Are the HRC derestriction boxes the same on the MC21 and MC28? I have one but not sure which. Any one have the part numbers on both or either? Are they interchangeable? Sorry for the stupid questions.
The MC18 and MC21 delimiters are in the form of an in-line unit between the wiring harness and the PGM unit, the MC28 utilises an HRC "card" in place of the usual ignition card.
The MC21/28 HRC units will not simply fit a standard wiring harness. See the ignition page in the 250 tuning section to see how to modify the MC28 harness to accept the HRC card, and the MC21 harness to delimit the stock PGM unit.
To fit an HRC delimiter to an MC21 requires slightly more major surgery, but is basically a case of splicing in the wires colour-for-colour, in-line.
The MC18 delimiters plug directly into the stock harness.
Any idea as to the part numbers? I have one but not sure what it fits. Any other clues that might be helpful? I like the idea of using a derestrictor but I don't want to do anything until I find out if I have one for the correct model!
Well, that "card" naturally only fits the MC28! :)
The MC21 delimiter has 2 grey plugs that need to be cut off and then the wires "spliced" into the corresponding coloured wires in the harness.
The MC18 units will plug directly into the MC18's PGM unit, which has a different socket to the MC21.
From memory, there are no part numbers on the HRC delimiters, or any other HRC part for that matter!
For the MC21, a recommended alternative by Ethos Design (an official Japanese HRC dealer), is the KISS Racing delimiter. Last price was „13,000 (US$123/UKŁ65.88 at current rates) but this was a couple of years ago.
Andy.
NSR-WORLD.COM
Last edited by Andy on Sat Feb 14, 2004 3:23 pm; edited 1 time in total
Ok, I've got this thing in front of me as I write. It has one large plug at one side (PGM) and two plugs coming out the other side (gray). Is this an MC18 or MC21 derestrictor?
Sorry Don, my error! (I've corrected my previous post to prevent any further misunderstanding!)
The MC21 HRC delimiter has two grey plugs (the only delimiter with 2 grey plugs!) that need to be cut off, and the wires 'spliced' into corresponding wires on the harness. This means you will also need to cut the black connector off the standard harness. The Black connector on the HRC unit then plugs into the PGM.
In the interests of resale, or the unlikely event that the HRC unit is damaged, make sure you cut into the stock harness far enough back that you can easily re-splice the standard black plug back in if you need to.
What you have does indeed sound like an MC21 HRC delimiter. E-mail me a picture if you can and I'll tell you for sure.
Andy, thanks. That's exactly the information I was looking for. Looks as if I do have an MC21 HRC derestrictor which will work well with my MC21 (large grin). I hate having to splice into the wiring harness but I guess if I want the gains............
The HRC de-restrictor is meant to be run with the HRC wiring loom. When run with the HRC wiring loom, you don't need to wire splice it in. However, since the HRC wiring loom doesn't have the bits for lights, etc... you probably don't want to run it on the street.
This is why you need to splice the HRC unit into the stock wiring loom.
A very nice alternate to the wire splice is to take a dud PGM unit, chisel the plug off it, and have a good auto sparky fix it to the cut end of your HRC unit.
This way the HRC unit plugs into the PGM, and the loom plugs into it.
Not the cheapest way to go by any means, but this way it is easily removed and replaced.
An alternate to that is to have a sparky fit a common multi-point plug to each end of the HRC unit, and another set to form the break in the loom.
I dont wish to cast doubt on peoples ability to perform grafts themselves, but do suggest the aid of a good sparky, as I have seen more than my fair share of sub-standard cutting, soldering and insulating.
Given how much rides on the need for good electrics, this is one area not for the ham-fisted.
I have the HRC box on my 21, and it does not affect lights or anything else a roadworthy machine needs - you're getting confused with the 28!
On mine, I removed the 2 grey plugs from the HRC unit, and crimped on pins to mate with the NSR loom. I then installed the pins in the loom sockets, put masking tape round the whole joint to create a bath, and filled the thing up with silicon sealer.
This is a recognised aircraft 'Battle Damage Repair' technique, and has lasted for two years of racing without a single mishap.
Should I wish to remove it, the whole lot will clean up and the original loom will plug back into the PGM.
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