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