Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[HWYMAN1]

When the heads are re worked for "free flowing" what determines the throttle body size? If the stock is 42mm and being bored to 48mm, but offer an option of 55mm (HP inc) why not put largest in for max flow? in other words how large is too large? john

[Hoist!]

When the heads are re worked for "free flowing" what determines the throttle body size? If the stock is 42mm and being bored to 48mm, but offer an option of 55mm (HP inc) why not put largest in for max flow? in other words how large is too large? john

You can get into all kinds of flow characteristics of everything and all that stuff, but for the most part, things have been tested and proven, and you pretty much know what size TB's you can use for different displacement engines. The 110 seems to be an anomaly. It's seems to be requiring a much bigger TB than anyone expected. Hoist!

[HWYMAN1]

You can get into all kinds of flow characteristics of everything and all that stuff, but for the most part, things have been tested and proven, and you pretty much know what size TB's you can use for different displacement engines. The 110 seems to be an anomaly. It's seems to be requiring a much bigger TB than anyone expected. Hoist!

Howie,
I get that certain displacement can tolerate only so much flow, and that these traditionally mean if you have x you use y throttle body, but why if the upgrade uses a 48, do you then offer a 55? If increasing intake via 55 is best why not do it that way to start or am I missing something? john

[Hoist!]

Howie,
I get that certain displacement can tolerate only so much flow, and that these traditionally mean if you have x you use y throttle body, but why if the upgrade uses a 48, do you then offer a 55? If increasing intake via 55 is best why not do it that way to start or am I missing something? john

Everybody was missing something on the 110's. HD was too. Their TB's are 50 mm right now on the '08 110's as I understand. I'm using a 62 mm now. The initial calcs musta been wrong. It's starting to come out now is all. Hoist!

[rlavigna]

Everybody was missing something on the 110's. HD was too. Their TB's are 50 mm right now on the '08 110's as I understand. I'm using a 58 mm now. The initial calcs musta been wrong. It's starting to come out now is all. Hoist!

Howie, You may be right.  See my Dyno chart attached.  50mm TB, SE251 cams, PCIII, and D&D Fatcats.  I am not impressed with the numbers but it rides great.

Rich

ps: Howie I could not figure out how to send you a PM with an attachment so I posted it here. 

[Hoist!]

Good Tq curve except for the dip between 3000 and 3800. He didn't give you the AFR curve, and that dip should be tunable. I think you can pull better overall numbers out of it, but it should be a good ridable bike like it is. If you want it tweaked a little more, have Rosa spend a little more time with it, or I'll bring you up to Joe's. I really hope you get to take it to Sturgis and beat on it a little! Enjoy it Rich! Hoist!

[erniezap]

Having too large of a throttle body causes 2 things:
1 - Waste gas
2 - Lose low end torque

You want pistons, cams, ports, vales, exhaust, and throttle body to be a good match together for the type of riding that you do.

[Midnight Rider]

John, It's all about the heads, bro.  Velocity in the heads, and chamber size/configuration, plus valve sizing (bigger is not always better), is what gives you the power all the way accross the rpm range.  These motors make good power (TQ) down low, but the heads just can't allow enough flow when you get above a given rpm, depending on the cam.  The problem with these motors is the heads, if you want to release the full potential of the engine.  You can make it a lot better with just cams, but to do it up right, the heads need to be changed, or else weld up your 103/110 heads and start over with the machine work if you want to keep the badges.

Every competent builder I've talked to in the past few months has said the same thing...if you want these motors to run at maxium efficiency, bite the bullet and do the heads.  Quicker machine, better fuel milage, faster revving, and COOLER running.

[EZRIDN]

John, It's all about the heads, bro.  Velocity in the heads, and chamber size/configuration, plus valve sizing (bigger is not always better), is what gives you the power all the way accross the rpm range.  These motors make good power (TQ) down low, but the heads just can't allow enough flow when you get above a given rpm, depending on the cam.  The problem with these motors is the heads, if you want to release the full potential of the engine.  You can make it a lot better with just cams, but to do it up right, the heads need to be changed, or else weld up your 103/110 heads and start over with the machine work if you want to keep the badges.

