Problems Again! Engine Splutter?

Hi Everyone

Sorry to be a pain, but I've got problems with my XJ650RJ (82) engine again.

What I've done recently:
New carb rack, cleaned in a hydrosonic tank (I think thats what it's called, the wife went nuts to find all the small parts in her jewellary cleaner!). Replaced all the butterfly shaft seals, refitted and synced them - all now identical. Colourtuned each carb, couldn't get an orange flame on any cylinder. All I can get is either a nice blue one or white so I set them all at the botom end of the blue. (I know white's not good!) If I tried to get a orange spark, the spark goes blue, then intermittant, then the engine starts to die so back the screw off back to blue and it ticks over ok. Until I got to number 4 plug. There is a really bright spark from the colourtune but a very intermittant blue flame, accompanied by a popping at the exhaust.
I re shimed the valves 2 months ago and all the gaps are within the gap tollorance as per the Haynes manual (and other shim charts shown on this forum).

Today I took it out for a run and she ran like a dream. Plenty of power and felt like she just wanted to run away! Then I went back out later on and she was spluttering terribly, with the throttle held half open she holds back then now and then bursts into life for a second or so. I have checked the plugs and as you can see from the picture below #1 is on the left and is very black and sooty but dry. #2 & #3 are a nice tan colour and #4 has black soot around the rim but other than that very little markings at all.



The coils are 2 months old (only done about 200 miles) and the plug caps (boots) are about a month old with 100 miles at the very most on them.

I really can't think of what to try next. Any help would be very gratefully received if only to protect my garage wall from me keep banging my head against it in frustration! :evil:

Thanks again
Lea

Forgot to add, the float bowls are full of fuel to about 4mm from the top on each carb.

 

I'd clean your plugs and swap 1 & 4, see if your problem moves. If it does change that plug, if not, recheck everything on that cylinder.

 

Just pulled the plugs after 75 mile thrashing on my kangarooing trike. #4 still as before after swapping with number 1. Checked the coils and are in tolerance, sparks very visible with colourtune but intermittant flame.

I'm now leaning towards rechecking the valve clearance on the inlet valve on #4, or some kind of timing issue? ie valve opening at the wrong time, so lots of sparks no fuel, then loads of fuel and intermittant flame when the 2 coincide, Am I on the right track or completely wrong??????

Lea

 

What intake is your vacum line for the petcock connected to ?

 

Haven't got one, it's a custom tank with a universal tap with one fuel line going straight to the carb fuel port between #2 & #3 carbs. All the balance tubes have got covers on.

 

I'd check your choke and re-check float level in #1.

 

All the enrichment valves are closed and the float level in #1 is the same as the other carbs approx 4mm off the top of the bowl.

 

I'm far from an expert and maybe not sure about giving advice but anything such as fuel being intermittent on #4 may be a sign of a leaky carb boot or rubber cap on the test nipple. Maybe the exhaust valve in leaking by and not pulling fuel in on the intake stroke but why would that be intermittent? Don't mind me, I'm just trying to learn....I took a small engine coarse in high school just after the dinosaurs became extinct. :lol:

 

Since you cannot adjust the Pilot Mixtures to indicate they are too Rich during ColorTuning ... I find it hard to understand how the #-1 Plug can be so Dry-Fouled.

I'd have a close examination of the Enrichment Valve Operating arm and Linkage forks.

See that the Forks are allowing the Enrichment Valves to Close. Have a look at the "Hats" at the end of those Valve Shafts. An Enrichment Valve Top, bent-over ... will lose its end-play surrounding the forks that open~close the valve.

The Forks need to be synchronized within the Enrichment Valve's Up~Down or Side~Side movement ... what-have-you.

Aside from No Fuel Leaking

The YICS Port for the #-1 Cylinder may be blocked with carbon or something ... you'll have to make a Probe with right angle and explore the YICS Passage (if so equipped)

Beyond that there isn't too much further to look.

Either there is a Main AIR Jet Passage Blockage ... or,

The Air Injection Ports surrounding the Emulsion Tube for the #-1 Carb are Clogged ... causing the Fuel to enter the Combustion Chamber insufficiently atomized resulting in the inefficient combustion of the Fuel straight-out from the Main FUEL Jet.

 

Once again Rick you're spot on the money!

It was the enrichment valve on #1. It looked ok and the "lifting fork" on the bar seemed to give it slack but the rubber cap had slid off just slightly and was holding the valve slightly open. Thanks to everyone once again.

Lea
(Now a happy Triker!!!! :lol: )