swapping out throttle boddies - Honda RC51 Forum : RC51 Motorcycle Forums
 
LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old 01-24-2009, 10:48 PM Thread Starter
 
Join Date: Jan 2009
Posts: 64
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
swapping out throttle boddies

is it worth swapping the older smaller throttlebodies for the larger ones from the sp-2 if i can get the pair for under 50 or so?
pushover is offline  
Sponsored Links
Advertisement
 
post #2 of 5 (permalink) Old 01-26-2009, 08:45 PM
Senior Member
 
Join Date: Jul 2008
Location: Dallas
Posts: 863
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
I don't think it will work. Someone else might chime in and tell me im wrong.
jgos929 is offline  
post #3 of 5 (permalink) Old 01-27-2009, 01:57 PM
Moderator
 
SubSailor's Avatar
 
Join Date: Oct 2008
Location: Sarasota, FL
Posts: 6,461
Mentioned: 24 Post(s)
Quoted: 88 Post(s)
I think there's a lot involved there.
Not having compared an SP1 to SP2, it would make sense that the intake port diameters would match the throttle body runners and that would get all upset.

The injector length is different, so you'd have to buy 4 SP2 injectors as well, unless they also came with the T-B's.
And I don't know if an SP1 ECU will work with SP2 T-B or injectors.
May as well get the SP2 heads to make everything fit and work right.

But that's what projects are for.
If you do it, let us know how it goes. Knowledge is power
SubSailor is offline  
 
post #4 of 5 (permalink) Old 01-28-2009, 11:36 PM Thread Starter
 
Join Date: Jan 2009
Posts: 64
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
will do thanks yeah ifigured i would need to change the head but wasnt sure. ill take a look at it, might make a good project on some rainy weekend
pushover is offline  
post #5 of 5 (permalink) Old 01-29-2009, 02:46 PM
Moderator
 
SubSailor's Avatar
 
Join Date: Oct 2008
Location: Sarasota, FL
Posts: 6,461
Mentioned: 24 Post(s)
Quoted: 88 Post(s)
From a theoretical side, the smaller SP1 T-B's should allow higher velocity air flow than the SP2's.
This is ideal for low to middle throttle settings.

On carburated engines, too large a throttle bore meant flow stagnation at lower revs and throttle openings.
So on an engine with huge throttle bores, if you wacked the throttle opened at low revs, it would spit back when the flow stagnated.

Also higher flow velocity means greater opportunity for ram effect at lower revs.
This was one of Suzuki's secrets to mid-range power on it's GSXR's for years.

Honda increased the SP2 race bike T-B's to 62mm from 54mm for greater top-end HP.
SubSailor is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda RC51 Forum : RC51 Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome