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It aint no good locking the doors, when the madnes
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Discussion Starter #1
According to the HD website the "side draft throttle body and ham can cleaner" cant be that bad, as the Nightster is chucking out 79 ft/lb at 4000 rpm and the XR is only 73.9 ft/lb at 4000 rpm, and its lighter by 23 lbs !!!

Even the 2007 was putting out 79.1 ft/lb at 4000 rpm so the side draft throttle body seems to perform as well if not better than the downdraft, and you would get better airflow from the filter surface on the side draught throttle body with it being a larger filter surface area so you get a better CFM rate. The filter surface is a very small area on the XR and no matter how much bigger the airbox was made (not that you can get it much bigger) the surface area of the filter is very limited, and restricts air flow.
This, in my mind is why the XR is down on power from the XL's. Not the airbox but the filter surface size.

Matt was talking about the ram effect on these things, to my mind that has no effect on the XR as it has a ram style airbox and is down on power.

And the 2006 carburated XL1200's were putting out 79 ft/lb at 3500 rpm, which again is higher than the XR. Which also gave the same MPG figures as the XR 45/52 MPG, so much for EFI :rolleyes:

Now, why is it EFI runs much hotter with the same MPG as a carb...!!

And that is why i am not a great lover of the EFI on these bikes, just a lot of electronic witchcraft with no benefits as far as i can see.
It costs you an arm and a leg to buy something that gives you access to play with it.
You have around 10 electronic parts you could throw in the trash if you had a carb on the bike, which is then easily tunned.

Maybe if the airbox was bigger it might perform a little better but i dont think a bigger airbox is gonna give you much more than 6 or 7 ft/lb's anyhow, and even then you would have to raise the filter surface area, which would put it right in the same figures as the XL1200.

Maybe the top end HP would be ever so slightly better, but torque is where its at with these things, anyone that was buying an XR or any Harley for that matter, for the HP is playing with the wrong bike.



As much as i love the XR, it is a bit of a pig in a bag if you look into it properly, its the heaviest and has less torque than the rest of the 1200 range...Go figure.

I can see when folks start tunning the XR for performance that air box and downdraft manifold is gonna go completely, to restrictive and impractical to do anything with.
Most people in my opinion loose sight of the fact that this is a pushrod motor and i honestly dont think the downdraft intake makes the slightest difference, Harley's own figures pretty much tell you that.

The only thing that makes the XR feel quick is the 883 gearing, without that it would feel exactly the same as an XL in the motor department

My recipe for more power out of the XR is...

11/1 Compression
Stage two or three headwork (which is a bit of a grey area as yet)
A good performance two into one exhaust system comprising of Remus headers and Supertrapp tunable muffler.
Free flowing larger surface air cleaner, which in my eyes will mean stretching the filter surface area around the side of the airbox.
And cams (again a grey area as yet)

Nearly forgot...A 40/42mm Mikuni carb to make tunning much easier :D (another plus side to a carb is you could dump the oil cooler)

Whatcha think??__________________
 

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hmmmmmm

I'm gonna mull that over for a while.....
 

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Carbon Fibre Hooligans
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The reason why the XR is down on torque over the other models is nothing to do with the downdraft throttle vs side draft. In fact if you fitted the side draft throttle body/filter assembly the XR would probably have less power and torque than it has now.

The XR has a lighter crank, different pistons, different heads and all sorts of other differences from the Nightster and other XL 1200 models, so a direct comparison is a lot more complicated than just looking at torque figures and all up weight.

The XR trades torque for horsepower at higher revs, so a direct comparison with the other XL1200 models isn't really correct. In a straight race the XR would blow the Nightster away in a straight line and round corners. Any torque advantage the XL has would be negated after about 20 yards.

My local farmer's tractor has way more torque than my car, but he wouldn't win any races in it, and you wouldn't want to be driving it all day.

Simply measuring the surface area of the filter is not an indication of air flow. The filter may be bigger on the 'ham can' style filters, but the actual size of the air inlet is tiny (just the small gap around the edge of the filter). The XR has a more direct and larger air inlet than the older design, and I guarantee you that it will flow better.

Add that to the less efficient side draft throttle body and poor, old fashioned design of the ham can and it is no contest. Why do you think that Buell moved away from the ham can in 1996 in an attempt to get more volume into the airbox?

