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Has anyone installed an S&S IST IGNITION on their twin cam? How well do they work? Sounds like a good set up if everything works ok. Thanks for all feedback.
 

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IronButt
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COst wise they are pricey, but from the little feed back I have gotten they seem towork. At least I have not heard back from the customer. The heat inthe summer here will really tell the story to see if they work.
 

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Good in theory and work well for many but the design has a listening device so to speak to detect detonation. On high performance motors there are things that can give that device false positives. I prefer to control the curve myself.
 

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I've been running the IST on my 04 FLHT 95" ,6H cams, HQ heads, Mik.42, and Rinehart TDs since a little after Sturgis last year. Have put on approx.1500 miles ,it takes a little while to learn what your motor needs but after that it works "super". I have no more worries if on my travels I can't get the " good juice" for a tank or so. I may not be able to get the max performance for the dyno sheet but it should be fine. I have used a IST on my 124" S&S chopper for a couple of years now with no issues what so ever. Just make sure your knock senser is mounted properly. TT
 

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Used the IST on my Turbo FLHT and had know problem with it. Figured the extra engine heat picked up by the temp sensor would cause performance to fall off. Made the same number as with DTT ignition. Rode the bike hard hard when air temps were high and never a hint of ping or performance fall off.

My S&S 124 came with IST with Guardian Software installed . The Guardian software is a minor pain to deal with due to controlling rev limit during break-in. Limits engine to 4200 rpm for the first 8 hours of operation and then 5200 rpm for the next 20 hours then goes to preset 6240 rpm limit. Standard IST does not do this and can have different rev limits programed in. The one I used on turbo bike came set at 7000 rpm and I had it re-programed by SnS to 6500. I believe the ones now are preset at 6240. They can be raised to 7200 rpm with guardian software.

When the IST was first released there were problems with the software and maybe even the hardware. I talked to SnS before buying my first one and was told to wait and not buy one until after 11/03. Did this but got old stock from Drag so I sent it back to SNS to update software. They didn't even bother to update it, sent me a brand new one instead. Be sure to follow installation instruction to a tee if you buy one and make sure the knock sensor can not come into contact with anything are ignition will retard and run like crap.

PS: I've heard report that they cause around a 4 HP peak HP lost compaired to standard type performance ignitions, but peak TQ is uneffected. Will be putting that to the test in near future. Even if it did I'd still run it on the street with the IST. The guy that repoted that still uses the IST when drag racing his street riddend 124" Dyna and first time out even with slipping clutch turned 10.3 1/4 mile times. By the way, he races professional and so does his wife.
 
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