QT50 with fresh engine cutting out

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So I went for my first longer(only went on 2 miles due to this issue) ride this morning.

So I’m about a mile into it and at mid throttle, running good. I hear this sound naaaah followed by a light non breaking pop, bikes dead. So I pull over, give her some throttle and she fires back up, I did this every 1/4 mile headed back home. It’s like I’m fuel starving it or something. I don’t know.

Re: QT50 with fresh engine cutting out

Check for seizure .

Re: QT50 with fresh engine cutting out

I think your forks are on backwards

Re: QT50 with fresh engine cutting out

The forks are on backwards, I did it on purpose, long story. When my powder coat guy gets things done that will change. But for now I needed a brake and didn’t want to argue with the tool store people about the expensive snap ring players I bought that broke first use.

I found a 77.5 main I’m going to swap for the 70 that’s in it now. I’m also going to install a choke and an oem Mikuni(in place of Minky) and see what don’t happen. I do have better exhaust, clean polished ports and new performance reeds in it now. May need a bit more fuel.

Re: QT50 with fresh engine cutting out

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Just seems like a better situation. Fresh Yamaha gaskets, actual Mikuni jets. A choke, so no free flow or leaks.

Re: QT50 with fresh engine cutting out

Seems to run fine now.

Re: QT50 with fresh engine cutting out

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Alright put a new(fresh rebuilt) carburetor with the 77.5 and I made it three times as far before the soft seizing which I think is the term for what I’m having happen. Again it started back up and drove on home this time. So...

Bigger main jet is getting ordered, I’m thinking an 85 or 90 and I’m going to mix my fuel with more oil, maybe 30-1 over 40-1.

Yamaha shop told me 25:1 but that’s insane

What if I got a bigger one of these as well?(see photo) current ones a 40 (edited)

Re: QT50 with fresh engine cutting out

> Geoffrey C Wrote:

> -------------------------------------------------------

>... and I’m going to mix my fuel with more oil, maybe 30-1 over 40-1.

> Yamaha shop told me 25:1 but that’s insane

I used to run Yamalube 2R at 16:1 in my race bike.

Re: QT50 with fresh engine cutting out

The injection runs rich, could well be 25:1 ratio, my Hobbit suggests 25:1 right on the tank, I ran 32:1 in my QT. (no oil injection)

Re: QT50 with fresh engine cutting out

I’m going to try this 77.5 (seemed like a good spare to order being I didn’t know what I was doing). Tomorrow I’ll up the oil in my fuel.

I’m going to check and see if I can get a cooler plug, what’s the coolest plug(that’s good for a 50cc QT50)that’ll still start and run good?

Re: QT50 with fresh engine cutting out

You can go 40:1 50:1, I just use 32:1 because I have a 4oz bottle. :)

Re: QT50 with fresh engine cutting out

> Geoffrey C Wrote:

> -------------------------------------------------------

> I’m going to check and see if I can get a cooler plug, what’s the

> coolest plug(that’s good for a 50cc QT50)that’ll still start and run

> good?

http://www.strappe.com/plugs.html

Re: QT50 with fresh engine cutting out

Years ago I’d got a new outboard motor and was told to break it in(first full tank) 25:1

Re: QT50 with fresh engine cutting out

So what about this little jet I held up a photo of, I never hear of anyone changing that one....

Re: QT50 with fresh engine cutting out

> Geoffrey C Wrote:

> -------------------------------------------------------

> So what about this little jet I held up a photo of, I never hear of

> anyone changing that one....

That's the pilot jet . If the bike idles fine , leave it as is .

Re: QT50 with fresh engine cutting out

Bike idles Just fine.

Re: QT50 with fresh engine cutting out

Jack Rutherford /

No air leaks? Are your seals installed correctly? Leak down test in order?

Re: QT50 with fresh engine cutting out

They sure seem to be installed correctly but I’m going to do a leak down test and see if I’m losing something somewhere.

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