As for ram air. It has been proved beyond doubt by numerous manufacturers/engineers that any amount of ram air effect is beneficial to air intake volume . We have had two customers who have dyno'd their XR before and after fitting the larger air scoop and Pipercross filter, and both showed a 3bhp increase, so it works.

The only thing that makes the XR feel quick is the 883 gearing, without that it would feel exactly the same as an XL in the motor department
No it wouldn't. It is a more powerful engine than the rest of the XL range, so would still be more powerful and quicker if you changed the gearing. That is without taking into account the better chassis and handling than the other XL's.

My recipe for more power out of the XR is...

11/1 Compression
Stage two or three headwork (which is a bit of a grey area as yet)
A good performance two into one exhaust system comprising of Remus headers and Supertrapp tunable muffler.
Free flowing larger surface air cleaner, which in my eyes will mean stretching the filter surface area around the side of the airbox.
And cams (again a grey area as yet)

Nearly forgot...A 40/42mm Mikuni carb to make tunning much easier :D (another plus side to a carb is you could dump the oil cooler)
I agree that a compression increase would be good. However, you have to be very careful doing head work on both this and the Buell XB models, because the head design is extremely good to start with. It is extremely easy to make it worse rather than better. For instance, I know a race team in Germany that had great results fitting smaller exhaust valves than stock and welding in a 'step' into the inlet tract to their XB12 racer rather than the traditional route of bigger valves and larger ports.

Why do you think that the Supertrapp muffler would be better than the Remus or other modern 'Acoustic wrap' designs? The Supertrapp muffler is old school and not that great compared to more modern pipes (how many racers outside Xr7850 flat trackers do you see using supertrapp 'tuneable pipes').

Stock cams are about as wild as you can go without having to do more head and valve train work, and are good for around 130bhp before you need to change them.

Stretching the air filter around the side of the filter will NOT increase airflow. The throttle body can only flow a certain amount of air at atmospheric pressure. Making the opening larger at the side or removing the airbox altogether will not make it flow any more. The only way to do this is to increase the pressure in the airbox, and that means intelligent airbox design incorporating some form of ram air.

Even if you could fit a carb, the Mikuni HSR40 would be too small. You would need a 45 or 48 to make performance on par with the stock EFi system. Doing that would increase fuel consumption without necessarily increasing power. I know plenty of people who have gone off on long and fruitless carb fitting journeys for their Buell XB, and I have yet to find anyone who has actually improved performance or rideability over the stock system. Modern fuel injection is so much better in every respect than carbs, that I really don't think it would be a viable option for performance tuning. EFi does run hot due to emissions regulations, but that can be altered very easily without throwing the whole system away.

If you want a living example of what your mods would end up with, take a look at the old 2003/4 XL1200S models.

Most of the mods that you mention yet still 20+bhp down on the XR1200.
 

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raising compression

Matt-Thanks for the information. Would raising the compression to 10.5 to 1 cause the engine to run hotter and decrease engine lifespan? Especially for those of us who live in warm climates and get stuck in slow traffic? Just going .3 higher from 9.7(stock XL) to to 10.0 to 1(stock XR) resulted in Harley adding the oil cooler and oil cooled heads. Is that enough cooling to safely cover and .5 increase? Mort
 

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Carbon Fibre Hooligans
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Matt-Thanks for the information. Would raising the compression to 10.5 to 1 cause the engine to run hotter and decrease engine lifespan? Especially for those of us who live in warm climates and get stuck in slow traffic? Just going .3 higher from 9.7(stock XL) to to 10.0 to 1(stock XR) resulted in Harley adding the oil cooler and oil cooled heads. Is that enough cooling to safely cover and .5 increase? Mort
An increase in compression ratio doesn't necessarily mean a big increase in engine heat or a necessity for an oil cooler. The XR needs the oil cooler simply because it revs much higher than the normal Sportster, where cooling is not so crucial. Higher revs mean more firing strokes per minute and of course more heat. What used to happen with the early Buells was that the rear cylinder would overheat badly and seize. This was before they started fitting an oil cooler as standard, and were using basically the same motor as the XL but with a lighter crank and Thunderstorm heads. Fitting the oil cooler on the later XB models and providing oil jets to the underside of the pistons has now made this a thing of the past thankfully. The XR motor should really be viewed in very much the same way as the Buell rather than as a XL engine, as that is the only other H-D air cooled motor revving to around 7000.

