NC35 RVF400
Newcastle Australia
Track project
Was running before

Alright so I bought this bike with a slipping clutch and a charging problem,
After some quick deliberation and investigation I deduced the stator was frizzled.

So what do I do? Total loss track bike.

Now I pulled out the starter motor clutch to get a better idea of a quick clutch basket inspection.
Then I pulled off the flywheel and stator, too easy right?
Wrong.

The plugs were <300km old, the oils new, the carbs are spotless perfectly balanced and tuned and the valves were all within tolerance.

So now the bike doesn't start, if i crack the throttle with the choke on i'll get a backfire through the carbs, I have spark(plug to frame, I havn't checked coil to frame yet). But there isn't even a hint of pop. I've tried bumping and aerostart.

The battery and reg rec are new.

I've cleaned the plugs and blown out the cylinders.

Now I have Air, I have Fuel and I have spark(Lets not confirm this as a strong spark yet). So I am stumped.
What could possibly go wrong.

So since it refusing to start I replaced the stator with a working one and replaced the flywheel. Still nothing.

Any ideas or experience?

The starter clutch provides the timing reference for the ignition, it is keyed so that it only goes on one way, so it should not be wrong, but you could check by rotating the engine to TDC, using a screw driver down the spark plug hole and valves closed, and see where the timing marks align. Miss-timed could give you backfire through carbs or exhaust.

Agreed, however how could it possibly be moved out of timing as the spline teeth are only cut one way?

As I said, hard to see how it could get out of wack but a place to start that involves very limited dis-assembly of the engine. Did the starter clutch fit on in only one place?

Was focusing on parts of the bike that have been disturbed since it was last running ok.

My tuppenth..your plugs are dead. They are fragile little buggers and when the bike fails to start it exacerbates the problem and they die some more..

If you can clean them up on a hot gas flame (they get fecking hot) and allow any wetness to evaporate from the cylinders you might get them back..

So, some pics of the CBR250 to keep us entertained please and get some new plugs..

CMSMJ1 wrote:My tuppenth..your plugs are dead.

+1

Em sea 19 wrote:if i crack the throttle with the choke on i'll get a backfire through the carbs

Take one of the rear plugs out and see if it's wet. Any fuel on them and the bike will never start, the small plugs are very fussy.

When you've dried the plugs out (or bought new ones) start the bike using FULL choke and NO throttle. Cracking the throttle can flood these bikes easily.

I'll post up some pics of my bikes for sure,

Thanks alot everybody.

I Have cleaned all 4 plugs around 5 times to no avail. Even tried old unfouled plugs at $120 a set here it's a last resort.

And they are coming out wet fouled. I'll check the starter clutch assem again for good measure.

Failing that I suppose I'll buy some new plugs.

Any other ideas?

If you hang about on here long enough, you'll see that dead plugs account for a good 30% of non starting bikes..the rest of it is vacuum hoses on wrong and then some more serious issues..

So, plugs it is!

on the plugs get a new set if its no that at least you`ll have new plugs then

looking bike