Author Topic: Main jet size on BWS  (Read 280 times)

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Offline Richard BWS

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Main jet size on BWS
« on: February 22, 2017, 09:13:53 PM »
I was told to fit a bigger main jet (#80) to prevent my motor from running lean< its only fitted with a Leo Vince exhaust and still standard air box. Fuel/air screw is turned out two and a half times and the clip on the needle is in the middle. From 0 to 70km/h the bike goes fine, but if I open throttle further the bike hesitate a few seconds and goes fine after that until 90km/h. The bike also feels like its taking longer to pick up speed. Should I rather try a #75 jet or go back to standard???? (Moenie krap waar dit nie jik nie)


Offline blujeenz

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Re: Main jet size on BWS
« Reply #1 on: February 23, 2017, 03:07:31 PM »
The airscrew is usually only for the 1st quarter throttle and idle.
Id try lifting the main needle higher to see if the mid range hesitation improves before buying a new jet.

Offline Skaap

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Re: Main jet size on BWS
« Reply #2 on: February 24, 2017, 02:58:10 PM »
do plug chops test. what color is the saprkplug buring?

standard size for BWS is 72.5. idd suggest with leao vince pipe, run about a 75-76 main.

who did the carb work?
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Offline Richard BWS

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Re: Main jet size on BWS
« Reply #3 on: February 27, 2017, 09:10:51 PM »
I did the settings, where can I find jets in that sizes, I've    tried Motocomp but no luck :ill:

Offline Skaap

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Re: Main jet size on BWS
« Reply #4 on: February 28, 2017, 09:52:25 AM »
I might have one or two at home. Will check. Otherwise use jet drills. But yamaha should have a size or 2 up from that size.

In the meantime play with the needle.

Are you still using air box? With or without snorkel? Also how dirty is the air filter?
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Offline Richard BWS

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Re: Main jet size on BWS
« Reply #5 on: February 28, 2017, 07:45:54 PM »
I spoke to Andrew today, they can get the jets, but it'll take some time.  Yamaha here in Cape Town only stocks the standard jets #72.5 @ R220 a pop  :sleep:  My air box is still stock standard. Now I want to know if I can use a #80 jet in the mean time (air screw two and a half times, clip in the middle position, standard plug), want to cruise around and look for rain  :pray:

Offline Skaap

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Re: Main jet size on BWS
« Reply #6 on: March 06, 2017, 03:06:14 PM »
you should be fine.

the term 2.5 turns is a guideline.

go for a ride and check what color the spark plug burns. then take a picture of the plug and post it here.
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