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Post Info TOPIC: No start issue


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No start issue
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Ok guys im new and i have a 2000 ttr250 and it wont start and didnt when i got it as i had to pull the head and re tap the spark plug hole as someone stripped half the thread. So i replaced the sparky and head gasket i also stripped and cleaned the carby it was full of hardened fuel. It wont start at all not even a backfire i have spark there is fuel coming through the carby and float level is perfect and the valves are moving but the timing on the cams is out a bit from a worn chain. Also the sparky is bone dry even after cranking for ages so i dno wtf is going on and im ready to burn this thing to the ground i need help guys please any help at all 



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sounds annoying .

so 

Good spark , plugs OK ? 

plugs dry , no fuel getting through .

carby drain confirms fuel is getting through to carby bowl 

a bit of cam chain wear shouldn't affect it 

compression OK ? (check with kick start or roll in gear to check for compression ). extreme loss of compression could result in loss of Vacuum and not drawing fuel/air in 

back to dry plug , the carbys are notorious for although appearing clean have still got a bit of crud in the jets ( only bit between the bowl and the inlet tract that could stop the fuel  ) 

 

A check 

a little squirt of fuel through the carby , or a little down the plug hole re assemble and see if it fires a bit . (  the accelerator pump may provide enough fuel with a few quick openings of the throttle then crank ) , if it fires with added fuel again falls back to Jets and or float height .

 

something to consider if the sparks ok 

 

 

 

 



-- Edited by ttboof on Wednesday 17th of April 2019 05:23:40 AM

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Yeah mate just chucked some fuel in the carby and kicked it a few times and i got 1 giant backfire that gave me a heart attack haha but didnt fire up or even sound like it wanted to im starting to wonder if maybe the timing is like 180° out or something


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I can feel the compression but not sure if its as good as it should be

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Nothing like a good bang to confirm you have spark and fuel 

Only way the timing can be out is if you used tdc not the timing marks on the flywheel (on exhaust stroke) 

Sounds like you have OK compression 

Will see what others say but I'm thinking something not 100% with the carby

 



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Yeah i might pull it apart again and try a rebuild kit maybe hopefully that will do something

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See what others suggest it's annoying  but once everything adds up it should go well 

 I'd have a look with you but it's a six hour drive just to get to the Queensland border 



-- Edited by ttboof on Wednesday 17th of April 2019 09:33:45 AM



-- Edited by ttboof on Wednesday 17th of April 2019 09:42:40 AM

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Whenever I need to quickly diagnose a no-start condition (like the one you now have) and the history and condition are unknown, I use a fuel substitution method. Essentially, you separate the engine from the carburetor and air box and leak a combustible gas into the intake boot while cranking. I typically use propane. This is how it works:

1. Remove carburetor from the intake boot and set aside (you don't need to completely remove it, just expose the intake)
2. Using a propane bottle torch (or similar), open the gas valve just enough to leak gas into the intake boot - not much gas
3. Attempt to start the engine 

A few things may happen at this point:

1. Nothing at all (try again or pursue engine diagnostics)
2. Spitting backfires and trying to run (problem likely from intake boot back to air box)
3. Starts up and idles (problem definitely from intake boot back to air box - pursue carburetor and air intake diagnostics)

I hope you find a resolution to this no-start quickly and relieve the frustration that goes with it. Please don't incinerate yourself in the process - seek help if you are uncomfortable with any repair suggestion.



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Fat leopard Cheers mate ill give that a go tomorrow and see how it goes



-- Edited by Evil ttr on Wednesday 17th of April 2019 01:44:47 PM

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You could always try a squirt of Start Ya Bastard in the airbox biggrin

We don't have that in the UK - our equivalent is EasyStart which smells lovely - some sort of ether-based spray I guess.



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i use brake cleaner in a spray

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It's the carb! It's always the carb!! (Well, almost always, assuming the carb boot has not completely failed - but I think you'd have noticed this when pulling the carb off)

If it was full of hardened fuel when you got it it's guaranteed. Full stripdown, ream out the main and pilot jets with copper wire strand, remove and check fuel screw circuit. Ultrasonic clean if you have access to one. Check the pumper diaphragm - this should pump a jet of fuel that you can see from the air filter side when you twist the throttle even if the other jets are blocked.

Then do it all again just to be sure!!

If it was timing I think you'd still be getting a wet plug.

Good luck, and welcome to the forum! Glad your first post gave us something to chew on

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Mossproof i did pull the carb apart completely and use my reamers to clean it out but i think ill do it again today to be sure. Also is there a way to check its definitely firing on the right cycle i tried a timing light in the check hole thingy but no mater how slow i kick it it just spurts a heap of oil out so i cant see if its firing on the correct cycle.

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I am pretty sure the TTR operates on a "lost spark" system such that it fires every revolution and the spark on the exhaust stroke is "lost".

What might have happened is that the valve timing is out. Check the photos on here to make sure that the cam lobes were facing outwards when you timed the sprockets up.



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TTRfan ok awesome so atleast i know its sparking either way haha

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Agree with the carb comments. I'm not convinced you got the carb done (because I've had the same experience). My 2 cents, worth exactly 2 cents, is buy the All Balls rebuilt kit with OEM jets.

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PlumasDude yeah ill be pulling the carb and rebuilding it. Also guys a friends old man said something about checking the airflow chamber gasket anyone know what that is or where it is

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Ok i tried the fuel straight in the intake with no carby and nothing definitely has spark and definitely firing on the comp cycle also checked valves specs in pic and also checked cams at TDC and i think the chain is well worn looking at it level would that make much difference 



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Evil ttr wrote:

PlumasDude yeah ill be pulling the carb and rebuilding it. Also guys a friends old man said something about checking the airflow chamber gasket anyone know what that is or where it is


 Think he might be talking about the inlet stub, looks like this

Carb Stub / Inlet Manifold - genuine Yamaha part



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Oh ok yeah that was separated but i gooed it together with fuel safe gasket goo and also put a hose clamp on it so it should be fine

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