There’s a lot of ink and pixels spilled over these little devices, and most of the folks opining seem to have no experience with them — which makes them obvious experts! Then there’s the people that swear by these. We’ve got one in Albuquerque’s Royal Enfield community. I did some research and the basics are this: the booster plug fools the ECU into thinking it’s cooler than it is, getting the computer to kick more fuel into your mix. Pretty basic. There’s a lot of folks that then go on to sing the praises of this device, which apparently cures everything from rough idle to hair loss.

As mentioned in other posts, I’ve gone temporarily insane and had the bike hopped up seriously — S&S pipes, the high performance cam, 11:1 pistons in the 650 cylinders…and after scouring the interwebz I seem to be the only guy that’s done this and not gone big bore. I’m also a mile up, so there’s that. As a result, I’ve been having issues with hard starting and mild to moderate detonation under high throttle between 4500 rpm and up in 5th and 6th gear. Initially, there was a serious timing issue that we sorted, and the problem lessened with the “summer gas” here in New Mexico. (They stop putting the ethanol in the gas — so you get better gas mileage and performance.)That got me thinking that my 65-72mpg I’m getting on the 91 octane (the best we get here), I might be running way too lean.

We’re going with a Power Commander V to try and sort these issues, but we’re waiting on a slot to dyno my Interceptor out in Farmington (5-6 hours away…) What the hell? I thought; if this widget sorts being lean, let’s try it. So does it work?

First: TEC Bike USA was excellent to deal with. I explained the situation and they told me if it didn’t solve the issues to return it, no questions asked. I got here quickly, and I popped it in without issue. You simply take the seat off and there’s a big white connector right there. Pop it apart, stuff the leads from the Booster Plug in and shove the sensor somewhere out of the way. You’re done. If it doesn’t work, you can just as easily pull the plug and reconnect the original sensor.

She fired up easily and the idle did seem smoother. Around town, in the lower gears and rarely getting above 3500rpm, she was smooth and did seem to be pulling a bit more. No scientific, I know, but basically, it seems like there is a minor improvement in the fueling at the lower gears/RPMs. That’s not enough, however, to know if this was going to sort my issues, so I took the bike to the Sandia Crest road — a long twisting 10 miles that climbs 4000 feet from base to top. It’s perfect for putting a heavy load on a motor. On the ride out I noticed the bike seemed to be running a bit cooler, indicating she might be a bit closer to balance on the fuel and air.

What I found quickly was I was getting detonation at 3500rpm in 3rd and 4th gear under heavy throttle! She hadn’t done that since the initial modifications when she was way out fo time. I returned to the bottom of the crest and pulled the booster plug, then did the same run and about the same speed, snapping the throttle where I had, leaning on her hard in the same spots. No detonation in 3rd gear, and mild detonation in 4th and 5th gear at 4500 to 5000rpm, then it settled down. Two tries yielded the same results.

So what does that mean? Keep in mind, I’m not a mechanic, don’t play one on TV, and won’t claim to know a ton about motors, but… This does make me think that 1) yes, this enriches the fuel/air mix a bit, and 2) most of the effect is going to be low down in the power band. It didn’t sort my issues, but it was a handy diagnostic tool, as it now suggest that in addition to being lean, I’m still a bit off on the timing — something the new PCV can sort on both fronts.

Is the booster plug a replacement for a good fuel map and/or PCV on a heavily modified bike? Nope. Might this be useful for a stock bike running a bit lean? I think so, although at $125-175 (that’s what I’ve seen these go for), the price might be a bit too much for folks looking for real improvements in the bike’s operation. If you want a quick fix that isn’t too expensive (the PCV will set you back between $325 and 400, then if there’s no map for you, there’s a dyno run or the autotune module at about $500) for minor improvements, it might be worth a go.

So is it snake oil and useless? Provisionally, no. It depends on what you want out of it. It’s not going to turn your 45ish HP Enfield into a Ducati, but it might smooth out some minor foibles caused by manufacturers bowing down to Euro4/5 emissions requirements.