Timing Pickup Question

[skids]

You said, "The MAC 4 into 1 pipe is not a "true" performance exhaust but with its baffle pretty much gutted it is a straight through setup. It must be allowing the engine to breath better and there must be some exhaust scavenging going on. "

There enlies the problem. If you get "exhaust scavenging" in one rpm range, you will suffer in another. Unless you enjoy taking off from the start line at 5000 rpms, you had better find a decent baffle. This is just from my own experiences....you can't tune your carbs for that "reflection resonance."

[79XS11F]

Hey skids ... Tuning is not my strong point that's for sure so correct me as you see fit. I have always been under the impression that the idea is to make the engine breath better across the board and alter the fuel supply to match the engines breath. The MAC pipe came with a all steel baffle that if your know them is like 2 tubes back to back which creates a stop plate. So exhaust hits that central stop plate and moves outward around it through rows of what were rather small holes in the tubes. It was pretty restrictive to say the least. I drilled out all the holes but the bike still ran rich and there was no improvement. I ended up also removing the stop plate.
In the past on my 1978 bike I used a Kerker with minor jetting changes and that bike was GREAT in all ranges. It was a longer pipe with a drilled Central pipe and no stop plate. I was hoping to get similar results.
SO .. are you suggesting I completely replace the baffle or just find something better to put into the baffle I have? Any input would be as usual greatly appreciated. What would you suggest keeping in mind that a 1179 kited engine will be going into this bike.
Rob

[skids]

I really don't know how to retrofit a baffle into an existing mac. I do think that exhaust volume (hence added length of the kirker) play into the whole engineering thing. I am not an exhaust engineer, but I believe that if you effectively break-up the returning echo pulses with a good baffle, you can have a better running engine.

Originally posted by 79XS11F

SO .. are you suggesting I completely replace the baffle or just find something better to put into the baffle I have? Any input would be as usual greatly appreciated. What would you suggest keeping in mind that a 1179 kited engine will be going into this bike.
Rob

[79XS11F]

HELP

An Update.
I did not use my bike for 4 days while waiting for a front tire. The bike was on main stand. After installing the tire I wanted to go for a ride but NO WAY. # 3 and #4 MISSING too bad to use the bike :-( It was running reasonably well when I parked it.

Here's what I got:

The timing pick up coils are brand new factory units that are gaped correctly
The timing was right on including auto advance the last time I checked which was less then a week before I parked it .

#1 and #2 cylinders are A OK ( they also have dielectric grease on the plugs and plug wires)

Carbs are off the bike now and diaphragms are working. When I cover the air inlet the slides stay in the up position. the slides work smoothly.

Floats are good and all it the same position.

Bike runs the same with or without the ballast resister in place.

The timing light blinks very rapidly on #1 And #2 but blinks slow enough to count the blinks on both #3 and #4

OH spraying quick start around the carbs when they were on the bike made no difference.

HELP WHAT THE HECK IS GOING ON HERE. I know that #3 and #4 on on different coils but share fuel supply.

ANY IDEAS WHAT I SHOULD BE LOOKING FOR???

Rob

[TopCatGr58]

Hey Rob,

Just reread this thread.

Well, there's only 3 things needed, air, fuel, fire. You're getting air! Your tests suggest missing fire. The PU coils are not bad, cause both coils are firing, #1 and 2 cylinders. The coils are probably not bad, again, cause firing 1 and 2 cylinders. You say they are new Accel, with new wires and non-resistor caps! Did you try swapping the wires/caps, just plugging #1 wire/cap onto #4 cylinder, same for 2 to 3, and see if the problem stays with 3-4? If so, then it's fuel, not spark! If it hops to 1 and 2, then something is wrong with the wires/caps!

As stated, 3 and 4 share same fuel supply lines. Both acting up makes me think outside the carbs. They share same fuel supply "T", and I've seen these very corroded and almost clogged. Have you separated carbs 2 and 3 and checked the "T" for good passage? Also have you checked the filter screens under the float needle valves? Verified that you don't have a kink in the supply line for that pair. Are the Vent "T" lines clear, not clogged?
T.C.

[Ken Talbot]

Sure sounds like you're not getting any fuel to the right side for #3 and #4. Possibilities include:
- kinked fuel hose
- incorrect plumbing in all of that mess from the right side petcock through the octopus, and back to the carbs
- trying to test on the sidestand and all the fuel from your almost empty tank is sitting over on the left side
- indicator plate on petcock upside down or backwards or something so you've actually got that one tuurned off instead of on????

Have you tried setting the petcock for the problem side to prime?

With everything mounted, you can test fuel flow by yanking the hose off of the 3-4 fuel supply "T", and applying cvacuum to the octopus diaphragm.

[79XS11F]

Originally posted by TopCatGr58
Hey Rob,

Just reread this thread.

