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Bike starts but wont idle, cuts out when not on choke?

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Whosthedaddy
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Joined: 11 Dec 2005
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PostPosted: 14:15 - 28 May 2010    Post subject: Bike starts but wont idle, cuts out when not on choke? Reply with quote
The TRX will start from cold with just a flick of a switch but no sooner started have the revs dropped and cuts out.

If I start with choke then again, fires into action but this time the revs stay at just under 1000 revs / min. A few minutes on the sidestand or even down the road at idle, the revs remain lower than the 'warmed' up idle and have cut out again if not gently blipped.

After a few more miles, no problems, idle at 1,250+ revs.

This is summer? No real problems during the winter as always started on choke, but come on, I shouldn't be needing choke now to this extent?



Its a standard bike with standard cans, service was done a few 1000 miles ago.
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy
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Crafty
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Joined: 24 May 2010
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PostPosted: 15:13 - 28 May 2010    Post subject: Re: Bike starts but wont idle, cuts out when not on choke? Reply with quote
[quote="Whosthedaddy"] but come on, I shouldn't be needing choke now to this extent?



Clealy the engine is saying it does need choke then.
Have you tried starting it on full (or even 1/2) choke & then reducing it to so the engine idles @1500rpm once its running?
Unfotunatly the electronic fuel injection systems have ruined the art of knowing how to start an engine the old skool way Crying or Very sad
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Jesta_ZX6R
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Joined: 23 May 2010
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PostPosted: 15:59 - 30 May 2010    Post subject: Re: Bike starts but wont idle, cuts out when not on choke? Reply with quote
Crafty wrote:

Unfotunatly the electronic fuel injection systems have ruined the art of knowing how to start an engine the old skool way Crying or Very sad


Agreed.

Have you checked the possibility of the usual suspects, ie clogged jets and float heights? If an engine is lean it will run better once hot, if an engine is rich it will run worse when hot, so it sounds like its very lean IMO

Once warm, can it hold revs around 9k for a mile or so, if not it could be fuel starvation, which usually boils down to a kinked fuel pipe
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temeluchus
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Joined: 01 Oct 2008
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PostPosted: 16:15 - 30 May 2010    Post subject: Reply with quote
Yeah make sure its all clean. Factories also often specify leanish settings stock. Try turning out your idle mixture screws a 1/4-1/2 turn.
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Whosthedaddy
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PostPosted: 22:42 - 31 May 2010    Post subject: Re: Bike starts but wont idle, cuts out when not on choke? Reply with quote
Jesta_ZX6R wrote:
Once warm, can it hold revs around 9k for a mile or so, if not it could be fuel starvation, which usually boils down to a kinked fuel pipe


Nope, it cannot hold 9k revs as being the TRX and a twin maxes out at 8.
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy
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Jesta_ZX6R
Borekit Bruiser



Joined: 23 May 2010
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PostPosted: 23:21 - 31 May 2010    Post subject: Re: Bike starts but wont idle, cuts out when not on choke? Reply with quote
Whosthedaddy wrote:


Nope, it cannot hold 9k revs as being the TRX and a twin maxes out at 8.


I see, the max RPM of your bike is not something I am familiar with and so you would have to improvise with a suitably high point in your rev range, perhaps 5-6k would be more appropriate as is the scenario of your bikes capabilities.

The purpose of what I am requesting is that as your rpm increases, as does your fuel consumption, if you have a blockage in the fuel delivery system then your bike will not be able to sustain a prolonged period at the rate of higher consumption. Which will be down to float height being set too low, a kinked fuel pipe or blocked fuel filter.

My money is on float or pilot.
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molex
Renault 5 Driver



Joined: 07 Aug 2007
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PostPosted: 03:45 - 01 Jun 2010    Post subject: Reply with quote
For my experience "opinion" your TRX start air leak.!
better to check the joint between carburetor and engine
is it old enough to replace the parts.?

How to check air leak

https://www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf

good luck.!
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Whosthedaddy
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Joined: 11 Dec 2005
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PostPosted: 07:41 - 01 Jun 2010    Post subject: Re: Bike starts but wont idle, cuts out when not on choke? Reply with quote
Jesta_ZX6R wrote:

The purpose of what I am requesting is that as your rpm increases, as does your fuel consumption, if you have a blockage in the fuel delivery system then your bike will not be able to sustain a prolonged period at the rate of higher consumption. Which will be down to float height being set too low, a kinked fuel pipe or blocked fuel filter.

My money is on float or pilot.


Oh no, the bike will more than happily pull and pull all the way towards a very long way past the NSL and quite comfortably stay there. Not that this is done on a regular basis Officer.

Very Happy

Will have a little nosy today for leaks.
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy
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Jesta_ZX6R
Borekit Bruiser



Joined: 23 May 2010
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PostPosted: 07:47 - 01 Jun 2010    Post subject: Reply with quote
Thats a good point molex, I havent had one before myself, but it would also give the same symptons, you havent made any modifications to the airbox/filter have you?
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molex
Renault 5 Driver



Joined: 07 Aug 2007
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PostPosted: 16:31 - 01 Jun 2010    Post subject: Reply with quote
My suggestion is tie up the pipe intake screw and clamp then test run.
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Old Thread Alert!

The last post was made 15 years, 268 days ago. Instead of replying here, would creating a new thread be more useful?
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