hard to start- never ending story

Hello, my bike have problems with starting since i remember.
its XJ550 1984, aprox 30 000 miles
things ive check/replace:

-full carbs clean in ultrasonic cleaner rebuild with every gasket new incl. trottle shaft seals
-new spark plugs
-clean starter motor, brushes 10mm
-valves check and adjusted (two where too tight, but only one size)
-fuses replace with blade type
-carb synched, fuel level set
-new battery (youasa)
-every electrical plug spreyed with contact

compression on cold engine
120psi---90psi---90psi---120psi
after teaspoon of oil no.2 no.3 cyl.
120psi---118psi---113psi---120psi

any ideas what should i do to start this damn thing with starter?
second question i bought colortune but on every bike ive tested shows only orange collor, any ideas why? thanks

 

Orange is rich so it appears that the pilots screws may need to be adjusted in. That's assuming that you have determined that the jets are correct. Hopefully the bike is stock which makes tuning easier. My bike doesn't like "rich" and I only use the choke to get it to start when it's cold. If you are satisfied that the carbs are correct, then you might try what I did. With the bike warmed install the colortune and close the pilot screw until you get a whitish color or the bike begins to stumble. Then open the pilot screw until you get a blue color and the bike smooths out. Do that for every cylinder. Then install a set of new plugs and take a ride and afterwards check the plugs for proper color. By starting from a lean setting I was able to tweak the pilot screws until I got the perfect plug color and the bike starts and runs well and my fuel consumption is good. If you can't get the colortune to show at least a blue color then you probably still have a carb issue or a filthy air filter.

 

Are these your compression readings before or after you adjusted the valve clearances?

 

Your enrichment jets may not be as clean as could be, I don't know if the ultrasonic is enough to clean them properly...these are very tiny passages.

There may be something wrong with the enrichment plungers seats and caps too.

 

Tutorial for cleaning enrichment circuit

http://www.xjbikes.com/Forums/viewtopic/t=8918.html

 

First i dipped carbs in a carb cleanig solution based on toulen. then i spreyed carb cleaner under hi prosure in every passage and using wire clean them, then clean everything in ultrasonic cleaner. They simply can't be cleaner.

compression readings are after valve adjustment.

how to check enrichment plungers and caps?
is it possible that enrichment caps are worn and bike doesent get proper chocke?


i cant reach whitish collor even if mixture screw are fully closed.
is it posible that this is because of too thick orings on them?

 

Looks to me like ya got a compression problem in 2 and 3 cylinder!

 

Oops. You'll need to replace the throttle shaft seals (along with the other rubber parts) if you submerged the carbs without fully disassembling them. Touline damages rubber parts (even synthetic rubber), causing air leaks.

 

how to check enrichment plungers and caps?
is it possible that enrichment caps are worn and bike doesent get proper chocke?


i cant reach whitish collor even if mixture screw are fully closed.
is it posible that this is because of too thick orings on them?[/quote]

You seem to indicate that the enrichment caps are still in place. If so, how did you adjust the "mixture screw"? The caps have to be removed to get to the pilot screws which control the fuel flow for the enrichment circuit.

If the pilot screws are closed and you still can't get a whitish color then fuel is coming from some other place. Float settings, drilled jets, or jets installed in reverse come to mind. Excess air entering the system would cause a lean condition.

 

I think that the enrichment plunger and caps he is referring to are the choke plungers and their seals (which are really enrichment plungers becasue of how they work), and not the pilot (idle) circuit.

I think that the orange color he refered to in the first post was from testing on another bike, and not form this XJ. Everything he's stated so far leads me to conclude that the bike is lean, even with the enrichment circuit (choke) open.

 

ok forom beginning, I romoved every silgle ruber piece incl throttle shaft seals before dipping in carb cleaner

i removed caps from idle mixture screws
yes k-moe i mean choke plungers and their seals
when i bump start and make her hot collor in colortune is always yellow no metter wtat im doing with screws...
ive spray'ed liquid start around carbs and it seems to be no air leaks

 

I had the same problem with one of my cylinders. Finally found that the gasket for the intake manifold had a big air leak. When I took the intake off about 1/2 of the gasket was gone. Made myself a gasket and that took care of the air leak.

 

Hold on and back up a minute.

This is a 550. Compression readings of 120psi are OK; readings of 90psi are NOT OK.

You can't tune a motor that has something wrong with the mechanical "mill." Until all 4 cylinders can produce compression numbers within spec and within 10% of each other, you're wasting your time.

Step one: double-check your valve clearances.

Step two: do another compression test, with a different gauge. If you get similar results, my best guess would be a head gasket leak between cylinders 2 and 3 and the cam chain gallery.

 

ok I finaly borrowed another compression meter, and the results were the same, but aprox 10 psi lower on each cyl so it could be because of meter.

Ialso replace gaskets on intake boots on custom made (thicker)

bigfitz52 do you have any tutorial how to replace this gasket?

 

Hi,
so I've check cylinder bores and they are in spec,
for safety replaced piston rings on cylinder 2.
all pistons was cleaned and measured
cylinder head was fuly rebuild incl valve seat cutting and valve job,
valve clearance set
all seals and gasket are new.

here are compression readings
on cold engine
120psi---90psi---120psi---120psi

Help guys! why there is still poor compression on cyl no2 ?!
on hot engine all cylinders have about the same readings even cyl 2.
is it posible that cyl 2 have poor lubrication and it cause this problems?

 

did you hone out the cylinders? before measuring and before installing new ring set on #2?
what happened with cyl 3 that gave it more compression?
is it possible you replaced the rings on 3 and not 2.
what caused you to decide to replace rings on #2 only ?
cylinder specs

 

oil flow chart i think the pistons are splash oiled and from oil dripping out/off of the piston wrist pin

 

If you haven;t got many miles on it then the rings on #2 haven't bedded in yet.

 

did you remove the mixture screws and replace the tin o rings?

 

i dont hone cylinder bores because there was still some of factory honing. compresion on cyl 3 goes up after puting manny times petroleum into cylinder. On cyl 2 this didint work so i decidet to take apart top end and change rings/clean pistons gruves. Yes i replaced orings i fund even thiker than original. So if oil comes from wrist pin we could eliminate my theory with poor lubrication, because ihave clean this small holes in piston where i belive drips oil.Im going to bump start and let it idle for some time to set the rings on cyl 2. See you later