Tuning issues

[Bullet]

just curious, did you check your diaphragms for holes.

pull a carb cap or 2, if they are wet up top .. bingo.

[Montreux_Blue]

just curious, did you check your diaphragms for holes.

pull a carb cap or 2, if they are wet up top .. bingo.

I've thought about that too but there is also the hole in the bottom of the slide that would more than likely let fuel in there since the slide has a very tight fit.

[DGXSER]

I know that on ym carbs that work perfectly I have pulled them after a run and seen the tops of the diaphrams wet with fuel. I assumed as MB did that this was due to the vapor getting pulled in through the relief hole under decel.

[petejw]

jat, no ones mentioned float levels,
at steady cruise the float levels become
more critical, what have you got them set at?
if there set to stock, try setting the fuel level half a mm on the lean
side and reset your mixture screws and see how
that goes.

[mack]

float height

I made them all 25.7 mm, what's your recommendation

[dbeardslee]

Last summer I had issues, and wound up taking my carbs off 15 times. Turned out it wasn't the carbs causing the problem , but I did learn something from the experience. I noticed that I could control the sooty black ring around the outside of the plugs with float height. I could drop them down a millimeter, and I'd get the ring, or raise them a millimeter and make it disappear. I've found the stock setting of 25.7 to be just about right. When I set mine I use a combination square, and I set it 1mm proud of what I'm looking for. Then I adjust my floats, and 'eyeball' one millimeter of light between the top of the floats and my square. Whatever you use for a measuring device, you don't want it to actually touch the top of the floats - they're way to easy to push down. And don't try it by holding a ruler next to the float - you won't get anywhere even close to what you're looking for - gotta use something that actually hangs over the top of the float.

[mack]

crude

It looks crude but was effective. Made out of a coat hanger. Took several attempts to get right but from the bottom of the little feet to the underside of the shoulders is exactly 25.7 mm




My plug electrodes look brand new but I do have a sooty ring around the inside of the threads. I was always suspect of the 2/3 coil as the wires were cracked. I ordered new accels in mid March and am still waiting for them but I checked today and they just shipped this am. Shouls have them next week. Somone had a post that showed mounting the accels with a drawer pull, but I can't find it. Does anyone have the number for the NGK plug caps.Anyway I'm going to throw in the new coils and see if he still stumbles. If so then I'll lean out the floats. That would be down to say 25.0 from 25.7. Is that enough?

[petejw]

hi mack,
from experience of messing around with my bike,
i found around .3 - .5mm on the leaner side of stock settings
to work well, this stopped any flooding at idle and also made
for smoother acceleration and smoother cruising.

a black ring around the plug isnt a bad thing, but u dont want it to be
too sooty, if the sootyness travels more than a thread or two down the plug then this usually indicates the plug isnt screwed in tight enough.


i use digital calipers for checking the float heights, they work well
and can be adjusted at smaller incrememnts.

[dbeardslee]

If so then I'll lean out the floats. That would be down to say 25.0 from 25.7. Is that enough?

That would be headed in the direction of richer. In terms of the range, what the manual says is 25.7mm plus or minus 1mm. If you want it 1/2mm leaner, then you want to go about 26.2mm. Also, you want to make sure you measure the floats on both sides. Set it with the tab first for one side, and then adjust the other one by slightly bending the cross member if you need to. Like Pete said, you can use a caliper as a gauge. The depth gauge part of the caliper is what is set for the measurement, and the shoulder on the lower part of the caliper is wide enough to extend over the float. Measure without a gasket from the seating surface.

[petejw]

when i was messing around with my float levels,
i found if it was set rich the bike had a vibration
at 4500rpm at steady cruise or upon acceleration, i then began to lean
the floats out when i had it set at .5mm from stock on the lean side
the bike was much smoother at 4500 steady cruise and on acceleration.
and im getting a nice colour on the spark plugs.

[mack]

Re-tuned

Pulled the carbs and reset the floats at 26.3. Colour tuned then sync'd. Plugs all looked good. Ran really good while sitting in the shop, never missed up to 6K. I have a short ramp about 3 ft long as my shop floor is about 10 inches above ground level. As soon as I backed the bike out to give it a ride it started to miss. I hadn't even pulled the clutch in. Since it was raining I just pulled it right back in the shop. I'll take it out for a few miles tommorrow and see what happens. I assume the floats are still set to rich if it floods the carbs on dropping the tail end 10 inches just for a second. Going to try it anyway.

[petejw]

hi mack,
i wouldnt go leaning the floats any more at this stage,
otherwise youll be messing around with pilot jets to compensate
for the leaner settings.

did you reset your mixture screws?
are you sure the needle and seats arent leaking which
could cause it to run rich.
did you put new plugs back in?
no kinked fuel lines?

[mack]

Yes I

colour tuned after and changed the mixture screws a little but nothing drastic was required. I didn't put in new plugs but mine looked OK. One thing though, when I reassembled my carbs, I didn't put a ring of yamabond around the diaphram lip. Could that be the problem?

[petejw]

ive never lubed the diaphrams, as long as there
pliable it should be sweet.
id personally put in new plugs or clean the ones you have,
the 'soda blaster' works real well for cleaning plugs, also
having clean plugs will let you know whats going on with the changes
youve made.

[xj11john]

One thing though, when I reassembled my carbs, I didn't put a ring of yamabond around the diaphram lip. Could that be the problem?

I definetly would not put any yamabond on the lip of the diaphrams. They are sealed by the caps that go over them, and you don't want them sealed since you will need to take them out every time you adjust needle hieght or clean your carbs.