XJ700-1986 starts up and runs smoothly on 'Starting Fluid' then dies

Hi XJers!

Back in December 2015, I bought a XJ700-1986 with 5,000 miles, which had been sitting for nearly 20 years. After three months of on and off working on the bike to fix things, I am now ready to start it after all the carbs, tank, and petcock cleaning. Although it starts right up on 'starting fluid', but then the engine dies right after it consumes the spray starter, almost as if no fuel is supplied through the carbs, it just dies instantaneously. More details below if interested:

Carb cleaning: Cleaned carbs completely, spraying carb cleaner into every orifice, removing and cleaning all jets and removing all deposits in the bowls. Inspected all 4 diaphragms for rips and tears, all checked out in good condition. Did not spend a lot of time on floats but just made sure all 4 are at the same level. Changed bowl gaskets with new. Also did a bench sunc of the carbs, which is making sure all throttle valves are at the same tight closed position and open to the same fully open position.

Plugs: Replaced old plugs with new OEM recommended BP8ES plugs.

Tank: Cleaned all corrosion completely, etched with acid and lined it with POR15 tank ceramic lining, looks brand new.

There is no leakage from anywhere from the airbox to the engine intake boots, all airtight.

What could be the issue here? Why the engine does not stay on past consuming the 'starting spray'?
Any suggestion is appreciated.

 

did you confirm that fuel flows through the petcock?
crack open the bowl drain screws to see if fuel is present in bowls.
You need to do a wet fuel level test

did you dissamble and clean the enrichment circuit/choke?
are you sure the long tube that goes into side wall of the carb bowl and the passages in the carb bowls are clean?
sounds like no fuel flow


The Information Overload Hour

this is what the carbs do.
THE SECRET LIFE OF CARBURETORS
this is how to claen carbs
IN THE CHURCH OF CLEAN

this links to cutaway of the carbs to show you all the passages and how they connect to each other and where carb spray should flow when you spray it in a passage
Something New, Something Naked

 

Does bliping the throttle open do anthing? Could be your idle is too low, or your floats are way out of whack or need to go all church of clean on your carbs and wet set your floats

 

+1.

Gary H.

 

Bench synching does not mean making sure that all the throttle plates are at the same tight closed position. It means making sure that all the throttle plates have the correct relationship with the pilot circuit bypass hole. the shortcut is to use a business card as a shim to set the throttle plates. http://xjbikes.com/forums/threads/how-to-bench-synch-your-carbs.6366/
This is not where your problem lies however.

Setting the floats to the same level is a good start, but it does not ensure that the fuel level in the carbs is corrrect. To do that you have to wet-set them (there is very little room for error here). http://www.xj4ever.com/setting fuel levels.pdf
Improper float levels can mimic a faulty petcock by shutting off fuel flow prematurely, leaving the idle circuit sucking air.

Rebuilding your petcock is a good idea, but you can check for proper fuel flow by removing the vacuum line from the intake manifold and sucking on it. Remove the fuel line, put it in a jar, suck on the vacuum line and see what the fuel flow looks like at all positions (no vacuum needed for prime).

 

I have the same bike. If the petcock is allowing fuel to flow then you need to go back through the carbs. I can tell you from experience that shortcuts don't work. I had my carbs off several times before finally going step by step from start to end in accordance with the instructions in The Church of Clean. The float levels have to be within specs, not just all the same. The enrichment circuit has to be perfect as does the pilot system in order to start and idle. It takes time and patience but it's worth it when you finally get it right.

 

If the carbs aren't right your bike will never run right.

Gary H.

 

It won't even run left.

 

This. You need to get your squirty carb cleaner so that it can shoot jets out of the tiny holes on the roof of the carb by the butterfly(pilot) or alongside (enrichment aka choke).
Judge it right and you won't even get an eyeful of carb cleaner (at my first attempt with CV carbs I didn't know these existed).
The pilot circuit and teh enrichment start in te fuel bow. The enrichment is the rod type thingy that dips into its own narrow 'well'.

 

LOL--Or down the center.

 

Not really. I checked again and one could see through the clear filter on carb inlet that no gas come into the carb. So I pulled the gas line from the petcock and there is no problem there, gas flows as it should. something blocks the passageway of the gas to the carb. Since seemingly none of the carbs see any fuel, the blockage has to be at the inlet tee. I'm thinking to pull the carbs out once more for further cleaning and testing the flow passages.

