dificult starting

Hi just purchased 1990 xj600
i have loved these bikes and always wanted one but feel ive boght a big problem

only bought the bike recently so i dont know the bikes history
the bike didnt have a air filter and the filter housing was broke so i got new ones when i went to see the bike it had no filter and the guy managed to get it started after a minute cold.
it ran great all the way home.
so next morning i tried to start it with choke nothing happened!!
i sprayed the carbs with wd40 and it fired up no probs!
so ordered new airfilter thinking this was all it was
now its very difficult to start the bike and it seems to lack power
best way to start it is to remove the seat and cover the airintake completely with ma hand
then it seems to start ok but it runs really rough untill running
new plugs made no difference
it seems to run ok once heated although when pulling away if you give it too much throttle
it seems to hesitate

any advice is well apretiated

cheers

 

Since it doesn't sound to have been maintained all that carefully, it's probably going to need all the basic stuff:

0. Get a service manual

1. A compression check wouldn't be a bad idea, just to be safe, and to save you time in case there are any major problems. You can get a compression checker from Harbor Freight for about $10 - $15. Assuming compression checks out OK...

2. Check and probably adjust valve clearance

3. Clean carbs, check float levels, maybe adjust mixture - there are a couple of tutorials on this site

4. Oil and filter change

5. Add a fuel filter, if it doesn't already have one

6. Assuming she's running better by then, checking brakes and maybe changing brake fluid wouldn't be a bad idea

Cheers,
Paul

 

If it doesn't start cold the fuel enrichment circuit needs to be cleaned.

 

Corby, ... Welcome!

These XJ Engines, even if tuned-up nice, are tough to start when its cold.
You need:
A fully charged-up Battery.
Carbs clean and Enrichment Circuit working 100%
A Rich and volatile starting mixture, which may include the use of Starting Fluid.
You might have to "Get it going" with Starting Fluid and "Keep it going" for a few moments with Start Fluid to take the chill out of the Combustion Chamber before it will ignite the Mixture supplied by the Enrichment Valves and run on its own.

As others have mentioned, ... you might be due for having a Full Monte Tune-up.
Valve clearances, Carbs, ... Cleaned and Bores scrubbed, Floats, Bench Synced and a running Sync.

After all that, the only reason for it not starting should be 'cause it's out of gas!

 

It's not the engines, it's the carbs.

With fuel injection instead, it starts immediately, even at 0F.

 

Interesting......

 

great advice there guys
ok 2nd question how do i clean the fuel enrichment system
is there a link on here to show me how?

many thanks for the welcome

 

Welcome.
It's all in the carb cleaning tutorials.It only looks
and sounds intimidating untill you start.After that it's a
piece of cake.
+1 on all the above.If the PO ran the bike for any amount
time without an air filter, then you need to address the carbs
now.
It makes sense that it won't start without restricting the air
flow as no filter will cause a lean condition.
How many miles are on the bike and did the PO keep up on
any regular maint?
Mine only had 23+k but no reg maint and ran like crap (untill
i found this site of cource,now it simply screams down the road
even with all the crap i've added to the wieght!).
Good luck and get to those carbs first.

 

ok wee update did a basic strip down on the carbs found 1 mixture screw to be sheared at the top so left the mixture alone
couldnt see much user servicable parts for the choke what i could see i cleaned opened up the floats they seemed ok there was a couple of breather holes blocked so cleared them.

re assembled was much harder to start had to use car battery to get started was very groggy dunni if that was due to carbs being dry

but after 5 minutes running with choke off is sounds so much better after a few backfires lol

will try again in the morning when cold

 

doen anyone have a set of carbs they can sell me all ballanced and set up to go?

 

Go to this link and do everything stated and you will fix the problem.
http://www.xjbikes.com/Forums/viewtopic ... linic.html

 

think these carbs have had it i cant ajust mixture

 

You will have to get the screws out and get new mixture screw and springs from chacal.

 

think it might be better getting a set of carbs second hand?

 

How many miles has she done? Mine has 48000 on the clock and my carbs are due for a clean/set-up. When she was running (Now in the garage after a bit more work than I bargained for) she started fine on the choke, but hesitated at low revs/throttle opening. I believe a sign the pilot jets are clogged. Another offender seems to be the vacuum fuel tap, which either leaks or doesn't open properly. Try starting it on the "Prime" setting, but remember to switch back to run when you have finished.

2nd hand carbs will probably want an overhaul as well but it might be easier to work on them (And have some spares).

Do you have a Haynes manual?

And welcome - I found this stie much more helpful than Yamaha owners club!

 

good news she started first time this morning
think the wee clean helped

 

she done 31000 miles

i took her out today wow what a difference no hesitating no more bat out of hell lol

 

What did you clean exactly - so I know where to start!

Mark

 

Hi everything i could see that didnt need setup or ajusted lol
evry hole nook and cranny lol

 

must say second day in a row and its started so easy hardly need enrichment system on

gotta say thanks to all the advice on here