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Tue Jul 08, 2014 12:08 pm

I always read that 009 mechanical advance distributers have a hesitation. Can anyone with a video or anything provide a better explanation of how bad the hesitation is. I want to compare it to mine. I run a stock 1600 built for off road use, Full flow external cooler 40 idf center mounted and more. I have always had a terrible hesitation. My question here is that All of everyone I ride with run mechanical advance 009's, and don't have this hesitation issue, and we run a plethora of different engine sizes all the way from 1600cc to 2500cc all with 009 mechanical.

My point here is I literally have to rev mine up to 1500 or 2000 rpm just to stop my motor from falling on its face and stalling, and that is just normal going to work driving. Stomp and go I don't even know what that is. :?

Does this sound more like Carburetor issues?

I have had one performance Engine guy look it over and he tuned my carb up but said my Idle circuits were constricted if not plugged, and that I would need a new carburetor. I don't know the guy very well and think he was just trying to sell me a carb. I mean the thing runs and drives but I just have this hesitation. How Valid does that explanation sound to my current situation. I just want to stomp and go. When I'm riding with my buddies I just want to be able to keep up!

Tue Jul 08, 2014 1:12 pm

What's the specs your 40 IDF ?

Venturies/Idles/Mains/Airs/Emulsion tubes....

Dan

Tue Jul 08, 2014 1:16 pm

What size jets and venturi do you have, you have to set them up difrent when used as a single. according to the CB carb book you should start with a 28mm vent 145 main jet, 150 air, F11 E tube and a 65 idle jet

Tue Jul 08, 2014 1:46 pm

earthquake wrote: What size jets and venturi do you have, you have to set them up difrent when used as a single. according to the CB carb book you should start with a 28mm vent 145 main jet, 150 air, F11 E tube and a 65 idle jet

I think general concensus is F7's with a single IDF.

65 idle sounds a bit fat...I'd start at a 50 and go up from there.

200 air also.

On my buggy I'm running a stock 1600 on a single 40 IDF @ 28 vents/160 main/200 air/ 55 idle. I modified my header for preheat and am running that as well.

Little to no hesitation on a 009/050 or svda..

Tue Jul 08, 2014 2:01 pm

danielzink wrote: What's the specs your 40 IDF ?

Venturies/Idles/Mains/Airs/Emulsion tubes....

Dan

I had help from John @ Aircooled.net picking out the jets but this is what I have.

120 mains
180 air correction
f7 emulsion
idle jets 50

28 Vewnturi's

Tue Jul 08, 2014 7:29 pm

Have you cleaned your idle jets lately? They plug up regularly.

Advance the timing a tad

I don think it's the distributer. I always heard about the flat spot in the 009s. I just got an 010 and now I recognize the difference . The 010 accelerates and the rpms increase at a steady rate. The 009 was not as steady of an rpm increase. I could really observe this as I have a long steep driveway and I could feel it under load at different gas on levels. Also cleared up a bunch of tuning variables I was having.

Tue Jul 08, 2014 9:00 pm

I was just going with what the CB perf Weber book says.
I have never ran a single IDF.

Casey

Wed Jul 09, 2014 9:21 am

all 009s are different. the springs and weights need to be tweaked.

Wed Jul 09, 2014 6:22 pm

dirtkeeper wrote: Have you cleaned your idle jets lately? They plug up regularly.

Advance the timing a tad

I don think it's the distributer. I always heard about the flat spot in the 009s. I just got an 010 and now I recognize the difference . The 010 accelerates and the rpms increase at a steady rate. The 009 was not as steady of an rpm increase. I could really observe this as I have a long steep driveway and I could feel it under load at different gas on levels. Also cleared up a bunch of tuning variables I was having.

I do clean them up regularly, I have had the help of numerous local experts so I going of a few suggestions they have said. Hopefully I can figure something out. I have two weddings two weeks in a row so I'm not gonna get to play with it for a few weeks other than driving it. but i will keep y'all informed to what I figure out.

Wed Jul 09, 2014 7:42 pm

The legendary 009 flat spot is due to using it with a carb that was intended to be used with a single or dual vacuum advance distributor, Like a 34PICT-3 with a DVDA.

I agree with the guys above that it is most likely a carb issue.

It could be a vacuum leak. A leak will provide a fair amount of air int the intake without matching fuel with the throttle closed at idle. Opening the throttle more reduces the vacuum and the percentage of air the leak allows in. With the engine idling, go around with a can of carb cleaner spray spraying near all mating surfaces and potential leak points. The engine will rev up a little if you find a leak with the spray.

And a clogged idle jet is NEVER a valid reason to buy a new Weber. Or any other carb for that matter. I would NOT recommend going back to that mechanic. Unless it's with a legal authority to discuss his sales methods.

