Bhawkins854
Member
I didn't see anything about optimal static CR for this cam. Just says good torque cam for larger displacement motors.
Cam change
- Thread starter Bhawkins854
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LA_Dog
Go Fast, Go Faster
Also good to know as a guideline, the earlier the intake close event the lower in the RPM range the cam will provide strong TQ. A cam with an intake close of say 41 will come on around 2000 rpm and start to drop say 4500rpm while a cam with a close if 51 will come on closer to 3000rpm and not start dropping until say 5000rpm. this is not meant to be accurate data just a general bit of info. In short, you also want to pick a cam that fits your riding and what rpm range you're typically in.
LA_Dog
Go Fast, Go Faster
Yeh that is one issue I noticed with the RS cams. there is no one to call and get good guidance. That's why I went with TMan's cam- gave me the straight scoop. Also Woods, Mackie were very helpful. I only chose the TMAN 625 since it fit my build and riding preferences best and is not as aggro on the lifters as the Woods. The Mackie would have been my second choice.
LA_Dog
Go Fast, Go Faster
holy shit .050 off the jugs- really? damn you must have had like an .080 quench if not more! :loony:
my 2001 motor had about an .080 quench. the piston was WAY down in the jugs. I probbly had a running compression in the low 8 range.
Bhawkins854
Member
Once again sorry for the guesstimate, this 117 was an emissions motor, had a static CR at 9:6:1 before and changes were made. Decided to get the heads done and the mechanic at the shop I bought the scooter from kinda talked us Into doing the full meal deal.. Lee has done piles of these big dog 117 '''s. I more or less gave him the parts and he did his magic. The cam I'm running is a s&s 600 which everyone and their moms run in these motors, plenty of info on this cam, I just want to change the feel of the motor. Seems like this bike is all top end, wouldn't mind a cam that came on earlier
LA_Dog
Go Fast, Go Faster
Yeh you had 9.6:1 static and a lame ass running compression of 8.4 / 164 cranking compression with the factory build based on what you've posted. that sucks.
Call T-Man and talk to Brian or TR. Even if you don't buy one of their cams, you can get good info / suggestion.
In short you will want to get a cam that has an earlier intake close like in the 42 to 49 range given your 10.5: 1 static. That will have the TQ come one lower in the range where you need it.
Based on your 600 cam specs you would be trading apples for apples with the RS cam swap. both of these cams show identical corrected compression and beginning TQ range
your SS 600 cam at 10.5:1 = 8.96:1 running CR and 182PSI cranking- but your intake close is 55 which means you don;t see TQ until higher RPM.
Your RS cam ha an intake close of 54. you'll probbly see no difference on the TQ coming in sooner. your running CR and cranking CR will be about the same. More lift will flow more CFM and you'll make a bit more HP, but where- at the top end? useless?
Now you said your cranking pressure is 200 so maybe your static CR is actually a bit higher than 10.5:1 - the only way to know for sure is to know your combustion chamber CC, bore, stroke, piston deck height and head gasket thickness. that equals your combustion area and static CR.
Call T-Man and talk to Brian or TR. Even if you don't buy one of their cams, you can get good info / suggestion.
In short you will want to get a cam that has an earlier intake close like in the 42 to 49 range given your 10.5: 1 static. That will have the TQ come one lower in the range where you need it.
Based on your 600 cam specs you would be trading apples for apples with the RS cam swap. both of these cams show identical corrected compression and beginning TQ range
your SS 600 cam at 10.5:1 = 8.96:1 running CR and 182PSI cranking- but your intake close is 55 which means you don;t see TQ until higher RPM.
Your RS cam ha an intake close of 54. you'll probbly see no difference on the TQ coming in sooner. your running CR and cranking CR will be about the same. More lift will flow more CFM and you'll make a bit more HP, but where- at the top end? useless?