 

Thanks for your input XJ550H.

Thanks for comments and links. Since seemingly none of the carbs see any fuel, I agree with your comment that there has to be a blockage at or near the inlet tee to the carb. Is there any way to remove the blockage short of taking the carbs off the bike? It was quite an involved process of squeezing the boots out and into the airbox and a lot of rocking of the carb to take off the intake boots the first time around.

 

Thanks K-moe, you're making a lot of good points. I would have tried wet-setting of the floats but I have to admit that when I put the bowl covers back, I switched the two right ones with the two left ones and now all drain plugs face the wrong way making them inaccessible for a screw driver. I messed up there! So my next thing is to take the carbs off the bike to re-position the bowl covers and adjust the float per spec, make a PVC support for the carbs and do the wet setting.

 

for the record it is called

Starter FUEL Jet Size: #36 (non-replaceable, in float bowl)

its for the enrichment circuit aka choke aka starter lever

 

It could be the filter blocking the flow. WHat filter did you use? Many of the small paper-element filters are not meant to be used on gravity-fed systems.

 

Ok, I pulled the carbs off the bike and opened the bowls. Damn me!... I had mounted all the floats upside down, like the leftmost one in the picture above. No surprise now that no fuel was going to the carbs. So I corrected this and made sure all floats are at 16+1 (-0) mm from the surface underneath the bowl gasket. Will put the carbs on the bike tomorrow and update you all on the outcome.

 

The filter I'm using is a rather large FRAM G2 filter that still nicely fits in the space between the carb rack and the bike frame. I found the main culprit that I had the floats upside down...!

 

Thanks for the suggestion. I will make sure to test the flow with the carb cleaner spray as you suggested before putting the carbs back on the bike.

 

Uh, yeah...... That could cause the issue. Lol

 

I'd say that would be cause for the bike to not run...

 

Breaking News!!!
I corrected the situation with the floats being upside down and mounted the carbs back on the bike and now it runs awesome. It started rough and somewhat smoking from 20 years of sitting and corrosion, etc but some sea foam and 1/2 hr of running, now it runs nice and smooth. Thanks for all the support and your great comments!! Here is a picture of my bike, still working on the brakes, so the front fender is off!

 

That is......beautiful

 

very nice looking bike

 

Your bike looks amazing

 

Where did you get your speedo and tach from?

 

Yamaha. Those are the stock gauges.

 

Oh lol I'm kind of new to this lol but I like them regardless, might have to find a set for my bike

 

I think your avatar shows a 750. If so you'll need to do a fair amount of wiring to use different gauges. Totally doable, but it takes some time.

 

I've got the Atari all but removed only 1 wire for tach and the spedo cable and fuel level are still hooked up

 

no oil light?

 

And you re-wired to bypass the systems monitor?

 

Beautiful job. Did you do the paint yourself?

 

Yes, I did. I got the inspiration from a Victory motorcycle when I visited the motorcycle show at Javitz Center last year. All painted with spray can. I also made the 'Maxim' decal on the side covers. A lot of work and rework striving for perfection. These 80's XJs have a very good potential and very solid parts to start working on. Also lots of used components on ebay to support any restoration project on them. I would do this again if I find the correct candidate.

 

What did you use to get a good fuel-proof clear coat?

 

Thanks a lot for all the encouraging comments.

 

I am moving the oil light to the handle bars but other than the tach and speedo and neutral light and fuel level everything elce is gone I'm just waiting for my motor to be finished in the shop

 

Fuel-proof perhaps it is not. I used Rostoleum clear over Krylon Maxx paint and Krylon primer. For preparation, stripped the original paint using a common paint stripper and used bondo to fill some minor dings on the front fender and gas tank and sanded somooth progressively from 80 to 800 paper.
See the pictures below:

 

Very nice bike

 

I put my bike up for sale on ebay. It is so hard to let it go!
http://www.ebay.com/itm/131908310042?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

K-moe that is the very first thing that I thought of too after reading his post! The butterflies should NOT be tightly closed!

 

Should we ask...why are you selling it?

Gary H.