Every competent builder I've talked to in the past few months has said the same thing...if you want these motors to run at maxium efficiency, bite the bullet and do the heads.  Quicker machine, better fuel milage, faster revving, and COOLER running.

Hey TC....just curious, what are the most effective head mods being done that will give the most bang for the buck?  Is there anything that the average joe can do?  Unshroud the valve pockets, straighten out the runners or raise & sharpen the D-port?   I've ported many small block chevy heads & intakes over the years...so, it doesn't scare me none to pull out the bits & grinder. 

[Midnight Rider]

Hey TC....just curious, what are the most effective head mods being done that will give the most bang for the buck?  Is there anything that the average joe can do?  Unshroud the valve pockets, straighten out the runners or raise & sharpen the D-port?   I've ported many small block chevy heads & intakes over the years...so, it doesn't scare me none to pull out the bits & grinder. 

EZ...I personally would not tackle something like this, as it has been 35 years since I've done any of that kind of work.  Most of the experts I've talked to recommend welding the heads up, then doing major changes on the intake/exhaust valves, and changing the way the chamber is shaped.  The most cost effective way, from who I've talked with, is to just change the heads, but you lose the badges on the head (the 103 script), which is OK if it does not bother you.  I personally would prefer to keep the badges, so would have to send the heads off to have them worked.  There are a couple of places I'm looking into for that type of work.  If you have access to the machinery, you might be able to do some research, or talk to a couple of these guys to get more information on the details, which I cannot provide.

But, the consistant response I get from talking to three different, competent builders, is always the same...get new heads, or modify the ones I have.

[HWYMAN1]

John, It's all about the heads, bro.  Velocity in the heads, and chamber size/configuration, plus valve sizing (bigger is not always better), is what gives you the power all the way accross the rpm range.  These motors make good power (TQ) down low, but the heads just can't allow enough flow when you get above a given rpm, depending on the cam.  The problem with these motors is the heads, if you want to release the full potential of the engine.  You can make it a lot better with just cams, but to do it up right, the heads need to be changed, or else weld up your 103/110 heads and start over with the machine work if you want to keep the badges.

Every competent builder I've talked to in the past few months has said the same thing...if you want these motors to run at maxium efficiency, bite the bullet and do the heads.  Quicker machine, better fuel milage, faster revving, and COOLER running.

Terry,
Appearantly  the heads changed in 2003(?), was told it was an EPA thing, but you're right from everythng I have found out the head are the weak link. unfortunately for us (as you point out)to improve the head (stock) requires replacement with non SE badged item(or someone who really knows what they are doing!). The concept that has repeated itself is that it is the compatibility of TB, valves, head flow, cam operation, in combination that create maximum performance. Getting it narrowed down, and now the mantra should be: GET SOME GOOD HEAD(S)! john

[Midnight Rider]

Terry,
Appearantly  the heads changed in 2003(?), was told it was an EPA thing, but you're right from everythng I have found out the head are the weak link. unfortunately for us (as you point out)to improve the head (stock) requires replacement with non SE badged item(or someone who really knows what they are doing!). The concept that has repeated itself is that it is the compatibility of TB, valves, head flow, cam operation, in combination that create maximum performance. Getting it narrowed down, and now the mantra should be: GET SOME GOOD HEAD(S)! john

John...HD actually did a fairly ingenious (depending on your perspective) thing is designing the new heads back in 04.  From a very trusted source, I was told that they actually designed the heads to CREATE heat for EPA purposes...kind of like sitting on top of a catalytic converter.  I'm repeating what I'm told here, but the story is consistant...the head/cams do not flow well at certain RPM's.  Not enough velocity because of the shape, valves/valve angles, etc.  I'm fortunate to have a spare set of heads and jugs that are good parts from an 05, so I can get the work done without much down time.  But, getting the stock heads welded up and fixed to actually function well is not an inexpensive proposition...costs about twice as much as just replacing them.  But, I want the badges on there so people will still think it's stock...   If/when I do this, I only want to do it once, and don't want to build a motor that is going to require drivetrain mods as well, so the numbers will be in the 120's on both sides, but be there accross the RPM range.  From my research thus far, because of the headwork, it opens many doors to good cams to do the job and have a motor that runs nice and cool, revs very quickly, and is QUICK.  Of course, it all depends on how good the crankshaft is (runout).  I do NOT want to go into the bottom of the motor, but do everything needed to make the top as good as it can be with different cam plate, etc.

