Hi guys.

Ok, I am restoring a R6K MC18 SP. The donor bike's engine was completely shot, casings included. I got my hands on decent set of MC21 casings (with GPS and 2T pump) and a decent MC21 crank. My plan is to basically install my R6K gearbox (after modifying the selector drum to accomodate the GPS) into the MC21 casings and use a set of MC18 barrels and heads with standard MC18 pipes. My question relates to carburetion.. Do is stick with standard jetting (size 128) or do I go slightly bigger? I am planning on doing the wire splice as soon as it is running, also want to attempt to mod the airbox. Do I need to increase the jet size then? Sorry, kind of newbie on such things, but this is how I learn, by asking questions.

What are your thoughts?

Thanks,

Jacques.

Please note the forum rules, specifically:

6. Please do not discuss specific jetting issues in General Discussion.

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Without getting into specifics, I would expect that you are going to be fairly safe on standard jetting.
As a general rule of thumb, if in doubt, start out rich and read the plug before going leaner.
There are a couple of pictures of spark plug colour here, if that helps?
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Howzit Jaques , the mc18 wiring harness does not use the gps sensor . There are plenty decent mc 18 casings lying around here and you would be able to modify the crank you have to fit . The cranks can be rebuilt with new rods and bearings etc . Read the tuning section of the forum and it will give you a guide line on how to do jetting .

Neal wrote:Howzit Jaques , the mc18 wiring harness does not use the gps sensor . There are plenty decent mc 18 casings lying around here and you would be able to modify the crank you have to fit . The cranks can be rebuilt with new rods and bearings etc . Read the tuning section of the forum and it will give you a guide line on how to do jetting .

@ Neal - I know the MC18 harness does not support the GPS. Thus, I have adapted it to work... Neutral works on the same principle as the neatral switch on the MC18, when it's in neutral the circuit runs to ground... simple. I have in addition to this utilized the other gear positions on the sensor to work with a custom built LCD gear position display. As for modifying/machining down of cranks, not really keen, I firmly beleive there was method in Honda's madness to increase the web size on the MC21/MC28 crank. I'd rather stick to my MC21 bottom end running MC18 barrels. I will at some time have the R5K/R6K crank repaired as I have secured a shipment of bearings for a local supplier, then I might be interested in those casings, i'll keep you in mind.

TuckerBag wrote:Without getting into specifics, I would expect that you are going to be fairly safe on standard jetting.
As a general rule of thumb, if in doubt, start out rich and read the plug before going leaner.
There are a couple of pictures of spark plug colour here, if that helps?

@ TuckerBug - Thanks, I'll check the plugs as soon as I get it up and running, just waiting on barrels to come back from replating. Did you receive my email I sent you?
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The mc18 and mc21 have very different fuelling requirements. I`d err more towards the mc18 jetting than mc21, just to be safe.
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