I had a friend help jet my bike like 4 years ago...took a look at my set up today and notice a couple of oddities...it is a HRC jet kit FYI. Here are the questions:

The + air solenoid on my bike is black and not red? It also has all four tubes connected. So I assume we did not have or use the correct solenoid? Were they all red? I assume he never changed it?

My "Y" joint looks very much like the one in the photo...how would I tell if it is still the stock piece? Mine still has the white paint marking on them.

Any info appreciated.
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'93 MC21 250sp Repsol "Doohan"

The HRC X-piece is red, the stock X-piece is black.

The HRC Y-piece has a white dot, the stock Y-pieces have a yellow/cream or blue dot.
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Andy.
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Ok got it.....Have you ever seen a situation were the HRC kit would not have had these pieces in it? Lastly, I believe you said they were no longer available separately? Thanks as always..
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'93 MC21 250sp Repsol "Doohan"

how important are these pipes ?

i have a stock Y-piece, but my X-piece is a couple random T-pieces i got from an auto store and plumbed up to make the X...this bad ?

where can i source some stock ones? or HRC? (HRC show any improvements, how do they actually benefit things?) is it bad to be running my current homejob setup ?

If it's wrking and making enough power for you then it's fine! Why spend cash on bits you don't need just because they say HRC on them?

If it's not running right or down on power, then maybe getting the right bits will help. Had it on a dyno?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

damo wrote:
how important are these pipes ?

Actually, they are EXTREMELY important. They have different sized jets in them (3 in total) and the wrong parts can (and will... I speak from experience) melt pistons.

HRC do not make parts for a joke.

If you cannot source the HRC parts, at least use stock parts. The higher the engine revs, the more air drawn through the jets. If these jets (or random "open" T-pieces) are too big it will lean the mixture out too much and seize at WOT/high RPM.
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Andy.
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Very interesting. Upon further review my jet kit which I paid plenty for years ago seems to not have come with either pieces...all of the various jets/needles are present but the red + and the correct 'Y" were never in the kit. My stock pieces are in place and the bike runs very well. I do have a little hunting at 4K steady throttle otherwise it is snappy and maybe just a tad rich..but it runs well. I think the key here is we all know what is "supposed" to be in the bike regarding these HRC jet kit pieces but nobody (everyone but Andy) really knows what they do or how imporant it is if you DON"T have the correct pieces...TIA
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'93 MC21 250sp Repsol "Doohan"

So...what happens if the top tube (the match to the "open' piece on the red +)on the black stock piece id left open/ Yes or No. Or is it best to just leave it all connected if you don't have the red piece? Lastly, If I want the correct pieces where do I start here in the states to find it?
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'93 MC21 250sp Repsol "Doohan"

Are you sure you don't have a JHA jet kit. I was told that one of my bikes had a HRC jet kit in it and was given a jet box with all the extras. Upon further inspection it was a JHA kit.

One of these guys will have to tell you if the JHA comes with a different color X piece because I don't remember now what mine has. I think the pieces might be the same in both kits as they all come from HRC.

Could be. Might explain why I am missing the parts...again, I will not worry about it if it becomes a wild goose chase for 45 days...but if i can get the pieces I would prefer to do it...again, I have no clue of the pro's and con's...
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'93 MC21 250sp Repsol "Doohan"

Hi

I seem to remember from a different thread that Chris Burke in Australia has all the HRC jets available individually. He has a bike shop and advertises on NSR World and on ebay.

For information on JHA vs HRC kits, both types are advertised for sale at the moment on Yahoo Japan. It's a hassle searching only by pictures and the odd word recognised by the Japanese search feature, but you can find it if you try. Infact here it is done for you. Try these links (first 2 HRC, 3rd is JHA):

http://page16.auctions.yahoo.co.jp/jp/auction/u26506617
http://page.auctions.yahoo.co.jp/jp/auction/113832761
http://page8.auctions.yahoo.co.jp/jp/auction/h66066201

Hope that helps.

NB. Read Andy's helpful jetting info on the tuning section as well, it will answer most of your questions.

Thanks

Dan

Yep. Use it all the time...thanks for tip on the Yahoo link.....
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'93 MC21 250sp Repsol "Doohan"

The Jha jet kit is (was) all HRC parts, still in the HRC packets, plus a sticker! They also added power jet blanks with their MC21 kits; something that HRC never did until the MC28 kits came out.

Your poor carburetion around 4000rpm could quite likely be due to the wrong X and Y pieces, but it could also be needle type and/or position. My MC21 carburetes almost perfectly from idle to 12000+rpm*, StephenRC45's MC18 carburetes absolutely perfectly across the whole rev-range, but he has dedicated countless hours to getting it right both on the road and on his dyno. Being a dyno operator it would be pretty hypocritical for it not to be perfect in his opinion, and it's an example of why I wouldn't take an NSR anywhere else in the UK to be set up.

*I don't have the patience of Stephen to refine mine any further. It's rare that I need the ultimate flexibility of sudden WOT below 3000rpm like he has achieved, even with the F3 transmission and a 63mph 1st gear!
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Good info...I am going to do some sorting out again...so where am I going to find the + and Y tubes? Who the hell knows where mine went...
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'93 MC21 250sp Repsol "Doohan"