Hey.how much head work can one do to a set of twin cam heads and still keep stock guides and valves performance wise. thanks.
The exhaust side is not much of a problem but if you have the 7mm 1.805 intake and its associated sized throat that limits airflow/power rather quickly. The guides are not so much of a constraint, also there are tools to taper the heads for only minimal gain.
The year heads dictates what the possible gains and roadblocks are.
For me (and my customers) it pays to just go ahead and use new parts and provide a product that is flow tested and works well. These heads will even help a stock motor in terms of longevity and horsepower.
What are you putting them on and What are your goals/expectations? If you're just
wanting the least inexpensive upgrade, nice gains can be had with stock stuff, but it's not that much more money to do bronze and a little better intake valve.
A basic pocket port will give you a huge bang for the buck. I know a guy that CNC ports them with the guides in. Unless you're just wanting to do it on the super cheap, I would get bronze guides and a little better intake valve.
how much head work can one do to a set of twin cam heads and still keep stock guides and valves performance wise.
Assuming stock 88" style castings:
99-05 heads about 50 CFM (intake)
06-16 heads about 30 CFM (intake)
Exhaust 30+ CFM
Edit: No edit, bad click.
:up: That's an accurate assessment. Sizable gain for just a little money.
Cylinder heads is one area I try to get the best I can find or justify lol . I seen the results of a really good set of heads on a engine . I not rich or ever will be but when it comes to head work I wont pinch there . I learned a few hard lesson on head work also , but only once
Quote from: 1workinman on June 05, 2017, 05:58:54 PM
Cylinder heads is one area I try to get the best I can find or justify lol . I seen the results of a really good set of heads on a engine . I not rich or ever will be but when it comes to head work I wont pinch there . I learned a few hard lesson on head work also , but only once
It's the icing on the cake.
My new S&S heads will be worked over by Star before they go on.
I'm about ready to get them done.
Just waiting for the new KB 117" piston to be available.
Quote from: harley#1 on June 03, 2017, 07:08:40 AM
Hey.how much head work can one do to a set of twin cam heads and still keep stock guides and valves performance wise. thanks.
The exhaust isnt a problem
The intake valve itself is a bit of a choke point
Any particular reason you want to keep the stock valves ?
mild porting with 1.900 valves works very well for milder builds
Remarkable gains can be had, even with OE valves.
Bowel work, short side radius, throat diameter, where the 75, 60, 45, 30, 15 are established, etc.
Changing up those angles can gain a bunch too :)
why i asked is i had a set of 2013 103 acr heads done stage 2 and bike got noisy after install. removed and found out 2 valves were not closing squarely to the seat, a double hit when closing. sent them back and fixed, not sure how. wondering if valve is to deep in seat. anyway they are on the bike with t man 590s and dynoed. bike runs great but not the quietest, heads,cams or both?. I am going to run them this year but want to send them to someone reputable to look them over this winter.
Seats not concentric will cause noise and premature guide wear.
had a set of 2013 103 acr heads done stage 2...... 2 valves were not closing squarely to the seat,
Lots of that out there. I'm wondering what "Stage 2" stands for in this instance. Please explain.
There are no standards. Stage xyz means something different depending on who you talk to.
Stage 2 to me; Full port job, bronze guides. 1.94 valve (or larger). (Anything over a 1.87 valve gets
a new seat) But everyone is going to have their own definition...
Quote from: MCE on June 06, 2017, 08:36:33 AM
There are no standards. Stage xyz means something different depending on who you talk to.
Stage 2 to me; Full port job, bronze guides. 1.94 valve (or larger). (Anything over a 1.87 valve gets
a new seat) But everyone is going to have their own definition...
