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Discussion Starter · #1 ·
Hi All

I am hoping someone has an answer. I have a 350 SB (one speed auto)w/ some engine mods. Over the winter I did some changes to the bike -new larger radiator - rebuilt trans - rebuilt the carb - HEI Dist. (new weights, 50,000 volt coil, new module, changed springs, adjustable vacuum advance) - New Holley red pump. I have everything working satisfactorily except when I go to WOT the bike bogs, then kicks in at takes off. I can roll the throttle slowly and the secondaries come on and don't bogs. I have rechecked the timing, and don't think that is the problem. The carb was done by a local speed shop and should be assembled properly (although I reinstalled it on the bike and set the adjustments).

Could someone give me some direction as to what to look fore. Because I made so many changes it could be a number of things.

Thank you in advance
Dean
 

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Couldn't say for sure from such little info, but I can tell you about a similiar situation I had once that was all because of the sudden opening of the secondaries creating a lag before the fuel started to flow in. Soon as the vaccuum got the fuel flowing it was fine but at first opening it would lean out. There is a fix for that by filing notches in the butterfies above the secondaries if that is what it is. I am sure someone here can tell you more about that if it turns out to be on track. Good luck...
 

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Hi Dean, Sounds to me like the secondarys are opening too fast.

The wind-up spring should be set at 3/4 to 1 full turn from zero tension.

Also make sure the vacuum pod is working right with the rod connected to the upper air valves. If the vacuum pod is opening in the 1.25-1.5 second range it has got to be the float level.

I could continue with more causes of the bog. But these are what I would start with.

Also would be good to know how much fuel pressure your running.

If you would like give me a call. 814-868-0170
 

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It sure sounds like the secondaries are opening too fast. Turn down that spring 1/8th turn and try again. Keep doing it until the bog stops. I'm sure this is the problem./..Joe
 

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Dean,
I had the same problem. It presents itself as either the spring tension on the secondaries or the acc. pump on the carb. On mine did the same but I had the braided steel ign. wires. They looked good but were "bleeding" off voltage and you couldn't even tell looking at it in the dark. Changed wires at the factories recommendation and worked perfectly. I have never used the braided wires again. I have also heard of people having the same issue with the long chrome wire holders.
Glenn
 

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Glenn Boglisch said:
Dean,
I had the same problem. It presents itself as either the spring tension on the secondaries or the acc. pump on the carb. On mine did the same but I had the braided steel ign. wires. They looked good but were "bleeding" off voltage and you couldn't even tell looking at it in the dark. Changed wires at the factories recommendation and worked perfectly. I have never used the braided wires again. I have also heard of people having the same issue with the long chrome wire holders.
Glenn
Glenn, now you got me thinkin. I'll start at the beginning and maybe someone has a solution.

My SB 385 was new last summer and it worked great, no bog at all. Then, of course it sat all winter until I sent it to Daytona for Bike Week. I had Twyla on the back most of the time and she starts hammering her fist on my back when I hit the secondaries, so I behaved. Then at Key Largo, I had a chance to ride without her for a few minutes and I nailed it. Instead of it launching, it backfired up through the carb, hesitated for a split second and then launched. :shock:

When I got home, I printed off Carburetor Mike's paper and took it too a mechanic buddy here. He understood everything that Mike wrote and set it up exactly as per Mike's direction, including the notches, roughing up the butterflies, all of it. He set the spring tension at 1 complete turn.

It still has the backfire up through the carb but not quite as bad as Key Largo. If I roll into it, no problem, but a quick snap will pop and then go.

I still have the factory spark plugs and wires and about 39,000 KM on her now.

Any ideas :?: :?:

Bryan
 

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I wonder if you have a problem with your accelerator pump plunger or your choke closing slightly when you grab a whole handful of throttle quickly. Just a thought .

Jack
 

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Jack,

He installed a new accelerator pump, fuel filter, and I put on a manual choke as well, in fact just like the way you did yours. 8) I also have a K&N filter with the X-Treme flow top. We really can't see where we overlooked anything. The carb works perfect otherwise. It runs leaner now, very crisp, the mileage has the potential to be better, but only if I stay off the secondaries.

When Glenn mentioned wires..............????

Bryan
 

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Discussion Starter · #9 ·
Engine "Bogs" with WOT

Bryan

I changed my wires today and it made a difference. I had a set made for my bike. Carb. Mike said to give him a call (which I will do next), but I wanted to change the wires first. I also changed to an K&N, but I don't think that has anything to do with the problem. I will post the results when I make the settings per Carb. Mike's instructions.

