I finally went through the carbs on my 28 and found a bunch of things wrong. First off, the carbs that were fitted on the bike had the floats set wayyy off, like 20mm+. Then i looked at the jets, main jet was a 120!? And the powerjets were blanks! Can't believe this thing has been runnin like this for so long. So now I get into the carbs to see that the carb sync things were on the wrong slides and were missing some vital washers. Now I pulled the carbs apart and rebuilt them properly with 142 mains and the correct slide parts. Only thing is, i left the power jets blanked.
Now I go on y lil test ride and the bike seems to bog and wont rev past 9k. There is no power at WOT. My assumption is that whoever did these carbs before 'made' them work somehow by reconfiguring the air solenoid lines. Does that seem like a good assumption seeing that I redid them in stock configuration w/o HRC X & Y pieces. They weren't on the bike previously either.

Any where else I should look? Prolly gonna run the X & Y pieces per HRC specs and see if that helps.
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MC21 300R w/SE bits, Rossi 2001
MC28SE Silhouette Repsol

Solved it guys! It was the solenoid routing and X & Y pieces. The bike really rips now. I should've done all this a loooong time ago.
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MC21 300R w/SE bits, Rossi 2001
MC28SE Silhouette Repsol

What did you do to correct the problem?

All I did was route the powerjet solenoid lines as per HRC instructions. Guy who had it before had it all backwards.
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MC21 300R w/SE bits, Rossi 2001
MC28SE Silhouette Repsol

I'm having a very similar problem. Where can I find the HRC specs about which you are talking?

Its all covered here.

http://www.nsr-world.com/tuning/250-tuning/carburation%20index/jetting/
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MC21 300R w/SE bits, Rossi 2001
MC28SE Silhouette Repsol