V-Twin Forum banner

1 - 20 of 20 Posts

·
Premium Member
Joined
·
483 Posts
Discussion Starter #1
I've been done alot of digging in all of the "build" threads to try & figure out what I want to do to breath some more life into my bike. After comparing the Dyno graphs on Dewey's & BigBoyz sites something caught my eye. If you look at Dewey's graphs for the 2002 FLHRI 95" C.I. & the 2004 FXSTI 95" C.I. (they are near the bottom of the list) you will notice a dip in the torque curve towards the low end (around 3K). I saw this same dip in the graph on BigBoyz site & I was wondering what could be causing it. Can you explain it to me?
 

·
Banned
Joined
·
5,114 Posts
nodoze said:
I've been done alot of digging in all of the "build" threads to try & figure out what I want to do to breath some more life into my bike. After comparing the Dyno graphs on Dewey's & BigBoyz sites something caught my eye. If you look at Dewey's graphs for the 2002 FLHRI 95" C.I. & the 2004 FXSTI 95" C.I. (they are near the bottom of the list) you will notice a dip in the torque curve towards the low end (around 3K). I saw this same dip in the graph on BigBoyz site & I was wondering what could be causing it. Can you explain it to me?
The dip in the torque at the lower rps are normally caused by an over scavaging exhaust system or the bike is over cammed. One good way to tell the difference is do a run and cover half of the exhaust with a board and if the dip goes away its the pipes...if the dip remains its over cammed. The one graph you looked at on the 04 FXSTI had V&H Staggered duals...that explains the large dip that graph shows. The 2002 FLHRI graph isn't bad at all it has a 37 cam and a +2* advance key will get rid of most of that flat spot but another thing....if the baffles where opened to get max hp it will lose a bit of torque down low like that also.
Hope this helped.
 

·
Premium Member
Joined
·
483 Posts
Discussion Starter #3
I had a feeling that you were going to say it was the exhaust. In the case of the FXSTI you said the V&H Staggard Duals would explain the dip. Not to pick any nits but the description said they were the V&H BIGSHOT staggard's. The Bigshot staggards have the cross-over & are supposed to perform better than the duals. Is the cross-over Bigshot Staggards not effective?
 

·
Banned
Joined
·
5,114 Posts
nodoze said:
I had a feeling that you were going to say it was the exhaust. In the case of the FXSTI you said the V&H Staggard Duals would explain the dip. Not to pick any nits but the description said they were the V&H BIGSHOT staggard's. The Bigshot staggards have the cross-over & are supposed to perform better than the duals. Is the cross-over Bigshot Staggards not effective?
I believe they are larger diameter than 1 3/4'' which will work on larger displacment motors but for the 88'' or 95'' the mean flow velocity of the exhaust gasses are too slow with the larger diameter pipe which hinders scavaging.
 

·
Registered
Joined
·
651 Posts
Fixing Over-Scavenging

The dip in the torque at the lower rps are normally caused by an over scavaging exhaust system or the bike is over cammed. One good way to tell the difference is do a run and cover half of the exhaust with a board and if the dip goes away its the pipes...if the dip remains its over cammed.

It seems to me one of the effects of over scavenging would be a lean condition. I am experiencing this after changing to a ProPipe. I have added band clamps to 2 rows of holes in the baffle to increase back pressure, but also seem to need to add fuel to cure 'stumbling' or missing. I know it's pretty hard to say with any certainty, but generally how much fuel in terms of percentage usually needs to be added to put the AFR in the ballpark?

How about retarding the time 2 or 3 degrees in the lower RPMs?
 

·
Banned
Joined
·
5,114 Posts
Mikie said:
It seems to me one of the effects of over scavenging would be a lean condition. I am experiencing this after changing to a ProPipe. I have added band clamps to 2 rows of holes in the baffle to increase back pressure, but also seem to need to add fuel to cure 'stumbling' or missing. I know it's pretty hard to say with any certainty, but generally how much fuel in terms of percentage usually needs to be added to put the AFR in the ballpark?

