Possible to install acr,s on older tc heads?

[jrgreene1968]

Can acr,s be installed on older tc heads? I'm thinking up ideas for the next project. My crank run out is more than I want, and I have a slight deep on rear cylinder o ring. I was thinking when my back heals up, I may pull the motor and go bigger. But I hate messing with manual releases. I'm running easy start cams now, but the acr idea sounds real good, if it could be done.

[FSG]

yes it can be done, they have even been fitted to EVO Heads although in a position alongside the Sparkplug and dumping externally rather than into the Ex Port

[D-1]

yes it can be done, they have even been fitted to EVO Heads although in a position alongside the Sparkplug and dumping externally rather than into the Ex Port

How do you activate them on a evo or carby TC? The fuel injected bikes modulate the acr a bit i think? Does hooking them up to the start button de compress too much?

[kd]

Can acr,s be installed on older tc heads? I'm thinking up ideas for the next project. My crank run out is more than I want, and I have a slight deep on rear cylinder o ring. I was thinking when my back heals up, I may pull the motor and go bigger. But I hate messing with manual releases. I'm running easy start cams now, but the acr idea sounds real good, if it could be done.

Factory ACR's have the bleed off hole in the wall of the exhaust port.  That will be a tough bill to fill if you want to go that route.  As FSG says it can be done other ways.  Having said that, used or new take-off ACR heads are readily available for decent prices.  You can recoup a few dollars by selling yours.

Get the newly acquired heads worked to fit your larger engine (if even required).  With a new larger build you would be smart to do your heads to maximize your work and dollars spent any way.  Avoiding the ACR machining costs (if it was possible) will allow you to put that money into your new to you heads.  Depending on your new engine size, I see a set of C&C SE ACR heads ready to use in the swap meet right now.

[FSG]

from previous posts you have an 02

as KD says later heads already stock for ACRs would be a good option

yes on FI models the ECM Pulses the ACRs, on a CARB Bike just wire them to the Starter

Does hooking them up to the start button de compress too much?

IMO NO but I'd wire them through a Toggle Switch so they could be individually enabled or both disabled if needed, i.e. compression testing

[rageglide]

Pretty sure all ACR solutions would require you to do special machining to provide an exit route.  As KD said the OEMs dump to the ex port because EPA and HD (emissions and customer experience).   

Buy late model heads or just push the button... how hard is that?

[FSG]

turboprop has done it on an FXR




ΚĜΗΟŜΤ did it or at least was going to do it on an 04 TC a couple years ago

[prodrag1320]

find a set of late model ACR heads,by the time yoy pay for machining & ACR`s,youd have the same $$ as a set of ACR heads

[dsvracer]

putting ACR's into an early set of heads is a no brainer.  Better shops have all the right tools to make this a simple operation that can be done in an hour or so.  look around.  dsv

[TorQuePimp]

putting ACR's into an early set of heads is a no brainer.  Better shops have all the right tools to make this a simple operation that can be done in an hour or so.  look around.  dsv

Agreed

Cost effective....not expensive as a service
Even less when combined with porting

Can also do s&s superstock heads in the CNC machine.....have to finish the vent hole by hand

[jrgreene1968]

Thanks for the replies.. I haven't decided which way I'm gonna go, as far as engine size etc. I'm gonna look around for some used heads maybe with the acr,s then get them built.
Are the rocker boxes different for oem heads with acr,s?

[rigidthumper]

No. Wiring exits under the box. The late model lower rocker boxes do have more spring clearance than the early boxes, but otherwise identical.

[jrgreene1968]

No. Wiring exits under the box. The late model lower rocker boxes do have more spring clearance than the early boxes, but otherwise identical.

Cool.. thank you sir 

[turboprop]

turboprop has done it on an FXR




ΚĜΗΟŜΤ did it or at least was going to do it on an 04 TC a couple years ago

Not the cleanest setup, but when the oem ACR's fail (and they did) having them next to the plug was very convenient. Probably took less than five minutes to change out a failed unit. Had they been under a set of OEM TC rocker boxes, the job would have been considerably more involved.