Wed Jul 09, 2014 9:10 pm

dustymojave wrote: The legendary 009 flat spot is due to using it with a carb that was intended to be used with a single or dual vacuum advance distributor, Like a 34PICT-3 with a DVDA.

I agree with the guys above that it is most likely a carb issue.

It could be a vacuum leak. A leak will provide a fair amount of air int the intake without matching fuel with the throttle closed at idle. Opening the throttle more reduces the vacuum and the percentage of air the leak allows in. With the engine idling, go around with a can of carb cleaner spray spraying near all mating surfaces and potential leak points. The engine will rev up a little if you find a leak with the spray.

And a clogged idle jet is NEVER a valid reason to buy a new Weber. Or any other carb for that matter. I would NOT recommend going back to that mechanic. Unless it's with a legal authority to discuss his sales methods.

I appreciate the advice!

I have tried checking for vacuum leaks with described method and have found none. :cry: I wish this was the problem as it would be an easy fix.

Also he didn't say my idle jets were clogged in fact they were all new at that point and he is the the one that resized them so the carb would run better.

What he was saying is that the idle circuits are constricted this is the path that your fuel runs threw the carb to deliver fuel to the Venturi while it is idling. His theory was that when I step on the gas going to full throttle that because the circuit is constricted that it is not able to deliver fuel fast enough and bogs the motor down because the carb is transitioning from the idle jets to the main jets. Without the idle jets being able to supply a sufficient amount of fuel to do the transition properly the motor doesn't get enough fuel and bogs down.

The idle circuits are not accessible on the carburetor and it take some matching to clean it up. That's why a new carb was suggested. He said to pay someone to do the machining and cleaning I would have about as much into it as it would cost to get a newer one thats not clogged.

I am just looking at every option before I write this carburetor off.

Thank you all for your input.

Sat Jul 12, 2014 1:59 am

When the idle jets become clogged, the engine will respond with popping or backfiring at the carbs (not the tailpipe). Loss of power from off idle to 2200 rpm occurs with a partial clog, such as a piece of lint stuck in the idle jet. You may be getting pieces of the air filter gauze or tiny specs of dirt passing through the filter or between the filter sealing surfaces.
Here's another viewpoint;
I rebuild the 009 distributors. The flat spot is in the distributor's mechanism and occurs when the lighter of the two flyweights has swung outward and maxxed its travel...the timing is at a standstill...until the secondary (heavier) flyweight overcomes the spring tension and begins to swing outward. On a Brazil 009 with a date code of June '84 I recently tested; The primary weight advances the timing from 0* to 3.5* (0* to 7* at the crankshaft). The advance usually begins at 1125rpm and will reach 1420rpm, with the timing in a holding pattern at 7*. From 1420rpm all the way to 1875rpm, the timing will NOT increase at all. At 1880rpm, the secondary weight begins to advance the timing from 4*(8* at the crank). It will advance as the engine increases speed until 2544rpm. Timing will be at 10.5*(21* at the crank). Any speed above 2544rpm will not affect the timing as both weights are pegged against their stops.
The bottom line is that the timing is freeze-framed from 1420rpm until 1875 rpm. 455rpm increase with no increase in timing. And it occurs when it is needed; pulling out of an intersection in 1st gear.
Here's a kicker; I tested a perfect condition 010 and a good 019 on my Sun 504 Tester. They both have a flat spot. Tested them on my engine and found out the flat spot is detectable.
I'll post more results if you are interested...
Aloha!

Sat Aug 02, 2014 5:51 pm

Not trying to steal a post but cb says for single carbs to drill a 2mm hole in the throttle plate anybody agree with this

Sun Aug 03, 2014 12:01 pm

Timwest007 wrote: Not trying to steal a post but cb says for single carbs to drill a 2mm hole in the throttle plate anybody agree with this

I am curious about this as well!!

Sun Aug 03, 2014 3:36 pm

Another little trick that helps with off idle stumble is closing the hole on the accelerator pump check valve that bleeds off fuel from the squirters. Number 13 in the diagram is the check valve located at the bottom of the fuel bowl. There is a small hole in the side visible in the pic, just remove it from the carb and peen the hole shut with a small punch and then reinstall it. The problem I have found with webers that hesitate is too much air and not enough fuel off idle, and this helps with that.

Also make sure that the spring on the accelerator pump rod is strong enough to push the pump arm without collapsing. I have installed washers between the spring and the pump arm to stiffen the spring and give it a better squirt off idle.

Sun Aug 03, 2014 4:00 pm

Most of the stumble is due to center mounted carbs without preheat. Fuel collects in the runner and is not fully atomized when it reaches the heads.

If you run dual carbs, like DLRA, IDF or IDA), you will not have that stumble.

While I dislike the 009 and prefer the 019 or 010 (depending on the application) the 009 will work just fine with dual carbs.