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-   -   XTZ 660 Cutting out when warm (https://www.horizonsunlimited.com/hubb/yamaha-tech/xtz-660-cutting-out-when-47816)

Mike Bubbles 18 Jan 2010 16:14

XTZ 660 Cutting out when warm
 
Can anyone offer advice on where to start looking to solve this problem?

XTZ 660 1992.
The bike generally runs well.
However, i keep having the same problem that has developed recently -

The bike starts fine and runs for about 5 minutes or so (or about 2-3 miles) when it simply stops.

The fuel supply is fine and there's plenty of life in the battery but it simply will not fire up.
The engine is not overheating either.

Once cold again (leave it for a couple of hours) and the bike will start and the same the same thing happens all over again.

I have the full workshop manual and have tested the coil which gives all the proper readings.

Otherwise, I'm stumped!

Can anyone offer any advice on what to look at next?

Thanks
Mike

Jens Eskildsen 18 Jan 2010 17:13

Have you checked the coil and stuff like that just when the bike has cut out and is still warm?

I've heard stories like theese before, I think it's because the ressistance builds up when the things get warm. When cold, theyr're still within spec.

Trix 18 Jan 2010 18:09

check the tank can breath. try opening the fuel cap when it cuts out if you get a hiss sound the there is a vacuum forming in the tank which stops fuel flow had this on a bike a few months back.

Mike Bubbles 18 Jan 2010 19:01

Thanks for the advice

I don't think it's a petrol vacuum problem (although I'd never have thought of this).

When it stopped (yesterday) I checked the tank by looking in it and it still wouldn't start.

I'm goint to strip it down tonight, clean everything and take it from there.

do you know if there is there any way of testing the coil on the bench?

Scottish Sam 18 Jan 2010 21:28

Hi Mike,

If your sure the fuel supply is fine, I would look at the ignition coil. You could check the resistence cold but as it starts the bike when cold this will probably proove to be all well. Checking the resistence when hot should give you some idea as to if this is the fault, although in my experience the time you get to the coil to test it has usually cooled down. A borrowed coil is quite often the best test. Without seeing the bike it sounds very like the ignition coil is breaking down when hot.

Good luck and let us know how you get on.

Cheers Sam.

Champ 18 Jan 2010 23:07

Hi Mike.
The guys seem to have summed things up and can be confirmed by Google,ing

XTZ660 cuts out when warm and won't restart - Yamaha Owners Club

Hope this solves your problem but I think the guys on site have their finger on the pulse
Kind regards
Champ:mchappy:

*Touring Ted* 18 Jan 2010 23:25

Does the choke have any effect.... ??

Maybe its stuck on but unlikely being the plunger type..

HMMMMMM !!

You say you've checked valves and its not vacumn starved either..

Coils can be funny buggers at temperature as can other electricals !

You need to be checking for a good clean spark while the engine is nice and hot (easier said than done I know).

I take it the plug is the book spec too.


How do you know the fuel supply is fine ?? When it cuts out, immeiately try and drain the carb bowl with the drain screw and see that it's full..

Often the bowl can empty and it will trickle fill again and restart in a few mins or hours...

MarkShelley 19 Jan 2010 11:31

Not sure if it can cause these symptoms but the rectifier is a known weakness on these. Mine has been replaced on my `91 model which I have owned for a year.

Pigford 19 Jan 2010 19:39

What with all this damp/salty weather you wanna check ALL the electrical connections linked to the ignition & coils.



A corroded terminal block or connectors could easily cause an intermittent fault, mis-fire, cutting out :(


Undo all blocks/connectors and check for corrosion & tight fit. Check loom as you go for splits, damage or snagged/bare wires.

:thumbup1:

BlackDogZulu 19 Jan 2010 22:05

I'm pretty sure your answer is up there ^^^ somewhere.

I would tackle it in this order:

Ride with the filler cap off to check no tank vacuum (costs nothing)
Check float valve is not sticking and any filters in carb are clean (ditto)
Swap coil with known good one.

My money's on the coil. The symptoms are identical to when I had one go funny on me (in a Land Rover, but same principle). Works 100% when cold, but fails totally when hot. A new one won't break the bank.

The symptoms all point to either heat or a fuel system that can't keep up with demand. The rectifier is unlikely to be the culprit as it is well away from any hot things (well, mine is, 3TB).

britch 19 Jan 2010 22:21

I also feel it will be a faulty coil, I had exactly the same about 15 years ago on a 1 year old GasGas trials bike.
The dealer said there was water in the windings.

My son had the same problem with a Beta-Zero, and that turned out to be the fuel tank breather pipe was crushed and causing a vacuum, but you have covered that
Whilst rectifiers commonly fail, I don't think they will stop it running unless the battery flattens

bacardi23 20 Jan 2010 01:19

Flat battery due to bad reg/rectifier won't cause the bike to die trust me! lol

any of the other solutions seem plausible... check'em! ;)
anything give us a shout!


Vando :innocent:

Mike Bubbles 27 Jan 2010 16:52

Miracle Cure
 
OK guys, thanks for all the advice.

Having run the bike for a few days now, the problem seems to have miraculously vanished.

I stripped the main components of the electrics (coil, battery, etc) and basically gave everything a damn good clean

Checked the plug & cleaned it too (although I'd already done this a week a
ago)

Hey Presto!

still don't know what the original problem was but it seems to have disapeared now

Thanks again to the help in the biking world

Mike (A happy big trailie commuter)

bacardi23 27 Jan 2010 17:06

Probably just some bad connections....


Vando :innocent:


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