103 upgrade disappointing
HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
I would have to say it is one of the most important.
For instance if you have a low flowing cylinder head u know you will need a tighter lobe separation. The overlap will help with cylinder fill. Also something to think about is on a long stroke small bore combination (like the 96'' twin cam) long stroke has less room for valves, so it may have less breathing capabilites. So once again u will need a cam with tight lobe separation. Knowing this will give u a good base to work from. This is why woods cams work so well in stock twin cams they have a lsa of 101.
For instance if you have a low flowing cylinder head u know you will need a tighter lobe separation. The overlap will help with cylinder fill. Also something to think about is on a long stroke small bore combination (like the 96'' twin cam) long stroke has less room for valves, so it may have less breathing capabilites. So once again u will need a cam with tight lobe separation. Knowing this will give u a good base to work from. This is why woods cams work so well in stock twin cams they have a lsa of 101.
You're the guy that posts up asking for input and the proceeds to tell the members that provide input that their input is wrong and now you are cam guru. I remember you bouncing all over the place deciding on the formula for your first build. Did you every finish the build? How does it run?
Same thing
I had the same thing happen. Upgraded to a 103 with TW6-6 cams, D&D 2 into 1, TMax, got 84hp / 95tq. Had 110 CCP on both cylinders. Sent the cylinders off, had them bored and matched to 107 pistons, had the bottom end trued and welded, timken bearings, had a set of heads done by the shop that bored the cylinders - 95hp / 106tq. Still disappointed! 195 & 198 CCP though. Figure now its the heads. Figure I could have made those numbers if I had just corrected the compression problem!
Tourer
Joined: May 2009
Posts: 432
Likes: 2
From: SW of Fort Worth
I am not an expert by any means, but I have reviewed and studied many cams and have tried quite a few in my 103 ci engine. I'm a tinkerer. I find cam grinds facinating and if I were to have the ability to go back in life, I must say I would have to take a hard look at designing cams as a profession.
Let's face it....with any build, regardless of cubic inch, the two things that will impact an engine's performance the most are compression ratio and cam selection. All other things can be perfect including headflow, but if the cam and CR are not optimized, you are wasting the money you spent on bore, stroke and headflow.
The rpm range I ride, requires that I have a cam with a wide power band. I do enjoy racing another touring bike from time to time but not often. In other words, you will NEVER find an SE255 or similar cam in my engine.
One can not deny, given two cams with the similar specs in lift, duration and intake closure, the cam with the tighter LSA will have a more narrow power band than one with a wider LSA. I'm talking rideability here.
If I am looking at two cams with similar specs, I will consider the cam with the wider LSA over the other.
Jim
Let's face it....with any build, regardless of cubic inch, the two things that will impact an engine's performance the most are compression ratio and cam selection. All other things can be perfect including headflow, but if the cam and CR are not optimized, you are wasting the money you spent on bore, stroke and headflow.
The rpm range I ride, requires that I have a cam with a wide power band. I do enjoy racing another touring bike from time to time but not often. In other words, you will NEVER find an SE255 or similar cam in my engine.
One can not deny, given two cams with the similar specs in lift, duration and intake closure, the cam with the tighter LSA will have a more narrow power band than one with a wider LSA. I'm talking rideability here.
If I am looking at two cams with similar specs, I will consider the cam with the wider LSA over the other.
Jim
Last edited by HardyHarHarley; Feb 9, 2011 at 10:50 AM.
HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
I had the same thing happen. Upgraded to a 103 with TW6-6 cams, D&D 2 into 1, TMax, got 84hp / 95tq. Had 110 CCP on both cylinders. Sent the cylinders off, had them bored and matched to 107 pistons, had the bottom end trued and welded, timken bearings, had a set of heads done by the shop that bored the cylinders - 95hp / 106tq. Still disappointed! 195 & 198 CCP though. Figure now its the heads. Figure I could have made those numbers if I had just corrected the compression problem!
Seriously, I think you are right; I have seen charts on similar builds with better numbers but not much better. The 6H cams with good heads will put both TQ/HP between 115-120.
HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
Let's face it....with any build, regardless of cubic inch, the two things that will impact an engine's performance the most are compression ratio and cam selection. All other things can be perfect including headflow, but if the cam and CR are not optimized, you are wasting the money you spent on bore, stroke and headflow.
