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Post by petenofear on Jul 21, 2019 19:16:38 GMT 1
I have a rd350 f2
On the fuel tape it’s on, reserve and prime
What’s the prime for and what is off prime seams to be off when I pull pipe off
What I am getting at is when I leave the bike for a wile it seams to flood it’s self out and then when I do get her running she throws the fuel out the exhaust
Any idea thanks
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Post by oldbritguy on Jul 21, 2019 19:37:39 GMT 1
On and reserve are just like normal motorcycle fuel tap settings but require the vacuum pipe connected to the carb inlet and the bike running to allow fuel to flow through the tap. If the bike is not running, there is no vacuum being created in the carb inlet and therefore no suction on the pipe to operate the diaphragm in the tap and no fuel flow.
Prime will bypass the vacuum operation of the tap and allow fuel to flow from the tank into the carbs even if the engine is not running. I believe this was designed to assist cold starting and allow the carbs to fully fill with fuel before kicking it over. Once started, the tap should then be turned to either on or reserve depending on fuel level in the tank.
If the carb float mechanism is sticky or there is some grit preventing the float valve from seating allowing the carb to overflow, the vacuum type tap in the on or reserve positions should prevent the flow of fuel into the carbs when the engine is not running, and flooding the motor when standing stationary as you describe. If left on prime, this may be the cause.
Hope this makes sense
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Post by earthman on Jul 21, 2019 20:05:35 GMT 1
I wish that my 4LO had this style of tap, not that I've experienced float valve sticking and lost petrol but I remember to manually turn the tap to the off position every time I leave the bike. I'm guessing that's why this prime style of tap were invented in the first place.
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Post by petenofear on Jul 21, 2019 20:09:47 GMT 1
On and reserve are just like normal motorcycle fuel tap settings but require the vacuum pipe connected to the carb inlet and the bike running to allow fuel to flow through the tap. If the bike is not running, there is no vacuum being created in the carb inlet and therefore no suction on the pipe to operate the diaphragm in the tap and no fuel flow. Prime will bypass the vacuum operation of the tap and allow fuel to flow from the tank into the carbs even if the engine is not running. I believe this was designed to assist cold starting and allow the carbs to fully fill with fuel before kicking it over. Once started, the tap should then be turned to either on or reserve depending on fuel level in the tank. If the carb float mechanism is sticky or there is some grit preventing the float valve from seating allowing the carb to overflow, the vacuum type tap in the on or reserve positions should prevent the flow of fuel into the carbs when the engine is not running, and flooding the motor when standing stationary as you describe. If left on prime, this may be the cause. Hope this makes sense yes makes since thank you just been out and turn tape to on so will give here today and see how she starts tomorrow thank you for you help pete |
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Post by 4l04ever on Jul 21, 2019 22:38:04 GMT 1
If no fuel comes out when on prime, the tap may be faulty or blocked.
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Post by petenofear on Jul 22, 2019 9:31:58 GMT 1
Fuel don’t seam to come out when on prime but I did forget to turn tape back to on and never ran out of fuel on me so must me working on vacuum or something
Just ordered some new plus last night and going to get her a good service oils ect
As has been off the road since 2015 so very due I would say
Thanks guys
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Post by earthman on Jul 22, 2019 11:54:04 GMT 1
Have you tried rigging up some hose into a clear/glass bottle just to measure the flow?
It sounds like the fuel filter/tap is at least partly blocked to me.
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Post by petenofear on Jul 23, 2019 8:53:38 GMT 1
Not really sure what you meen
The fuel comes out fine on and reserve
On prime it don’t come out when pipe pulled off ,
It’s flooding the engine bad and ending up in the exhaust , carbs are no over flowing
This is all when bike is not running and left over night then she is a right shit to start and when it dose start the fuel in the exhaust just blows out .
If on prime and no fuel coming out why it’s filling up with fuel i don’t no
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Post by 4l04ever on Jul 23, 2019 9:10:32 GMT 1
Maybe some sort of internal leak? Try a different tap??
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Post by headcoats on Jul 23, 2019 9:51:28 GMT 1
Got to be the fuel valves leaking then ?
Even with a dodgy tap the fuel valves should stop the fuel going into the engine
Also are the float heights correct ?
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Post by midlifecrisisrd on Jul 23, 2019 10:55:39 GMT 1
Fuel seeps by the float valves but doesn't cause it to go down the bowl overflows
It just seeps into the cylinders
Had it many times
£20 on a new pair of valves/seats from norbo sorts it fine
Fuel tap not running on prime is another issue
There was a mod you could do on these taps that changed the prime function to OFF to get rid of it
Maybe yours has had it done
Steve
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Post by petenofear on Jul 23, 2019 11:32:20 GMT 1
Fuel seeps by the float valves but doesn't cause it to go down the bowl overflows It just seeps into the cylinders Had it many times £20 on a new pair of valves/seats from norbo sorts it fine Fuel tap not running on prime is another issue There was a mod you could do on these taps that changed the prime function to OFF to get rid of it Maybe yours has had it done Steve Thanks Steve Have a you a link to the part I need I will get them ordered No idea what they are or where they go still learning Thank you |
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Post by midlifecrisisrd on Jul 23, 2019 11:46:09 GMT 1
2 of these from norbo Steve  |
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Post by petenofear on Jul 23, 2019 11:51:38 GMT 1
Thanks steve
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Post by petenofear on Jul 23, 2019 16:07:44 GMT 1
Just got home from work and pulled plugs out
1 barrel is fuel off fuel so can’t see it’s the tape must me the carb
So going to buy the kit your said about Steve and hope it sorts it
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Post by petenofear on Jul 23, 2019 16:33:22 GMT 1
Just pulled one of the carbs off and yes the little O ring is perished ,when I tried to take it off it it’s broke so I hope this sorts my problem,
As for the fuel tape now fairings are off I got a better look and the tape on prime is coming out but just a drip at a time ,
Should I get a new tap diaphragm or should this be fine
Thanks for all your help
Pete
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Post by midlifecrisisrd on Jul 23, 2019 16:54:49 GMT 1
Just pulled one of the carbs off and yes the little O ring is perished ,when I tried to take it off it it’s broke so I hope this sorts my problem, As for the fuel tape now fairings are off I got a better look and the tape on prime is coming out but just a drip at a time , Should I get a new tap diaphragm or should this be fine Thanks for all your help Pete I'd get a diaphragm at the same time from norbo Steve |
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Post by petenofear on Jul 25, 2019 19:15:41 GMT 1
It’s all ordered so hope to be here tomorrow
Then see if I get a chance to fit over the weekend as working
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Post by petenofear on Jul 26, 2019 15:12:33 GMT 1
Parts come today so had a spare hour
All new parts fitted had to take 1 exhaust off as it was full of fuel
First kick and she seems happy
Took for a little ride and all seams fine ,
The test will be tomorrow if she starts then happy days
Thanks for all your help
Pete
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Post by petenofear on Jul 27, 2019 16:52:30 GMT 1
Just been out to start the bike and she fired up first kick
So happy days thanks
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