JD jet kit RHC head 07

Anyone have a baseline jetting setup for RHC head, JD jet kit, 13.5:1 piston, sea level, 90degF, vortex ignition? Currently 180, 5th clip. Seems to be fat.

165 main, stock needle clip is a good place to start. You may end up with a 162 in the Texas heat.

Edited by Leardriver

Also, always mention the bike. We can assume it is the one in your sig but you never know for sure unless ou mention it.

Also, mention what the jetting was the last time it ran right and what the mods were and the effect on jetting you noted. This will make us guess more accurately.

Is you air box fully opend? Fire screen removed? Pipe have a spark arrestor? anything else???

The bike is an 07 with a JD jet kit (07 carb with 07 JD kit). It has a 180MJ, 42 pilot, 5th clip position, crower G2 cam, K&N filter, no backfire screen, MRD pipe with no screen.

There must be something different with this 07 carb or it's the Crower cam. Same setup with a different ported head was 180MJ with JD kit and 160 with the stock carb.

The longer I run WOT the leaner it get's. Shifting through the gears gives me low 13's, WOT long gear is close to 14:1. It seems the lighter load at high RPM is causing it to go lean.

Should I increase the MJ to 190 and lower the needle?

Isn't it odd it needs this much jetting?



I have a 07 bought used when i opened it, it has a 42 pilot and a 180 main , i just asked the question ''here'' about ''popular'' starting points and was pointed to 165/45

so i got to thinking after reading this thread , maybe i'll check some online sources to see what stock came with , motosport said 178/42 So.........problem with my situation is i didnt put any seat time to speak of , before tearing down the bike,but two things come to mind here one is: the pilot, mine did pop alot on decel so the advice about 42-45 pilot seems ok, but the 165-180 main doesnt seem right , one thing that would have been noticable if my main was that far off , is the plug would look like crap which it didnt,and the previous owner would have had to of noticed it down on power on top end , or running crappy on top end.

now im back to a wide range of starting point on the main,guess my bike is going to start with a180 and lots of wide open runs ,problem with the freakin 450 is you have to pull the tank to look at the plug what a pain in the ass

165 main, stock needle clip is a good place to start. You may end up with a 62 in the Texas heat.

Do you mean that MJ with a stock needle?

JD jet kits have a FAT needle which cause the mainjet to be 10-15 sizes larger than stock and clip positions mean a whole lot when changing 1 clip position.

My intention here was to get a ballpark of jetting with the RHC head and 07 carb. with JD kit. I don't have a stock needle to try so I can't compare what JD did to that year's needle or settings from other users.

With a highly ported head (non RHC head on 03) I had to drop 10 jet sizes than stock with a stock needle setup.

sorry not trying to highjack your thread ,im just concerned that people like to throw numbers out there , that might have a diff yr 450 or repeat what they have heard ,when it appears that the different yr carbs required different jetting, i need to look and see if the preivious owner of my bike put a differnt needle in mine. and that why i have a 180mj

a prime example of all this is the ''famous'' AP MOD I asked questions about it got typical oring /diaphram answers,I stated that i had an 07 then came to find out the 07 doesnt even need an ap mod the ap linkage followed the drum from open to closed ,and had a short diaphram all ready in it

another example would be theres a popular carb swap for a small cc honda , and to use a xr200 carb on it ,depending on what yr carb you got , they came with completly different jetting same size carb just a slightly different part number on the carb, diff jetting put in because it had different circuitry in the two carbs , so my advise ,to you salty is apperently you have use of a dyno , use the jetting ''your'' bike and dyno is asking for. and not worry about what people tell you to run threw a keyboard , because they forget to tell you they had a 02 carb , i would thing rch would be your best source

If you paid for the research that goes into a JD kit, then use their recommendations. Otherwise, with a stock needle, start with a 165 main.

Took it out today and I didn't have larger than 190. Started with a 185 and did a top speed run. Came in at 86MPH on the GPS. Bumped it up to a 190 and hit 92mph. I didn't have my logger setup today so I could not verify the AF. I think it needs more based on the 14:1AF with a 185. It seems so odd the jetting needs to be so high. I will take off the carb and see if it's a RHC carb. It's the only thing I can think of that causes it to need such a big main jet.

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