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AB
14th November 2022, 02:18 PM
Another quality Patrol question coming up lol

Before I take it to our local mechanic I want to have one last crack at trying to fix Lachys quad bike.

4 stroke Yamaha YFZ50 quad bike, fairly newish.

He rides it a lot but the other day it just stopped and I won't start again.

I noticed a heap of fuel coming out of the carby drain hoses too when it stopped.

It looked low on fuel so I topped it up and it never ran again, electric start, engine cranks but no firing.

Air filter all good.

So fuel was coming out of the carby drain pipe when it stopped running but doesn't do it anymore.

Checked spark, and even replaced spark plug.

Drained the carby, etc and still no joy.

Fuel is on and flowing through carby.

The fuel is fresh and not contaminated as i used the same jerry can in my ride on mower and that's been running fine.

I'm assuming something has gone wrong with the carby, like the float stuck open, but I'm not a petrol guy and not overly confident in pulling apart a carby.

Is there anything else I can try or do all the signs point to something wrong with the carby?

BrazilianY60
14th November 2022, 03:48 PM
My bet is on the carby. Obstructed for fuel somehow.

mudnut
14th November 2022, 05:20 PM
Humour me and try a bit of Start Ya Bastard into the throat of the carby. If it fires, then you know everything else is fine but for the carby.

AB
14th November 2022, 05:28 PM
Humour me and try a bit of Start Ya Bastard into the throat of the carby. If it fires, then you know everything else is fine but for the carby.

Yes, I do need to try that and completely forgot about the start bastard. I’ll get back to you on that one, I need to buy some.


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Plasnart
14th November 2022, 11:02 PM
Pull it's heart out and squirt carby cleaner through all the ports. Flush the bowl, don't worry about the floats, put it back in, and start it up!

mudski
15th November 2022, 07:21 AM
Pull it's heart out and squirt carby cleaner through all the ports. Flush the bowl, don't worry about the floats, put it back in, and start it up!

Yep. Theres not a lot to a carby. Open it up, use some compressed air in the fuel jet(s) to blow out any crud and give the carby a clean. Will be a simple job mate.

BillsGU
15th November 2022, 11:32 AM
If fuel was flowing out it could be the needle and seat that is blocked or held open. If it doesn't shut properly the carby will flood and the engine won't start. Usually an easy fix to either clean out or replace. Just follow the fuel line into the carby and the needle and seat is usually the first item you come to.

mudnut
15th November 2022, 12:13 PM
They're on the money. Unleaded produces a lacquer type substance when it dries out. It can cause plenty of problems. You might need to pull the fuel line off and check there is no crap in it, too.

AB
15th November 2022, 05:02 PM
Thanks for your help gents, it’s all working!

I just sprayed a tiny bit of carby clean lol down the carby and it fired up quietly and runs like a dream!

Must’ve dislodged some gunk etc.


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