As for the pressure being released directly into the atmosphere vs into the exhaust port, the elevation provided by the adapters put the residue a good deal above the head. The result was none of the typical residue left on the head that a traditional manual release would leave.   

In regards to the picture, that is an STD Evo head setup for standard 10mm manual compression releases. I had no issues with the manuals, but the automatics were a nice upgrade. Idiots at the bar would often come up with the most ridiculous ideas about what what they were. I would tell the pirates in a quiet whisper that they were 'Direct Plasma Injectors'.

[jrgreene1968]

Direct plasma injectors.. lol.. I bet that got them talking 

[BVHOG]

putting ACR's into an early set of heads is a no brainer.  Better shops have all the right tools to make this a simple operation that can be done in an hour or so.  look around.  dsv

Agreed

Cost effective....not expensive as a service
Even less when combined with porting


Can also do s&s superstock heads in the CNC machine.....have to finish the vent hole by hand

Done a few sets of the 89cc Super Stock heads with the Harley jig. Just back off 200 thou and drill the compression exit hole between the fins behind the pushrod tubes. You get the cool sound of the release and always know that they are working or if one should stick you would know it immediately. I do the same thing on the older twin cam heads. Did a set of each last week.
As for the ecm being able to run them only 05 and up has that capability and then only with a 176 level cal.  On my 2002 bagger I simply had a momentary on pushbutton and as soon as the engine cranked I let go and it would fire perfectly.  Wiring them in the starter circuit will only work on a bike with very high cranking pressure as the ecm will not see the crank slowing down and not fire the plugs if it rolls too easy.  After listening to many of the bikes I have done with the compression release exit behind the pushrod tubes you realize just how well the ecm operates them. At times you barely notice them and others they are on full.

[FSG]

.......

Wiring them in the starter circuit will only work on a bike with very high cranking pressure as the ecm will not see the crank slowing down and not fire the plugs if it rolls too easy.

if it rolls too easy  quite true  BUT if you wire them through a Toggle Switch you could just enable the front ACR

[ΚĜΗΟŜΤ]

turboprop has done it on an FXR




ΚĜΗΟŜΤ did it or at least was going to do it on an 04 TC a couple years ago

From what I remember, I looked into the ACR's. To make it work required an threaded adapter with the relief hole as seen in the pic. The cost was a bit much for my liking for the adapter and I choose manual.

If you don't mind the cost of the adapter (more of a principle thing for me as i felt it was way to expensive for a simple machined part) then that is all you need to make it work (from what I remember).

Electrically I would recommend a solid state relay to power them. actuate the relay with the start circuit.

[turboprop]

Electrically, the ACRS on my bikes are controlled by an aftermarket ignition module (Carb'd engines). The modules have a dedicated circuit for electronic compression releases. No relays required in this application.

Cost for the mechanical adapters will vary based on ones skill level and access to tools. These require a lathe, drill press and about four inches of stainless tubing. I typically screw around in the machine shop area at work. Took me maybe an hour to hand crank these. A pro could have done them in half that time. 

[jrgreene1968]

What ignition module did you use Turbo? I like that idea

[turboprop]

Daytona Twin Tech. The non-CARB compliant version.

[jrgreene1968]

I've got that ignition on mine, but didn't know it had that capability

[turboprop]

Daytona Twin Tech. The non-CARB compliant version.

Not so fast, I misspoke. Those ACR's in the picture were not fired by the ignition module. This bike uses a wiring harness from Wire-Plus that has a dedicated wire for the ACR's. Not from the ignition module.

My blue/white FXR with a TC124 has a DTT module and an oem wiring harness. I wired it's ACRs into the starter. Not the small green wire that goes to the solenoid, but to the big cable that connects the solenoid to the motor. Seems to work very well.