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Old 04-12-2017, 05:01 AM
CRbloke's Avatar
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Default 07 CR 85 fuel problem

     

So I will explain this as best I can
My boys 07n CR 85 is not running properly , it is bogging down badly and has a runny mix of oil and fuel coming out of the pipe , when I turn the fuel off while it is running it bogs down until the fuel is nearly run out and runs perfect then runs out and stops if you get to the point after you turn the fuel tap off where it runs perfect and turn the fuel on again before it runs out it starts bogging down again
to cancel out a few theories this is what I have done
1 , replaced the crankside main seal ( made no difference)
2. it runs boyesen reeds and put the standard reeds back in to see if there was any difference and nothing changed it ran the same way.
3. the jetting is the same as the bike ran all last year and it never missed a beat so I haven't tried some weird jetting set up
4. on that the carby and jets were taken out and was pulled down and blown out with a compresser so its clean.
5. have looked at the float level but this is a sticking point as I don't know the float level at the moment.

Now if you have the seat off and air filter out with the bike not running if you kick it over by hand with the fuel on you can hear a squelching of fuel through the airbox in the Carby now if you turn the fuel off and do the same procedure the squelching stops it sounds like way to much fuel is getting in even if the bike is not going some how

---------- Post added at 09:01 PM ---------- Previous post was at 08:55 PM ----------

P.S the fuel mix is 40 to 1 of motul 800 this bike has run this since we bought it 18 months ago with no problems
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Old 04-12-2017, 10:19 AM
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Do a compression test. It may be low which gives all indications of a rich fuel mixture.
The carb float height needs to be set and the needle valve replaced as it is leaking.

Paw Paw
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Old 04-12-2017, 11:58 AM
gusco's Avatar
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MOST carbs do well with the floats set parallel to the carb body. Give that a shot and see how it goes. It definitely seems to be rich.
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Old 04-13-2017, 04:39 PM
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put a new ring on the piston it didn't make any difference adjusted float level didn't make any difference , the float needle isn't showing any signs of wear at all
Does the air screw mixture needle have an small o ring on it ?
this is driving me insane
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Old 04-14-2017, 07:56 AM
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Default cr85 carb

Seem like the float , inlet valve is leaking , try polishing the seat with some kind of powered cleaner like scouring powder . Use a q tip to get into the bottom . This works well . Also change the mixture needle and main jet ,years of use will wear them out , but the wear cant be seen
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Old 04-21-2017, 05:09 AM
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Ran a all balls carby kit through it and rebuilt the carby THANK GOD IT IS ALL GOOD
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