I would say that increasing compression ratio to around 10.5:1 would certainly be safe with the stock oil cooler arrangement and oil cooled heads. It would probably be safe at higher CR as well, but then you run into problems getting fuel of high enough octane to run big compression.
 

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It aint no good locking the doors, when the madnes
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Discussion Starter #7
Matt, i disagree with a lot of what you say and its pretty pointless throwing things around on here.
I intend to do work on this motor so we will see what happens, I've been tunning HD's for around 23 years but this is my first sporty.
I am pretty sure i can squeeze a fair bit more out of the XR its just a matter of working through some stuff and seeing where i end up.
As i said before i am more interested in the torque than the HP, the smaller 42 Mikuni is gonna give me what i am looking for as far as torque is concerned going to 45 or 48 would just make it to flat in the torque department, that of course is if i decide to go with the carb. I managed to get 110 HP and 115 ft/lb out of a 95" BT with a stock size 42mm carb, jetted and tuned to suit the mods done on the bike.

Like i said the heads and cams are a bit of a grey area as yet, so i cant really comment on that side of things for now.
We are gonna have to agree to disagree on the intake side of things for now, i am not convinced that the downdraft makes a substantial difference on the XR.
As far as the scoop and the Pipercross filter making 3 HP, how much of that is the scoop and how much is the filter?
And as i have said before the ram effect wont show on a dyno run as the bike is stationary when dynoed, and if the airbox makes a difference by letting the motor take in less turbulent air, as i have read someone say, then the ram effect just cant be doing any good as this would fly in the face of what the airbox is there for.
i certainly dont see a problem with 11/1 compression on this bike.

Supertrapp 2-1 pipes have proved their worth over and over again, they can be altered to suit any mods you make on your motor unlike any other after market pipe you can buy, i have seen on several occasions over the years engines that have been tunned and not worked well with the pipes that were on their even though they were a performance exhaust but when a Supertrapp 2-1 system was fitted opened the motor right up, matter of fact if Boz that has just joined the forum is the guy i think he is he will back me up on that.
A good example of the exhaust side of things is Python AR11 pipes worked really well on engines up to 88" but if you went over that they would fall flat, this is the same for any unadjustable exhaust, it is tunned for so much and then it looses the plot when you go out of the manufacturers tune peramiters, the Supertrapp can be altered to suit work you have done, and can be tunned for torque or HP depending on what you are looking for from your motor. I've had far more success with Supertrapp than any other pipes, Python 11, Hooker, Khrome Werks AR100, Samson D&D Screaming Eagle and others, though believe it or not Screaming Eagle are one of the best. Companies like Remus and the like have not even made a dent in the BT market, why i ask myself, because their are hundreds of thousands of them on the roads worldwide, so they have a massive market to aim at.

As far as EFI goes, i have yet to see a tunned HD EFI motor making more power than a carburated one with the same engine work.

I also dont agree that the XR has an oil cooler because it revs to 7000, as far as I'm concerned the sportster has the oil cooler for no other reason than the EFI making the bike run hot, you must also remember that carburated BT dyna motors can rev safely to 7000, (31789-04A) without oil cooling. Screeming Eagle do a 7500 ignition unit for evo sportsters (32969-98A) and one for 04-06 Sportsters that revs to 7000, (31758-04A)
Its purely an EFI heat issue.

Like i said Matt, i aint new to this and have no axe to grind with anyone, but i aint behind the door with this stuff.

Lets just see how things pan out. :D
 

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Scotty, Scotty, Scotty, Carburetors (carburettor) are better the fuel injection? Please! Most of the automobiles on the planet use fuel injection, why? Tuning and air polution mainly. The Spitfire was a better fighter than the ME109 no question but the way to escape was to go into a power dive and the Spit could not follow, why? The ME109's had bosch fuel injection and the Spit had carburetors and would starve for fuel. Old story I know but it prooves a point.

With a carburetor you may adjust the float level, needle setting and main jet and idle jet on a Mikuni. If it is equipped with an accelerator pump also. If you need to make a change just stop and take the carb apart and make changes and try it again. If you're on a dyno with a sniffer you can make a good guess, but a guess.

With fuel injection you do a dyno run check results make changes to the exact mixture needed at the exact RPM. Doing a change takes minutes with no fuel spillage. Much better!

