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[REGGAB]

I use a 62mm HPI w/62mm plenum - and I love it....   

Is there some sort of mathematical formula, which determines appropriate throttle body size based on other components in the system?  Further.....I get the 55mm throttle body size, and I know what a plenum is, but I'm trying to figure out why on my TB the plenum is 3mm larger.  Is there a venturi effect, which increases the velocity of the air by having a larger plenum vice TB?

Generally.....I have noticed alot of folks using 62mm TBs on 110cid engines, 50mm TBs on 120cid engines, and in my case, a 55mm/58mm TB on a 117cid engine.  It appears, from that structure, that those with more displacement are using smaller TBs...........which makes absolutely no sense to me.  

[REGGAB]

The coating can be done inside - or inside and outside...

The thickness of the coating is insignificant to the flow.

You can buy the header pipe ceramic coated on the inside straight from D&D.

Or

You can have the coating applied to the inside - or both the inside and outside by

Jet-Hot - http://www.jet-hot.com/

or

HPC - http://www.hpcoatings.com/

or

many others...do a google search.....

Thanks for the great information, Scott.  Hopefully Rod ordered one coated directly from D&D, but I'll find out for sure.  Wish I'd known to do this before, but that's just Monday Morning Quarterbackin'.

GOOGLE!    Who needs GOOGLE?      I've got the world's most knowledgeable V-Twin experts right here.  If I want to know something about my Mac Pro or iPhone, or hunt down a Data Item Description for some obscure software documentation, I'll use GOOGLE.  Other than that, there's no greater source of V-Twin info than right here.
OK, I'll Google it.   

[hogasm]

Is there some sort of mathematical formula, which determines appropriate throttle body size based on other components in the system?  Further.....I get the 55mm throttle body size, and I know what a plenum is, but I'm trying to figure out why on my TB the plenum is 3mm larger.  Is there a venturi effect, which increases the velocity of the air by having a larger plenum vice TB?

Generally.....I have noticed alot of folks using 62mm TBs on 110cid engines, 50mm TBs on 120cid engines, and in my case, a 55mm/58mm TB on a 117cid engine.  It appears, from that structure, that those with more displacement are using smaller TBs...........which makes absolutely no sense to me.   

Different builders experiment with what works best with their head/cam combination.

On my motor, a 58 works best for middle-upper power band and a 55 works best for low end torque, but the motor runs out of fuel too early.

[sadunbar]

Is there some sort of mathematical formula, which determines appropriate throttle body size based on other components in the system?  Further.....I get the 55mm throttle body size, and I know what a plenum is, but I'm trying to figure out why on my TB the plenum is 3mm larger.  Is there a venturi effect, which increases the velocity of the air by having a larger plenum vice TB?

Generally.....I have noticed alot of folks using 62mm TBs on 110cid engines, 50mm TBs on 120cid engines, and in my case, a 55mm/58mm TB on a 117cid engine.  It appears, from that structure, that those with more displacement are using smaller TBs...........which makes absolutely no sense to me.  

The general answer is any of those sizes of TB will run well with any of those displacement motors.  The dyno may see some differences - buy your butt likely would not...

The difference between bolting on a 58 vs. 62 mm throttle body on the same motor is minuscule for general riding around...

When my family raced (road racing), we would have entirely different configuration motors and carburetors dependent upon the type of track we were running on ... and for this "all out" application - it mattered.  750, 830, 850 carbs - different jetting, different power valves, different flow work, ect. - dyno tuned for the exact type track we were running - and then further adjustments for the weather of the day, ect.  The combination of heads, cam, intake, carb would be very different from a slower "torque" track to a faster "horsepower" track.  Same with drag racing...these variables are incredibly important...

But for casual bike riding - you would be hard pressed to notice much difference from one throttle body to the next.

If you had a stack of throttle bodies available when your bike is dyno tuned - and you wanted to take the time to try the various combinations on your motor, you would likely find a throttle body best suited for your exact cam/head/exhaust combination.  But to the seat of your pants - anything from say  - 52mm thru 62mm - would provide a similar result.

So - no - there is no mathematical formula....it all goes to the "combination" of components that you read so much about.  Your throttle body is just one piece of the overall puzzle - and selecting the right one depends the rest of your puzzle  - combined with how you ride your ride!

[REGGAB]

The general answer is any of those sizes of TB will run well with any of those displacement motors.  The dyno may see some differences - buy your butt likely would not...

The difference between bolting on a 58 vs. 62 mm throttle body on the same motor is minuscule for general riding around...

When my family raced (road racing), we would have entirely different configuration motors and carburetors dependent upon the type of track we were running on ... and for this "all out" application - it mattered.  750, 830, 850 carbs - different jetting, different power valves, different flow work, ect. - dyno tuned for the exact type track we were running - and then further adjustments for the weather of the day, ect.  The combination of heads, cam, intake, carb would be very different from a slower "torque" track to a faster "horsepower" track.  Same with drag racing...these variables are incredibly important...

But for casual bike riding - you would be hard pressed to notice much difference from one throttle body to the next.

If you had a stack of throttle bodies available when your bike is dyno tuned - and you wanted to take the time to try the various combinations on your motor, you would likely find a throttle body best suited for your exact cam/head/exhaust combination.  But to the seat of your pants - anything from say  - 52mm thru 62mm - would provide a similar result.

So - no - there is no mathematical formula....it all goes to the "combination" of components that you read so much about.  Your throttle body is just one piece of the overall puzzle - and selecting the right one depends the rest of your puzzle  - combined with how you ride your ride!

