We all want the AH HA moment and then everything is right with the world....


I've always USUALLY found that it's something SUPER SIMPLE that only makes sense after it's accidentally discovered. In the mean time --- SO F'N FRUSTRATING!:thumbsup:

FYI Greg, that weatherpak connector is stock for MSD distributors.

http://www.hawaiiracing.com/shop_ima...e9e77f69a1.jpg

I KNOW!!!!


http://d26ya5yqg8yyvs.cloudfront.net/kboom.gif

Not on all of 'em - on some maybe -- like the "ready to run" -- but for years the MSD distributors have come standard with a two wire non weather pack (in fact a crappy little piece) connector.

I've been clipping them off and switching over to the weather pack style because it's such a superior connector.

Even the MSD boxes have the trigger wires (black with violet and black with green) pre-wired with the "other half" of the crappy little connector.


Not arguing here -- just sayin'

The carb could have an internal vacuum leak, although I do not know how to check that.(I had symptoms similar to this on my boat)

Also, are the valve adjust on this any harder than the KTM's?

Mike

The vacuum guage reading was similar during the symptoms 10"-11" not sure if a vacuum leak that's enough to create these problems would be detectable on the guage.

I guess I could spray it down with starting fluid while running but I'm a little gun-shy about fires right now! :D

I'm getting ready to go through the tach wiring to verify the power and ground points. That has been haunting me so it's time to eliminate it.

KTM valve adjustments on the LC8 and RC8 are a little more complicated but not once you access the valve covers since they use shims. :unibrow:

It takes a while to get to this point and the covers are still not removable!
http://sieg.smugmug.com/Motorcycles/...IMGP4485-L.jpg

My '83 750 & '84 500 Honda V-Four Interceptor motors were a breeze as were the XR500's.

Your suggestion to spray around the vacuum ports is a good one. Also, if you basically have the blades closed, what happens if you hold your hands over the carb to prevent most of the air from going through? If is still runs, air is getting in from somewhere else...

I can't tell from your picture, but are there vacuum hoses coming off the carb? If so can you just remove them and plug everything to rule out as much as you can there?

Another place that air can be pulled in is through the intake manifold gasket if it wasn't sealed well down in the valley area. Hard to tell with it all installed though.

I'm not very knowledgeable on distributors, but is it possible for you to completely lock the advance in some way to at least eliminate advance from the equation as you are trying to adjust the carb?

And time to ask the simplest of questions. Since it's running ok, I doubt this is a problem, but... You have double and triple checked the plug wires are ordered correctly, right?

And one more I can think of... When you pulled the distributor, everything looked ok with the gear, correct? I know a car which I had in the past started showing erratic timing when the gear was being eaten alive by the cam shaft due to using the wrong gear... :\

Just brainstorming as I type. Not sure much is helpful, but looking for outside the box ideas... Good luck!

As weak as it feels at idle I'd guess covering it would kill it quick. But haven't tried it.
No vac ports on this carb.
Motor is fresh, intake sealed with The Right Stuff and Edelbrock gaskets.
Mechanical advance is pretty simple and with the firmer springs installed with no change in symptoms I don't think that's it.
Plug wires are right:
http://photos.smugmug.com/photos/i-z...-zqJSBbX-M.jpg

Distributor gear looks like this:
http://photos.smugmug.com/photos/i-F...-Fz48qqq-M.jpg

Appreciate the brainstorming............like Greg said, it will most likely be something stupid simple and I'll feel stupid.............again. :D

I did trace the tach wiring and it's grounded to the instrument panel ground. The MSD is pretty sensitive to ground so I'm going to run it to a dedicate engine ground just to be sure. Though previously it was working with this wiring configuration.

are you getting idle signal from the secondary bores?

Cut your losses and trade it for a used SB2.

Fuel screws and throttle shaft idle screw impact idle, secondary throttle shaft adjustment seems more sensitive than primary.

When it was fired after running the valves yesterday it's feels normal above 2K rpm, between 1-2K is where it's weak and vague. While getting it up to temp when it would go below 1K heading to a stall, pumping the pedal lightly to catch it resulted in a backfire and little carb fire. That's leading me to think it "could be electrical, somewhat similar trait to the weak distributor ground.

After reading MSD's troubleshooting list http://www.msdignition.com/troubleshooting.aspx I'm going to check the magnetic pickup value and verify conditions listed in timing fluctuations, and improve tach ground or just eliminate the tach right now.

My SnapOn Timing light pick up clamp isn't directional but I'll experiment with flipping it just because.

:thumbsup:

Skip - That would be great as the conservative rebuild after the fire was done knowing this is not my ideal motor. LSx or dry sump LS7 would be nice
but since I'm currently unemployed for the first time in 36 years it would be a tough sell on the wife. :D

Just kiddin' Sieg. :D

It was just a friendly shot across the bow at our friend Flash68. :unibrow:

Hey I wasn't defending just clarifying conditions..........I like your intent :rofl:

. Don't dismiss a carb tuning issue. I'm leaning in that direction.

Agreed, it's going back on the bench for inspection. :thumbsup:

Sieg, didn't you put a new carb on with this new setup? What was wrong with the old carb? What size carb is it your running now and what was the old carb size?

The old 650 Demon was BBQ'd. Holley 650 Ultra HP now.

http://photos.smugmug.com/photos/i-b...-bZLQm2X-M.jpg

That's a well done carb right there.

