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Discussion Starter #1 (Edited)
Hello from Bologna, Italy. Please pardon my bad english.
I also ask for some mercy if this thread will be the same as dozen others on the same matter. I may have miss the search 'cause i lack the right words.

SUMMARY:
PROBLEM

  1. My B.400 won't start in the morning (so around 12 hours of stop) until i wire it to my car battery.
BEHAVIOUR, CLUES, USELESS INFO, WHATEVER :)

  1. Once connected to my car battery, it starts in less than one second
  2. After the first successful start, it will start everytime without problems
  3. The spark plug is dry if checked after the starting attempt failure
  4. The spark plug works during the attempts
  5. When it finally start, i don't smell gasoline.
  6. When started, the RPM rises and go down in a couple of minutes, so i'd say the auto-enrichner works
  7. after 10 hours of stop during the day (when i'm in the office) it starts in about a couple of seconds without needing a car battery
  8. It's summer here: 28°C during the day, 18° at night (more or less 5°, depending if we have summer storms)
  9. Bought brand new voltage regulator, battery and spark plug
  10. The starting motor run smooth: i've disassembled it and checked the ..."brushes" (right word?) inside it
  11. Piston compression is nominal (8.8)
  12. Checked with a transparent pipe, the Gasoline comes to the carburator without any difficult/air bubble/dirt particles
  13. The scooter runs smooth: it reaches 130kmh (with high windshield and a 120kg heavy driver), accelerates without "holes" and consumes around 20km/l (all city streets).
  14. This Burgman have 27.000 km.
QUESTION
What should i check? What's dependent on a night stop, and what benefit from the more current/voltage of a running car battery?


LONG STORY
In order to give you the most possible infos about my problem, i have to tell the full story.... sorry for this long post.

I bought a used B.400 two months ago, for a very low price 'cause the seller admitted that "it had problems when starting in the morning".

In Italy there's a very well mantained and rich of info forum, i checked it and checked the whole electric circuitry. Found that the voltage regulator was broken, and killed the battery also, so i changed both.

I have also connected a ground wire (section 2.5mmq, good for 16A) from the battery to a screw in the back (where the ... CPU? how to call it? is), and connected all the ground wires there.

Since nothing changed, i checked the starting motor: it's crankshaft rotate smooth (i mean there's not mechanical "bumps", just the magnet force) and the brushes inside it are not particulary worn.

Then checked the gasoline pump/filter, by adding 30cm of transparent pipe at the carburator intake: the pipe got filled in no time and never show a bubble or something else.

Then changed the spark plug.

Last, checked the piston compression, which is 8.8 as the tech manual says it should be.



I really can't think anything else to look at, which is dependent of a night stop and needs more current/voltage than what the battery can give...

Hoping for some help / clue / suggestion / inspirational idea.

Thanks
 

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Welcome Parduz! Have your battery load tested. Burgmans do not like weak batteries. What you describe is a weak battery. If you have a small battery charger/tender you may put it on overnight. Be careful not to overcharge the battery, most tenders have auto shut offs built in to them. A weak battery may turn the engine but not enough power to fire the plug and run the fuel injection unit. Also check your valve gap, tight valves will cause hard starting.
 

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Discussion Starter #3
Hey, thanks!
Welcome Parduz! Have your battery load tested. Burgmans do not like weak batteries. What you describe is a weak battery. If you have a small battery charger/tender you may put it on overnight. Be careful not to overcharge the battery, most tenders have auto shut offs built in to them. A weak battery may turn the engine but not enough power to fire the plug and run the fuel injection unit.
The battery i've bought a week ago is a 12V, 9Ah type (as stated in the manual).
I also thought that it could be born defective and got it tested by one of that stuffs that measures peak current and other things. The instruments said it was good.
I've also seen by my own eyes the fuel being pumped (by adding the transparent fuel pipe), while the spark... sparkled, and the starting motor running.
I may imagine that putting on a battery with 12Ah could make the Burg running but
- i don't have one to try to be sure, and a brand new is about 100€
- it feels to me (but i may be wrong) that it will "cover" the problem, not solve it.
Do you think i'm wrong?

Also check your valve gap, tight valves will cause hard starting.
Question: tight valves will not result in reduced compression?

Thanks again.
 

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Have you checked the no load output of the stator. You might have a stator that is going bad. It could be producing enough current to keep the bike running but not enough to do that and fully charge the battery. That could lead to the battery not having enough charge to start the bike when the engine is cold.

You test it by unplugging the stator at the plug before the regulator. With a multimeter you check the AC voltage between any two of the three wires. You should check all three combinations of two wires. I don't have specs for a 2000 model but the specs for the 2003-2006 models say you should get at least 55V AC between any 2 of the three wires at 5,000 rpm. I would suspect yours would be the same. If voltage is low on any of the three your stator is probably not keeping the battery fully charged.

If the stator is bad you will either have to replace it with a new one or find someone that can rebuild your old stator.
 

