42 pilot during the summer

[bmxatv]

Having problems starting in the cold and 99.9% of the people say bump up to a 42 pilot jet. I'm ready to do this but will it be ok for the summer. I bought the bike used a while ago and it already had the exhausty on it. How can I tell what pilot is already in there? Is it labeled?

[hornetgod13]

I have a #42 pilot installed and it ran fine in the summer in 90 degree weather at 265 feet above sea level with the mods in my signature.
If the #42 pilot works in the winter, the only thing you might need to do is turn your fuel screw in a little as the air thins out in the summer. It will work year around.

[YBRIK]

Yes your jet will be labled w/#.
keep in mind dyno jets r diff # scale than (Factory)keihin jets.

[hornetgod13]

Stock jet is #38K
The "K" stands for Keihin

[Ruby Soho]

i have a dyno jet kit installed on mine, so when i buy an exhaust (HMF) i need jets right?

[hornetgod13]

Yes! You will have to install a larger Pilot (40K or 42K) and Main Jet (? size), adjust the fuel screw, and possibly move the "C" clip on the needle.
I only have the DynoJet Needle. The rest of my jetting are Keihin sizes. You'll have to get help from another person that have DynoJet jets. There jet size numbering is completely different than Keihin.

[Ruby Soho]

well if i order the pipe from worldwideperformance1.com and they say they can include jets.. will those work? or should i buy a dyno jet or what...

[AbnMP13]

To convert from DynoJet to Keihin:

Dynojets numbers are simply the hole diameter. A 140DJ main has a 1.40mm (0.055") diameter hole in it at the threaded end. A Mikuni 140 has a 140 cc's of fuel flow per minute. I don't know where the Keihin scale comes from.

Width------Keihin # -- 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

[hornetgod13]

Originally posted by Ruby Soho
well if i order the pipe from worldwideperformance1.com and they say they can include jets.. will those work? or should i buy a dyno jet or what...

Yes you can use those jets. I prefer Keihin jets anyways. You can keep the DynoJet needle installed.