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Some more questions about my DRZ400SM

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I recently tore apart the engine and put it back together. Did some upgrades, new chain, sprockets, etc...

 

Anyways, my carb's jets may be off or something because when I was riding to work this morning, It wouldnt idle at all. I had to rev the throttle when starting up, then keep the throttle revved while adjusting the idle flex screw so as to keep it from dieing. Eventually, the idle screw was adjusted, and it stayed idling, then i backed off the idle screw and it was fine. Whats weird id that it gave me some other problems last week. While I was riding, the bike just died and would not start back up. It would turn over, and crank and crank, but it wouldnt fire up so i had to push it home. Right now it seems fine, just came back from lunch and rode it there and back, but it was definitely not normal.

 

I dont know whats up with the jetting/fuelling, or whatever, but its worrying me. :(

 

My engine mods are:

 

434CC BB kit

stage 1 hotcams

Yoshi RS3 full exhaust.

JD Jet Kit

3x3 mod

 

When i tore everything apart, I cleaned the carbeurator out and soaked the parts in cleaner for quite some time, and ALSO I did the loctite fixes for Stator, flywheel and CS sprocket.

http://www.thumpertalk.com/topic/1082147-some-questions-about-my-bb-kit-and-cams/#entry11552826 is when I tore it all apart and stuff.

 

Any thoughts guys? I might be able to get my buddy's go pro set up on my helmet and see if i can film it acting up if it does so again.

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JD Jet kit in a stock Mikuni carb or Keihin FCR?  I can't remember if it is bad to soak a Mikuni but it is definitely bad to soak the FCR in harsh carb cleaner.

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JD Jet kit in a stock Mikuni carb or Keihin FCR?  I can't remember if it is bad to soak a Mikuni but it is definitely bad to soak the FCR in harsh carb cleaner.

Stock Mikuni, but I didnt soak the entire carb, just took the jets out and screws and made sure those were clean. Seems odd, the bike ran fine the other days for about 2 hours straight and fired right up this morning when i barely touched the button.

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Stock Mikuni, but I didnt soak the entire carb, just took the jets out and screws and made sure those were clean. Seems odd, the bike ran fine the other days for about 2 hours straight and fired right up this morning when i barely touched the button.

hmmm Edited by Subbieman

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I would try a new float valve & seat, then check float height 12-14 mm.

 

Also if not done yet, a manual fuel valve (petcock).

Edited by billdirt1
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I would try a new float valve & seat, then check float height 12-14 mm.

 

Also if not done yet, a manual fuel valve (petcock).

 

Yamaha Raptor would be my recommendation too. Inexpensive, yet works good. :thumbsup:

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Check the condition of the vacuum line and that it is connected properly....

If the bike plays up again turn the petcock to "prime" and see if that makes a difference

Edited by Craigo 485sm

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So i thought I had fixed the issue, but Ive managed to capture a video of at least part of my dillemma. https://www.youtube.com/watch?v=pzCQmga2Irc&feature=youtu.be

 

As you can see, it dies right after turning on and wont idle sometimes. 80% of the time, it starts up right away no problem. The real problem was what happens sometimes when i ride. it will randomly die on me when the rpms get low, like when coasting while holding in the clutch. Anyways, after doing this, several times, I know  that I can repeat some of the issues reliably. The starting thing happens a bunch, dieing when riding happened twice so far, and it also feels a tad weak i think.

 

Im thinking when I took my carb apart and cleaned out the jets, I MAY have mixed one of the other, like putting the pilot jet where the main goes and vice versa. Is there any way to know where the jets in the carb go after taking the carb apart?

 

Thanks!

Gary

 

2nd video. Follow up, a lot clearer voice https://www.youtube.com/watch?v=JB33hkitrbQ&feature=youtu.be

Edited by pwnedbygary

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ImageUploadedByThumper Talk1400334554.372816.jpg

The only 2 you can really mix up would be the main and the starter, but the starter jet is so small you would definitely notice if you mixed it with the main. Starter jet should be a 62.5

Check your valves as well

Edited by Gsxrstuntdrz
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attachicon.gifImageUploadedByThumper Talk1400334554.372816.jpg

The only 2 you can really mix up would be the main and the starter, but the starter jet is so small you would definitely notice if you mixed it with the main. Starter jet should be a 62.5

Check your valves as well

Valves are fine, just took the top end and middle part of the engine apart and it was perfectly in time.

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petcock vacuum line bent or blocked/ crack in line

carb boots letting air in/not set correctly

 

 

?

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when did you tear your engine apart? did it start doing this before or after you did this? i would double check cam timing. also what jets do you have in it right now, needle position?

Edited by fuentes52

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I'm not sure on the jets, p.o. installed the jd jet kit, it ran okay before the tear down. Needle post I'll have to check also. Cam timing was perfect when I put it back together the final time. I added a mcct tho, and it seemed to not be tight enough, and caused some chain slop inside. The acct was put back on and the slop has been removed, so I've just gotta tighten that some more, but the issue still remains where it randomly dies and has a hard time idling and starting even with the acct. I feel like it HAS to be something with the carburetor jets or floats.

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I'm not sure on the jets, p.o. installed the jd jet kit, it ran okay before the tear down. Needle post I'll have to check also. Cam timing was perfect when I put it back together the final time. I added a mcct tho, and it seemed to not be tight enough, and caused some chain slop inside. The acct was put back on and the slop has been removed, so I've just gotta tighten that some more, but the issue still remains where it randomly dies and has a hard time idling and starting even with the acct. I feel like it HAS to be something with the carburetor jets or floats.

ive had that problem with my yz250f it would only run with me on the throttle or choke on its all in fuel and air mixture you should of took a look at the jets when you had them out you can read the numbers on the top of the jets. Cam tensionor really has nothing to do with this problem that just takes slack out of the cam chain it self hence the name "cam chain tensioner". I would take that carb out again verify your current jet settings. With your setting it should be 160 mj 22.5 pj with extended kientech screw #25 pj for stock fuel screw. Blie needle 4th clip. I would do that other wise you are gonna be running around in circles not figuring it out.

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ive had that problem with my yz250f it would only run with me on the throttle or choke on its all in fuel and air mixture you should of took a look at the jets when you had them out you can read the numbers on the top of the jets. Cam tensionor really has nothing to do with this problem that just takes slack out of the cam chain it self hence the name "cam chain tensioner". I would take that carb out again verify your current jet settings. With your setting it should be 160 mj 22.5 pj with extended kientech screw #25 pj for stock fuel screw. Blie needle 4th clip. I would do that other wise you are gonna be running around in circles not figuring it out.

Alright man, will do. I made a clearer set of videos for the problems i was having, care to take a look at these and see if it fits your diagnosis? Also, choke kills the motor, it doesnt change the revs at all, seems to make them lower even.

https://www.youtube.com/watch?v=28XxgRO2JPQ

https://www.youtube.com/watch?v=v5S98WT24qc

Edited by pwnedbygary

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it ran good before the tear down, but you upgraded it during the tear down???

so what did you install exactly?

did you just put the 434 big bore in it?.. and not jet it accordingly 

 

im sorta confused :thinking:

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I tore it down to see if it had the upgrades it was supposed to have, and so I knew what octane to use based on the base gasket size. It has everything the seller said it had so I put everything back together and it seemed okay at first but it now does what you see in the videos now.

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