two bikes now and you either do it right or you will be at it for a while-- until you DO it right. (...I almost said do do.)

XJ LAW: NO SHORTCUTS. Forget it and you're doomed. Do it right and you can actually enjoy the bike.

Pull the bowls, screw them to a board, get out the propane torch, use a little Kroil and get them out.

Or screw with the carbs forever until you do. You asked for advice, sorry.

 

Re: My Seca Woes Need Advice guys.

Ya, i really don't wanna have to try that without the correct tools, time is an issue as well till sunday. But i do totally hear what yer sayin fitz.

I can set them roughly by pulling the rack and setting the heights dry. I have the tools to do that at home (I always do work at Dezi's as he has almost any took i need)

So when i set them dry, what do i measure, like do i flip em over and measure from carb body to end of float in a particular spot?

Hopefully checking and setting them dry will get me through this week till i can get those screws out at Dezi's.

I do appreciate your input fitz! remember i've only ever had to deal with 2 carbs before lol the 4 carb is still a little new (as is the feeling of shaft drive)

 

Re: My Seca Woes Need Advice guys.

Yes, but it's only a start. I think it's in the Haynes, or do a forum search.

Honest. Nearly imperceptible, but it shows up RIGHT AWAY in the tube.

DRY SETTING will not be accurate; it might get you closer than you are now but only might.

 

Re: My Seca Woes Need Advice guys.

Those sound also like symptoms of contaminated fuel supply.
What was your reasoning to add Seafoam?

Backing off idle screw past point of control with bike still running can be accomplished if your carbs are out of sync.

 

Re: My Seca Woes Need Advice guys.

K i'll rip the carbs off tomorrow morning and check the dry height, it just has to get me to sunday where i can get those screws out and check fuel level properly. It's just so unrideable as it sits when cold.

mdee* The bike sat for 3 years before i got it, i went through the carbs and they looked and sprayed fine to pilots, polished emulsion tubes etc. I always throw seafoam through my bike gas every few months, just to keep things prestine

I'll report back tomorrow morning with what i find!

Thanx guys!

 

Re: My Seca Woes Need Advice guys.

An easy thing to do is flushing the gas tank. Cleaning the fuel tap and all filters in the gas supply. It helped me once when i had the same symtoms. I added an in line filter to be shure no dirt vas comming to the carburettors.
- and there is a lot af ugly things in an old gas tank.

 

Re: My Seca Woes Need Advice guys.

I can vouch for that.
I took the carbs apart in the beginning of July whilst waiting for supplies from Len and took a look in the bowls... tiny specs of rust lining up the insides of the bowls. The only part that can rust on the fuel line coming to the carbs is the tank. Needless to say, PO had not installed fuel filter.

 

Re: My Seca Woes Need Advice guys.

**UPDATE**

Ok so i reset the pilots first thing today, they WERE as follows from 1-4:

6 - 3.25 - 4.5 - 3.5
plugs looked as follows:

white tip rest black - white tip rest black - dark brown tip rest black - grey tip rest black

I pulled the carbs.. all the floats were WAY too high, set to prolly 12mm or so, so i reset them all to 17mm.

I DID get 3 of 4 drain screws loose.

Carb bottoms were prestine, reinstalled carbs on bike.

Checked the 3 levels that i could all were within 3mm from carb body.

Set all 4 pilots to 3 turns out.

Crossed my fingers and started her up, ran with choke very nicely for a couple minutes.

As soon as i took the choke off she started poppin and back fireing again out that hole.. put the choke on she was fine.

I'll take the truck into work today cause i don't wanna deal with a crap runnin bike lol but what am i lookin at to check now guys?

 

Re: My Seca Woes Need Advice guys.

This is a starting point not the final setting. Also did you vac synch them after playing with the mixes?

 

Re: My Seca Woes Need Advice guys.

There in lies the issue, she seems to not even like the starting point lol

I'll play with the pilots more tomorrow morning. When i FIRST got the bike (like i'm talking the first time i started it) it ran like this, popping and skipping etc etc.. and i turned everything out to 4.5 and it seemed fine after that till the other day.

(I was tweaking to get colour correct, hence the differing numbers I posted above.)

I've only ever done a bench sync so far, i have bottles but haven't done a good sync yet, they should be close enough that it shouldn't be running like it is.

 

No, no NO.

"They should be close enough.."

NO.

Screwing with the pilots before getting a good vacuum sync is doing things backwards.

TO GET IT RIGHT YOU HAVE TO DO IT RIGHT. All you're doing right now is painting yourself into a corner. Of course it "didn't like" the starting point-- you turn the idle knob up a hair, get it running on all 4 and sync it.

