Easter Bunny

G

ghwallice

Hero member
Location
Ipswich
The Zane crank project has gone to shit at the moment, but I?m regrouping and moving forward again with that soon. It?s got something to do with a hot summer and the money tree down the back is not bearing a lot of fruit.

And I?m writing a story for the Easter Bunny?.

So I?ve been mucking around with a 3CL project I have.  Totally stock 78 3CL, not been started for about  80 years. I fired the motor up a couple of months ago on an ignitec with 0 degrees base timing. It fired within one revolution, and idled. (i've got video to prove it).

I didn?t overhaul the carbs at all, just set the floats and replaced the o rings on the idle? jets. You?re all cringing already?
Valve clearances were a bit tight, but no point setting them until the motor has run for a while. Compression was something like 150/160/150, I think..

I did put new oil in it!!! And our Guru helped me with a map that started at 8 degrees?.

I figured that hard rubber tips were no different to the old brass needle and seats that I started life with?.
So, armed with an electronic  ?mercury? guage, an infrared temp guage, a sniffer, and a couple of 6 packs I decide to tune the motor?..Hmmmm.

I am not good (ie shithouse) with tuning Dellortos, even though I have managed to my Guzzi?s running ok in the past.

I?ve now taken 3 bowl  holders and set them up with tubes to check float levels. It doesn?t matter how much I try to set float by ruler, it does not work. Currently I have 2 carbs at about, using a spirit level from the front of the bowl/carby line, at about 4mm above, 1 at about 10mm above. They are consistent with the running of the motor, so old rubber tips are working ok?Comments?

I?m getting it to idle, but back firing at times at idle, and out of balance at idle, is an issue. Once on the throttle a bit balance is spot on the bench and backfiring goes away. There is no adjustment for idle position, and if I balance them at idle on the rail screws, they are out of balance once the throttle is cracked.

Another current post asks about  cold/hot  idle. I concur with these old bikes need to warmed up. This one is the same.
So, some questions?.

Q)If bike idles ok, then dies back and stalls after a minute or so, that is the idle mixture is too rich? (chokes etc checked). The idle screw is a fuel adjustment, not air ( as per the other thread), so is the best adjustment max rpm at idle? In this case about 2 turns.

Q)Leaking exhaust copper O rings. What effect does that have?

Q)Not having clamps on the 3 to 2 exhaust system. What effect does that have?

Q)Spark plugs that have fouled because it is all too rich, and are tracking down in the plug. Is the best way to clean them is in the blasting cabinet???

Q)The NGK caps for the plugs. How does one test them reliably? The coils on cylinders will throw a spark about 15 to 20mm, but fit the NGK caps and the spark looks weak. Does the Invitec impact on this. I?m using the Ktek coils (?) of a Kawasaki (?)

Q)Once the motor is hot the best I can get on the sniffer at idle is about 27:1, not the stocky o metric of 12.7:1, but then it is stuck down 1 or the other pipe measuring 3 cylinders?What  stocky o metric value should this run at at idle??

Q)Given the tools I have, what is the best process to get this old girl running correctly?

Merry Easter to you all, may you enjoy the time with your families!!!

Regards to all on the Forum,

Greg

PS If you see a pink Easter Bunny that?s been run off the road, don?t stop. The real Easter Bunny is white.
 
ghwallice said:
Totally stock 78 3CL, not been started for about  80 years.
Click to expand...

Greg,

Your idle issues are most probably one or 2 blocked idle circuits.  Afraid you'll need to totally strip the carbs, throw 'em in the ultra-sonic for an hour or 2, then blow through ALL air passages with at least 150psi.  With a bit of luck, you'll find air passing through in all directions, blowing through the pilot jet bore, the mixture screw bore and the idle air aperture at the carb mouth.  In all instances, you should also have air exiting through the idle mixture bores under and just aft of the slide on the floor of the mixing chamber.  Only if these bores are free from obstructions, can you expect a steady idle.