The rpm range I ride, requires that I have a cam with a wide power band. I do enjoy racing another touring bike from time to time but not often. In other words, you will NEVER find an SE255 or similar cam in my engine.
One can not deny, given two cams with the similar specs in lift, duration and intake closure, the cam with the tighter LSA will have a more narrow power band than one with a wider LSA.
If I am looking at two cams with similar specs, I will consider the cam with the wider LSA over the other.
Jim
The rpm range I ride, requires that I have a cam with a wide power band. I do enjoy racing another touring bike from time to time but not often. In other words, you will NEVER find an SE255 or similar cam in my engine.
One can not deny, given two cams with the similar specs in lift, duration and intake closure, the cam with the tighter LSA will have a more narrow power band than one with a wider LSA.
If I am looking at two cams with similar specs, I will consider the cam with the wider LSA over the other.
Jim
I am not an expert either and also have a bad case of "tinkeritus"; my last 107" had three cam changes in the first 2000 miles.
I agree with your logic and that LSA is an important factor in cam selection. However, I note that when you are choosing cams, your first criteria in cam selection is the profile, i.e., valve timing events, duration and lift; those are you first selection criteria. LSA is the final criteria you use in making the selection between two similar cam profiles to select the cam that best suits your riding style. That has been my point; I don't know anyone that starts the cam slection process based on the LSA.
Tourer
Joined: May 2009
Posts: 432
Likes: 2
From: SW of Fort Worth
The general statement that got this topic started was that cams with narrow LSAs "hit early but steadily falls down fast"; that statement is misleading.
I am not an expert either and also have a bad case of "tinkeritus"; my last 107" had three cam changes in the first 2000 miles.
I agree with your logic and that LSA is an important factor in cam selection. However, I note that when you are choosing cams, your first criteria in cam selection is the profile, i.e., valve timing events, duration and lift; those are you first selection criteria. LSA is the final criteria you use in making the selection between two similar cam profiles to select the cam that best suits your riding style. That has been my point; I don't know anyone that starts the cam slection process based on the LSA.
I am not an expert either and also have a bad case of "tinkeritus"; my last 107" had three cam changes in the first 2000 miles.
I agree with your logic and that LSA is an important factor in cam selection. However, I note that when you are choosing cams, your first criteria in cam selection is the profile, i.e., valve timing events, duration and lift; those are you first selection criteria. LSA is the final criteria you use in making the selection between two similar cam profiles to select the cam that best suits your riding style. That has been my point; I don't know anyone that starts the cam slection process based on the LSA.
Yep, exactly my point.
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Joined: Jun 2009
Posts: 79
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From: orlando, fl
This will probably be my last post on this subject. After I changed out my clutch plates with the SE kit, and re-installed my stock spring, the bike seemed sluggish taking off from a dead stop. Seemed like the clutch wouldn't lockup the way it did with the heavier SE spring. I was starting to look at other options like the AIM VPC clutch plate. Then this morning I decided to adjust the clutch lever. When the stock spring was put back I noticed the lever play was zero and the release point was real high. So I added about 1/4 inch of play like recommended for a proper adjustment. That made a big difference. It still doesn't grab like the SE spring, more like it was when stock and better than before the adjustment. No slippage and very good response.
After going thru 4 different cams, 4 exhausts systems, 3 air cleaners, and 2 sets of bars, I am ready to declare this bike finished. I know you never say never with these bikes, but I can't think of anything I want to do to the bike right now. Thanks to all on the forum who provided advice, some good, some not so good. I've learned a lot and could probably save someone a boatload of money if they were starting out stock and wanted what I have now. But sometimes the fun is in the learning. The lessons learned. Decide on how you ride, where you run the engine, pick a cam, exhaust, and engine build that work together and match your riding style, and when it's all done, get a professional dyno tune by a competent tuner.
After going thru 4 different cams, 4 exhausts systems, 3 air cleaners, and 2 sets of bars, I am ready to declare this bike finished. I know you never say never with these bikes, but I can't think of anything I want to do to the bike right now. Thanks to all on the forum who provided advice, some good, some not so good. I've learned a lot and could probably save someone a boatload of money if they were starting out stock and wanted what I have now. But sometimes the fun is in the learning. The lessons learned. Decide on how you ride, where you run the engine, pick a cam, exhaust, and engine build that work together and match your riding style, and when it's all done, get a professional dyno tune by a competent tuner.