Most race cars use down draft induction. Why? Because it works. The fewer turns the intake charge takes the better it is for flow. In a turn the intake charge has differant speed depending on where it is. Fast on the outside and slower on the inside causes turbulence and hurts flow. Try falling up a hill sometime.

Air scoops crowd more volume into the throttle body (fuel injection talk) which can increase intake speed and flow. It is hard to measure the differance on a dyno but one run without and one with with all other conditions equal the results are the results.

I am an oldtime carb guy and a real good guesser. Raiseing the needle helps but I think the needle jet is too small. Reading the plugs is a talent many don't have. Reading the lap top is much easier. Opinions are like assholes and belly buttons every one has one.

Don't be pissed Scotty, be encouraged to maximize your fuel injection and you will com out ahead. We're your friends and will wait for you to start your bike after you flood it. :D Later,
 

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My giant goes with me wherever I go.
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hey,hey,hey.......

Y'all don't be gettin' my Scottish mate all cranked up! Scotty, I got 'chur back dude!

They said the Titanic was unsinkable, the Hindenburg was crashproof, that cold fusion was the powersource of the future, and Y2K computer glitches were gonna shut down the world! You know what? They were wrong.....I'm not sure what my point is but I think it's this...just because everybody knows you're wrong is no reason for you to stop being wrong! :D
 

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I agree with all of you.
 

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It aint no good locking the doors, when the madnes
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Discussion Starter #12
Billy, Billy, Billy, I aint got a dyno, i aint got the money to keep paying the guy with the dyno, and i aint good with a computer :)
Its a Harley pushrod motor for goodness sakes, i can understand what you are saying and I'm sure it all works fine with a high reving high performance motor, but i aint got one of those either, I've got a Harley V-twin that was designed when by a Brontosaurus.
Like i said above i aint ever seen a fuel injected HD outperform an EFI HD yet with the same mods.
I like to keep messing and uprating stuff and for me a carb is far more accessible, just the cost of Thundermax or TTS is way up on a carb conversion and then i gotta start saving all over again to pay the dyno guy every time i change anything.
i aint saying that i am gonna do the carb thing for sure, but it is an option i am considering, thats if it can be done!
Down draft may perform fine on high tuned race motors, but last time i looked, i could still see them Bronto prints on my motor :D
Look at the figures i layed out in my first post, XL side draft carb and XR downdraft injected, carb sidedraught made more power, same mpg, so the old carb aint doing to bad now is it.
If Harley had a choice in the matter their aint no way they would have injected these things.
Cars are injected, yes, they are multicylinder liquid cooled motors that run at specific temps and injection works just fine, but on air cooled V-Twins it aint that easy, engine temps are eratic, so injection is being given different signals so i cant see it working half as efficiently as it does on multi cylinder liquid cooled vehicles....Which explains the HD heat issues.

A couple of guys over here have converted their EFI TC's to carb and are loosing no performance and loosing no MPG, and both are much happier with the carb on their bikes, just saying its an option.
I've spent a lot of time reading up on folks that are using Thundermax and TTS and its quite outputting to read, now imagine a Luddite like me trying to use it :eek:

I've seen people spend $1300 on twin carbs and loose HP and torque on Harley's, you can only go so far with these things, and EFI thats set up on a dyno 100% is gonna be 80% the next time the ambient air temp and humidity changes, come on Billy its a Harley, and its got pushrods and the motor heats up and cooles down, the motor expands and shrinks, the EFI spends most of its time chasing its own arse.

Carb, thats different, it just sits their and lets the fuel go when its needed without O2 sensors, temp sensors, injectors, throttle positioning sensors, fuel pump, map sensor, air temp sensor, engine temp sensor, fast idle solinoid, the list goes on.....

People need to stop treating these things like they are Bussa eaters they aint and they never will be.

Maybe before i decide what i am gonna do some fancy EFI controller will convince me thats the way to go, but as yet the jury is still out!

Billy, i aint never been one for going with the flow, thats why I've got a 10 year old 95" BT (carburated) that will pull over 140 mph, a 103" BT EFI wont touch it.
I cant be that wrong now, can i :cool:

Each to his own Billy ;)

I aint telling anyone else to do it, I'm just throwing it out there, thats what you do on these forums!

We have a saying over here "it will all come out in the wash" lets see how we go, i might be right and i might be wrong!

