Any information or recommended upgrades? The machine is stock and I just bought manual, air filter, oil filters, brake pads and needing rear tires.

What tires are recommended for snow and dirt track riding?

I have seen sale ads stating "jet kit". What is the recommended jets? I don't know what a jet kit includes, but the dirt bike I have uses three main jets for the changes I need do to temperatures. Do I need anything more than just three main jets for the quad?

Any information would be great. Thanks. Lots to read now on the forum with this new machine, but information given will reduce my searches. Thanks

 

I think a good idea would be to put a pipe on it before you jet the carb. then, you dont have to jet the carb twice if you ever decided to get a pipe later on. Thats just what I think. Have fun with your new ride!
Kevin

 

The jetting currently will be good for a stock bike, If you plan on putting a pipe or filter on, or build the engine you will need to jet accordingly check out www.exriders.com for a ton of 400ex information.

 

I had a set of Razr mx I liked alot. In my opinion jet kits are a waste of money, some pipes come with jets and if they don't go to exriders and learn how to read plugs then you only need to buy the jets you need. Also on that model there was a recall on a spring problem somewhere in the tranny that would allow the bike to go into reverse while riding in I think 5th. When I bought mine it had an x stamped into the case right above the shifter to mark that it has been taken care of. You can call a dealer and they can run the vin to see if it's been done.

 

I figured the entire jet kit was a waste. I only use 3 jets for my crf450R. Now I came across someones post about Klein vs. other brands of jets. The numbers are not the same across the board. How do you know what brand you originally have? What is stock on a Honda. With my dirt bike, I assumed it was Klein brand and now I am unsure. Nothing I have seen in the service manual has this information. I do have a service manual on order with the 400ex, but not sure what details will be there.

I will look into the tires. Thanks for the information given so far. I didn't want to upgrade the pipe. So many people on the dirt bike say pipe up grades are not worth the money and mostly power is lost due to jetting being wrong. I thought I read the factory settings were not correct. Now I can't find those post again! ARG!

 

This is now confusing me. I found this chart...

Width------Kehein # -- DynoJets # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9
0,0870---- 222,5------- 196--------- 183,7
0,0880---- 225--------- 198--------- 185,6
0,0890---- 227,5------- 200--------- 187,5


I assumed I had Kehein jets in my Honda CRF and it was a 170. I bought 168 and 172 jets. At work right now and I will need to verify the manual and the jetting chart. Looking at this information, the stock jetting is Dynojets? Is this true for all Honda's. If I recall, the manual did call out the temp range and suggested the 168 and 172 jets. Kehein doesn't even make this number I take it. Am I reading into this correctly?

 

I believe correct jetting is very important

 

05 and later 400ex's are jetted extremely lean from the factory. Your 400ex will have come with keihin jets in also so should your crf. The chart reads left to right Example the with of 0,0360 will have a kehein jet number of 95 a dyno jet number of 94 and mukuni of 86. 99-04 400ex come with a stock main jet of 148. 05-up come with 138 main irrc. The chart can be confusing to read becuase of example 157,5 is actually a 158. The pipe is the least cost effective mod but it does free u some power. Don't buy the kits, just buy the keihin jets there alot easier to understand and keep your stock needle and clip. A good airfilter replacement is always a good mod you most likely might need to go up with a jet to compensate for it tho.

 

Have you guys tried the removing the choke performance trick? ATV Technical Article, Honda 400EX Carburetor Choke Removal Instructions

They also have a good understand jetting post. http://www.atvriders.com/articles/jetting.html

 

Reading the chart is confusing with the 172,5. I do know the jets I have for my bike are 168,170,172. Looking at the chart made me feel like the jets are Dynojets. I am getting a twin air filter for it and should be good enough for what I am using the quad for. I know it will not pull like my 450R.

Thanks for the input!