I just finished a total engine rebuild on my 93 mc21. I am running stock carbs with 132Mains, Jolly moto pipes and a deristricted PGM from twostokelabs. I have cleaned and checked carbs several times. Bike starts and idles perfect. I can rev the engine freely to any rpms. When I try to take it for a ride, i cant get passed 5,000 rpms. It feels like it starves for fuel. When i reach 5000 rpm, i pull in the clutch and and the rpm wont raise, not until i let it settle for few seconds or so and then i can rev it again. as soon as i put a load on it, same thing, cant get it passed 5000.

Stock carbs with 132 mains
Stock air filter and box
jolly mot pipes
wire splice
derestricted PGM

Please help! this is my first nsr and am really down in the pits since i cant ride it. I have been restoring the entire bike from the ground up and was so excited to ride it after 6 months of late nights!!!

Thanks John G

Sorry, there is no support for jetting in the public forums. Please see the forum rules.

All I can suggest is you put it back totally stock, and work the problem from there.

Any more quoting of jet sizes will see this topic locked.
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Andy.
NSR-WORLD.COM

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Hi John
This sounds like faulty spark plug.Try two new spark plugs.
It is very common after an engine rebuild cause of the extra 2Τ oil which you put on the parts for the assembly.
It is also very possible for an engine that sat for a long time cause of the oil that cringe at the crankcases.

Check also if the choke lever or the whole choke mechanism is fully closed.
What is the condition of the battery,did you check the voltage of the battery with a multimeter?

If it is not something from the above which are easy checks then you must check other things like the spark coils resistance / reeds / air leaks etc.

Wish you good luck and hope to be an easy fix

Cheers
Stefanos
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Owner of : Honda NSR250 MC28 95sp colours / Honda NSR250 MC18 R6K SP / Honda RS250 NF5 89 in boxes / Honda C50 12V cub / Honda C50 12V super cub Japanese version /Yamaha XT600 89 benetton

sorry Andy, I didnt mean to break any rules. just figured i would give the bikes setup so that it would be easier for everyone to help my issue.

Stefanos, thanks for the reply. This motor is freshly rebuilt. I purchased a bunch of parts for you. clutch assembly and many others...... Spark plugs are new and so is the battery. I pulled the carbs out today and everything checked out. I also check the reeds and they look fine. how do i check the coils?

Hi John i didn't realized who you are.

Ok you installed new spark plugs during the rebuild.
Now with the problem did you check with an other new set of spark plugs to see if the problem still exist?
How much is the battery voltage,did you check it with a multimeter ?

To check the coils you need a multimeter to measure the ohm resistance.
Read Dave Ett's post here about how to check the coils http://www.nsr250.net/forums/viewtopic.php?t=11280&highlight=coils+check+cheque
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Owner of : Honda NSR250 MC28 95sp colours / Honda NSR250 MC18 R6K SP / Honda RS250 NF5 89 in boxes / Honda C50 12V cub / Honda C50 12V super cub Japanese version /Yamaha XT600 89 benetton

I replaced the plugs and the same. I also checked the coils and i got the 3ohms as suggested but i dont get the 20. I guess my next step is to replace the coils. Anyone have any laying around?

Try removing the two hoses from the solenoids, located just under the fuel tank and check if the problem has improved somewhat. This will indicate an issue with the carbs and airbox compartment.
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2t-racelab.com