This isn't just a Dellorto trait, I've come across several jap carbs with identical issues, so much so that I had to junk a pair of carbs that simply wouldn't clean up.  Haven't had to do that yet with Dells.  :D

How you want to set float levels from the outside beats me... just having them the same height is not the same as having them at the correct level.  Dellorto PHB/F carbs are specified with 18-19mm float height, mounting the carbs at an angle as on the triples will result in a fluid level that has nothing at all to do with the actual float height.  Only if the float is set to the correct height can it be used as a reference with a level tube.  It's a less-than-10 minute job to set the float heights with a ruler...

Plug caps are checked with probes of a multimeter stuck in both ends, resistance should be no more than 5 kOhm.

I don't see slight leakages at the headers or collector stuffing up the idle noticably.

If mixture screw adjustment at idle differs greatly from 1.5-2 turns out, pilot jet is too small/large.  Mixture adjustment should ideally be the same on all 3 carbs, check that idle screws are not worn/corroded and are all identical.  Set throttle stop to a fast idle and look for highest rpm with the mixture screws, then set 1/4 turn leaner.  Use the throttle stop only to adjust idle rpm from there.  If spitting occurs on opening the throttle, go richer 1/8 turn at a time until spitting stops.

Chuck fouled plugs (far) away, especially if you're using NGKs.  I've rarely had luck with cleaned plugs.

Innovation brand A/F instrument generally shows somewhere between 10.5-12 at idle.  3.5% CO is also acceptable.  Is your oxygen sensor correctly calibrated?

piet
 
Thanks for the info Piet. I'll print it out and work through it.

I did actually set the floats off the bike, tilted to the appropriate on their side angle, to the 19mm(?), but #3 was running cold on header temp and a cylinder was "popping". When I fitted the hoses to check fuel height, #3 was very low.

There are no throttle stops (slide idle adjustment screws) on these carbs. They have been blanked off.

Interesting point about calibrating the sniffer. Thought I had done that, but will recheck.

Like I said, fuel tuning of a motor is something I have never been good at.

Regards, Greg
 
ghwallice said:
There are no throttle stops (slide idle adjustment screws) on these carbs. They have been blanked off.
Click to expand...

Correct. Idle speed is set with the knurled screw on the throttle linkage. It adjusts all 3 carb slides together. If they're synched OK, the slide lift at idle should be even across the 3 carbs.

Carb synch can get messed up if the mounting plate that holds the 3 carbs together is bent or twisted. That plate is a bit flimsy, so it's not uncommon to find one that's been twisted out of alignment by some gorilla who has had the carbs off and on before you got to it.
 
Dellortoman said:
Idle speed is set with the knurled screw on the throttle linkage. It adjusts all 3 carb slides together.
Click to expand...

Is this not considered a throttle stop??  It limits downward movement of the slides...  ::)

clueless piet
 
sfcpiet said:
Is this not considered a throttle stop??  It limits downward movement of the slides...  ::)

clueless piet
Click to expand...

Well, yes I suppose it is a throttle stop. But Greg was obviously referring to the individual adjustable stop screws in the carb bodies, like you see on cable operated carbs.
 
It is something I am doing wrong with the tuning.

My other 3CL has 36mm Dellortos which has a throttle stop on each carb, which is where the confusion has started.

On it, I've just changed the needles from K2's to K1's (it was running rich) and BOTH bikes are now doing exactly the same thing at idle. Over running on throttle off, and popping/backfiring at idle.

The 36mm carbs were ultrasonic cleaned not long ago, and the 32mm carbs were surprisingly clean in the bowls (but may still need the ultrasonic).

I think it is just a case of working it through and learning. As stated, I've never been any good tuning fuel.....

Thanks to all!

Greg
 
Piranha Brother 2 said:
So 3x36mm singles fitted into the bank of three bracket. That?s why it has throttle stops!
Click to expand...

For clarity.

3CL #1, 36mm into a bank of 3 bracket, c/w with individual throttle adjustment stops.
3CL #2 OEM 32mm, no individual throttle stops.

Regards, Greg
 
Piranha Brother 2 said:
32mm being factory standard, 36mm being not. I'd blank off the stops and use the balancing via the throttle shaft.
Click to expand...

Way to go... (bigthumb)

Unless of course if Greg is using individual throttle cables, these are a pain in the arse no matter how you look at them.  No advantages, all disadvantages... ::)

piet
 
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