You changed the carb along with the cam? from your original setup, which I assume was running well? Correct? You're still running the same, but new ignition system?

If the cam was changed, any chance the timing chain wasn't correctly aligned? Was it degreed?

Same cam grind, new MSD Ready to Run kit.

Gear drive. The issue is below 2K'ish rpm. I pulled the carb and set the transfer slot exposure and nothing else..........It's coming off again for a thorough once over, base plate seal, bowls, and metering blocks inspection, and blow out the passages.

Sieg,

I can ask a troubleshooter to stop by your place and have a look.


One question-is the airport closest to you big enough to handle 'Weld One' landing there? ;)

That's an easy question.....................NO!

If it's a C-130 deviation YES!

Went through the tach wiring and altered the light and ground sources, and to make Greg happy my engine ground strap that was back-ordered finally came in. :D

http://photos.smugmug.com/photos/i-H...-H9Bpwbd-L.jpg

Haven't fired it yet, but the needle response on the tach has change when switching the key to the on position. Just made it to 32* and I'm in no hurry to open the garage to fire it. :D

If the cleaned up wiring makes no change........off with the carb!

You know why they call doing electricity "making a circuit" -- cause the positive side also travels thru the negative side... :unibrow:


I don't think this is the "solution" --- but it certainly won't hurt anything.


BTW -- 32*'s REALLY? And you're whining about that?!?! Come over to Sun Valley.... it's 21* right now (5:00 PM) and will be -2* tonight.

But it sure is pretty!! Thus the "SUN Valley" :D

Baldy -- from our parking lot this morning!


http://i919.photobucket.com/albums/a...ley/file-1.jpg

Har-de-har-har

It probably won't but it's PITA detail work that needed to be done. :yes:

Yes I am whinning, I was out in it for 4+ hours today...........that resulted in serious shrinkage.

Enough with the pics of storage buildings and baldy top, I want to see one of you in your snow bunny costume. :unibrow:

http://photos.smugmug.com/photos/i-p...-p8WmgMN-M.jpg

Pulled the carb apart and blew everything out to make sure all passages were clear and double checked all settings. Re-installed and fired it, similar results. I DID NOT pull the fuel screws previously so I pulled then and blew the passages out. Reinstalled the screws at 2 turns out vs 1.5-6 and fired it and it still felt a little hollow off idle......went to 2.5 and conditions improved, still stumbled a bit with quick off idle input, took the .017" slack out of the primary accel pump and bingo it's close. Checked the initial timing and bumped it to 12* with no floating problem.

:bang:

Lean condition caused the erratic timing? Fuel screw passage partially blocked? Symptoms compounded by considerable temperature drop and air density increase? Either way it appears I have a drive-able baseline to tune from. Feel like an idiot but I'm getting used to it......to honor the fact Jody gave me my own special smiley. :sieg:

X2. :thumbsup:

It's certainly no fun for you, but a little tech during the middle of winter is good for us restless natives here. :D

You know I didn't think about how the cold and dense air could excasperate the problem.... My car runs like crap below 40....

I'll sleep a little better tonight! :thumbsup:

It's all good, anytime I'm wrenching it's a good thing and the shop is warm. What ticks me off is my trouble shooting and experimentation. Either there was debris in that carb or I didn't richen the fuel screws enough. Holley specs 3/4 turn out as starting point but doesn't give a desired final range. Most of my tuning has been on bikes 1-1 3/4 turns and the old Demon carb was 1/2-3/4 out. So 2.5 turns is extreme to what I'm accustom to and the idle by-pass adds another unfamiliar variable. It appears the learning curve will never end, so I'll never be bored. :lol:

Turned out that much seems extreme -- and I wonder if that's a bandaid - but I'm not familiar with that carb. Might be worth a call to their tech in the morning??

I plan on emailing the tech I have a relationship after a little more experimenting. This carb appears to be pretty sensitive to input which is great once you figure out how sensitive it is. I should be able to alter the fuel screw range with the idle air bleed jets so no biggy.

The recommend 7 psi fuel pressure with 5 psi min, I thinking a new fuel pump that delivers 7 psi might be advisable as well since mine is 6 psi max. So do I go with electric or mechanical?

For years - 5 was max on a Holley... I think 6psi is fine and wouldn't touch it.

This is really where you need a chassis dyno - because the only way you're going to know if it's going lean do to low fuel pressure (I doubt it is) would be
with the numbers you'd get.

I have a guy up in Kirkland -- Alex at Carb Connection -- that has a chassis dyno and is a master around a carb. He's amazing really. Maybe that should be a Weld/Sieg road trip in the rig.

I've always went by the 5 psi guideline - The Ultra HP is spec'd for 7.5 psi max.

:confused59: :excited:

I have to get GNRS behind me first... and am hauling a Range Rover down for a buddy -- and bringing back another hot rod for another buddy... but it would be an easy run to Eugene and back... and the trailer is enclosed so winter worries don't count. We'll talk.:idea: :thumbsup:

Right -- but 7.5 psi would be appropriate to keep a high winding race car from leaning out. Not saying that you're motor isn't exceptional in every way.... :bitchslap:

Greg,

IIRC you hauled bro-outlaws' red Camaro around, now you're planning to grab this orange creamsicle thing Sieg's got. So after that, if this rainbow trend follows it's gonna be another '69 Camaro, a yellow one.

Hmmm....



:lol:

Charley won't even let me in the same building as Jackass.