Dean
 

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It just seems strange that it worked great before you put it up for the winter .

This has nothing to do with your problem but
Here's a story about what happened to a buddy of mine with his Harley . One winter a while back , he decided to get his bike painted . So he sent all the parts to the painter . When the paint job was finished he put the bike together and every now and then it would seem to run out of gas even though the tank was full. Then it would start up and run fine for a while and a couple of days later he'd be riding along a it would act like it ran out of gas again and again he had plenty of gas in the tank . This went on for about a month and he couldn't find anything wrong . So finally he took a flash light and looked down into the gas tank and he could see something floating around in the gas and it looked like the picture of a motorcycle . He fished it out with a set of long tweezers and it was a full page out of Easy Rider mag . with a picture of what he wanted his paint job to look like that was stuck in the gas tank bung when he sent the tank to the painter . Seems it got pushed down into the tank by accident and was floating over the petcock screen every now and the and shuting off the flow of gas to the carb. Has run great ever since . He dried out that page and framed it .

Jack
 

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Jack,

Your buddy has a good attitude and a sense of humour. Most people would have burned the paper while it was still wet. :evil: :roll:

I'm leaning toward some new wires. It seems like it's not burning all that gas when I nail it. I don't think it's a fuel / carb problem, but I'm starting to think ignition. I'll check the fuel pressure this weekend and let ya'll know.

Bryan
 

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Re: Engine "Bogs" with WOT

Dean said:
Bryan

I changed my wires today and it made a difference. I had a set made for my bike. Carb. Mike said to give him a call (which I will do next), but I wanted to change the wires first. I also changed to an K&N, but I don't think that has anything to do with the problem. I will post the results when I make the settings per Carb. Mike's instructions.

Dean
Thanks Dean!!
 

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Bryan ,

I bought the plug wires that Tim Siron has made up for the Boss and I'll tell you they are top notch . He told me that they had a stock Boss on the dyno and did nothing but change the stock wires to his wires and I think he said it picked up 2-4 more horsepower . I know there are others that can attest to what top quality wires they are . Not cheap , but top quality

Jack
 

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Jack,

Any idea about the brand, numbers etc. on the wires? I'm sure I could get them around here if I knew exactly what they were.

Bryan
 

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Bryan ,

I don't think you can buy these wires . He had them made with a weather resistant sheild over the outside of the wires , heat reisitant plug connectors etc. Best thing would be for you to call him and let him discribe them to you . He's a great guy and will talk to you personally . Like I said the are the best I've seen but I'm not a expert , there my be as good or even better out there but I'm very satisfied . timsironbosshoss.com I think .


Jack
 

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Bryan....Jack is correct. Tim Siron's wires are fantastic. I have a set and put them on just because. Turns out I found many abraided areas on my 5 year old wires and was glad I did. Just call him and you'll have them in a few days. He's a great guy. The wires are all numbered and the connections are very secure on both ends and give you that nice "snap" when connected. The wires also have a high temp protective sleeve around them which makes them a tight fit in the wire looms and don't move.....Joe
PS. Get em'..you'll love em'
www.boss-hoss.com
 

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I was wondering why my ears were ringing this afternoon. Now I know why!

It take's more than carburetion to make them run right.

Another thing to remember is how hot the fuel gets sitting in the carb.

If you run a long time nice and easy in the heat, don't expect the engine to perform flawless when you nail it. You'll need to rev that boiling fuel out of the carb first. Once you've gotten cooler fuel in there it should then run the right way.

Just something else to be aware of.
 

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Mike,

Yes, I knew about the fuel temperature, etc. and she still falters on cold fuel. So I'll check out a few things this weekend: fuel pressure, wires, timing, plugs and see what happens. I don't want to touch the carb because I don't really feel that's the problem.

Joe,

I phoned and left a message for Tim Siron. Sounds like he was busy selling a new Boss to somebody :)

Bryan
 

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Wires

Bryan;

I agree with Jack and Joe on getting wires fitted for the Boss. I got a set of really nice "Taylers" from Ecklers Corvette (just up the road from me), and they would have been wonderful, if they would have fit correctly.

I didn't want a "clip on end" kit and thought they would know the correct fittment WRONG!

I still have to get a couple longer ones for my Boss, good reccomendations to stay with someone who knows Boss' for some things! (IMHO)

RIDE SAFE!
HAWK88
Jack Phillips
 
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