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Discussion starter · #22 ·
Per the Haynes manual "To reduce the amount of unburned hydrocarbons released in the exhaust gases, a secondary air injection system is fitted. The system consists of the control valve (mounted behind the right side cover), the reed valves (fitted in each cylinder head) and the hoses linking them. The control valve is actuated electronically by the ECU. Under normal operating conditions the control valve is open allowing filtered air to be drawn through the reed valves and cylinder head passages and into the exhaust ports. The air mixes with the exhaust gases, causing any unburned particles of fuel in the mixture to be burnt in the exhaust port/pipes. This process changes a considerable amount of hydrocarbons and carbon monoxide into relatively harmless carbon dioxide and water. The reed valves are fitted to prevent the flow of exhaust gases back through the control valve and into the air filter housing."

All that to say, the little solenoid draws filtered air from the air box and sends it into both cylinder head exhaust ports. This usually happens at higher RPMs and its really just a little puff. Since we're running quite unrestricted now, this extra air into the exhaust causes the popping. We cannot unplug the solenoid without throwing a CEL on the dash, so I opted to just cap my hoses from the cylinder heads and the outlets from the solenoid valve. I opted to keep my inlet from the air box connected to try and prolong the life of the valve.

Remove the right side cover
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It's a lot easier to do this by unscrewing the two bolts and taking the unit out. You can see here where I removed the left and right side hoses, capped the valve sides and then the hoses as well. They're stuffed back in there, not going anywhere, its pretty cramped.
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In this view you can see I left the air box hose still connected, I figured since the unit will still actuate, might as well be drawing in clean air. You can also see I drilled a small hole into the ends of both rubber valve caps to relieve some of the air pressure from the still functioning valve.
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I went to two auto parts stores trying to find the right hose caps. I didn't find what I was looking for (not sure what that was anyways) ended up buying this small $8 assorted package of hose by-passes and they actually worked really nicely to cap the hoses and the valve ports. The hose caps fit nice and tight but I did put a little smear of gasket maker around the hose ends to ensure they stay sealed up. If they're not sealed you'll know as your popping with be 10X more exaggerated, as was the case when I ran the bike with the hoses totally unplugged just to see what the condition would sound like.

If you have any loose joints in your exhaust system you'll still get a lot of popping so be sure and check it all for a nice tight fit. Hope this works for you guys, if not its easy to put it all back together like nothing ever happened.
 
That’s a bummer, I’m about to send mine out. I was talking to David at Rexxer about the popping on decel (not sure if you have that issue or not). But wanted to know if the re-flash would help and he said not really. It has more to do with the Secondary Air Injection system still compensating for the non-existent catalytic converter.
Thanks for the fantastic & descriptive write up of what you did!

When you were talking to David, were any potential negatives discussed beyond the annoying noise? Will leaving the system as is and dealing with the popping have any long term negative affects? will plugging the system like you did benefit the overall operation or performance?

...if any of that was discussed
 
Discussion starter · #24 ·
Yeah sure thing. When we talked he said its something everyone should do regardless of a re-flash. Once the cat is removed this SAI system is pretty much useless. He didn't say anything about it affecting long term performance. It was brought up when I asked him about leaving my o2 sensors installed post flash, as I am opting to disable them. This is what he said, kind of cryptic.

"On EU4/5 bikes we use the O2 for adaptation. It’s a smarter processor and allows for best drivability and fuel economy in varied riding styles. They stay in place and connected. SAI should be blocked as well as the evap canister vacuum line. This prevents decel popping."

I said:

"Do you mean I should do this before the re-flash? If so, do I disconnect the hoses from the control valve between the engine and evap canister?" (me not understanding the DDS SAI system yet, still not sure how the evap can plays into our set up if at all yet)

David:

"Regardless of the flash you should do this. You can get block off plates for the heads or put a marble in the hoses. whichever works for you. "
 
Discussion starter · #26 ·
Got my ECU back. The lean condition is definitely gone, bike pulls smooth and it's not hard to get the front to lift. On start up my dash reads EVO1, I thought it was going to say RACE but I read the remap for the Termi hi-pipe reads EVO1 and the low slip on Termi will read RACE. I'm not really sure.

My cold start seems somewhat sluggish. It might stall and require me to start it again. David thought the ECU may have lost memory and to "take it for a good ride and all will be back to normal". That may be true cant really tell yet. I did take it for a 30min ride with no issues. I tried the old car trick where you let it idle for 10-15 min to let the ECU re-learn after having the battery out for some time. Seems the same to me, but also a condition of richer mixture.

Over all fairly satisfied but wonder if I'll end up taking it to the dealer for the Termi map. Going to put the bike through its paces this weekend and see how it does.
 
Good to hear, mine is still scheduled out a few weeks but will report back - one data point I can give is my hypermotard (2017) with the high mount termignoni and associated map worked a bit like you are experiencing on cold starts, sometimes would stall after a few seconds and need a retry, if it sat a week or 2 might need 3 tries to sit and idle but ran great otherwise.
 
Discussion starter · #28 ·
Ah, thats reassuring, thank you. Based on my experience, with carbs anyways, thats just a symptom of a richer mixture. Which we would rather over the leaned out situation anyways. Looking forward to hearing about your results.
 
Ok got mine done yesterday, interestingly the bike had sat for a week and it was a bit cooler, not cold like 65-70 and my cold start took 3 tries before it idled (this is before flashing it). Bike was flashed by the dealer now reads evo1 like yours with the himount flash. Pulls a bit harder, almost no pops on decel now, I didn't feel too much of a flat spot before coming from testastretta bikes (3 in a row) which barely run at 4k rpm and surge like crazy the scambler was way better stock but flash improved things. Mostly was a highway ride so need to get out and around where I normally ride to report any more feel (if it stops raining!)
 
Discussion starter · #30 ·
Nice, sounds like we're sitting about the same all in all. One other thing David at Rexxer had me do was plug the smaller vacuum hose coming from the intake manifold into the charcoal canister (left the tank vent alone). This really got my idle to improve, he said with all the changes I had made with the tune and whatnot that "The check valves in these things go bad and it sucks raw fuel when you close the throttle plates". Not sure if it was a placebo or what but the bike now feels like it has the tune I was after, no more stumbling idle or stalling.
 
Nice, sounds like we're sitting about the same all in all. One other thing David at Rexxer had me do was plug the smaller vacuum hose coming from the intake manifold into the charcoal canister (left the tank vent alone). This really got my idle to improve, he said with all the changes I had made with the tune and whatnot that "The check valves in these things go bad and it sucks raw fuel when you close the throttle plates". Not sure if it was a placebo or what but the bike now feels like it has the tune I was after, no more stumbling idle or stalling.
Thanks I will try that and was also thinking of doing the SAI delete which I have left alone thus far.
 
Discussion starter · #32 ·
I still get some popping even after the SAI delete and I checked my piping for leaks, found none. Part of me wonders if everything is snake oil, unfortunately I have a problem and can't leave anything I own stock or unfucked with.
 
With the weather cooling down, I started to notice the bike running pretty shitty after a cold start; sputtering and popping more than when it was warmer. So, I decided to finally omit the SAI system; instead of plugging the hoses, I removed them and called the ports at the heads. I did plug the intake hose though, and left the 3 ports on the valve open (didn't really see a need to cap them).

Start up was better and it definitely ran smoother from a cold start up; the sputtering I had experienced was gone.
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