Phase 1 of Seca 750 fixing done, new problems

I put a post here in May and did some things to fix the cycle, but still not running quite right.

I pulled the carbs and cleaned the bottoms of the carbs without taking the tops apart of taking the needle stuff apart. A friend was helping me and didn't want to tackle the needle jets yet. The goal was to get fuel into the system. I also rebuilt the fuel petcock. And changed the engine oil.

Strange observation: the oil seemed to have a bunch of gasoline in it.

So now fuel does get to the carbs and engine. Yippee! The little beanie filters had been cloged with varnish. Cleaned the carb bottoms and all parts in lemon joiuce solution and carb cleaner.

It was an extreme hassle getting the rubber boots back in place between the air box and carb until I unbolted the air box and moved it back - duh - only mentioned a bunch of times in these fourms. It was late.

Now when I first start with "choke" set a bit, engine first starts for a few seconds, then dies. With carb starter spray, starts. After warming up a LONG time, engine won't idle with choke totally off. Runs fine at higher revs. So perhaps some kind of idle circuit or jet is clogged? Played around with idle adjustment in back also.

Problem 2: when it does warm up, and I have to keep on choke, tried to put into first gear. Always causes engine to stop. I think I have now adjusted clutch cable to the max down ay bottom, and top. Still dies.

So any ideas from the audience about: 1) Idle problem, 2) dies when put in gear. Can the clutch plate system be totally shot? Or some malfunction in some circuit connected to the cluth that kills the engine?

Thanks.

 

Your biggest problem is almost certainly the carbs are still dirty. There are several threads on this site dedicated to the excruciating details of completely (and I mean COMPLETELY) cleaning your carbs and the necessity for doing so. The cleaning should be followed by a detailed bench synching then vacuum sync and then colortuning.

I don't have the tools (or patience) for the vacuum sync and colortuning but have found that once the carbs are cleaned thoroughly with a good bench sync, the bike runs pretty damn good.

 

All your problems are tied to Carbs that need to be THOROUGHLY Cleaned.

Just squirting Carb Cleaner on the open Floats and Bowl is not enough.

In order to function as the heart of the Fuel Delivery system; the Carbs need to have the Jets and Metering Parts removed, Cleaned and ALL the Fuel Passages flushed and cleaned.

Clean and scrub exteriors
(Do 1 as a time)
Remove Bowl
Flush Bowl Starter Jet Reservoir and Ports
Remove Hinge Pin
Remove Float and Needle
Remove Float valve
Remove Pilot Jet
Remove Main Jet & Washer
Remove Top Cover
Remove Diaphragm Assy & Spring
Remove Innner Cover Plate (If so equipped)
Remove Center Nozzle (Emulsion Tube)
Remove Pilot Mixture Screw, Spring, Washer & O-ring
Remove Enrichment Plungers after disassembling Rod and Forks.
Clean everything
Flush every passage
Scrub Main Bore & Polish

 

PLUS:

FIRST THINGS FIRST: Valve clearances have to be IN SPEC BEFORE you attempt to sync the carbs, no ifs ands or maybes. First.

Then once the carbs are fully cleaned as above, they need to be bench sync'ed and have their float levels set using clear tubing and fuel.

Once back on the bike you'll need to do a running vacuum sync with the YICS blocked; something you cannot do if the valves are not in spec.

Read: http://xjbikes.com/Forums/viewtopic/t=32118.html

You can't rush, or skip steps, or "gloss over" stuff or you will keep having "problems." They're NOT problems; they're symptoms of stuff you skipped.

XJ LAW #1: NO SHORTCUTS. Or you will be at this for quite a while, fighting "problem" after "problem." You have to approach it thoroughly and methodically or it won't solve.

 

LIke rick and fitz said you have to completely take your carbs apart especially if you have gas in your oil you probably need ad least new needle and seats. then put your carbs on. If it starts without fuel going everywhere adjust your valves then try and sync them. What your doing on the bike right now there is no short cut it has to be done right or just don't do it at all . Not trying to tell you what to do or sound like a hard ass but if you do it right it will save you so many headaches and time in the end

 

There is no clutch problem, just stupidity. I forgot that the engine will die, with the cluth in, if you put it into first, and the kick stand is down.

I got it to run OK so that I could ride it around local roads a bit yesterday.

The problem left is that I have to leave the "choke" partially set, or the engine won't idle. Does anyone know which part of the carbs would have to be gummed up to cause that? It just would be interesting to have an idea of what I think the problem is before I take the carbs apart. Like a theory.

I did all of what Rick listed up until the point of takin out the jets, or anything having to do with the carb tops. I even cleaned out that little passage from the bottom of the float bowel that feeds back up through that little metal tube into the top.

So what part of taking apart the carbs causes me to have to resync the carbs? Do I need some kind of special device to do that? I see a video about some fancy digital device to do that. I'm a bit nervouse about that part. But for me its a hobby, so may be OK by me.

 

Another thing is that I put a new air filter in it yesterday, and that seemed to be the key to making it run better. The old one's foam between the filter and air box had disintegrated, and was real dirty. And I don't have an air compressor. Its amaizing how many things in the system have to be just right in order for it to run nicely.

 

If you didn't take the tops and jets off you didn't take the emulsion tubes out which have a bunch of tiny holes in them that you are very unlikely to get clean by spraying them while they are in the carbs.

look around the site at people that have idle problems. may of them play around at cleaning the carbs 5, 6 or more times until they finally break them down and clean them right.

as far as the synch you can build your own manometer for a few bucks. there are a number of plans on the site for how to make them

 

Failure to run at Idle means you Pilot Jets are clogged or the Mixture Screws are set wrong.

It don't take much to clog a Pilot Jet.

Looks like you are due for a Carb Cleaning and Tune-up.
Sometimes, there's no getting around what needs to be done to have the bike respond the way you want.