Another B4 no start... Yes I've used the search..

[Lucid_Garage]

So, new member but longtime lurker..

Picked up my 91 B4 last summer..  Can't seem to get it to fire..

This is what I've tried/checked:

New Battery
New oil/filter
New air filter
Spark- Yes- strong on all four cylinders.
New plugs- check
Made sure plug wires are on correctly
Compression- Good all 4 cyl.
Carbs- Cleaned multiple times (soaked in yamalube non-corrosive carb cleaner for days on end, three separate times), Did not disassemble the rack, checked the best I can for leaks; no torn diaphrams on vac slides

From here I was thinking about checking valve clearances...

Any pointers??  

I really want to get this puppy on the road!!  

HELP!  

 

[pmackie]

Hey Lucid

This thread may give you a place to start:

http://forums.banditalley.net/index.php?topic=8319.0

[Lucid_Garage]

Hey Lucid

This thread may give you a place to start:

http://forums.banditalley.net/index.php?topic=8319.0

Thanks for that!

Unfortunately that thread dealt with water in the tank/gas... Neither of which are causes for my woes...

Seems so simple..  anyone else have any ideas?

[bullet5]

Hello there, would you mind going into more detail?

Does the engine crank over when you hit the starter button? If so does it maintain a constant speed or does it slow down?
If it doesn't crank, are there any sounds (clicks for example) when you press the starter button?

If the engine slows down while turning over, when was the last time you charged the battery, and had it replaced for a new one?

All the best,
Bullet5.

[Lucid_Garage]

Hello there, would you mind going into more detail?

Does the engine crank over when you hit the starter button? If so does it maintain a constant speed or does it slow down?
If it doesn't crank, are there any sounds (clicks for example) when you press the starter button?

If the engine slows down while turning over, when was the last time you charged the battery, and had it replaced for a new one?

All the best,
Bullet5.

Oops!

Sorry I wasn't more clear.. 

The bike also has a new battery.  It will crank (turn over) and crank and crank, doesn't taper off until after MULTIPLE tries of constant cranking.. The bike only gives me a minor puff of ignition if I spray starter fluid directly into the carbs as I'm cranking. But just BARELY..

 I've tried with choke on full, partial, and off.  I've been using a good size auxiliary fuel tank (hanging gravity feed) so the petcock is not the issue.

I've swapped plug wires around, tried push starting, checked for intake leaks @ manifold and carburetor

It is getting strong spark as I'm cranking it, so I know none of the safety switches are faulty (i.e. sidestand, clutch, neutral, etc.), and I know the coils/ignitor are good.

The bike has enough compression to lock the rear wheel when push starting, so compression shouldn't be the issue..

I'm stumped!

[pmackie]

Hey Lucid

No start can be frustrating, but keep one thing in mind...if an engine has sufficient compression, approximately correct fuel/air ratio, and spark at approx the correct time, by the laws of physics, IT HAS TO RUN.

So, it is a matter of making sure each of the above is happening. Given that you feel you have spark and compression, then you need to focus on the fuel side. Make sure you have FRESH fuel, as it needs enough vapour pressure to allow it to evaporate. Do the plugs come out wet? You can dribble some fuel into the carb inlets (with the air box removed) and see if you get any life.

I am concerned that you mention that you are only getting a chuff or two out of the engine when using starting fluid, as this points to other issues. I would want to verify compression with a tester, both dry and wet (after adding oil to the top end).

[bullet5]

Almost certain it's to do with your timing of the sparks

Are the pickups connected to the correct place on the loom? There are two, one from either side of the top of the engine. If I remember right they are 3 pin plugs. One is white the other black. Make sure these are the right way around. Next make sure you have the coils on the correct way around and the leads in the correct places. They are set up very oddly on some of the B4's.

For example on my B6, coil 1 (left) feeds 1 & 3, whereas coil 2 (right) feeds 2 & 4. Whereas on my '93 VVC B4 coil 1 feeds 1 & 4, and coil 2 feeds 2 & 3 (left and right being when you're sat on the bike).

