Topic: Odd timing issue, the closer to F the worse it runs.

[scottly]

The bike absolutely will not run if the blue and yellow wires are swapped: the timing would be 180 degrees out, not the 10 or so degrees Jore has.

[Jore]

Yes the wires are correct also, I tried to fire up the bike but the plugs got gas fouled, so I'll try again tomorrow.

[Jore]

So I've made a video of the bike idling with the other set of springs on the advancer, I found that the yellow wire was grounding with the condenser so that might have also been an issue, my idle speed is around 3000 rpm as the bike is currently running, here's the video:

[Jore]

I hooked up the strobe light and dwell meter. At around 3100 rpm (current idle) the notch on 2-3 is in between the 2 parallel marks of the advancer, on 1-4 it's a bit off to a side, with a 4 cyl dwell meter 1-4 are around 50° and 2-3 around 40°, I do have another meter with an 8 cyl scale but I couldn't get it to work for the moment.

[Deltarider]

The bakelit knob will wear and gap increase by time so smallet gap is a good start.

Actually it's the opposite. When the fiber knob wears, the gap will decrease (increasing the dwell).
Jore, try to set the dwell between 46^o and 49^o on a 4 cyl scale or between 23^o and 24,5^o on a 8 cyl scale. Ideally 1+4 and 2+3 should show more or less the same dwell reading, but it's practically impossible to have them both exactly the same.

[Jore]

Thanks for the info DR, btw does dwell change with engine speed?

[Deltarider]

Thanks for the info DR, btw does dwell change with engine speed?

Nope, it shouldn't. If it does, there's something wrong. That's the advantage of a dwellmeter over feeler gauges btw. It will detect any problem of the advancer assembly.

[flybox1]

The bakelit knob will wear and gap increase by time so smallet gap is a good start.

Actually it's the opposite. When the fiber knob wears, the gap will decrease (increasing the dwell).
Jore, try to set the dwell between 46^o and 49^o on a 4 cyl scale or between 23^o and 24,5^o on a 8 cyl scale. Ideally 1+4 and 2+3 should show more or less the same dwell reading, but it's practically impossible to have them both exactly the same.

+1

[Jore]

I've set the dwell as close as possible on both sets, so here's the readings:

1-4


2-3


Afterwards I played with the strobe light and this is what I got
1-4


2-3
I wasn't able to get a good picture, but the notch lines up with the first notch of the parallel lines, pretty much like 1-4.

So it seems to me that timing is spot on, but the idle still hangs around 3100 rpm, even with 1 turn out from the idle screws, my eyes feel irritated a bit, so it's running rich I guess.

[Jore]

I took the bike out for a ride, it's down on power, doesn't rev that high, probably got it up to 50 km/h in third gear max, it smells rich.

[Jore]

I took the plugs out, they're black soothy and dry equally.

[scottly]

Black sooty plugs are caused by too much fuel/too little air: carburation problem, not ignition. Are the choke valves fully open? Burn the black off those plugs with a propane torch before using them again.

[Jore]

Yes the chokes are fully open, but I've been pondering the rich condition all afternoon. On another 466 build I read that the original carb settings where on the lean side and it was recommended to move the carb needles one notch up, so I did that before the bike ran, I've been reading on the symptoms of a rich carb and it all points to what I have, we have a long weekend here so I'll take the carbs out tomorrow and reset the needles. Thanks on the torch tip! 

[scottly]

Are you using stock main jets? Have you done a "clear tube" test of the fuel levels in the float bowls? I would verify the fuel levels first, before removing the carbs.

[Jore]

Are you using stock main jets? Have you done a "clear tube" test of the fuel levels in the float bowls? I would verify the fuel levels first, before removing the carbs.

Everything is stock, the floats where set to 22mm and the last time I did the clear tube test they where all equal, but I might as well recheck that tomorrow.

[scottly]

Stock air-box and air filter?

[Jore]

Stock air-box and air filter?

Both stock and the filter is new.

I have all of the rich running symptoms except the slow idle, but the bike starts easily without using the choke even in the morning and once it's up to temp he looses power, also the acceleration is pretty sluggish.

[TwoTired]

Isn't the advance cam active (advanced) at 3000 RPM?

If you align the marks with advanced mechanical timing, it will be set retarded for street run regime.

Why can't you get the idle speed down?    Can't do proper strobe light idle timing with 3000 RPM.

CAN do static idle timing with the engine stopped.  Then check advance with the strobe.

Need some carb internal details.  Are the carb balance ports plugged?  Have the carbs been balanced?

How are you checking the RPM?  Stock, correct for model tach?

[Jore]

Isn't the advance cam active (advanced) at 3000 RPM?
If you align the marks with advanced mechanical timing, it will be set retarded for street run regime.
Why can't you get the idle speed down?    Can't do proper strobe light idle timing with 3000 RPM.
CAN do static idle timing with the engine stopped.  Then check advance with the strobe.
Need some carb internal details.  Are the carb balance ports plugged?  Have the carbs been balanced?
How are you checking the RPM?  Stock, correct for model tach?

