hard to start cold, pilot jet?


31 replies to this topic
  • PumpkinHumper

Posted January 20, 2005 - 09:50 AM

#21

Hey Indy and yzman, I read what you said about the 48 pilot and 72 starter jet. Went to the shop and picked them up and wow, what a difference. :cry:
Thanks again, Brock.


They finially see the light :cry:

  • tgodwin

Posted January 20, 2005 - 11:36 AM

#22

OK guys. I was out starting my bike last night, about 40 degrees in garage. I followed your suggested starting proceedure and this is what happens. Fired second kick with choke on, ran, but didn't idle up, then died.

With the choke still on I kicked about 4 more times no ignition. On the 5ht kick I got a good kickback from the bike, Keep in mind I've not touched the throttle since the initial 3 quick blips during the first start.

I turn of the choke and give it a kick and it fires on first try, but dies shortly after. I kick it a few more times (choke off) no iginition.

Choke back on, fires 2nd kick and idles up, runs fine.

Does this sound normal (I'm a rookine afterall). Could I have a problem with the fuel delivery? I'm definitely going to switch out the jets as recommended, just wondering if this may indicate another problem?
Thanks. -Tim

  • PumpkinHumper

Posted January 20, 2005 - 12:35 PM

#23

OK guys. I was out starting my bike last night, about 40 degrees in garage. I followed your suggested starting proceedure and this is what happens. Fired second kick with choke on, ran, but didn't idle up, then died.

With the choke still on I kicked about 4 more times no ignition. On the 5ht kick I got a good kickback from the bike, Keep in mind I've not touched the throttle since the initial 3 quick blips during the first start.

I turn of the choke and give it a kick and it fires on first try, but dies shortly after. I kick it a few more times (choke off) no iginition.

Choke back on, fires 2nd kick and idles up, runs fine.

Does this sound normal (I'm a rookine afterall). Could I have a problem with the fuel delivery? I'm definitely going to switch out the jets as recommended, just wondering if this may indicate another problem?
Thanks. -Tim


That dosn't sound too normal to me. At 40 deg you should need the choke for sure to start it. Although that is not overly cold it is still cold enough to affect jetting. The starting and stalling in cold temp is a symptom of a lean choke circuit. At least bump the starter jet up 1 size at that temp. If it drops under 30 go 3 sizes bigger, or 72 as indy suggested. I went from a 65 to 72 in sub 30 deg weather. Above 30 deg would be a 68. Below 30 deg you may need to go 1 size bigger on the pilot, main, and raise the needle 1 notch. That is what I did. Runs great. But every bike is a little differant. It takes a little experimenting to figure out exactly what your bike needs.

My yz400 is a worn out old war horse. Even with correct jetting it can be a pain to start in the winter.

Hey. Download this excell spreadsheet. Insert your jetting specs and see what it suggests. IT really helped me.

http://motoman393.th.../426jetting.xls

  • tgodwin

Posted January 20, 2005 - 12:44 PM

#24

Thanks YZ. It is new bike to me AND I'm new to biking. Your help is much appreciated.

  • Frostbite

Posted January 20, 2005 - 02:16 PM

#25

If you use my caveman method rather than proper jetting, you have to retwist after it runs and quits. I see that you didn't retwist after the initial start. My guess is that the extra squirt of fuel burns up and then the engine quits, so you have to resquirt. Only resquirt after it runs though, not after the 1st kick if it doesn't fire. If it doesn't fire after a few kicks, pull in the decomp, hold wide open and kick 10 times to clear the engine out and then start from the beginning cold start procedure again. It's important that you don't blip the throttle, hold steady wide open, or the AC pump will squirt in fuel.
You can see that the best advice here is from my fellow TT'ers and not me, and that is to rejet. They make it sound so good I may just have to reorder one myself. I have learned to adapt and settle for whatever works up here but I don't want to fall too far behind in the technology or my posts will get bumped down to TT for dummies. :cry:

  • tgodwin

Posted January 20, 2005 - 02:41 PM

#26

TT for dummies is good for me. It is always good to know the other way around a problem. It surely helps understanding the process and why I'm getting the response I am. Thanks again.

