Starting

[xtzrick]

My 660 was always a pig to start if it was left for a few days ( )
I put it down to petrol evaporating out the float bowl & pump, maybe getting an air lock in the process.

You could try tapping the bowl,pump & hoses for a few seconds next time you want to start it after it's been stood a few days or if you have enough petrol in the tank, connect the carb direct to the tap, bypassing the pump, open the tap for a few seconds before you try to start so the bowl has time to fill & see if that has any effect.

The mixture screw problem could be a blocked passageway between the pilot jet & screw in the carb.
You might have compensated for this by setting your throttle slide (tickover screw) high which would bypass the mixture screw circuit but allow the engine to start.

Rick

[nolimits]

hey guys i am having the same problem i can tell you that my compression is ok as i have 2nd oversize wossner forged piston in it with hi flow inlets and outlets, and dinojet second stage ,crd header pipes and arrow end can
and i had all this set up on my xt 3tb ..and it was fu..... pulling and going well , so decided to use it on my tenere 3aj rebuild .i have used all the parts from my xt even the wiring loom , the only thing that i have changed is i got a rebuilt kit for the carbs just as our friend has done ..

i have tried a few things like...
pull the choke right out and it fires first shot but dies very quickly so i try it with the choke again but nothing happens ...i try it with the choke half in nothing happens ..if i push the choke back in and crank it a few too many times it starts ... it also does not like any throttle ..the thing that the bike after starting runs like a beauty and goes well also i drove last week from Ancona in ITALY all the way to AUSTRIA and had no issues ..
i have been thinking the other thing thats deifferent is the airbox!!!!

I DONT KNOW WHAT ELSE TO SAY I MUST RESET MY SELF!!!

[nolimits]

a photo of my baby

[MaltaBike]

The compression tester arrived earlier this week, but it was only on the following Saturday morning that I had some time to work on the bike.

I brought the engine to normal operating temperature by revving it around 2000rpm for a couple of minutes. I took off the sparking plug, disconnected the CDI box to avoid any sparks, connected the compression tester and cranked the engine a couple of times. The reading on the gauge showed 135psi.

I did some research to understand what that meant in terms of compression ratio. It turns out that it means something around 5:1 not good.

Before throwing in the towel I decided to do the test again.

This time the engine had cooled down and I did not start it to get it to operating temperature. I also made sure that the throttle was fully open (as I was unsure whether I had it opened in the first test). This time the reading came 150psi. I did it a couple of times and the gauge reliably read 150psi. I took it off, threw a couple of squirts of oil inside the chamber and did the test again. Always 150psi.

Doing some further research on one of the XT600 manuals, it says that the test pressure should be 153psi. So that's spot on!!

[MaltaBike]

You might have compensated for this by setting your throttle slide (tickover screw) high which would bypass the mixture screw circuit but allow the engine to start.

Rick

Rick, would you mind elaborating a little bit on this one, as I am not sure I am understanding it.

Thanks.
Neil

[MaltaBike]

Low compression should also mean a weak power output and smoke, any of that?

Compression seems to be ok as I tested it with a tester and it is around 150psi.

I noticed that it puffs some light white smoke as it starts up when cold, say for the first 10 seconds, after which it disappears. If it's warm, it does not show these puffs.

Regarding power output, my feeling is that it is rather low for a 600, although whenever I meet another bike on the road, very few actually keep up with it. I do not know if my impression is misguided?

Thanks.

[xtrider]

Ya that is good compression so no problems there. Now with that tester you can retest it every so many miles to moniter the engine, same with all motors you own. The delayed start might just have to do with the carb somewhere.

The one thing to try now is to let it sit for a few days to a week and test, without starting first. that's the condition it'll be in when trying to start it.

[xtzrick]

You might have compensated for this by setting your throttle slide (tickover screw) high which would bypass the mixture screw circuit but allow the engine to start.

Rick

Rick, would you mind elaborating a little bit on this one, as I am not sure I am understanding it.

Thanks.
Neil

When your engine is ticking over normally fuel comes into the air stream at "A" above the mixture screw. As you open the throttle the slide lifts & allows fuel to enter the air stream at "B".

If the passage to "A" is blocked your engine will still tickover if you lift the throttle slide high enough with the tickover screw with fuel is entering the air stream at "B".

To check "A" is clear you need the carbs & float bowl off, open the mixture screw 4-5 turns, cover the pilot jet & hole "B" (finger & thumb) then blow down one of the small holes in the rear of the carb where your air box connects (not sure which one )
You should feel air coming out of "A" half way down your finger covering "B".

Rick

[xtrider]

I have another "maybe" , I had the stock exhaust on my '88 and it always started with my outlined procedure, time and time again, even when I took the cork out of the end(I put a mesh and down tube in there to quiet it down). Now I had picked up another XT with a Cobra exhaust that was a standard straight though type. I put the pipe on the '88 and it has been taking several more kicks to start even though the bike runs rich and I put my bigger pilot in. Harder after a week sitting and still need to shut the choke off right after the motor starts so it won't flood. I'm wondering if you had recently put a different exhaust on it.





.

[MaltaBike]

The one thing to try now is to let it sit for a few days to a week and test, without starting first. that's the condition it'll be in when trying to start it.

I tried it again this morning, Saturday. The bike had been sitting in the garage since Monday evening. I recorded the whole test process, together with the readings in another post on this forum here: http://www.tenere.co.uk/forum/viewtopic.php?f=54&t=1533. The readings do not show any difference, so the delay in starting must be related to another area.


I am linking a video showing how it starts here:

phpBB [video]

After warming up, this is how it starts:

phpBB [video]

See the difference?!