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05 crf250r big bore jetting

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After experiencing many problems with my build, I finally got it running.

05 crf250r 

05 Head -- re worked head, cut seats, ground exhaust valves. New intake valves, springs, keepers ect. New oem cam shaft, and bearings. Wiseco shim kit. 

05 Carb - running #165 main, #42 pilot, NCVS needle, 3rd clip position. Fuel screw 1.5 turns out. TPS mod

Cylinder Works 269cc Big Bore Kit

06 Bottom end -  Milled bottom end for Big Bore kit. Hot rods crank and crank bearings. New crank seals. All new oem transmission bearings and seals (including shift drum bearing). New timing chain. New oem center, left, and right case gaskets. New oem shift shaft aka "spindle". Hinson clutch basket. Heavy duty clutch. 

Rebuilt water pump (bearing,seals, impeller shaft), water pump impeller mod. 

New spark plug. New air filter, and filter element. New chain & sprockets. New front tire. Rebuild rear brake caliper. New brake fluids. New grips/ throttle tube. New bearing connections swing arm bushing kit. New all balls linkage bushing kit. New rear shock. All new hardware for plastics, ect. 

I'm still playing with the jetting a bit though, trying to get it really dialed in. If anyone has any suggestions, my altitude is around 800-850 ft.

 

The jetting im currently running was actually suggested to me from another member on the page. I'm still messing with it to get it dialed in. I feel like im running a little lean.

My altitude is 800-850ft if anyone has any suggestions. Thanks

I also have a stage 1 dynojet kit I could use aswell. Along with the stock NCYQ needle, #172 main, and a spare #45 pilot.

 

Is the ncyq needle "richer" then the ncvs needle? Think i might go back to oem needle and see how that works. 

I know how to do a plug chop, but this is a fresh engine. I didn't want to start it up and fly down the road at wot. Engine has only been through 1 heat cycle, with about 15-25 minutes of run time. 

The plug is black on the metal outside edge of the plug. The electrode is completely white. I'd tend to think 20 minutes of run time at varying rpm that I should atleast have some kind of color on the electrode. Which makes me think it's running lean. It runs pretty good though from idle to wot throttle though? Obviously I wasn't hitting the limiter.... yet hah. 

What do you guys think? Thanks again

 

 

 

Edited by AlotL1keVegas

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Heres a couple of pics so you can see what I mean. Kind of hard to tell. I was thinking the black around the edges is from the excess oil burning off. Has a max of 20-25 minutes on engine. To me the electrode should have some color to it.

20170610_155249.jpg

20170610_155332.jpg

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1 hour ago, AlotL1keVegas said:

After experiencing many problems with my build, I finally got it running.

05 crf250r 

05 Head -- re worked head, cut seats, ground exhaust valves. New intake valves, springs, keepers ect. New oem cam shaft, and bearings. Wiseco shim kit. 

05 Carb - running #165 main, #42 pilot, NCVS needle, 3rd clip position. Fuel screw 1.5 turns out. TPS mod

 

06 Bottom end -  Milled bottom end for Big Bore kit. Hot rods crank and crank bearings. New crank seals. All new oem transmission bearings and seals (including shift drum bearing). New timing chain. New oem center, left, and right case gaskets. New oem shift shaft aka "spindle". Hinson clutch basket. Heavy duty clutch. 

Rebuilt water pump (bearing,seals, impeller shaft), water pump impeller mod. 

New spark plug. New air filter, and filter element. New chain & sprockets. New front tire. Rebuild rear brake caliper. New brake fluids. New grips/ throttle tube. New bearing connections swing arm bushing kit. New all balls linkage bushing kit. New rear shock. All new hardware for plastics, ect. 

I'm still playing with the jetting a bit though, trying to get it really dialed in. If anyone has any suggestions, my altitude is around 800-850 ft.

 

The jetting im currently running was actually suggested to me from another member on the page. I'm still messing with it to get it dialed in. I feel like im running a little lean.

My altitude is 800-850ft if anyone has any suggestions. Thanks

I also have a stage 1 dynojet kit I could use aswell. Along with the stock NCYQ needle, #172 main, and a spare #45 pilot.

THAT MAIN JET IS TOO BIG. WHEN YOU GO BIG BORE YOU OFTEN HAVE TO GO DOWN ON THE MAIN JET DO TO THE EXTRA VACUUME ACROSS THE CARB. 165.

YOU PICK THE PILOT BY THE FUEL SCREW. IF IT TAKES MORE THAN 2 TURNS TO GET A HIGHER SMOOTHER IDLE, IT'S TOO SMALL. LESS THAN 1 AND IT'S TOO BIG.

Is the ncyq needle "richer" then the ncvs needle? Think i might go back to oem needle and see how that works. 

THE CLOSER YOU GET TO "Z" THE LEANER THE JET. SO, A NCYQ IS LONGER (LEANER) BUT SMALLER DIAMETER (RICHER) THAN AN NCVS

I know how to do a plug chop, but this is a fresh engine. I didn't want to start it up and fly down the road at wot. Engine has only been through 1 heat cycle, with about 15-25 minutes of run time.  YOU CANNOT DO A PLUG CHOP WITH A FOUR STROKE ON PUMP GAS. YOU ARE WASTING YOUR TIME WITH THIS.

The plug is black on the metal outside edge of the plug. The electrode is completely white. I'd tend to think 20 minutes of run time at varying rpm that I should atleast have some kind of color on the electrode. Which makes me think it's running lean. It runs pretty good though from idle to wot throttle though? Obviously I wasn't hitting the limiter.... yet hah.  YOU CANNOT READ A PLUG USING PUMP GAS.

What do you guys think? Thanks again

YOU SHOULD BE ABLE TO RUN COMPLETELY STOCK JETTING SINCE YOU DID NOT INCREASE THE FLOW THROUGH THE HEAD, CHANGE THE COMPRESSION, OR ALTER THE HEADER LENGTH. THE LARGER PISTON WILL PULL MORE VACUUM, HENCE MORE FUEL THROUGH THE CARB, WITH THE SAME JETTING.

 

 

 

 

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Sorry, I forgot to include in the original post that I'm running a cylinder works 269cc big bore kit. 

Thanks for the reply Krannie, but I'm a bit confused as to what your saying? 

I'm currently running a 165 main jet, 42 pilot, NCVS needle, 3rd clip, and around 1.75 on the fuel screw.

I lowered the main from a 172, the pilot from 45, and swapped out the original ncyq needle. 

So your saying I should go back to stock jetting?

Or keep my current jetting?

Edited by AlotL1keVegas

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It was running pretty good on that jetting.  The throttle response was pretty crisp, although it felt a little flat on top. 

I swapped the ncvs needle for the stock ncyq this evening, but it was to late to see how it rode. I'll test tomorrow. 

Are these engines known for the valve train to be noisey? Seems kinda clanky to me, but then again my gsxr 1000 is the same way. They're just noisey engines. 

Thanks for the help. 

Edited by AlotL1keVegas

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