Hi all,

I hope this doesn’t come under jetting.

My 88 R2J with a newly rebuilt bottom and top end R5K engine is falling flat at 11,300/11,400RPM with the standard airbox and filter and stock carb settings. De restriction done.

Having fitted a set of foam pod filters I was able to pull to 12,500 rpm and just over however I noticed my right silencer ( non OEM ) was considerably smoking for 10 minutes after the engine was switched off.

Would this be the unburnt residue/ silencer packing reaching very hot temperatures? Never experienced this before when riding hard.

What options do I have to obtain the additional power using the standard airbox as the pod filters are understandably loud. Also rejecting would be required.

Any information appreciated.

A delimitef R5/6K makes peak power about 11300rpm, so what you are experiencing is to be expected.

If you fitted foam pod filters without rejetting, there is a good possibility it was running lean, and therefore very hot at MAX RPM/load, and giving it a good spanking could indeed [and often does] leave the packing in the silencers smouldering a little! If it's set up well, I always consider it a sign of a good blast!

Best results with an airbox we've had has been with 4x 20mm holes in the front slope of the lid, with the standard foam filter, and jetted to suit. (You can apply duct tape over two of the holes in very cold conditions to richen it up just a tad if necessary, to save a temporary re-jet.)

The OEM R5/6K expansion chambers are actually very hard to better, although they are very heavy and of course don't make peak as high as a set of "race" pipes. They trounce the mid-range of even the best race expansion chambers though, which makes them much nicer on a road bike!
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Andy.
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Thank you Andy,

How far apart should the centre of the holes be? Would they be through the white diagram sticker or to the side of it?

Is anyone aware of a turbo filter element to fit an mc18 airbox or one that can be cut to fit?

sami1 wrote:
How far apart should the centre of the holes be? Would they be through the white diagram sticker or to the side of it?

It's not really that critical, but we just drill them as neatly and symmetrically as possible, centres probably about 30mm apart, as close as possible to the middle of the front slope.

There's little wrong with the OEM filter if you're keeping the airbox, but you could get a RAMAIR foam panel and cut it to the correct size using the inner support grid as a template. [Ensure you order a panel large enough, if you go this route!]



Red trace is all stock with wire-splice and 4 holes in the lid. Jetted to suit, of course.
Blue trace as above, with Swarbrick race silencers.

A well prepared all-stock delimited MC18 R5K is very hard to dismiss on the road.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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