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Discussion Starter · #1 ·
Anyone make the switch on their Scrambler and feel like she doesn't have the power she had before? I had it done and all the re jetting was done as well. I can't help but think she has less pick-up at higher RPMs. It could be the new sound making me think this, but I don't know. It sounds great, but feels sluggish.

[ This message was edited by: Malibu on 2007-03-09 10:36 ]
 

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this would seem only possible if it were not re-jetted correctly, or something was put back out of place.
what are the new jets?
G
 

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this would seem only possible if it were not re-jetted correctly, or something was put back out of place.
what are the new jets?
G
 

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Dare I suggest it, but your TORs would not completely flatter the advantage you offered your bike by removing the air box. Everything has to work in concert with one another:
You're now getting more air via your new intake system,
with increased air, you may need more fuel via your jetting,
but TORs are not known for being a "free flowing" exhaust, so all this effort you've done to your bike is for naught if the resulting "air pump"/your engine, won't allow the exhaust to exit freely.
I think your TOR's might be a bit constrictive to fully appreciate what you've done so far.

I would suggest that you consider some pipes that have a bit of a bark to 'em.
 

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The TORs are good pipes. it sounds to me like what you need is a bigger main jet. Rule of thumb is that the first 1/4 of the throttle is the pilot, the middle is the needle, and the last 1/4 is the main.

I remember that the jets supplied for the TORs were on the small side. If you switched over to pod filters at the same time, you have enough airflow that they are likely too small to handle the increased airflow.

I'd consider a bigger jet before getting too worried. :)
 

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Can you get a dyno? The only other thing I think you could have done was benchmark with a stopwatch before and after. We have guys swearing better performance after removing the air injection. But really, perception is everything right?

I'd think a dyno would help clear things up if you think you have a problem.
 

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Discussion Starter · #9 ·
135 main
42 pilots
thruxton needles
I also swapped out my 18 with a 19 front sprocket at the same time. For this bike, I don't think this was a good move. She can't Scramble anymore. I am riding around in 4th gear all of the time now. I liked being able to really balance at slow speeds and cruise in 5th. I plan on switching it back.

[ This message was edited by: Malibu on 2007-03-09 10:37 ]
 

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I am VERY satisfied with the factory sprocket......
Seems always something people are swapping out, but I'm cool with the factory set up.

With regard to jetting, I'm guessing here..... that sounds about right for your set up. I think I've heard of some folks running as big as a 150 main jet with the air box removed, and maybe I'm wrong about the TORs being restrictive. EVERY bike is different, what the hell.... it's easy to stick some 145's in there and try it out!
 

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According to the "Jetting Calculator", with TOR's, Thruxton needle, and airbox removed (twin pod filters), and 42 pilot jets, you should be running a 149 main jet. Since I don't think there's a 149 main jet available you should go up to the next size which is a 150.
 

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Discussion Starter · #12 ·
On 2007-03-05 12:26, Jimbonnie wrote:
According to the "Jetting Calculator", with TOR's, Thruxton needle, and airbox removed (twin pod filters), and 42 pilot jets, you should be running a 149 main jet. Since I don't think there's a 149 main jet available you should go up to the next size which is a 150.
Thanks.
 

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Where'd you get that Jim? I checked with Sean and he said 125/42 for my Thruxton with K&N/TORs, no other mods.
 

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Discussion Starter · #15 ·
So again I ask: Has anyone (with a Scrambler) done the mods I mentioned? This seems to be a specific issue with this bike and the information available to date. I was told by my mechanic that we need to try a Dynojet kit. That it's as close as it can be right now.
 

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Whoa; I simple punched Malibu's configuration into the "Jetting calculator for Triumph" and it spits out the jet size. You can download it from here:

http://www.dinqua.com/

It's near the top of the page. Sorry about not hyperlinking it; I haven't learned how yet.

Malibu; I think your mechanic is wrong (or wants to sell you an expensive Dynojet kit). My dealer told me the same thing - that I needed a Dynojet kit - I think it was something like $120. I said thanks but no thanks, but I'll take a pair of 125 mains please. Also, your Scrambler doesn't know it's a Scrambler, and will respond to the same modifications in exactly the same way as any other Triumph twin with the same displacement and with the same cam timing, so there's plenty of expertise in this group to get you where you want to be without paying for your mechanic to educate himself at your expense.

This is probably a good place to add that there's not necessarily an easy fail proof way to determine exactly the right jets, needles, shims, and adjustments on the very first try. The best solution to jetting will be to start somewhere close, and to fine tune afterwards. The advice you'll get here will get you close, but only riding and testing and adjusting will make it perfect.

Pat's jet size recommendations are somewhat richer than Jenk's jet size recommendations; both are close and sometimes one or the other might be spot on. My suggestion is to get some 145's and 150's, and to try them out. The worst thing that will happen is you'll need 140's or 155's. But eventually, and probably sooner than you think, you'll have a sweet running Scrambler you'll be completely satisfied with.

That's, of course, assuming you're dealing with a carb jetting issue and not a timing or ignition problem.

[ This message was edited by: Jimbonnie on 2007-03-06 09:49 ]
 

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I'm running 140 mains with thruxton needles(no shims) with no airbox and TORs. THe only difference after I swapped the TORs for Bubs which are unrestricted was to reduce the mains from 155 to 145. I have no power issues except after 6000RPM with the swap
 

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Discussion Starter · #18 ·
Wow, this was a long time ago.... Sorry I never replied. Yes the main jet switch to a 150 did the trick. For some reason my mechanic wouldn't listen to any suggestions about going up to a 150, until I finally insisted (of course I know nothing), and that finally did it. She's been running great ever since. P.S. A Scrambler isn't a Bonneville, if it was the first mod would have worked! That was the problem.
 

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Ya do know that Jetting Calculator is for the Speedmaster, right? That's why there's no choice for 40 pilots (which the 865cc Bonnies have as stock), and that's why they refer to multiple snorkels.

Jenks says, for open exhausts and no airbox, 140/40/1 shim//3 turns on the 865cc Bonnie with stock thrux needle.
 

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The scrambler has the 270 motor just like the speedmaster, so info on those 2 should interchange. you cant jet em the same as a bonny, tho
G
 
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