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Discussion Starter #5
Yes, checked before buying the new regulator, it's fine (and yes, same voltage as your).
The battery also get fully charged; with the old one (ruined by the broken regulator) i had about 3 short tries to start the engine before it was down, now i can try much more longer with much more longer "burst", and the battery still never go so low to see the mileage display going off or not able to run the starting motor.
 

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Sounds like you have checked out the charging system fairly well and it appears to be good. Compression is good so not rings.

Other possible causes:

Valves out adjustment (yes this can cause hard starting).
Decompression cam not working.
Weak coil.
Timing off.
 

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Discussion Starter #7

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Do you mean the cam that moves the valve?
It is part of the camshaft, but not the part that moves the valves. It is a cam plate on the shaft between the first valve and the bearing journal on the sprocket end of the shaft. It has a pin that locks it in place when the engine is running. It's purpose is to allow the valve to open slightly when you start cranking to release engine compression and allow the starter to turn the engine over easier. You check it by turning the plate to see if moves freely and the pin moves into place.

Is this the "thing" that provides current for the spark plug?
Yes

I really don't know what's is this
Timing refers to when the spark occurs relative to the piston position. I'm not sure how it is controlled on you year model. On the later models it is controlled by the ECM based on input from sensors like the crankshaft position sensor. The ECM retards it to get the engine to start and advances it as the engine speeds up.
 

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Just a thought.... Check and see if the light in your trunk is turning off when you close your seat, that would drain your battery.
 

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Discussion Starter #11
Unplugging it was one of the first things i've done, 'cause the frequent trunk removal for all the subsequent checks i've done. So no, it's not that light the problem.

Thanks again for all the help.
Checking the valves myself scares me a bit. While, even if i'm a programmer, i'm not afraid to work with my hands, i usually try to avoid "high precision" tasks. I'll read the repair manual one more time and i'll try to take a decision about doing it.
A friend of mine (fairly competent) thinks it's a carburator fault, and i should disassemble it and clean/blow everything.... i still can't figure how more current can help with valves or carb problems, but this is becoming a so misterious things that i'm givin up to sort it out by logic :)
 

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Discussion Starter #13 (Edited)
Ok guys, today i checked the valves.
They were a bit loose (i have spacers in steps of 0.05mm -which means that the 0.10 one is in the middle of specs for intake, 0.20 is in the middle of exahust spec). The valve were a bit loose (0.15 and 0.25 passed) so i tuned them.

The Burgman the started immediatly!!!! YEAHHH!!!.... but...

the idling is terrible, not "constant" and it stopped two times with a big "PUFFFF", and one time with a loud "PAK!" (not from the exahust pipe... seems from the carb or the piston... i' really scared now).

What i've done wrong?

Uh, and why i have TWO lines (3mm apart) by looking in that hole to find the piston position?
AND
that line(s) should'nt appeat after the intake valves closure (which are the higher ones)? While i was under the shower i realized that (if i'm not wrong) it appeared after the lower ones closure.....

I'm a bit confused now, and with the fear to have ruined something.
 

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Sounds like it is out of time and backfiring through the carb.

You said you used spacers so I'm assuming it has bucket and shim type adjusters instead of nut an screw type like the 2003-2006 400 has. Did you have to pull the cam to change the spacers. If so you may have not gotten the chain back on exactly in time.
 

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Discussion Starter #15
Sorry for my bad english.
With "spacer" i meant "thickness gauge" (just found this words in this forum).
Everything looks just like the video linked some post above.
This is a pic (not mine, but it's the same thing):
 

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Discussion Starter #16
Another question:
It is part of the camshaft, but not the part that moves the valves. It is a cam plate on the shaft between the first valve and the bearing journal on the sprocket end of the shaft. It has a pin that locks it in place when the engine is running. It's purpose is to allow the valve to open slightly when you start cranking to release engine compression and allow the starter to turn the engine over easier. You check it by turning the plate to see if moves freely and the pin moves into place.
Where's this stuff in the pic?
 

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OK then you did not have to pull the cams. That means unless it was already out of time it should still be OK.

Go back over everything you unhooked and make sure you hooked it back up right and did not leave any wires or tubes unhooked.
 

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Discussion Starter #18
Ok, tomorrow (it's near midnight, here) i'll redo everything and see if i can shot a movie of the whole process, so we could see if i do any mistake,

Thanks a lot
 

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Another question:

Where's this stuff in the pic?
Starting on the left of the picture. First is the outer bearing cap, next is the cam chain, then the middle bearing cap. Just to the right of the middle bearing cap is what looks like two thin silver plates. That is the decompression cam. The first plate turns to move a pin that you cannot see in the picture. The pin is under the arm just to the right of second plate.

Bad news is that in the manual it shows you have to pull the cam to check if it is functioning properly. You check it by turning the first plate and seeing if it moves freely and if the pin moves with it. While if it is stuck in the decompression mode it could make the engine do what yours seems to be doing, you will want to rule out other things before you start pulling the cam to check it.

For one thing I would check to see that the cam chain adjuster is working properly and the cam chain is not loose. If it is that would let the cam move slightly out of time which could also cause the symptoms you are experiencing.
 
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