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Bike very hard to start and won't crank with choke on?

By pdee4t,
in 250-530 EXC-F/XCF-W/XCR-W

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pdee4t

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Ok , what is the fuel screw setting ?

mine is 3.5 turns out from fully closed. stock setting as per the manual. i run everything stock or as per the manual. this is the 1st time ive had an issue with it.

Edited by pdee4t
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mojave500

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don't think my bike has a tank filter.

fuel flow from the tank is fine anyway. i think its when it reaches the carby that there is an issue.

there was barely any fuel in the float bowl when i took it all apart...maybe just a few little drops and when i took the fuel hose off when i was disconnecting my carby, barely any fuel came out of the hose(after it had been running for a couple mins and fuel switch in the closed position). usually there is a lot that comes out but tested the fuel switch in the on position with the hose and heaps pours out.

 

what would it be caused from? and would fuel starvation cause low cranking?

You say   (barely any fuel came out of the hose after it had been running for a couple mins and fuel switch in the closed position) that woud be normal..and no fuel restriction would not cause a slow crank,but air restriction could or poor connections ground powers etc could. Check all the major powers and grounds for poor connections.

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pdee4t

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Is this the carb you have?

Part # 72 is accelerator pump.

Also #96 tps sensor.

yeah that's the carb ive got. everything inside the carb seems to work fine. accelerator pump pushes the push rod down and squirts fuel via the diaphragm.

my TPS hasn't ever been touched.

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pdee4t

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You say   (barely any fuel came out of the hose after it had been running for a couple mins and fuel switch in the closed position) that woud be normal..and no fuel restriction would not cause a slow crank,but air restriction could or poor connections ground powers etc could. Check all the major powers and grounds for poor connections.

what would cause air restriction?

just went to the garage and checked all wires/connections for looseness. all are tight. now with carby off bike, the bike cranks just as normal.

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gimped up

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what would cause air restriction?

just went to the garage and checked all wires/connections for looseness. all are tight. now with carby off bike, the bike cranks just as normal.

it may be getting a false reading on the tps.

That could cause it.

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mojave500

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what would cause air restriction?

just went to the garage and checked all wires/connections for looseness. all are tight. now with carby off bike, the bike cranks just as normal.

Plugged air filter,or air not getting around carb-slide in the choke position. Try setting the idle screw up and see what happens during cranking. I had one bike that had a problem with the carb choke circut not pulling fuel when cranking,had to twist the throttle about 5 times to prime carb for it to cold start.

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pdee4t

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Plugged air filter,or air not getting around carb-slide in the choke position. Try setting the idle screw up and see what happens during cranking. I had one bike that had a problem with the carb choke circut not pulling fuel when cranking,had to twist the throttle about 5 times to prime carb for it to cold start.

Ok thanks. I'll try that and see what happens. Thanks so much for all the advice ? its much appreciated.

I remember when I took the carby apart, the butterfly was slightly open. Not sure if that has anything to do with it though?

Edited by pdee4t
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The Spanky

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don't think my bike has a tank filter.

fuel flow from the tank is fine anyway. i think its when it reaches the carby that there is an issue.

there was barely any fuel in the float bowl when i took it all apart...maybe just a few little drops and when i took the fuel hose off when i was disconnecting my carby, barely any fuel came out of the hose(after it had been running for a couple mins and fuel switch in the closed position). usually there is a lot that comes out but tested the fuel switch in the on position with the hose and heaps pours out.

 

what would it be caused from? and would fuel starvation cause low cranking?

 

 

If plenty of fuel flows through the hose coming from the tank, but there is very little fuel in the float bowl, you have a float problem. Either there is trash in the carb inlet, the float is sticking, or the float level is WAY too low.

 

Take the float bowl off, and remove the float. Re-connect the fuel line and turn the petcock on. If there is little fuel flow through the carb, there is trash in the carb inlet. If there is plenty of fuel flow, the float is the problem.

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The Spanky

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 The floating slide seal plate is very easy to install upside down. There is an "M" stamped on the front of the plate that you can see through the front of the carb.... if it says "W"... that stands for WRONG.

 

It's also super easy to install the diaphragms backwards.

Edited by Chokey
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pdee4t

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well i did a clean out and re-tested everything using the reserve tank/switch. i do have very little fuel left in the tank. probably under a quarter(which I thought should still be enough to start a bike).

i am wondering weather that makes much of a difference? when i flick it onto reserve and test the carby, fuel pisses out the bottom with the float bowl off like it should but when i test the carby with the fuel switch in the normal 'on' position, not AS MUCH pours out. just little drops which stop very quickly.

so seeing as i had the choke on with the fuel switch in the 'on' position and not on reserve, being that there isn't much fuel in the tank, would that have been a possible cause of the issue(low cranking/choking the bike for air) with not much fuel left in the tank and choke on?

Edited by pdee4t
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  • 6 years later...
Grand Master

Burnrider

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https://www.dirtbikeaddicts.com/content/threads/bike-very-hard-to-start-and-wont-crank-with-choke-on-urgent-help-needed.7158/page-4

Float level issue? 

I know mine starts in warm weather -cold w/o the choke and I pull the choke to let it idle 20 sec and push it back in for normal idle. The crank speed is not affected.

Edited by Burnrider
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