Now you said your cranking pressure is 200 so maybe your static CR is actually a bit higher than 10.5:1 - the only way to know for sure is to know your combustion chamber CC, bore, stroke, piston deck height and head gasket thickness. that equals your combustion area and static CR.
Bhawkins854
Member
Yeah that sounds about right because we measured the "squish" as he called it and that was also right at. 030 where it needed to be after the machine work
Bhawkins854
Member
Copy that buddy, I can find all that info, I know my nominal chamber volume of the heads are 89.2,so I can figure everything else out. Oh well I guess I'll just have to settle with the RS for now, good thing I put the quickee pushrods in, if don't like it I'll just look elsewhere, maybe have to give Tman a call!
LA_Dog
Go Fast, Go Faster
cool- good luck brother- once you "know your numbers" you can make an informed selection on cam upgrades and you'll know what to expect on gains (or problems!)
Based on what you're saying on the 89.2 CC heads, assuming an assembled quench of 0.030 (which means your pistons are zero-deck with jug tops and using a 0.030 head gasket), and add 1.77 of CC volume for piston valve reliefs, that would put you at 10.83:1 static CR and 9.23 cam corrected CR with the S&S 600, about 190psi cranking pressure.
With the RS cam, you are going to have almost the same numbers with a slight bump to corrected compression (9.29- not much). see pic attached- this is from the calculator link in my prev post.
That's why I'm saying double check since this already sounds like a really good strong build- but - you want more TQ down lower say 2200-4800 range, you'd need a cam that has an earlier intake close like 46-49. Cam duration, cam advance and other aspects make a diff too, which is why if you know your exact current numbers you can have the right conversation with the cam maker and get exactly what you need.
Based on what you're saying on the 89.2 CC heads, assuming an assembled quench of 0.030 (which means your pistons are zero-deck with jug tops and using a 0.030 head gasket), and add 1.77 of CC volume for piston valve reliefs, that would put you at 10.83:1 static CR and 9.23 cam corrected CR with the S&S 600, about 190psi cranking pressure.
With the RS cam, you are going to have almost the same numbers with a slight bump to corrected compression (9.29- not much). see pic attached- this is from the calculator link in my prev post.
That's why I'm saying double check since this already sounds like a really good strong build- but - you want more TQ down lower say 2200-4800 range, you'd need a cam that has an earlier intake close like 46-49. Cam duration, cam advance and other aspects make a diff too, which is why if you know your exact current numbers you can have the right conversation with the cam maker and get exactly what you need.
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LA_Dog
Go Fast, Go Faster
PS another consideration is to find out your overall gear ratio- you can pick up power by gearing lower. For example, on my bike it is currently geared at 3.14 overall - way too tall with the Baker OD6 and .86 6th gear. I am swapping the front drive pulley from a 32 to a 29 tooth. that will give me a 3.54 ratio and much better off the line as well as not lugging the motor under 90mph in 6th.. lol
Bhawkins854
Member
I just did that! I had to customize my own Baker steel 32 tooth pulley. Original pulley was a 34, they put that pulley in due to clearancing issues with the Baker pulley/clutch actuator cover. What a difference that made! Not to mention a giant pain in the ass machining the pulley in a bunch of spots, wouldn't recommend it to any other big dog owners with RSD unless you have a buddy with a machine shop
LA_Dog
Go Fast, Go Faster
Kewl- ya I heard that was a massive pain in the ass. Way to go on that 
Thank God mine is a staightforward FXR / Big Twin mid-90's pulley. I picked up an Andrews 30t steel pulley. Was going to run a 29 but I'd then haveto get a new belt. I figure I'll be swapping to a chain drive in the next 5k miles or so and put on a 180 rear (160 now, it is a whisker away from the 1.5" belt pulley). the rear swingarm will accept a 180 but looks like the BDM rear pully sort of fooks that all up. ya I could prolly massage the wheel spacers, get an offset front pulley, but seems easier to just go chain drive. I may even have an open primary by then.. we'll see
Thank God mine is a staightforward FXR / Big Twin mid-90's pulley. I picked up an Andrews 30t steel pulley. Was going to run a 29 but I'd then haveto get a new belt. I figure I'll be swapping to a chain drive in the next 5k miles or so and put on a 180 rear (160 now, it is a whisker away from the 1.5" belt pulley). the rear swingarm will accept a 180 but looks like the BDM rear pully sort of fooks that all up. ya I could prolly massage the wheel spacers, get an offset front pulley, but seems easier to just go chain drive. I may even have an open primary by then.. we'll see
LA_Dog
Go Fast, Go Faster
Here is my gearing ratio and speed / RPM data based on the new 30T front pulley. the 1-6 gears are stock Baker OD6 with the .86 6th gear.