The only other thing it would be is the regulator/rectifier as these are well known for blowing on the 400's.
My Virago 535 wouldn't start up properly and just cranked for ages. I replaced it and it was back to working perfectly again.

I've just checked your coil setup, and #1 should feed to cylinder 1 & 4 then coil #2 should feed 2 & 3.

All the best,
Bullet5.

[Lucid_Garage]

Hey Lucid

No start can be frustrating, but keep one thing in mind...if an engine has sufficient compression, approximately correct fuel/air ratio, and spark at approx the correct time, by the laws of physics, IT HAS TO RUN.

So, it is a matter of making sure each of the above is happening. Given that you feel you have spark and compression, then you need to focus on the fuel side. Make sure you have FRESH fuel, as it needs enough vapour pressure to allow it to evaporate. Do the plugs come out wet? You can dribble some fuel into the carb inlets (with the air box removed) and see if you get any life.

I am concerned that you mention that you are only getting a chuff or two out of the engine when using starting fluid, as this points to other issues. I would want to verify compression with a tester, both dry and wet (after adding oil to the top end).

I'll have to try an actual compression test..  That was my next move..

[Lucid_Garage]

Almost certain it's to do with your timing of the sparks

Are the pickups connected to the correct place on the loom? There are two, one from either side of the top of the engine. If I remember right they are 3 pin plugs. One is white the other black. Make sure these are the right way around. Next make sure you have the coils on the correct way around and the leads in the correct places. They are set up very oddly on some of the B4's.

For example on my B6, coil 1 (left) feeds 1 & 3, whereas coil 2 (right) feeds 2 & 4. Whereas on my '93 VVC B4 coil 1 feeds 1 & 4, and coil 2 feeds 2 & 3 (left and right being when you're sat on the bike).

The only other thing it would be is the regulator/rectifier as these are well known for blowing on the 400's.
My Virago 535 wouldn't start up properly and just cranked for ages. I replaced it and it was back to working perfectly again.

I've just checked your coil setup, and #1 should feed to cylinder 1 & 4 then coil #2 should feed 2 & 3.

All the best,
Bullet5.

Thanks for the tip, I too considered this..

I have a factory service manual and cross checked the coil layout/plugs.. But it's definitely worth a second (or third?) go.. 

A buddy of mine is the service manager at a local yamaha/suzuki dealer, he said maybe my flywheel/stator has sheared the woodruff key, hosing timing.. Or it could be that valve clearances are so far off it's not sustaining compression long enough to allow for ignition.. Does any of this sound viable to you banditos??

[pmackie]

Or it could be that valve clearances are so far off it's not sustaining compression long enough to allow for ignition

Possible, but not likely. Start with the simple things first. But it would be usefull to know the compression.

I would still focus on fuel. Are the plugs wet when you pull them after cranking? Check and advise.

[bullet5]

If the valves were that far off, then you'd hear a bang and the engine would sieze due to the valves hitting the pistons.

Even if the valves are out they will not stop it combusting, as some fuel vapour is still in there, which would ignite and cause the vapour in the exhaust to go aswell, creating a rather large back fire.

Next step is to definitely remove the plugs, check their condition, then plonk them back in (with the correct gapping) and plug the coils back in in order. Then check the coils are linked upto the loom in the correct place. 

All the best,
Bullet5.

[Lucid_Garage]

If the valves were that far off, then you'd hear a bang and the engine would sieze due to the valves hitting the pistons.

Even if the valves are out they will not stop it combusting, as some fuel vapour is still in there, which would ignite and cause the vapour in the exhaust to go aswell, creating a rather large back fire.

Next step is to definitely remove the plugs, check their condition, then plonk them back in (with the correct gapping) and plug the coils back in in order. Then check the coils are linked upto the loom in the correct place. 

All the best,
Bullet5.

Thanks!

On the valve note, you have a point.. I agree..

I've gapped the new plugs according to the Suzuki factory manual.. Looks like I'll check the coil connections @ the harness, and yet again check plug wires..

I'll report back soon!