How about retarding the time 2 or 3 degrees in the lower RPMs?
You know I hear of people using clamps on the baffle or drilling holes but everytime I do a change to the propipe baffle I lose tq or power. I never heard of a propipe over scavagining before except when GRock said it will lean out the frt cylinder on a efi bike. Now my question to you is what are you running in your build? Knowing that I can answer your question better.
 

·
Registered
Joined
·
651 Posts
That's the real heart of the matter Doc - whether or not I'm doing the right things to correct the problem. In short, the problem is: after installing a ProPipe, I got a lot of stumbling or missing at exactly 2500 RPM, up to 3000. Also, I got repeated code P1353 (no combustion front cylinder).

I posted the problem in the Exhaust Discussion but only got replies about modifying the ProPipe, and nothing regarding fuel. The obvious and correct solution is to dyno it, but I have not found anyone in the area that has a decent reputation for getting it right and not charging a month's pay.

The ProPipe really wakes things up and performs great, but I don't want to risk any damage by running way too lean. The sound is the best I have heard. I want to stay with the ProPipe because the stock headers suck no matter what you do with mufflers.

I attached the canned PCIII map which is for SE203 cams which is the closest one available in http://65.38.172.84/forums/showthread.php?t=64502

Thanks.


04 Road King
95" BB Kit
Flat Top Cylinders, stock head gasket
SE211 Cams (may change to 37G this winter)
Stock Heads (yeah, I know...looking at head word along w/ the cams)
ProPipe HS
 

·
Banned
Joined
·
5,114 Posts
Mikie said:
That's the real heart of the matter Doc - whether or not I'm doing the right things to correct the problem. In short, the problem is: after installing a ProPipe, I got a lot of stumbling or missing at exactly 2500 RPM, up to 3000. Also, I got repeated code P1353 (no combustion front cylinder).

I posted the problem in the Exhaust Discussion but only got replies about modifying the ProPipe, and nothing regarding fuel. The obvious and correct solution is to dyno it, but I have not found anyone in the area that has a decent reputation for getting it right and not charging a month's pay.

The ProPipe really wakes things up and performs great, but I don't want to risk any damage by running way too lean. The sound is the best I have heard. I want to stay with the ProPipe because the stock headers suck no matter what you do with mufflers.

I attached the canned PCIII map which is for SE203 cams which is the closest one available in http://65.38.172.84/forums/showthread.php?t=64502

Thanks.


04 Road King
95" BB Kit
Flat Top Cylinders, stock head gasket
SE211 Cams (may change to 37G this winter)
Stock Heads (yeah, I know...looking at head word along w/ the cams)
ProPipe HS
Yes Mike you have to get the fuel straightened out...you can do each cylinder seperate with the PCIIIusb so according to GRock the frt cylinder needs attention. Retarding your timing isn't the fix.
You might go to the to the advanced mode on the PCIII program and richen up your canned map by 5 or 6 units across the board and send it to the frt cylinder which is the #2 cylinder on the program. Take off the hose clamps first and try that and see if that wil take out the dead spot.
 

·
Registered
Joined
·
651 Posts
Doc, I yanked the clamps off of the baffle, 'split' the map to advanced, and added 6 units to the front jug. Finally got a chance to make a test run last night and you were dead nuts on. Talk about smoothing out! All of the stumbling, surging, etc. was gone and it ran like a champ.

Thanks again for your expert advice.
 

·
Banned
Joined
·
5,114 Posts
Mikie said:
Doc, I yanked the clamps off of the baffle, 'split' the map to advanced, and added 6 units to the front jug. Finally got a chance to make a test run last night and you were dead nuts on. Talk about smoothing out! All of the stumbling, surging, etc. was gone and it ran like a champ.

Thanks again for your expert advice.
Good Job...now get it on the dyno to see if there is more room for improvment.
 