The calculators are located here:
Motorcycle gear/rpm/speed calculator
Gear Ratios
.........
The calculators are located here:
Motorcycle gear/rpm/speed calculator
Gear Ratios
.........
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Bhawkins854
Member
A buddy of mine had a BDL open primary, bad ass peice, but nothing but problems. I actually ordered a 31t pulley but they accidentally sent me a 32t..which is good because I would have never gotten a 31to work. Seems to have more pop off the line for sure, but wow what a joke. The guy at Baker didn't recommend me going down any further than 2 teeth for the final drive ratio either. Had to buy a new belt too.. But I needed a new one anyway
LA_Dog
Go Fast, Go Faster
cool- yeh check out my 1st and second gear ratios / speeds / rpm chart with the 30t. If I went 29t, it would really be short-short- but 6th would be more usable. As long as my motor turns out as expected I should be able to romp some ass off the line 1st-5th with the 30t.
I'd prolly go with a baker open primary or maybe karata - don't know. hard to get shit for an FXR primary anymore these days. everything is softy-based. But at that point I can change everything including conversion to chain drive and get it all dialed in. that's a ways off though I'm totally sick of working on this rebuild and having bike down since September!! gonna just ride it for a bit.. hopefully be on it in a couple of weeks and then put-putting it for the 1st 1000 miles.
I'd prolly go with a baker open primary or maybe karata - don't know. hard to get shit for an FXR primary anymore these days. everything is softy-based. But at that point I can change everything including conversion to chain drive and get it all dialed in. that's a ways off though I'm totally sick of working on this rebuild and having bike down since September!! gonna just ride it for a bit.. hopefully be on it in a couple of weeks and then put-putting it for the 1st 1000 miles.
francoblay1
The Spaniard
Here ya go! It could be a good idea to fabricate some and sell them? I am in for a 32 tooth :up:
Bhawkins854
Member
I had photos of the entire thing and my screen broke on my phone, I had to take about an inch off the front side of the pulley along with the flange, the original pulley doesn't have a flange.. then I had to machine the inside on an end lathe quite a ways out to clear the actuator cover.. Took me two attempts to get it dialed in. New quad seal and mainshaft seal while I was in there too! Then I did some calculations to come up with a 132 tooth belt(133stock). The guy at Baker says it's as easy as 1 tooth down on the belt for every 2 teeth on the pulley. Now my 6th gear is much more usable like LA was saying, seemed to lug the motor anywhere under about 70mph. There is a guy on this forum with a bulldog bagger I got some info from, he did the same thing!!
Bhawkins854
Member
The whole thing would be a lot easier if a guy could find a smaller primary drive pulley.. We have a 29tooth and I couldn't find anything smaller to save my life! If I can remember right going down to a 32t pulley increased my torque and raised my rpms by 7% or so and going to a 31t would have been over 10% which is a huge jump.. Almost too much for my liking
Bhawkins854
Member
Here is a photo of the stock pulley if anyone hasn't seen one with the Cover off. The pulley is completely different than any other pulley you can buy, the Super thin sidewall is the biggest obstacle
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