true,a stage II head can mean a lot of different things to different head guys,that said,there has to be a way to lable the extent of porting,we don't use silly names here (thrasher,killer,mo flo,ect).just street port,stage II & III,you really need to just look at their site or ask what each degree of porting is,but never assume a "stage II" ported head can be compaired to any other "stage II" head
Killer, thrasher, monster, venom, etc,.......that's funny Kirby...... :hyst:
"Thrasher Extreme Stage VIIII HO"......... :hyst:
Quote from: Scott P on June 10, 2017, 02:18:23 AM
Killer, thrasher, monster, venom, etc,.......that's funny Kirby...... :hyst:
"Thrasher Extreme Stage VIIII HO"......... :hyst:
But they come with a gold lettered laminated flow chart with wallet card and a gold pin for my vest. Bob
Quote from: FXDBI on June 10, 2017, 07:40:52 AM
But they come with a gold lettered laminated flow chart with wallet card and a gold pin for my vest. Bob
I write them on the back of a napkin. lol
Quote from: MCE on June 10, 2017, 09:40:06 AM
Quote from: FXDBI on June 10, 2017, 07:40:52 AM
But they come with a gold lettered laminated flow chart with wallet card and a gold pin for my vest. Bob
I write them on the back of a napkin. lol
Make sure you dont use the ones that have been up against the fries.....those greasy spots are unprofessional
in. 1.900 ex. 1.585 .20 off heads 83cc chamber flow 150cfm @.600 lift
Quote from: TorQuePimp on June 10, 2017, 12:23:30 PM
Quote from: MCE on June 10, 2017, 09:40:06 AM
Quote from: FXDBI on June 10, 2017, 07:40:52 AM
But they come with a gold lettered laminated flow chart with wallet card and a gold pin for my vest. Bob
I write them on the back of a napkin. lol
Make sure you dont use the ones that have been up against the fries.....those greasy spots are unprofessional
What! You think I'm gonna use NEW ones???
Quote from: harley#1 on June 10, 2017, 12:40:54 PM
in. 1.900 ex. 1.585 .20 off heads 83cc chamber flow 150cfm @.600 lift
That doesn't sound right, are you testing at 10"? (I get mid 270s out of a 1.9 valve)
Add: Test pressure should be 25" or more (28 is the industry standard ). Low test
pressures can me misleading b/c you may not see vortices that can rear their ugly head.
I don't care if they call it prostreet, hybrid, thrasher or monster..
As long as they put out like they should is all that matters to me.
How about "monster stage III King Thrasher pro-street killers". I hear thems the bomb.
yea, not sure of the flow numbers either. looking twice i see what you mean. maybe i can find out more info.
The stage description of my heads was "Done by Eagle Jim." Works for me.
mine were done at jprecision of montreal quebec. I have conflicting feelings about their work
Quote from: Hossamania on June 11, 2017, 03:06:17 PM
The stage description of my heads was "Done by Eagle Jim." Works for me.
does he do different degree`s of porting? if not you don't need any way to distinguish them apart,is so like us (& most other porters) have different levels of porting & need some way to categorize them
Quote from: harley#1 on June 12, 2017, 04:13:55 AM
mine were done at jprecision of montreal quebec. I have conflicting feelings about their work
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ote]
I have used JPrecision . I got their 2B heads . I'm preaty impressed with the gains .
Could you Pm me if you could on your concerns .
I figured they make AV&A Valves and guides, I figure they would have a preaty good handle on it.
F.K.
Quote from: prodrag1320 on June 12, 2017, 05:06:36 AM
Quote from: Hossamania on June 11, 2017, 03:06:17 PM
The stage description of my heads was "Done by Eagle Jim." Works for me.
does he do different degree`s of porting? if not you don't need any way to distinguish them apart,is so like us (& most other porters) have different levels of porting & need some way to categorize them
He is long retired. These were done in about 2004 or 2005, early on in the twin cam horsepower wars. He set them up for my build using SE flattops and Andrews N55G cams, so I am assuming a "stage 3" type of work, but I have no real idea. I think it has Kibblewhite valves, but it's been a while since I looked at the receipt. I know they were not cheap to have done. Since then there have been many more cams and info made available.
I can tell you that they have lasted for over 85,000 pretty hard miles, and I was just beating hell out of them again last week. Poor motor. Not sure how it is still holding together.
I know they will need rebuilding one day, but not sure if they can be done, or should be, or just start over with new cores and cams.
Quote from: Hossamania on June 12, 2017, 05:31:23 AM
I know they will need rebuilding one day, but not sure if they can be done, or should be, or just start over with new cores and cams.
At the most, replacing guides and seats is all you should ever need to do. They should last as long as you do.
I aw a post about t man 590 noisy
Quote from: MCE on June 12, 2017, 11:12:06 AM
Quote from: Hossamania on June 12, 2017, 05:31:23 AM
I know they will need rebuilding one day, but not sure if they can be done, or should be, or just start over with new cores and cams.
At the most, replacing guides and seats is all you should ever need to do. They should last as long as you do.
That's what I'm hoping for.