Oh yea, i cant remember the last time i flooded a motor :p

And when its done...I did it http://www.youtube.com/watch?v=WIXg9KUiy00
 

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It aint no good locking the doors, when the madnes
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Discussion Starter #13
Y'all don't be gettin' my Scottish mate all cranked up! Scotty, I got 'chur back dude!

They said the Titanic was unsinkable, the Hindenburg was crashproof, that cold fusion was the powersource of the future, and Y2K computer glitches were gonna shut down the world! You know what? They were wrong.....I'm not sure what my point is but I think it's this...just because everybody knows you're wrong is no reason for you to stop being wrong! :D
I agree with all of you.
:D :D

 

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Whew!

Man you guys are all fired up about weather a xr has more power than a xl. Well let me tell you all that the xr is faster at least. a good friend of mine has a 06 xl1200 with cams, weight reduction, and straight pipes. We lined 'em up and I won. That's good enough for me at least until the warranty is up.:cool:
 

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My giant goes with me wherever I go.
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ha!

Man you guys are all fired up about weather a xr has more power than a xl. Well let me tell you all that the xr is faster at least. a good friend of mine has a 06 xl1200 with cams, weight reduction, and straight pipes. We lined 'em up and I won. That's good enough for me at least until the warranty is up.:cool:

Now, there's a man who likes things in black and white! I dig it!
 

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Some of these useless sensors(such as; Engine Temperature, Manifold Absolute Pressure, and Intake Air Temperature) address your concerns about changing air conditions. Also the O2 sensors can also make short term and long term adjustments to the tables to attain the target air/fuel ratio.
Carburetors cannot match fuel injections accuracy.
And, I would say, your buddies that were unsatisfied with their fuel injection did not have them tuned properly.

Fuel Injection = dead on accurate(properly tuned)
Carbs = close enough

Put the carb down...walk away...:)
 

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carb v efi

I've got a lot to add to this debate, based on experience of both, but for the moment I'm working 14 hour days, 7 days a week, getting customers motors built and bikes tuned, plus my own R&D work. To do justice to it I need to sit at the computer for a while and write a proper article. When the pressures off a bit, I'll make the time and start a new thread.
 

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Sorry Scotty, I forgot that there's a guy that comes around and lights the street lights every evening in your neighborhood. You are correct the fuel injection is always chasing it's arse but the the results are it's always correct based on engine conditions. The Harley motors are an old design forsure but why not make it better. We all love the V-Twin Bussa beater or not. All the single cylinder motocross bikes are going fuel injection. Why? It works! Harley motors do get hot, no question, fuel injection adjusts for that and yes we can change it to make it better. Sorry for the move to the modern technology. You gonna go back to kick start? :D Later,
 

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It aint no good locking the doors, when the madnes
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Discussion Starter #19
Sorry Scotty, I forgot that there's a guy that comes around and lights the street lights every evening in your neighborhood. You are correct the fuel injection is always chasing it's arse but the the results are it's always correct based on engine conditions. The Harley motors are an old design forsure but why not make it better. We all love the V-Twin Bussa beater or not. All the single cylinder motocross bikes are going fuel injection. Why? It works! Harley motors do get hot, no question, fuel injection adjusts for that and yes we can change it to make it better. Sorry for the move to the modern technology. You gonna go back to kick start? :D Later,

Like i said above i aint ever seen a fuel injected HD outperform an EFI HD yet with the same mods.
:D

Its OK harping on about how good this "Fool Injection" is but i just cant see any evidence of it being better :D


The figures that i posted in my first post sorta say it all, if you go from the last carb XL1200 to the first EFI XL 1200 their is no difference in either power or fuel consumption,both putting out 79 ft/lb at 4000 rpm and both giving 45/52 MPG and both with the same gains with a stage one, I'm sorry but you just cant argue that EFI is either more efficient or more economical


That said i cant see a way of converting the XR for a couple of reasons, one being the fuel pump, if it were a BT you could just go ahead and change the tank to a pre EFI one, so its looking like its gotta stay injected for now.

So lets get back to the downdraft V's sidedraft thing
I aint even slightly convinced that works on a Harley motor in any beneficial way whatsoever!


Which takes me to the option of a sidedraft XL intake conversion to give me more options as far as air intake goes....

Billy stop harping on about the carb/EFI part of this thread (Downdraft V's Sidedraft) and give me some shit over the intake ;)
 

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Serenity Now!

Serenity Now, Insanity Later!:)
 
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