Still with problems

Helo
After I have done valvs work, some carb adjustment, cant get an stedy RPM in idle after the engine reach some temp. It came down in the RPM and just stop running, if I pull the trotle I can get it run again.
Also I m getting some smoke from the engine wen it reach temp, about 15 min , this smoke it´s coming from the hose thats goes in to the air box,
not from the exaust sistem.

 

Sound like you have some air getting in, around the boots or throttle seals.
With the smoke, sounds like blow by, the piston rings are worn & letting gasses past & into the crankcase.
Check the compression.

 

I did compression test I got, two cilynders with a little over 90 psi and two with 100 psi.
If I have some air like you say, why it only happen with a hot engine?
by hot engine I mean at running temp, 10 or 15 min after it start.
Thanks for your help

 

Compression reading are very low, were thes dry readings, if so check again with a tablespoon of oil in each cylinder, if the readings go up, the rings & or the bores are worn. Problem gets worse when hot because the oil gets thinner.

 

I´m agree with you, and what about the other problem, the one that make the motor goes down in the RPM and stop when reach working temp
could thet be for the same reason??
Don´t forget that only happen in iddle RPM in high RPM does not do
the problem.

 

I guess that today everybody is resting, It´s sunday hope to get some answer by tomorow, I realy want to have my bike running as it should.

 

Come on, I´m still waiting, please.

 

Smoke from crankcase sounds like blow-by to me, too. You probably need new rings.

 

some smoke from that hose is alright but a lot means something is wrong
like Wizard said
set the idle RPM when it's fully warm
the choke will keep it running while it's cold

 

How many miles on it ?

Have you checked the oil for fuel? Changed the oil lately ?

 

Why would I have gas on the oil?? and yes I just have the oil changed
It´s has 30.000 miles.
Wen the engine it´s cold, I have no problem starting it , the problem comes whith the engine at working temp.
And other thing is that I just have this machine, so I dont have it history, and I dont want to open the engine without some idea of what I have to do whit it.

Thanks

 

Hope that by tomorrow Ill get some more help, with my problem,
Good night

 

OK it´s monday, need help

 

Igor, you need to do a wet compression test as mentioned above given the mileage. It would also be helpful to mention what model and year your bike is.
As for the idle issue, you could have your idle set too low or your TCI may be suffering with a temperature sensitive connection or component.
I would start by raising the idle (1050 rpm +/-50 rpm) as that is the cheapest fix (free! What's not to like about that?).
Then I would take a look at the TCI solder runs.

 

It´s a 1983 XJ 400 Special, the one with the four cilynders and equal number of carbs.
Thanks

 

I think that the only chance that I have in order to repair my moto,is to open the engine and perform some heart surgery.

 

ok,but before you do that, a question or two....
you mentioned valve adj-and carb sync. but you don't mention
whether you cleaned the carbs. i mean a complete tear down,
all parts removed and cleaned untill they look new,have done a clunk
test.bench sync before final gauge sync.
if you have done these steps you may have left something out.
i did just the other day-skipped the bench sync and had to pull the carbs
again and do it right.
i think it was Len that said "there are no short cuts,do it right every time"
or something like that AND BOY HE WAS RIGHT!

 

Dirty carbs aren't going to account for low compression readings.

Mal-adjusted valves will. IIRC from his other thread, the valves still need to be adjusted. From there, if the compression is still low, the engine will probably need to be opened.

An engine with bad compression will probably not idle reliably. My GPz had bent valves. It started easily, and would idle OK when cool if you set it to idle at 1500 RPM or so. It wouldn't idle at 1050, though, and once it got hot it wouldn't idle at 1500 either... it would just die at lights.

After replacing the bent valves, it idles perfectly at 1050, hot or cold.

 

yes SQL, your right, i wasn't thinking. thx for the correction

 

I really apreciate all of your help, and I think that the only way now is to open the engine and perform some mayor surgery, and could use some help getting the parts that I can´t here. Of course I will pay for every piece
that you may get for my.

 

Hope someone it´s going to help me with my proyect.

 

PLEASE

 

all the parts you will need can be found in the xj market place and chacal
from this site.

also access e-bay from here and you should be good to go

 

Definitely contact Chacal, he is in our supporting vendor forum. I know he ships overseas and has just about everything. Otherwise, I won't be down in South America until the end of next summer at the soonest. Good luck Igor!

 

Well if you come to Chile let me now, I´m shure that we could go to many interesting places, and I would be glad to help you once you are here