Still trying to get the bandit going...

Really interesting thread. I actually think I might be in the same boat as you were mate, with the exception that I've got decent compression.
Rather than starting a new thread, I figured maybe I can continue on with yours and if I (or a mechanic) find the solution, it might be helpful to you.

History:
I pulled apart a running bandit to do the valve clearances and rebuild the carbs with a litetek kit

Everything seemed to go well, except that the bike RAN very rich after the rebuild - yes, it was firing and going when the ignition button was pressed.

I pulled the float bowls off to check them and tightened everything - the jet/needle assembly was a bit loose so I tightened it. After putting it all back together, it wouldn't fire up and just crank endlessly.

Testing so far:

• Compression on all four cylinders is about 165psi dry (wet closer to 200)
• All spark plugs spark blue. They've been cleaned and usually have a bit of carbon a fuel on them when I pull them out
• Removed carbs and have been spraying 'Start ya bastard' into the intake - doesn't get it going (I really did think it was a carb issue until this point)
• Timing is the same as yours - 16 links between the intake and exhaust cams (3 & 2 positions like your) with the timing mark line directly after the '1.4T'
• Sometimes with 'Start ya bastard' sprayed in the intake, a blue flame will emerge (spitting) visible at the intake

Based on the advice in this thread, it could be sparking at the wrong time - When the intake cam is at position 3, cylinder 1 is at the exhaust TDC.

Would an engine run though if the timing was 180 degrees out?

 

Have you got the plug leads in the right order?
Left coil does cylinder 1 & 4, right coil does cylinder 2 & 3.

 

If the timing is out by 180 degrees, valves will be opening on the wrong cylinders at the wrong time. I suppose it depends on the number of cylinders. My thoughts are that the exhaust valves are opening when the intake ones should be. The FZR250 for example, has 2 cylinders on the compression stroke and 2 on the exhaust. The timing goes 2-3-4-1 (firing order). When at TDC for cyl #1 on the compression stroke, cyl #4 is also at TDCm but I'm unsure if it is compression stroke or exhaust. You would have to look at the cam, but you need the timing right for that

The timing must be right for it to run. When all the timing marks line up correctly, you should be at TDC on cyl #1 - compression stroke.

Assume the timing is out by 180 degrees. The timing marks like up but cyl #1 is on exhaust stroke, not compression stroke. Take off the cams, look in cylinder #1 through the spark plug hole. Feel it with something to gauge if it actually is at TDC. If it is, then rotate the crank until piston #1 goes down and comes back up to TDC. Put cams back in. All timing marks should line up, and you'll be able to rotate the crank without resistance.

If the timing is out by 180 deg, use the cam(s) timing marks. Once lined up, remove cams, rotate crank 180 deg, put in cams and try again.

Ed, if it was running rich and now won't fire, you may have fouled the plugs. Clean them up or turn off the fuel tap and crank for a bit, then turn fuel back on. Or use old/spare/new plugs

 

Plug leads are in the correct spots, just like you said Pygmegod

I have been checking for TDC with a screwdriver down in cylinder 1. I know it's the exhaust TDC because the intake cam lobes on cylinder 1 are at the 90 degree position and about to open up (to start the intake stroke, right?)

I'm gonna try tomorrow to rotate everything by 180 degrees, spray some of the 'Start ya bastard' and see how it goes. I'm not putting the carbs back on until I know for sure she fires correctly

 

From Stu's post here, it looks like he's got 15 rather than 16 links separating the intake and exhaust timing?

I should also make the note that I've got the 92 model which I believe is unrestricted

 

^ Yeah that's what I've been using.

I may have jumped the gun in stating the timing was off by 180 degrees though as everything seems to suggest that I've got it right :|

Might just be a weak spark from the wires being mixed up on the ignition coils. I'll play around with the multimeter tomorrow before doing anything drastic

 

OK. If you know it's exhaust TDC by the cam, what does the timing mark say on the stator/crank?

 

Says it's at the

Looks like this, except it's on the line after the 1.4T

 

Update, sick today which sucks.
I've confirmed that the positive of the ignition coils (both sides) are wired correctly. I measured the voltage on the positive terminal and it comes up at 10.84V. It's lower than the 12V at the battery (which also drops when the bike is on) but I don't know if that's a big deal.

Spark Plug lighting up / engine sound when cranking video


I cleaned the plugs earlier but they come up with a bit of carbon around them after a few rounds of 'Start ya bastard' and cranking that goes no where

Few more pictures of the parts on my bike:





I'll keep uploading pics to the album here: http://imgur.com/a/jGSar/all

 

The video looks like it's only sparking every half-second or so?
Doesn't look like a steady pulse of spark?

 

Cheers Stu,

I checked out the GJ72A manuals this morning (3 of them) but they seem to suggest the same thing in regards to timing as the Across manual?

Blair - The lighting takes away a bit from the spark brightness but it's the blue colour that's most important right? (not a yellow/orange)

More on the 180 degree timing out - This isn't the case. The crankshaft timing mark applies to both TDCs for intake and exhaust, the manual really just specifies getting it right on the exhaust TDC to align the crankshaft with the camshaft 3 (intake) and 2 (exhaust) markings...

 

Injecting 1ml of petrol into the spark holes for all cylinders seems to get it firing.

I'm gonna put everything back together and try this again as I think this is a winning formula to get it starting. I really don't wanna call a mate over to try the old push start haha

 

Stupid stupid me

The choke and main jets were switched on the 3rd and 4th carb. Finally got it working enough to take it for a spin around the block.

If you look at the jet housing, it should be main - pilot - choke (MPC) going counter clockwise. The main and pilot jet are horizontal when the jet housing is installed on the carbs.

Now I can begin to try and tune the carbs

I can confirm that the timing should be how it's described in the service manuals now that the bike runs successfully.

In retrospect, all the signs did point to something on the carbs

 

Well done, she goes all the time now then?