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Mechanics 101 Can't get it to run right? Find a trick to add HP?
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Old 10-11-2017, 09:00 PM   #1
XSocialx
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Are the carb diaphragm slides supposed to lift up and down when you try turning the engine over?

My bike starts up if I spray gas into the intake. Once it's warmed up I can shut it off and start it up no problem.

I've just replaced the oil, plugs , oil filter and oem air filter.

Bought the bike last week, I've torn down the carbs and rebuilt them. I haven't synced them yet and I've heard that can be an issue as well.

I'm going to eliminate any vacuum leaks I have this week. But I'm pretty confident the diaphragms used to move up and down when I cranked the motor before I rebuilt the carbs.
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Old 10-11-2017, 09:20 PM   #2
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They can flutter up and down. open the pilot screw to 2.5 turns out?
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Old 10-11-2017, 09:49 PM   #3
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Originally yes bit it ran a tad rich so I backed them off a 1/4 turn.

I've got it running nicely when it does get running. Bit of a rev hang, seems like a vacuum leak. I hate this stock airbox system it's so prone to leaks.

I've read that if you drain the floats and turn your idle adjuster all the way out and try to start the bike unsuccessfully it means your (I think he said) pilot jets are bad.

Last edited by XSocialx; 10-11-2017 at 09:49 PM.. Reason: Automerged Doublepost
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Old 10-11-2017, 10:05 PM   #4
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Sync the carbs
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Old 10-12-2017, 02:05 AM   #5
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If you drain the floats, yes you're gonna have a hard time starting. Them carbs need fuel!
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Old 10-12-2017, 06:17 AM   #6
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I thought that was a mute suggestion... draining the float bowls. Lol

I'll sync them today hopefully. So to be sure the slides don't have to be moving when I'm turning the engine over? Any idea why it won't start?

It sounds like it's not getting fuel, just clean cranks not even a burp. Initially there is a burp but I think that's just from residual fuel left in the cylinder or something.
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Old 10-12-2017, 06:44 PM   #7
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hanging idle is lean condition.

less than 2.5 turns generally will mean lean on US and CAN models.

If the a/f screws are turned out further than 2.5 turns, and no change... all the way up to 4.5 turns out... then THAT would be a clear indicator that the pilot system is clogged up.

Sync is really important, and out of sync is a vacuum leak.

Cranks but no start could be a weak voltage issue at the coils. Check voltage 3 times at 2 locations. 1- Key off. 2 Key on. 3 Starter turning the motor over. Locations at the battery positive post, and the coils.

If you see more than 1v variance from key off battery post to the starter turning the motor over at the coils... then you probably have an issue.

Under 11v at the coils when the starter is turning the motor = start will turn and turn but the engine will never start.

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Old 10-12-2017, 10:09 PM   #8
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Thanks for the info guys!

I haven't been able to sync the carbs. I'll either have to make a monometer, take it to a shop or buy an expensive tool.

I'll check the voltage too, thats great information thank you. I actually turned the idle screw, what seemed like most of the way, in and the bike started up. Is that more indication of a vacuum leak?

I've got new o rings coming for the mounting flange on the cylinder head. Although I did spray test those areas and didn't find any surging. The flanges themselves and the carb-to-airbox boots are pricey... Is there an aftermarket airbox that's easier to install? I feel like those boots are so prone to leaking.

I can get it to idle nicely and it drives really well. Before it would surge but I adjusted the idle screw a bit and cleared that up. But still at idle if you blip the throttle it climbs to about 3k and bounces slightly. If I give it a clean rev to about 7k it will come down to normal idle (1,200rpm). But if you blip it, it goes to 3k.

Last edited by XSocialx; 10-12-2017 at 10:12 PM..
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Old 10-13-2017, 08:18 AM   #9
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Quote:
Originally Posted by XSocialx View Post
Thanks for the info guys!

I haven't been able to sync the carbs. I'll either have to make a monometer, take it to a shop or buy an expensive tool.

I'll check the voltage too, thats great information thank you. I actually turned the idle screw, what seemed like most of the way, in and the bike started up. Is that more indication of a vacuum leak?

I've got new o rings coming for the mounting flange on the cylinder head. Although I did spray test those areas and didn't find any surging. The flanges themselves and the carb-to-airbox boots are pricey... Is there an aftermarket airbox that's easier to install? I feel like those boots are so prone to leaking.

I can get it to idle nicely and it drives really well. Before it would surge but I adjusted the idle screw a bit and cleared that up. But still at idle if you blip the throttle it climbs to about 3k and bounces slightly. If I give it a clean rev to about 7k it will come down to normal idle (1,200rpm). But if you blip it, it goes to 3k.

Blip it and it hangs... lean idle.

Hard to start but starts fine when warmed up... voltage.

I'd check and fix voltage first, then set the a/f screws correctly, then sync the carbs.

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