GSF400 VP not starting - please help!

[Nick V]

Good day all!

Me and my friend urgently need help from other Bandit 400 owners. We have a bike here that's refusing to start, and the circumstances are really weird.

Known facts so far:

- Year of manufacture unknown, but somewhere between 1993 and 1994 (the sticker under the seat describes it as a GSF400 VP). It is a later-model (53 BHP) Generation 1 Bandit 400 with VVC and 13 000 RPM rev limit.

- Apart from the VVC refusing to kick in above 10 000 RPM, the bike was running fine one day.
It was then parked, and the next day, it refused to start.
When it's cranked over, the engine seems to be right on the verge of catching and turning over, but it never does. There also seems to be a very occasional backfire (a sharp 'puff' through the fuel tap vacuum hose, which is exposed with the fuel tank removed.)

- The bike is stored outdoors, but is usually protected with a bike cover.

- The camchain is intact. We know this through lifting one corner of the rocker cover and watching the intake cam turn as the starter is activated.

- There is a healthy spark on all four cylinders.

- The battery is a bit tired, but boosting the battery power by hooking the bike battery up to a healthy car battery doesn't help.

- The fuel tank is full.

- The fuel tap is working perfectly.

- The carbs were removed from the bike and dismantled for cleaning and inspection. Nothing odd was found, except for a very small amount of compacted sediment at the bottom of each float bowl. After being reassembled and the carbs primed, still no joy.

- The main jets in the carbs are all 87.5. This seems really strange, since the bike is still wearing it's standard exhaust. (I believe these jets should be 102.5?)

We don't yet know:

- What kind of compression the cylinders are giving.

- What condition the head gasket is in.

- Whether the ignition system is giving trouble unknown to us, and if so, what nature that trouble could be taking (Static ignition timing? Igniter unit processor? Weak capacitors? Throttle-position sensor trouble?)

What I really need to delve deeper is diagnostic procedures for this particular engine.
We've tried several times to download the appropriate manual from Bandit Alley, but we're struggling with one or both servers timing out. Is there anyone who might be able to forward us the manual via E-mail? (to nikatreus@gmail.com).

Apart from that, can anyone help us out with potential causes, or known issues that might be causing this annoying fault? We REALLY need to get this bike working again. Any help will make you a friend for life... we promise!

[pmackie]

Hey Nick

I know these types of things can be frustrating, but keep in mind, that the engine needs 3 things to run...1) Approx correct fuel/air ratio, 2) A spark at the correct time and 3) sufficient compression. If the engine has these 3 things, by the laws of physics, it MUST run. So...start with the simple things first. After cranking the engine, do the plugs look wet or dry? How's the air filter? Can you drain fuel from the bottom of the carbs?

Based on your description, is sounds like the bike is flooded, or loaded up. Which means there is an overly rich mixture. If it's popping and trying to start, then you need to get the overly rich mixture out of the engine. Remove the plugs and turn over the engine with the throttle held wide open. This may help. If the plugs are wet, let the whole thing sit for a while with the plugs out.

If this doesn't get it going then I would concentrate next on the spark. If you don't have sufficient current from the battery, the plugs may not fire under compression. Find a good battery if you can, otherwise charge the exising one with a charger. Check the gap on the spark piugs, or replace them. Check all the connections to the coils and plugs, etc.

If that doesn't yield results, then start working your way through the fuel system. You can always put a few drops of fuel into each cylinder before cranking, and see if you get any results.

Let us know what you find