·
Registered
Joined
·
2,589 Posts
hdmd88 said:
You know I hear of people using clamps on the baffle or drilling holes but everytime I do a change to the propipe baffle I lose tq or power. I never heard of a propipe over scavagining before except when GRock said it will lean out the frt cylinder on a efi bike. Now my question to you is what are you running in your build? Knowing that I can answer your question better.
Sometimes GRock actually knows what he's talking about....... in spite of the fact that you never heard of it before! And Doc, it's really the T-Header that is famous for the over scavenging front, more so than the Propipe.

Mikie, a higher velocity pipe almost always needs more fuel. And 4 to 8% greater increase in the front is the general rule with a build like yours. There are times with high efficiency, high velocity heads that you need to take out fuel, but in that case you would reduce the rear by more than the front. Another trick after you have the fuel done is to set rear cylinder timing offset by 2 to 4 degrees.
I know this question was for the Doc, so hope you don't mind the input.

Later
 

·
Delinquent
Joined
·
1,780 Posts
Doc and G,

Well done!!!!!!!!!!
 

·
Cabo Wabo '06
Joined
·
587 Posts
fuel/timing curves

Wanted to wake this one up.

So, you either retard the front cylinder or advance the rear 2-4 degree's, right?
 

·
Banned
Joined
·
5,114 Posts
Leave the front alone and change the rear...offset is just what it says...it's off set from the front, either advanced or retarded.
Find out which way produces more power on the dyno.
 

·
Cabo Wabo '06
Joined
·
587 Posts
timing offset

Doc,

I've read many of your posts/threads (and glad to see you back by the way),and it's just too damn bad you're in Florida. It's the general condensius around here that you are the Dyno guy. Wish I could have had you do mine, but Oklahoma is just a wee bit too far away.

When I talked to my dyno guy before the run, I asked about an advanced map and he agree'd, no prob. Asked about timing, too. He had to drill two holes in the street baffle to get to each cylinder, so I'm sure he did the maps in advanced mode. When I got home I went to save the map to computer and it was not an advanced map. I called him and he said he made the runs in advanced mode and then switched back to non advanced...Does this make any sense? He agreed to put it back in advanced when I return for a touch up-once this humidity clears up, but it just didn't make sense-but what do I know.

Also, once I got up there I realized I still had one row of holes (outer)covered with a hose clamp, and a 1" washer about 3" from the front of the baffle. About a week after the run, I took the hose clamp off and plugged the hole in the washer (left it in) and the top end came alive. I think this is why my top end died around 5k. Better after this change. I've read posts where you used a washer in many baffles and had excellent success. In my case, seat of the pants said leave the strapping off but keep the waher in. Guess we'll see.

Also, tried richening the forward cylinder +5 across the board today and it did make a difference. May try offset with the tuner. I know my bike pretty well, and could feel a slight improvement everywhere but mostly down low. Another reason I tried it was because my rear cyl. plug shows color and the front none.

At any rate, if you could give some feedback that would be great. Thanks for your time, and sorry for the long post. Dyno run chart:
http://www.v-twinforum.com/forums/showthread.php?t=105923
 

·
Banned
Joined
·
5,114 Posts
Those washers in the tail pipe will get some torque down low but you WILL pay a price on top end. I don't use them at all...I will however alter the baffle to get the most hp without disturbing the tq.

If you ''Get Map'' from you Power Commander it should come back as an Advanced Map....if not it isn't a advanced map. If he set it back to Basic map and down loaded it thats what you got now plus a lot of waisted time doing the other cylinder. Again ''GET MAP'' and see what comes up on your screen.
Good Luck
 

·
Cabo Wabo '06
Joined
·
587 Posts
map

HDMD88 said:
Those washers in the tail pipe will get some torque down low but you WILL pay a price on top end. I don't use them at all...I will however alter the baffle to get the most hp without disturbing the tq.

If you ''Get Map'' from you Power Commander it should come back as an Advanced Map....if not it isn't a advanced map. If he set it back to Basic map and down loaded it thats what you got now plus a lot of waisted time doing the other cylinder. Again ''GET MAP'' and see what comes up on your screen.
Good Luck
Thank you Doc. I will try that.

Sorry, I must have gotten you confused with someone else about the washer thing. Appreciate the info.

Chuck
 
1 - 20 of 20 Posts
Top