Engine turns over/not starting

[jdm9123]

Hi guys. I am re-building my 78 xs650se. I am putting it all back together now and I am not able to get the bike to start. Starter motor is turning over motor just fine and is very strong. Good spark to both plugs and the carbs have been cleaned. The bike has not ran in at least a year. I do not own a compression test gauge but I can hear and feel the pistons building pressure when the plugs are removed and I turn the bike over. Any ideas on what I may be missing at this point? It appears to be getting compression, fuel, and a spark so I am kind of lost now.

 

[retiredgentleman]

Did you set the points gap and the static timing of the points?

You said you cleaned the carbs...............did you confirm that the choke jet (in the float bowl bottom) is clear?

What colour is the spark.........yellow or blue?

Do you still have those pesky original fuse holders (glass fuse type)?

 

[pumps]

You have done all the stuff in a tune-up? Adjusted the cam chain, adjusted valves, checked timing? A 78SE is a points bike yes? Check points gap etc? A lot to read but good stuff. Keep us posted
Bike wont start?, Running rough?
http://www.xs650.com/forum/showthread.php?t=390

trouble shooting
http://www.xs650.com/forum/showthread.php?t=2736

 

[jdm9123]

There is a blue spark. Yes, I do have the old fuses but I don't see that being a problem. It's obviously a fuel issue. Either the carbs were not cleaned properly or there is a constriction from the petcock to the bowl to the venturi. I will have to take the carbs out to inspect. I will check the points on both cylinders to make sure the gaps are correct at TDCC. Please explain the static timing since I am unfamiliar with this process. Thanks.

 

[gggGary]

Try kick starting it. The points system is weak at best. Sometimes the electric starter draws the voltage low enough that the plugs aren't firing in the cylinder even though they look fine to the eye. While doing a points bike that doesn't want to fire I use a torch to dry the plugs on a frequent basis. Use all cautions with flame and gasoline. It's not obviously anything. It's often a combo of little things that stop you. Are the plugs wet or dry when you pull them? I like to think I know my way around getting old bikes running but sometimes points systems can be very frustrating. Once it runs then they are fine. Weak coils bad condensers bad spark plug caps they all can give grief. And unless everything fuel related is new, rust and crap from the fuel tank on down can fuggle the best carb overhaul in seconds.

 

[gggGary]

I even have a jumper wire made up that goes straight from battery to coils with a house hold wall switch to remove low voltage from the list of gotchas.

 

[jdm9123]

The spark plugs and wires are new. It is possible the condensers and/or coils could be bad but I do not have a PVA to attach to my meter to check the spark. This is the first xs I have owned therefore I am learning as I go. I am proceeding to re-check the points gaps now. Valve lash is correct and well as cam timing so those are ruled out.

 

[littlebill31]

Here's a little link: http://www.xs650.com/forum/showthread.php?t=9837&highlight=points+plate
Static testing is when you use a test light to see when the points open in relation to where the rotor is without the bike running. It's to make sure the left, or right, point opens in time correctly, when it should.

You can use a light tester.


OR


Which is a 3 watt dome light bulb. I solder a ground wire to the bottom and a positive wire to the side nub. Each wire gets an alligator clip.

Then I clip the Pos wire to the specific point I'm testing and the Neg to a cylinder fin to ground it.

With the key on (make sure it's on) if you turn the rotor around the light should come on when the line hits the "F" mark for the specific point. If not, set the rotor at the "F" mark and adjust the point plate/points so the light comes on when it's supposed too.
I like the lamp version 'cuz I can just clip it and it hangs right in front of me. Then I have freedom to mess with the plate/points or rotor.

 

[retiredgentleman]

There is a blue spark. Yes, I do have the old fuses but I don't see that being a problem. It's obviously a fuel issue. Either the carbs were not cleaned properly or there is a constriction from the petcock to the bowl to the venturi. I will have to take the carbs out to inspect. I will check the points on both cylinders to make sure the gaps are correct at TDCC. Please explain the static timing since I am unfamiliar with this process. Thanks.

Its not a question of if those stock fuse holders will cause problems, its a question of when they will cause grief. They may or may not be your specific problem to-day, but you should change them out to blade type ASAP.

To start a cold engine you need an extra rich mixture, which can only come from one location. That location is the choke jet in the bottom of the float bowl. You will want to inspect that jet to confirm that it is clear. You should see light through it.

 

[jdm9123]

Also, I have 2 vacuum operated petcocks. I am learning more and more out about this bike as I go. Can you guys explain to me the proper way and orientation of the vacuum lines to get the petcock to flow fuel? This could be as simple as the carbs not getting gasoline.

 

[gggGary]

petcocks are on reserve prime. Prime will flow fuel without vacuum. If you don't have the vacuum lines hooked up you need to block off the vacuum ports on the intake spigots.

Leave petcocks "on" open float bowl drains, put a catch bottle under them (cut up a quart oil bottle to fit) turn petcock to prime see what kind of fuel flow and other crap comes out. then turn petcock back to on see if the fuel flow stops (not likely!!!) then rebuild the petcocks.

 

[jdm9123]

fuel is flowing freely from both petcocks. I checked them both so i guess I will rule that out. Also, both plugs are wet when I pull them out. Could the starter just be drawing too much amperage from the starter motor to not give the plugs enough voltage? This is a brand new battery from mikesxs.

 

[gggGary]

Do they shut off? Did you do the float bowl drain? Do the petcocks shut off? It's fine if "I don' wanna" but PLEASE tell me (us) so we know where we are. Keep heating and drying those plugs do the heat dry install and try KICK starting it. The jumper often helps also. I just went through this last week on my 79 so it's fresh for me. And mine runs and starts with electric easily now.

 

[jdm9123]

it appears that they are not shutting off. i haven't cleaned the bowls out yet but I will do that now as well as trying to dry and heat the plugs. I do not have a torch but I may try my stove top.

 

[hmusket]

Correct order of wiring to the coils?

 

[XSLeo]

Bieng a points bike if the wires at the coils are reversed then the spark is happening 180 degrees out of time. An easy check for this is to pull the plug wires off the plugs and swap left to right.
Leo

 

[jdm9123]

I believe I had the connection incorrect from the capacitors to the coils but I fixed that now. One of my coils is getting a lot hotter than the other one is. They are both firing a spark but it hasn't fired up just yet. Any ideas on why the one coil is warmer? Also, what is the best way to check and make sure the coils are still in good shape, I have already check the resistance between both leads from the capacitor.

 

[jdm9123]

also, is there any way to judge the left and right coils? They are stock coils and I do not see any markings as to which is which. Lastly, this is a points bike and there is a orange and a gray wire coming from the point, which coil does the orange and gray each go to?

 

[jdm9123]

Anyone??

 

[gggGary]

also, is there any way to judge the left and right coils? They are stock coils and I do not see any markings as to which is which. Lastly, this is a points bike and there is a orange and a gray wire coming from the point, which coil does the orange and gray each go to?

Coils are ambidextrous the only thing side dependent is points.
If it doesn't run or gives a good healthy backfire one way, switch sides. There are several ways to mix up whether gray or orange fires one side or the other.