I moved the needles down one notch from they where previously, the bike now needs a tab of choke to start and afterwards the exhaust isn't gassy smelling like it used to be, with the screws out 3/4 turns the bike now idles at around 2000 rpm on start up and after it gets hot they go down to around 1300-1500, it bounces a bit. I'm checking the rpm with the original tach, for the moment the carbs are only bench synced, I used a 1.3 mm allen key to set the lowest point. Carbs are all stock, should I recheck timing and reset accordingly?

[TwoTired]

I moved the needles down one notch from they where previously, the bike now needs a tab of choke to start and afterwards the exhaust isn't gassy smelling like it used to be, with the screws out 3/4 turns the bike now idles at around 2000 rpm on start up and after it gets hot they go down to around 1300-1500, it bounces a bit. I'm checking the rpm with the original tach, for the moment the carbs are only bench synced, I used a 1.3 mm allen key to set the lowest point. Carbs are all stock, should I recheck timing and reset accordingly?

If you strobe light set to the idle timing marks while it was on the advance cam, then yes you must redo the timing.

As I recall, there is no master carb for the 400.  So the drill bit or allen key sync does ensure the slides can reach the bottom of the carb bore, and this can force a high idle that the idle stop screw can't correct.

You have to pick a master carb from the bunch, back way out the idle screw and adjust the master carb so it can reach the carb bore floor.  Lock down the master and remember not to fiddle with it again thereafter.  Use the idle screw to lift the master slide to your drill bit/allen size, and then adjust the other three to be the same as the master.

I use a bright light on the far side of the carb throat, instead of the drill bit/allen technique when the carbs are off the bike.  No risk of marring the slides or carb bore with hard metal objects.  The slide blocking the light ensures the slides can close later leaving the idle screw as the dominant idle speed control.

[Jore]

I moved the needles down one notch from they where previously, the bike now needs a tab of choke to start and afterwards the exhaust isn't gassy smelling like it used to be, with the screws out 3/4 turns the bike now idles at around 2000 rpm on start up and after it gets hot they go down to around 1300-1500, it bounces a bit. I'm checking the rpm with the original tach, for the moment the carbs are only bench synced, I used a 1.3 mm allen key to set the lowest point. Carbs are all stock, should I recheck timing and reset accordingly?

If you strobe light set to the idle timing marks while it was on the advance cam, then yes you must redo the timing.

As I recall, there is no master carb for the 400.  So the drill bit or allen key sync does ensure the slides can reach the bottom of the carb bore, and this can force a high idle that the idle stop screw can't correct.

You have to pick a master carb from the bunch, back way out the idle screw and adjust the master carb so it can reach the carb bore floor.  Lock down the master and remember not to fiddle with it again thereafter.  Use the idle screw to lift the master slide to your drill bit/allen size, and then adjust the other three to be the same as the master.

I use a bright light on the far side of the carb throat, instead of the drill bit/allen technique when the carbs are off the bike.  No risk of marring the slides or carb bore with hard metal objects.  The slide blocking the light ensures the slides can close later leaving the idle screw as the dominant idle speed control.

Thanks TT, i'll do that tomorrow, I noticed that on the choke side there's another stop screw in about the same position of the idle screw, can that also be causing the the high idle?

I took the bike out for a ride around my neighborhood, the bike pulled harder, didn't stumble like the last time but I decided to head back home once the idle started climbing like crazy, I didn't have the tach hooked up but I'm guessing it was around 4000 rpms.

[TwoTired]

Thanks TT, i'll do that tomorrow, I noticed that on the choke side there's another stop screw in about the same position of the idle screw, can that also be causing the the high idle?

If it were mis-adjusted, yes. 

This model has a fast idle cam which is coupled to choke application.  With the choke off there should be no interference with the main idle screw setting.  Only when choke is applied will it take over the slide idle stop position from the main idle screw.

It's actually a very nice feature to have when all is adjusted correctly, as when cold, you need to hold the throttle open a bit for predictable idle speed.  When warm, choke off and set idle speed is as predicted for a warm engine.  I wish the same year model 550s and 750s had that device.  It would keep many owners from "idle knob twiddle" on a daily basis.

[scottly]

I wasn't able to get a good picture, but the notch lines up with the first notch of the parallel lines, pretty much like 1-4.

This is correct for 3000 RPMs, when the advance is fully in, and should return to the F mark at Normal idle speeds of 1200 or so. If the advancer is working properly, it's NOT a timing issue.

[PeWe]

The bakelit knob will wear and gap increase by time so smallet gap is a good start.

Actually it's the opposite. When the fiber knob wears, the gap will decrease (increasing the dwell).
Jore, try to set the dwell between 46^o and 49^o on a 4 cyl scale or between 23^o and 24,5^o on a 8 cyl scale. Ideally 1+4 and 2+3 should show more or less the same dwell reading, but it's practically impossible to have them both exactly the same.

Thanks for the correction Delta. I missed that description :-)
I should know better since I adjust for lowest dwell that will continue to work even when knob get wear.

[Jore]

I had no time to mess around with the bike today, but I did give it a quick start up, the revs went sky high!
What could cause that? I did need to use the choke for starting, so I'm intrigued.