Explosion at start up with Dynatech

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Dec 9, 2010 | 02:39 AM

Javieret

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From: Valencia, Spain

Explosion at start up with Dynatech

Hi everybody.

I've just installed a Dynatech 2000i single fire ignition module in my 99 Softail and I've adjusted the timing as it says in the instructions (static timing with the led of the module) and now I almost always have a big explosion through the exhaust when I start up the bike. It's just one and only explosion.

The ignition kit uses a Single Fire coil that was installed with the module and the only thing that wasn't replaced were the plug wires, which are the stock ones.

What do you think? Can be the explosion produced by a bad static timing or can be produced by the plug wires or what else could I look at?

Thanks a lot,

Javi

Dec 9, 2010 | 08:47 AM

KBFXDLI

Big Kahuna HDF Member

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From: USA

I would be looking at fuel & timing

Dec 13, 2010 | 01:20 AM

Javieret

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From: Valencia, Spain

Do you think that the bike runs rich and this is the cause of the explosion at startup? I suppose that if the mixture was right there won't be any gas residue when you turn off the bike, isn't it?

Dec 13, 2010 | 02:33 PM

MCSarge

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From: Michigan

When you say explosion do you mean backfire thru the pipes. If so check you timing, you may have to much advance dialed in. Also check to make sure your float isn't sticking and filling the cylinders up with fuel while it sets. How does it run after it starts, hiccups? stumbling? does it rev smoothly or seems like it stutters?

Dec 14, 2010 | 02:32 AM

Javieret

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From: Valencia, Spain

Quote:

Originally Posted by MCSarge

First of all, thanks for your answer. When I say explosion, I mean a big backfire (just one) at the moment that I push the start button and just when the bike has been sitting for some hours.

The bike has a Mikuni HSR42 in it and V&H short shots and I think that it goes fine. I replaced the ignition because I the cam sensor was almost burned and since then I've noticed less backfiring when the bike is running, but I have the problem of the big backfire at startup.

How could I see if the float is filling the cylinders whet the bike is stopped?

Dec 14, 2010 | 07:56 PM

MCSarge

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From: Michigan

Take the air cleaner of and look down the carb throat and see if you see any gas bubbling out of the carb after you shut off the bike.

Some common causes of backfiring in the exhaust:

Ignition:

If exhaust system popping is very loud, irregular and accompanied by loss of power, then you should suspect that the ignition system is not performing as it should. If, for some reason, the ignition sometimes fires at the wrong time, then exhaust popping can become very energetic (loud). Look for failing high tension leads (plug wires), failing ignition coil(s) and especially switches or connectors as possible causes.

Last edited by MCSarge; Dec 14, 2010 at 07:58 PM.