Well, there's only 3 things needed, air, fuel, fire. You're getting air! Your tests suggest missing fire. The PU coils are not bad, cause both coils are firing, #1 and 2 cylinders. The coils are probably not bad, again, cause firing 1 and 2 cylinders. You say they are new Accel, with new wires and non-resistor caps! Did you try swapping the wires/caps, just plugging #1 wire/cap onto #4 cylinder, same for 2 to 3, and see if the problem stays with 3-4? If so, then it's fuel, not spark! If it hops to 1 and 2, then something is wrong with the wires/caps!

As stated, 3 and 4 share same fuel supply lines. Both acting up makes me think outside the carbs. They share same fuel supply "T", and I've seen these very corroded and almost clogged. Have you separated carbs 2 and 3 and checked the "T" for good passage? Also have you checked the filter screens under the float needle valves? Verified that you don't have a kink in the supply line for that pair. Are the Vent "T" lines clear, not clogged?
T.C.

Hey TC ... I could not switch out the wires because the coils have their towers on the sides and the only way to fit them was with the towers facing outward so the wires don't fit for a switch out. I will buy some cheap auto wires and test that if I find nothing wrong with the carbs. I will check the Fuel supply "t" between #3 and 4 tomorrow.
Yes I did find and clean those little filter screens.
Where is the "vent T" you are referring to? OH fuel supply from the tank is good and no kinks in supply lines.
I'm just about ready to put pods on these carbs to make re & re easier and faster.
Rob

[79XS11F]

Originally posted by Ken Talbot
Sure sounds like you're not getting any fuel to the right side for #3 and #4. Possibilities include:
- kinked fuel hose
- incorrect plumbing in all of that mess from the right side petcock through the octopus, and back to the carbs
- trying to test on the sidestand and all the fuel from your almost empty tank is sitting over on the left side
- indicator plate on petcock upside down or backwards or something so you've actually got that one tuurned off instead of on????

Have you tried setting the petcock for the problem side to prime?

With everything mounted, you can test fuel flow by yanking the hose off of the 3-4 fuel supply "T", and applying cvacuum to the octopus diaphragm.

My fuel petcocks don't have an off. they are on, reserve or prime. No octopus involved. just a fuel line and a vac line. I always test in prime. I actually had the tank off earlier with with vac lines plugged and the tank on the bench beside the bike on prime with longer lines so I could fiddle around while the bike was running. fuel supply from the tank is GOOD to go

[skids]

Pull those plugs and see if they are fuel fouled.

[pggg]

If those 2 wires are blinking slowly and the other 2 blink fast, it's surely the electrics, the black box or it's wiring could be dodgy.

[79XS11F]

Originally posted by pggg
If those 2 wires are blinking slowly and the other 2 blink fast, it's surely the electrics, the black box or it's wiring could be dodgy.

Thats what one would think but with #3 and #4 having the issue .. well they don't share the electrical... they are on different coils? what are the chance of gets 2 black boxes with the same fault? anyone selling new after market black boxes. I really want this issue fixed once and for all.
Rob

[79XS11F]

Is this normal ... with the carbs on the bench upside down should I be able to blow through the upright tubes at the bracket of the carbs. This is the tube that goes through the gasket. I currently can not blow air through any of them. Also the floats on #3 and 4 are slightly lower then the ones on #1 and 2
Rob

[Ken Talbot]

Originally posted by 79XS11F


My fuel petcocks don't have an off. they are on, reserve or prime. No octopus involved.

Oops - my bad. I looked at your handle and profile and transposed the S from before the 11 to after, had me thinking you were riding an SF (special, with octopus, etc)

[TopCatGr58]

Rob, pull the choke/fuel enrichener lever and you should then be able to blow air/carb cleaner thru that tube! If your 3-4 floats are lower than 1-2 when it's upside down, then they are richer, which could possibly be flooding those cylinders, not allowing them to fire properly! Try setting them even with 1 and 2 . Hang in there, you'll get it!
T.C.

[Ken Talbot]

Originally posted by 79XS11F
Is this normal ... with the carbs on the bench upside down should I be able to blow through the upright tubes at the bracket of the carbs. This is the tube that goes through the gasket. I currently can not blow air through any of them. Also the floats on #3 and 4 are slightly lower then the ones on #1 and 2
Rob

Well, now we're getting somewhere. Yes, you should be able to blow through the brass tubes. They supply fuel to the enricher circuit. If you can't blow through them something is plugged, and it that is plugged, there's a very good chance something else is still plugged too. This means 'tripple clean'.

And the float level inconsistency - that is not good either. When you say 3 and 4 are a bit lower than 1 and 2, how much are you talking about? Also, do you mean they look lower while the carbs are sitting upside down, so in fact they would be sitting higher inside the float bowl when reassembley and right side up?