Triumph Rat Motorcycle Forums banner

Scrambler exhaust and tuning questions.

12K views 8 replies 6 participants last post by  NumberthreeScrambler  
#1 ·
Greetings fellow motorcycle fanatics,

So, after owning my new scrambler for a few months and coming to the conclusion that I wanted to be able to make it sound like something other than a sewing machine I decided to do something to make it louder. After about a month of research I found that one of the best kept secrets (and most economical) was that sock VW type-1 exhaust tips will fit perfectly on the stock Scrambler header pipes.

Now cut to me installing the pipes and calling a local dealership to schedule a EFI re-tune just as you would on say, a Harley Davidson.

Upon speaking to who I assumed was a Harley Davidson/Triumph service technician, he initially agreed with me and told me that a remap was needed. He then asked me if the new pipes were for sound or performance. I said sound. He then told me that a remap would do absolutely nothing to correct the lean mixture the bike was now running and that an air box removal kit, aftermarket filters, and a variety of other modifications were necessary to get the bike to run right with a simple pair or "tweeter" pipes attached.

So, what is the general opinion you guys have about this? I was under the assumption that a richer mixture would presumably remedy the problem. Are there a specific set of modifications that must be installed for these pipes to work with the fuel injection properly? Or is it simply install the pipes, get a remap program from someone like Triumph Twin Power, and make the mixture richer.

Engine-wise, my bike is completely stock. Sorry for the textbook sized question. Thought I would just lay as much info out about my situation as possible.

Thanks for your consideration,
Alan
 

Attachments

#2 ·
IMHO if all you've done is change the stock units for the VW end pipes you shouldn't need a retune. You need to retune and increase the fuel injection rates to match an increased air flow, but most of the air restriction on a stock machine is in the intake system, (air-box baffle, stock filter and snorkel), plus the restriction of the O2 sensor units in the header pipes. If they're all still in place there will be little or no increase in air flow with the new end pipes so you should be fine.

I wouldn't worry about it, if you decide to go further and remove all of the above you will need a retune and will gain an increase in power at the top end of the rev range but you may well be happy as it is.
 
#3 ·
That was my idea as well. I've heard all about how plugged up the stock intake and exhaust systems are with the O2 sensors and all the air-box parts that naturally restrict airflow anyway. So opening up the air-box like the dealership tech had suggested would have only resulted in an even leaner mixture.

The bike is making some convincing backfires upon deceleration, and I've also noticed a noticeable lack in top end with these pipes installed as well. So, considering that the VW end pipes are essentially "straight pipes" would a re-tune to increase the fuel injection rates lower the frequency of backfiring as well as fix my lack of top end? Or do some homemade washer baffles need to be affixed as well?
 
#4 ·
In a word, nope!

The backfiring, (which I understand to be considerably less frequent on the latest bikes), is a common issue and either caused by the Secondary Air Injection system, (which will not effect performance), or, if it's a new phenomenon, then you probably have a leak around your new tail pipes.

I'd be surprised if you are experiencing a noticeable lack of top since fitting these pipes as they are less restrictive than the originals. The lack of top end on these bikes is mostly due to the restricted air flow and the retarded ignition spark. Most of the restriction is in the air intake system so it's still there. Depending on how you ride your bike, you may or may not want to remove this. Paired with a new ECU tune it results in huge benefits at the top of the rev range as the engine can now breathe properly but if you don't red-line your bike much you might not notice and you might loose some bottom end grunt which you will notice.
 
#5 ·
Thanks for the timely responses,

The lack of top end honestly could have been my imagination. I only ran the VW pipes through town once to hear what it sounded like on the road. After which I replaced them with the stock units after being told by the dealership that I could potentially destroy my top end with the apparent lack of back pressure. This was really just to cover my own ass in the event that he was right about burning the top end up.

I suppose eliminating the Secondary Air Injection system would be a good start. I hear its a fairly straightforward procedure.
 
#6 · (Edited)
Changes to just the pipes alone is said to require a different tune , for example the TOR tune ( which is for stock airbox set up ) for Tor pipes . Although I don't see anyone having a boxed tune for those VW pipes so if it was me I would be going with at the very least the tor's tune .. Most of us that have installed free flowing exhaust ( TOR's) Experience the popping etc on decel and the removal of the AI practically eliminates it . Now according to some on recent threads , the 2014 and 2015's have changes in their tuning http://www.triumphrat.net/twins-technical-talk/624625-stalling-after-ai-removal.html Some are saying removing the AI will mess things up on those bikes , and others are saying not :) ????????IDK

OH and when changing stuff , pipes , AI , pulling the snorkel etc you should carry out the 20 minute adaptation procedure . Should have been done both when you put the vw pipes on and when you reinstalled the stock ones . And if you try the temporary AI plug method to see if it suits you , install the plug , run the 20 min adaptation and then try your bike . I believe it still applies to the 2014 and 2015's but the waters sometimes get murky on here .
 
#9 ·
Changes to just the pipes alone is said to require a different tune , for example the TOR tune ( which is for stock airbox set up ) for Tor pipes . Although I don't see anyone having a boxed tune for those VW pipes so if it was me I would be going with at the very least the tor's tune .. Most of us that have installed free flowing exhaust ( TOR's) Experience the popping etc on decel and the removal of the AI practically eliminates it . Now according to some on recent threads , the 2014 and 2015's have changes in their tuning Stalling after AI removal Some are saying removing the AI will mess things up on those bikes , and others are saying not :) ????????IDK

OH and when changing stuff , pipes , AI , pulling the snorkel etc you should carry out the 20 minute adaptation procedure . Should have been done both when you put the vw pipes on and when you reinstalled the stock ones . And if you try the temporary AI plug method to see if it suits you , install the plug , run the 20 min adaptation and then try your bike . I believe it still applies to the 2014 and 2015's but the waters sometimes get murky on here .

Hi All - just a quick note - I changed out my stock (2012) scrambler pipes to the VW tips, and tried to delete the AI and add the Arrow 2-1 map. It as as bad as the stock tune.
I brought it back in to my local shop and had them put the TOR tune on, and I'm thrilled to report that worked like an absolute DREAM! Everything else is stock.
Thought I'd share this with the forum - hope this helps, it's a GREAT cost saver on the pipe side, and it sounds MEAN afterwards!

Cheers,
-M
 
#7 ·
@Ajsmk2, did you remove the secondary air system in the end, and did it make a difference? I just put BC shotguns on my 2016 scrambler and am on the fence about an ECU remamp - some say it's critical, others say only if you're taking it to the racetrack :/ BC themselves say Power Commander 5 (300 odd quid) plus a remap is "absolutely necessary" but I'm loathe to part with extra cash for only a handful of hp - I'm mostly just interested in not wrecking my engine from overheating. Any thoughts appreciated gents!