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Serf27 |
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Serf27 Derestricted Danger
Joined: 15 Dec 2016 Karma :
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Posted: 04:35 - 28 Sep 2017 Post subject: Yamaha 450 backfires flame & no idle. |
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Hi again everyone!
2013 YFZ 450, not exactly a 2 wheel bike, but hopefully I can get some help on it please, it's driving me crazy.
Short story,
Stock jetting from factory is 152.5 Main jet, 47.5 pilot, 55 power jet.
Mods, K&N filter full pro circuit t4 exhaust.
Re-jet to, 162.5 main jet, 50 pilot jet, power jet stayed the same(55)
Sometimes it will idle, and if I slowly accelerate, it will take off and run fine till I stop. In neutral, it used to rev up ok. Other times, it will just bog and go about 5 miles an hour if I punch it or even if I slowly accelerate, which it is constantly doing now, back fires and shoots flames.
Now it won't idle, and if I get it to idle, and rev it in neutral, it just bogs and rarely revs up. Spits fuel into the intake side of the carb and gets fuel into filter air duct.
Any ideas?
Long story.
I got the quad and it didn't idle, and ran ok, same bogging at wide open throttle, had to slowly accelerate to get full power.
Cleaned the carb, cleaned the filter, put A/F screw 2.5 turns out, upped main jet to 162.5, pilot jet at 47.5 and would idle, if I slowly accelerated, it would run fine. When slowing down around corners, if it would bog, I would hold the clutch in, rev up the engine and release the clutch and it would take off, still shot flames.
Nearby shop said the diaphragm spring was either to weak or too strong, tried weaker and stronger spring, seemed to make it worse either way, put stock spring back in, now it wont even idle and won't ride like it did the other day.
I put stock main jet in, no difference, still rarely revs up in neutral.
The only difference from the other day when it ran alright, (still had to slowly accelerate or rev up with clutch engaged and release clutch) is I changed the pilot jet to a 50.
But today, it was running okay, would take off at a decent speed, and idle. Took it to the trails, and it just stopped idling or moving.
The shop is telling me to get the older style carb for it. I plan to get it, but i just want the bike running good till I get the older stayle carb.
Any ideas please?? Really want to take this thing out night riding tommorow.
Thank you in advance. |
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 08:55 - 28 Sep 2017 Post subject: |
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Carb settings don't suddenly alter themselves so if it was running properly before, fucking with the jetting/screws/springs in the carb is going to make no difference. Yes if there was dirt in the carb but this would have been fixed first attempt. Incorrect jetting wouldn't cause intermittant problems, it would be consistant.
90% of carburettion problems are electrical. People mess with carbs because they don'tunderstand electrics.
From your description of what's happening, I genuinely wonder if it's spun the flywheel. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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Serf27 |
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Serf27 Derestricted Danger
Joined: 15 Dec 2016 Karma :
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Posted: 19:40 - 28 Sep 2017 Post subject: |
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Thanks for the reply.
I agree that carb issues would be consistent.
The only electrical part on the carb is the TPS sensor, it runs the same way with the sensor connected or not.
Is there anyway to check if the flywheel has spun?
I've probably rode the bike 1 good hour since I've got it.
It didn't run right, but was good enough to get through that ride, now this. |
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stinkwheel |
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stinkwheel Bovine Proctologist
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Serf27 |
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Serf27 Derestricted Danger
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 09:22 - 29 Sep 2017 Post subject: |
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To be frank, I'd go with the $200 to get it up and running.
I'm not saying it's definately ignition timing but as I say, an electrical problem is more likely given what you've described. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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Serf27 |
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Serf27 Derestricted Danger
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Old Thread Alert!
The last post was made 6 years, 140 days ago. Instead of replying here, would creating a new thread be more useful? |
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