As usual, Scott, great information.  Thank you very much!   

[SBB]

Is there some sort of mathematical formula, which determines appropriate throttle body size based on other components in the system?  Further.....I get the 55mm throttle body size, and I know what a plenum is, but I'm trying to figure out why on my TB the plenum is 3mm larger.  Is there a venturi effect, which increases the velocity of the air by having a larger plenum vice TB?

Generally.....I have noticed alot of folks using 62mm TBs on 110cid engines, 50mm TBs on 120cid engines, and in my case, a 55mm/58mm TB on a 117cid engine.  It appears, from that structure, that those with more displacement are using smaller TBs...........which makes absolutely no sense to me.  

Henry

TR of Tman Performance said to buy the HPI 56mm T/B for my Jim's 120.
The numbers were 140/141.
Your "Rod" seems to be very knowledgeable and competent.
My 120 used what it used because my builder wanted to use it.
Trust your builder, he's a good one!

 

[REGGAB]

Henry

TR of Tman Performance said to buy the HPI 56mm T/B for my Jim's 120.
The numbers were 140/141.
Your "Rod" seems to be very knowledgeable and competent.
My 120 used what it used because my builder wanted to use it.
Trust your builder, he's a good one!

 

Was a little gunshy initially, since he first touched my bike summer before last, installed V&H Duals and PCIII USB, forgot the attachment hardware above the starter and shoved the ECM to PCIII union under the battery box.  I think I told that story back then.
Anyway, as others have stated, Bob Wood endorses him.......and I've seen his work 100K miles later still performing flawlessly, so......it is what it is.
I'm just trying to understand throttle bodies and exhaust coating.  I think I got it now.  That's the main reason we're all here........to learn........well.........some of us anyway.   

[SBB]

I'm just trying to understand throttle bodies and exhaust coating.  I think I got it now.  That's the main reason we're all here........to learn........well.........some of us anyway.   

Henry

I tend to trust the ones that have the experience and can back it up.
Brad Yuill of Freedom Cycle suggested that I let them powdercoat my pipes on my 05 SEEG.
He stated the cooling factor and mentioned about the exhaust velocities as the reason for having it done.
So if Brad says yes, TR says yes and Scott says yes, what choice do I have?
                                                          

[spydglide]

Henry

I tend to trust the ones that have the experience and can back it up.
Brad Yuill of Freedom Cycle suggested that I let them powdercoat my pipes on my 05 SEEG.
He stated the cooling factor and mentioned about the exhaust velocities as the reason for having it done.
So if Brad says yes, TR says yes and Scott says yes, what choice do I have?
                                                          

Did they do it for you Chip?  I'm surprised that performance pipe mfgs. wouldn't offer that as a option on thier pipes if it really makes a difference.   You'd think.    har!  spyder

[SBB]

Did they do it for you Chip?  I'm surprised that performance pipe mfgs. wouldn't offer that as a option on thier pipes if it really makes a difference.   You'd think.    har!  spyder

Freedom had it done for me.

 

I should have my header Monday or Tuesday and will take some pictures.

 

[REGGAB]

Henry

I tend to trust the ones that have the experience and can back it up.
Brad Yuill of Freedom Cycle suggested that I let them powdercoat my pipes on my 05 SEEG.
He stated the cooling factor and mentioned about the exhaust velocities as the reason for having it done.
So if Brad says yes, TR says yes and Scott says yes, what choice do I have?
                                                          
[/quote]

Exactly, Chip.  Pretty much sums it up for me.   

[REGGAB]

Did they do it for you Chip?  I'm surprised that performance pipe mfgs. wouldn't offer that as a option on thier pipes if it really makes a difference.   You'd think.    har!  spyder

Spydy,
It is my understanding from a post made earlier today by Scott, that D&D will do this, which is the discussion I intend to have with Rod on Tuesday.  I want it.

[sadunbar]

Spydy,
It is my understanding from a post made earlier today by Scott, that D&D will do this, which is the discussion I intend to have with Rod on Tuesday.  I want it.

D&D does offer ceramic coating...  I did not know this until recently...they don't advertise the fact that this is an option.

[REGGAB]

Freedom had it done for me.

 

I should have my header Monday or Tuesday and will take some pictures.

 

That would be great Chip.  I'd like to see the product, so I can confirm/update the visualization in my mind.  I can't help but be concerned about the durability of the coating tho'.  The header will endure untold heat cycles.  Most of us here remember the old style metal bath tubs and their coating.  Simply put, it was a matter of heating the tub and applying a substance, which formed into the ceramic coating upon contact and as the tub cooled.  Wondering if the pipes are done by the same process.  That said.......and the destructive little f**k that I can be, I'm just concerned about chipping the coating when the muffler needs to be removed for whatever reason.  

Probably overanalyzing/worrying too much based on visualization.    I'll wait for your pictures.  

[sadunbar]

That would be great Chip.  I'd like to see the product, so I can confirm/update the visualization in my mind.  I can't help but be concerned about the durability of the coating tho'.  The header will endure untold heat cycles.  Most of us here remember the old style metal bath tubs and their coating.  Simply put, it was a matter of heating the tub and applying a substance, which formed into the ceramic coating upon contact and as the tub cooled.  Wondering if the pipes are done by the same process.  That said.......and the destructive little f**k that I can be, I'm just concerned about chipping the coating when the muffler needs to be removed for whatever reason.  

Probably overanalyzing/worrying too much based on visualization.    I'll wait for your pictures.  

The coating of your headers will be under your chrome heat shields...