3AJ not starting
 

Hi there, Ive just had the head replaced on my 3AJ, the newer head is also a 2kf, but I cant get it to start reliably with the tappets set to the recommended settings. It will start with them opened up, but not when set to the correct tolerances.

Its driving me nuts, any ideas?

Pete

Panic over, the mechanic did the head just tightened the tappets and jump started it from a landrover and its sweet as.

Sorted

Pete

Went to pick the bike up last night and it wouldnt start whatever. Going to try a new battery today hopefully. Seems to have a weak spark, should a new battery help this? We checked the wiring and tidied up some connections, but the spark is still weak. Also swapped the coil but it didnt make any difference.

Pete

No
 

The 3aj does not need battery power to run. If you have a spark, any spark, that should be ok.
Since you just replaced the head, make sure everything is connected and installed allright, valve timing ok, fuel arriving at the carburettor (with the fuel pump this can sometimes be a problem!), idle mixture set correctly, idle speed set correctly etc.

Give some more info, we might be able to help.

Auke

Hi there, thanks for that. We are getting fuel, and have sparks. The valve timing was checked when the head was replaced. The bike will run fine when it does go, but its getting it to start thats the problem. When it wont start, the bike will sometimes backfire as if there is unburned fuel in the engine. I was going to try the battery, as I have found myself, if the battery isnt great, the electric start wont fire the engine. Any other ideas?

Pete

When the bike was running it was ticking over fine, but seemed a little high. What should the tickover be set at?

Pete

Also, when the bike is running, the battery voltage is healthy (13+ v) but it doesnt seem to have the kick to get it to life from cold.

Pete

test with lights on
 

Try to test when all the lights are on. If you have problem with your light machine sometimes the V are correct with the lights off and too low with lights on.

Ciao
Alp

First things first
 

Let's first sort out the battery / starter motor issue. Try it with another (car?) battery hooked up. If it's allright then, you probably have a bad or uncharged battery or worse, a defective charging system.
If the extra battery does not help, it might be in the starter motor system: check all connections are tight and clean, especially the earth connection?
If connections allright and still problems, take the starter motor apart and clean the collector of the motor with some sandpaper. A b*tch to put together again BTW.
That should sort the cranking issue and ends part 1.

Let us know how you fare!
Auke

Connecting car batterys to bikes
 

Hi.

This is maybe a bit out of the thread. A bike mechanic once told me that it´s a bad idea to connect a car battery to a bike. The car battery usualy puts out 50-70amps while your normal bike battery usualy ranges between 9.5 to 14amps. The starter system on a bike is not bulit to handle all that power and cranking it over time and time again while sorting out a hard to start bike might damage it.

Ok latest update, it seems to be an intermitant spark, sometimes it will start and run no problem at all, sometimes it will backfire hard enough to blow the carbs off.

When it runs ok, there no smoke and it will tick over no problem, but it will eventually cut out and thats when the "fun" starts.

Pete

One more strange thing, you can connect the coil up either way around and the bike will run either way.

Pete

Both ways
 

connecting of the coil; that's OK. It's just that, a coil does not mind which way the electrrons go.

Did the bike run fine before the head overhaul? Was anything changed (to carb or ignition etc?) but the head?
Are you absolute sure everything is allright with head and valve timing? (reality surpasses fantasy in f*ck*ps!) Timing chain tensioner correctly installed, spring installed?
Are you absolutely sure all connectors are tight and clean; that you are not chasing this tiny little pin that connects and disconnects, just to tease you?

If all of the above is OK, would start thinking of ignition problem. Do you have access to known good parts from another bike? If so, start swapping: coil, CDI, stator and see what happens.

As for connecting car batteries: no prob: it is the consumer that determines how many Amps are drawn, not the battery. As Volts are the same, the Amps will also be the same. To put it simply, the Volts are the driving force, the Amps the result. So, more rated Amps on the battery do not give you more Amps through the consumer.

Auke

I learn new things every day.
 