[Hoist!]

John...HD actually did a fairly ingenious (depending on your perspective) thing is designing the new heads back in 04.  From a very trusted source, I was told that they actually designed the heads to CREATE heat for EPA purposes...kind of like sitting on top of a catalytic converter.  I'm repeating what I'm told here, but the story is consistant...the head/cams do not flow well at certain RPM's.  Not enough velocity because of the shape, valves/valve angles, etc.  I'm fortunate to have a spare set of heads and jugs that are good parts from an 05, so I can get the work done without much down time.  But, getting the stock heads welded up and fixed to actually function well is not an inexpensive proposition...costs about twice as much as just replacing them.  But, I want the badges on there so people will still think it's stock...   If/when I do this, I only want to do it once, and don't want to build a motor that is going to require drivetrain mods as well, so the numbers will be in the 120's on both sides, but be there accross the RPM range.  From my research thus far, because of the headwork, it opens many doors to good cams to do the job and have a motor that runs nice and cool, revs very quickly, and is QUICK.  Of course, it all depends on how good the crankshaft is (runout).  I do NOT want to go into the bottom of the motor, but do everything needed to make the top as good as it can be with different cam plate, etc.

Hmmm, that plan sounds very familiar! Hoist!

[Midnight Rider]

Hmmm, that plan sounds very familiar! Hoist!

Howie...I move slowly on this kind of thing, as I "study" on it and do a ton of research trying to learn all I can learn to make a good decision.  The advantage I have over you guys with the 110's is that my motor is running just fine as is (knock on wood), so I don't have to be in any big hurry to fix HD's f'ups.  With your situation, I would have taken a similar route to yours, if I didn't just hand the bike back to HD via an attorney and Lemon Laws.  But, we do get attached to the damn things, and I would not relish the thought of giving up my bike, so I completely understand why you've done what you've done on your dime.  The problem we have with the 103's is the cam chain mechanism...it's a time bomb waiting to go off and screw up the motor.  With 18K+ on my bike now, I'll be getting real nervous about this time next year, so will either just repair/replace the existing components for the cam chain, or do something like is being discussed.  I have a perfectly good engine with a 7 year extended warranty, so I'll either do it all next year, or just do what's needed to get it by another year or two, postponing the inevitable.  I've got way too much money and time into this bike, getting it the way I want it with regards to looks/comfort/functionality, to get rid of it.  I may have this same bike 10 years from now, or longer.  It's all about how much funding I can come up with in the next year...I'm tapped out presently.

[Hoist!]

Howie...I move slowly on this kind of thing, as I "study" on it and do a ton of research trying to learn all I can learn to make a good decision.  The advantage I have over you guys with the 110's is that my motor is running just fine as is (knock on wood), so I don't have to be in any big hurry to fix HD's f'ups.  With your situation, I would have taken a similar route to yours, if I didn't just hand the bike back to HD via an attorney and Lemon Laws.  But, we do get attached to the damn things, and I would not relish the thought of giving up my bike, so I completely understand why you've done what you've done on your dime.  The problem we have with the 103's is the cam chain mechanism...it's a time bomb waiting to go off and screw up the motor.  With 18K+ on my bike now, I'll be getting real nervous about this time next year, so will either just repair/replace the existing components for the cam chain, or do something like is being discussed.  I have a perfectly good engine with a 7 year extended warranty, so I'll either do it all next year, or just do what's needed to get it by another year or two, postponing the inevitable.  I've got way too much money and time into this bike, getting it the way I want it with regards to looks/comfort/functionality, to get rid of it.  I may have this same bike 10 years from now, or longer.  It's all about how much funding I can come up with in the next year...I'm tapped out presently.

True dat Terry! You have the luxury of time, as you have no immediate issues to address. My dilemma left me w/HD's normal half-assed repairs as one option, and looking forward to future repetitive failure, or doing it my way. And I know my way will also prove to be way more fun in the end! Hoist!