THEN mess with the pilots.

Keep up with the shortcuts and you're going to be at this a while...

 

That's the problem fitz, i'm not cutting corners here now, it won't idle, i can run it up to 3k and it still pops and backfires, all this stuff wouldn't be an issue if it actually ran without backfiring.

That's my issue right now. Something is WAY off, when i've got the fuel levels good, the pilots set to where a lot of you guys run them, and i get issues like i have, there's something terribly off that i can't find. That's where i need some advice that i may have been stupid and forgot.

It's hard to start the normal tuning process when i can't even get the bike to run at all right when it's cold.

THAT is what mystifies me about it... struggle through the crap running when it's cold and then it runs like a dream, will idle all day, no problem whatsoever.

It's acting like it's running WAY lean, but you advised me it must be raw fuel in the exhaust somehow. So i need to find out why it's doing the backfiring (all of a sudden remember too) THEN i'll have no problems with the rest.

I know you guys are trying to help, but telling me i'm trying to cut corners still, when I do what you suggested, and it didn't help any, isn't helping my issue to improve. I really need to just find out what i can check and look for that will solve the backfiring when cold problem.

Sync should be set so it won't do what it's doing, i checked that again today. Pilots should be set to at least get a good idle.. it's not.

 

if you think it's lean a little choke would help it if you suspect rich take the air filter out or pull the vacuum hose to the petcok, plug it and let it start to run out of gas
i'am trying to not make you pull the rack again till you have something to go on
do you have any idea what the throttle shaft seals are like ?

 

I haven't taken the seals out, but i have sprayed ether on the shafts and it didn't change rpms at all, so they seal ok.

I will try those couple things tomorrow morning Pol see what she does, may give me a starting point. as to which way she's running.

I'll report with what i find in the morning.

 

Your carbs are not all working together. Like you wrote in your original post, some are too lean, some are too rich relative to each other. The procedures to get them working together is multi stepped and ALL the steps must be preformed on each and ALL carbs.

You are having difficulty with doing all steps to each carb due to reasons like drain screws you can’t loosen. Leaving out a step on any carb will likely result in that carb not working properly together with the other carbs. Many different issues with carbs present themselves with similar symptoms. That is one reason to do all the correct procedures. Otherwise it can be difficult to diagnose. It can be easy to convince yourself you have completed all procedures as a whole, when it fact you have not on each carb.

You should set the 4 pilot screws to about 3.5 to 4.5 turns out and set all to the same setting. Then ignore them till all other carb issues are dealt with. More precise settings of the pilot screws will be the last step in tuning after you have float level and sync set correctly.

You sound like you are frustrated because you are considering too many possible causes. Try to focus on the procedures you have completed with the most confidence as a process of elimination.
I think you should get that stuck drain screw out of the last carb so you can be confident of the wet float level.

My example story:
I ran into difficulty syncing my carbs because the left adjusting screw was rusty and would not turn smoothly. I had seen it was rusty, but I skipped the bench sync adjustment because all carbs matched on bench. I did not want to bother with the rusty screw if I did not need to. But then on bike when I attempted to balance (sync) carbs I became confused with the procedure results I was getting. Took me a while to realize the rusty screw was jumping high and low and also pushing idle too high and low. My lesson re-learned is try harder to do ALL a given procedures steps in the proper order. Otherwise I will likely be doing the skipped procedure later on when it’s more difficult, time consuming and frustrating.

 

That's the exact reason why when i first got the bike, the first thing i did was go through the carbs, and reset the pilots.

I have been reading this site for 2 years, so i have amassed a large amount of info, and technique over that time. I usually only post when something, be it an adjustment or whatnot, doesn't react the way it should.

The big stink in this whole thing, is it ran perfectly for a few weeks and then BAM, i'm stuck with what it's doing now.

The problem i'm having with the whole "leave the pilots till last" is if i ran at 0.5 turns out or i run at 6 turns out, i should have VASTLY different problems. Most ppl start at 3 turns to get running then tweak from there, which of course i tried and failed. So i can't really tell if anything else is buggered till i get an idling bike.

That's why the first thing i'm doing tomorrow is check the plugs from my test start this morning, and see what the plugs tell me, then adjust pilots and idle set screw till i get a smooth idle, that will rev without hanging or backfiring at any throttle level.

Once i get a running bike, the fine tuning is nothing.

If i sound frustrated from considering too many possibilites, it's because there COULD be THAT many things to consider, that's causing my problem.

I'm not so much frustrated, as i am baffled that my 400 and this 750 are such completely different beasts in reacting to my troubleshooting. BUT i'm not even close to giving up. The 400 didn't beat me, this bike won't either lol.