:thumbup1:
Well I guess that makes sense when you think about it
Thanks Auke for the enlightment on the amp vs. volt issue

Going to try the CDi and coil from my brothers 1VJ on the bike today. Is the CDi the same as the 3AJ one? It's marked 1VJ.

Pete

Ok, we tried the coil from the 1VJ, no difference, both showed the same (correct) impedence. The CDi from the 1VJ has different output wiring to the 3AJ, so we couldnt try that. The mechanic is going to have a look at the stator to see if it is gunged up. If not, would the 1VJ stator be ok to try (with its CDi) to try and rule that out?

The bike can have a good blue spark one minute, then a crappy yellow one the next. Would the CDi cause this, or would it just die if not working? Weve been over the wiring with a fine tooth comb to check all the connections and check for broken wires, cleaned some up, but still the same result.When the bike is running it gives a healthy 13.3v at the battery, and switched off, 12.5 volts.

Really beginning to do our heads in!


Pete

Whatever
 

Pete,

Has all the makings of a great saga by now.

Still wondering, before the top end replacement, did the bike have any sympton then of a malfunctioning ignition?

If you just swap the sidecover of the 1VJ for yours, and the CDI, with some temporary wiring you'll probably be able to get a functioning ignition system. I checked the wiring diagrams for 1VJ and 3AJ, and they are almost identical with respect to the ignition. So, by cutting and connecting wires you could also make the 1VJ CDI fit to the 3AJ. Afterwards, make sure to solder all wires back to each other and use good insulation tape to protect the connections. Although the wire colours (might) differ, the stators are identical, here's the translation table for the colours (wires on CDI, not stator!) from the diagrams I have:

3AJ - 1VJ
alternator: 3 x white - 3 x white
pulse to coil: orange - orange
stop signal: black / white - black / white
from clutch switch: blue - blue
from sidestand switch: blue / yellow - blue / yellow
pickup 1: white / green - white / green
pickup 2: white / green - white / red
central pickup: green - green
charging wire +: red - red
charging wire -: brown - brown

Another thing that might be problematic, is the protections built in on the 3AJ:
- Sidestand switch: get rid of it; the two wires going there should be connected.
- Clutch switch: also get rid of it, don't know wether the wires should be connected or not.
- Emergency engine stop switch: is it OK?
- The relay under the seat collects the information from the neutral switch, clutch switch and sidestand switch enabling the CDI to pulse to the coil.
All this protects you from driving away with your stand out and doing other things that might hurt you. I removed this sh*t long time ago and never had an accident because of it. What's more, the older models did not have this at all and there's a lot of examples of people surviving ....

CDI's can fail partly, intermittently or totally. No way to test without swapping with another one.

I can only stress the importance of a systematic approach in this, otherwise your brains will be cooked, your wallet empty and your bike not running in a few weeks ....

Succes!
Auke

Thanks for that. The bike stopped for no aparent reason before the head was changed, twice. The second time the breakdown lorry that came to pick it up dropped the bike off the back which is when the bike was stripped to get the work done! However, after the bike had sat for a bit and cooled down it ran fine. I thought the initial breakdown was due to the ht lead shorting on the head so we swapped the coil for a new one.

Obviously, the problem was not what we had thought and is raising it's horns more seriously now. The side cover is coming off tommorow to inspect the stator. I cleaned up the side stand switch yesterday to no avail, not checked the clutch switch as yet or the relay.

Thanks again

Pete

Checked the relay for the side stand etc today, it gives no continuity with either the ignition on or off.

Bypassed it, and the bike ran fine, but cut out (think it may have been due a short on the wires bypassing the relay) and now I have no neutral light, and no power to the ignition at all. Checked the main fuse, it was fine and all the other lights indicators etc work fine.

Any ideas?

Pete

Diode I think
 

There is a diode (could be resistor, I can't remember) that is embedded well within the wiring harness (just above the battery and slightly forward along the length of harness and not easy to feel for, at least for the XT600E) that was causing my engine to cut off whenever I hit the left side pod (can't quite remember whether the lights were affected). Cleaned and tightened the contacts and all were well. Hope it helps. Cheers.