firing up an old engine, part II

Still trying to get my old 650 to fire up. This is the first time anyone has tried to start this thing in five or ten years. Today, the engine finally fired, ran for a second or two, then died. A minute later a really loud pop came out of the bike, made me jump. Tried again later, got the engine to run for a few seconds (longer than the first time), gave it a little gas, then it died. No pop this time. Since then, the engine refuses to fire.

Kind of a side note, but maybe related: At the same time as all of this, the headlight, whose fuse was was blown when I bought the bike, died. The new fuse I'd put in is not blown, but the light won't shine. Confusing.

I checked the spark again after the headlight died, no problem there either.

My queries:
1) There's no way the headlight problem could be affecting the engine, right? I've got spark...
2) Should I be involving the prime setting on the petcock in all this somehow? I'm not sure how to use that setting.
3)What kind of work is usually needed on carbs after they've been sitting for so long? I think they're my problem. They seemed fairly clean when I removed the reservoirs.
4) Is there psychological help available for people who like to try and fix up old bikes when they could just buy something brand new and shiny from the dealer?

 

Well The headlight is on a relay so it will only come on when the engine is running. You should leave it set to prime as that is how you fill the carbs when they have been drained or left and fuel has evaporated. It sounds like there is a fuel starvation, so make sure you use prime to fill the carbs up and make sure there isn't a kink in the fuel line, that got me for an hour once.

 

Here's where to look first--deep inside each of the carbs are 2 jets that are so small you will need the wire from a stainless steel brush and carb cleaner and lots of patience.
If you have an air box and not "pods" then you can load it with a fuel soaked rag to test the engine..WARNING fire hazard leave a hose running.
With pods, just shoot each with a little ether. If it runs real smooth, then you got lots of carb work to do. Be careful.

 

Do not leave set to prime. Normal operation you use the fuel valve set to "ON". "RES" is the reserve, for getting the last 3/4 gallon or so from the tank so you can make it to fuel when it quits getting fuel on "ON".

Both "ON" and "RES" should only deliver fuel when there is engine vacuum. "PRI" is meant for filling the float bowls when they've been drained. If you leave it on "PRI" and you have a leaking needle/seat all your gasoline will get into the oil - not good.

When the fuel valves fail (which a lot of old ones have) fuel can leak past on "ON" and/or "RES" even without engine vacuum.

My suggestion is that you make sure the fuel valve is working properly before you proceed.

Have about 1 gallon of fuel in the tank (more and you might waste it).

Set fuel valve to "RES". Remove fuel hose - fuel should not flow.
Set fuel valve to "ON". Remove fuel hose - fuel should not flow.

Now, if both of those tests are ok set the fuel valve to "ON". Remove fuel hose. Turn valve to "PRI" fuel should run so be ready to turn it back quick. Smart thing for these tests is probably to have a length of fuel hose on the valve and the other end in a suitable container for gasoline.

If all these tests worked OK count yourself lucky. I think everyone else here has had to tear into a fuel valve.

Post results!

 

There are anynumber of reasons you can't get her going right away.
First, the Carbs need to be in a state of Cleanliness and fully operational.

On Bikes that have sat for years ALL the Passages need to be flushed Clean.
The Pilot FUEL Jet and Pilot Fuel Passage ...
(which connects to)
The Pilot AIR Jet and Pilot AIR Passage.

The Main FUEL Jet and Main AIR Passages and Metering Ports.
(Which involve pushing out the Emulsion Tubes and Cleaning the 16-to-24 Tiny Ports in the diameter of the Emulsion Tube.
Shooting Carb Cleaner IN the Main AIR Jet with the Emulsion Tubes removed.

The Starter JET Siphon Tube and the Starter Jet Fuel well Metering Ports at the Bottom of the Fuel Bowls.

The Pilot Mixture Screws and their connecting Passage to the combined Pilot FUEL and AIR Passage allowing fuel to be presented to the Idle Mixture Port controlled by the Pilot Mixture Screw.

All the Enrichment Valves and the Passage to the Starter Jet Siphon Tubes.

Once that all verified and cleaned ... starting and tuning can begin.

 

Fuel valve is behaving normally - flows when turned to prime, not when turned to on or res. I need to see if fuel comes out of "on" or "res" when under suction, can't think of anything besides a big syringe that would work to create a vacuum.

Tried the engine again, after using the PRI setting, and it ran for two to three seconds, then died. Seems to be the pattern.

 

Then you need to get over to the XJ FAQ Suggestions section and dig into Rick's carburetor cleaning instructions.

 

Right. Time to do my homework, learn about carbs. Thanks fellas.

 

Stick the hose in your mouth and give it a toke. 8)

 

try running seafoam threw the carbs befor taking apart, may save some time by useing it

 

Somebody sent me Carbs that sat for over 10 Years, last season, for Cleaning.
I think running Seafoam through them just messed them up even more.
Mind you, there was residue thick enough to scrape inside those Fuel Bowls and the Seafoam just turned it into a thick, brown mud that got into everything.

The best advice I can give to anyone who has Carbs that sat for more than a year is to pull them off and go inside and Clean them out the right way.
The Seafoam is just going to loosen foreign matter that you'd like to keep out of Jets and Passages.

I know miracles do happen; but on sitting-around Carbs you're asking for a lot of Divine Intervention Cleaning out a mess made by gas that evaporated away leaving behind a residue that can get as solid as a rock.

 

Rick, when you use wd40 for a liquid for polishing/clunk test stuff, you have to clean that out with carb cleaner, too, right? Seems like wd40's not something you want sticking up your carbs.

 

I wet the paper with the WD40 and do the refinishing.

After the Bores are refinished; I spray them all clean with Carb Cleaner.

Lately, I been carrying it an additional step and Polishing the Bores for Carb Customers. It's a Race-Prep Tuning Trick ... But, I don't have to do them by hand, any more, because I bought the Flexible Extension Accessory for the Dremel and its easy to get right down to the bottom of the Bores with the Flex cable.

 

We used to use WD-40 to test engines in the wrecking yard. Supports combustion and is a great lubricant. Won't hurt a thing to run it in the carb bore.

 

I'm missing the float valve assembly beanie-screen thingies on my carbs. How important are they?

By the way, thanks for answering all these inane questions.

 

I wouldn't replace the needles and seats just to get the beanies.

I would put an in line filter on whether I had the beanies or not.

 

Install an Inline Fuel Filter and you won't be needing the Beenies anymore.

 

They can be left out or installed. They act as another line of defense against crud hitting the float needle seat. If they are there, leave them. If they are messed up, chuck them.

 

If they are missing ... you might have aftermarket Float Valves. Many aftermarker Float Valves are made without the shoulder that Beenies clip-on too.

You might have new floats.
That would be nice.