Hot starting problem

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redbandit12
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Re: Hot starting problem

Post by redbandit12 » Sun Oct 02, 2016 5:41 pm

Just another question re my bike struggling to start when its hot (leaving for about 20 mins after a run. Switching off then back on is no problem).
Had the carbs off last week, fitted new pilot jets and gave them a check over. Went for a test run, came home and left it for a while. Same problem, only starts with a wide open throttle and just holds tickover.
I did notice that the exup valve didn't reset although it does when cold. Could this have anything to do with it. Just clutching at straws. Maybe the valve is 'nipping up' when hot.
Any ideas ?

Robotnik
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Re: Hot starting problem

Post by Robotnik » Sun Oct 02, 2016 10:25 pm

You could try tapping the float bowls with the handle of a screwdriver in case the float valves are sticking when warm, the vibration of the engine would probably keep them from sticking when it's running.
Neil

Evilchicken0
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Re: Hot starting problem

Post by Evilchicken0 » Mon Oct 03, 2016 6:28 pm

redbandit12 wrote:Just another question re my bike struggling to start when its hot (leaving for about 20 mins after a run. Switching off then back on is no problem).
Had the carbs off last week, fitted new pilot jets and gave them a check over. Went for a test run, came home and left it for a while. Same problem, only starts with a wide open throttle and just holds tickover.
I did notice that the exup valve didn't reset although it does when cold. Could this have anything to do with it. Just clutching at straws. Maybe the valve is 'nipping up' when hot.
Any ideas ?
I'd probably look at the EXUP because you say it didn't cycle when the bike was hot. If it's open it will make the mixture weak so holding the throttle open would work because it the carbs would be using the main jets and slow running. I'm not sure what might be causing this but maybe start with obviously inspecting it. Take the chrome cover off and have a look at the cables - they might need adjusting - and make sure the pulley is returning the closed position when it cycles.

begbie
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Re: Hot starting problem

Post by begbie » Mon Jun 11, 2018 9:19 pm

Old topic I know, I have this same problem on my 5000 mile YB7, did OP ever find the problem

Evilchicken0
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Re: Hot starting problem

Post by Evilchicken0 » Tue Jun 12, 2018 2:09 pm

I don't think so.

Its difficult to know how to advise when you can hear or see the bike .... your engine is a FZR400R SP the 2TK model, ask Desmo on facebook. I'd probably look at the fuel mixture first

begbie
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Re: Hot starting problem

Post by begbie » Tue Jun 12, 2018 2:21 pm

Hoping I have fond the problem, mixture screws were turned 1.5 turns out from seated, after a carb balance
(these were spot on as i done them last year) I ended up setting the screws at 3 turns out i upped the tick over to 1200 rpm and got it really hot on the bench and so far so good.

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Re: Hot starting problem

Post by Evilchicken0 » Tue Jun 12, 2018 6:49 pm

On a 3tj SP it's 2.5 turns out and tick over 1250 - 1350 rpm
try that as a base setting


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