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  • Frostbite

Posted January 20, 2005 - 02:44 PM

#27

Hey. Download this excell spreadsheet. Insert your jetting specs and see what it suggests. IT really helped me.

http://motoman393.th.../426jetting.xls


Hey, the file must've got corrupted when I downloaded it, it only goes down to 20 degrees. Where's the rest??? :cry:

  • Indy_WR450

Posted January 20, 2005 - 04:42 PM

#28

Hey, the file must've got corrupted when I downloaded it, it only goes down to 20 degrees. Where's the rest??? :cry:


Only Frostbite would need a chart that goes down that low!
:D :D :worthy: :cry: :cry: :cry: :cry: :devil: :devil: :D :D :mad: :mad:

  • liv2ride

Posted January 21, 2005 - 07:54 AM

#29

unable to find a starter jet but did have a 48 pilot jet to put in.
tried starting it up on one of the coldest mornings we have had in texas and i'm not sure if the starter gear made it around a full turn before the beast fired right up!!! i am sooo impressed, can't wait to find a starter jet, then it will be perfect.

i live in central tx between waco and austin
where are you texas4play???

  • PumpkinHumper

Posted January 21, 2005 - 08:07 AM

#30

unable to find a starter jet but did have a 48 pilot jet to put in.
tried starting it up on one of the coldest mornings we have had in texas and i'm not sure if the starter gear made it around a full turn before the beast fired right up!!! i am sooo impressed, can't wait to find a starter jet, then it will be perfect.

i live in central tx between waco and austin
where are you texas4play???


You need to rejet for weather there?? Whats the coldest it gets down to there?? Like 60 deg? :cry:

  • darrenTX20

Posted January 25, 2005 - 07:10 PM

#31

I know where the starter jet is, where do you buy them? The Yamaha parts salesmen I spoke to stated there are no options to purchase a different size starter jet, except for stock jet.

  • Indy_WR450

Posted January 25, 2005 - 08:42 PM

#32

Just tell your dealer to order by the part numbers. Dealers for the most part are useless. You have to go behind the counter and punch in the part number for them on their PC ! :cry:

Treebanger posted this a while back:


MAIN JETs

4MX-14943-42-00 .JET, MAIN (#175) AP 1
4MX-14943-40-00 .JET, MAIN (#165) STD 1
4MX-14943-91-00 .JET, MAIN (#168) AP 1
4MX-14943-41-00 .JET, MAIN (#170) AP 1
4MX-14943-92-00 .JET, MAIN (#172) AP 1
4MX-14943-93-00 .JET, MAIN (#178) AP 1
4MX-14943-89-00 .JET, MAIN (#158) AP 1
4MX-14943-39-00 .JET, MAIN (#160) AP 1
4MX-14943-90-00 .JET, MAIN (#162) AP 1
4MX-14943-88-00 .JET, MAIN (#152) AP 1
4MX-14943-38-00 .JET, MAIN (#155) AP 1

PILOT JETS

4MX-14948-06-00 .JET, SLOW (#48) AP 1
4MX-14948-04-00 .JET, SLOW (#42) STD 1
4MX-14948-05-00 .JET, SLOW (#45) AP 1
4MX-14948-07-00 .JET, SLOW (#50) AP 1
4MX-14948-01-00 .JET, SLOW (#35) AP 1
4MX-14948-02-00 .JET, SLOW (#38) AP 1
4MX-14948-03-00 .JET, SLOW (#40) AP 1

STARTER JETS

3TJ-1494F-13-00 .JET (#65) AP 1
3TJ-1494F-12-00 .JET (#62) AP 1
3TJ-1494F-14-00 .JET (#68) AP 1
3TJ-1494F-15-00 .JET (#70) AP 1
3TJ-1494F-16-00 .JET (#72) STD 1
3TJ-1494F-17-00 .JET (#75) AP 1
3TJ-1494F-20-00 .JET (#82) AP 1
3TJ-1494F-18-00 .JET (#78) AP 1
3TJ-1494F-19-00 .JET (#80) AP 1

PILOT AIR JETS

7A9-14943-27-00 JET (#100)
7A9-14943-17-00 JET (#75)

LEAK JETS

4JT-1494F-19-00 .JET (#80) AP 1
4JT-1494F-15-00 .JET (#70) STD 1
4JT-1494F-23-00 .JET (#90) AP 1
4JT-1494F-03-00 .JET (#40) AP 1
4JT-1494F-07-00 .JET (#50) AP 1
4JT-1494F-11-00 .JET (#60) AP 1
4JT-1494F-27-00 .JET(#100) AP 1




 
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