Re: Rebuilding an 84/79 QT50

Jack Rutherford /

Exactly, nothing good comes cheap and easy.

Re: Rebuilding an 84/79 QT50

I have looked all over and for under a $180 I can’t find a way to do a yz60 kit with OEM parts. Would and OEM 60 head help out or is this just a situation where I need to quit trying to be different and get the malossi kit like everyone else?

> Jack Rutherford Wrote:

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

> One reason why that knockoff kit won’t work.

>

> Heads

Re: Rebuilding an 84/79 QT50

Jack Rutherford /

It’s a yt60 or yf60 cylinder you want. Not yz60.

Here’s a post about same topic - problems with these aftermarket cheap top ends

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Re: Rebuilding an 84/79 QT50

Fresh powder!!!!

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Re: Rebuilding an 84/79 QT50

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Getting somewhere....

Re: Rebuilding an 84/79 QT50

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Is this pistons rings in the right spots? Top and bottom that is?

Re: Rebuilding an 84/79 QT50

> Geoffrey Carlley Wrote:

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

> >

> Is this pistons rings in the right spots? Top and bottom that is?

Looks right to me . Treated ring always goes to the top landing .

Re: Rebuilding an 84/79 QT50

I like the black and blue so well that I think I’m going to have my control housings that go on the handlebars done in black and order decals to replace “stop” “start” “run” “horn” “hi” “low” and so on.

I am pretty happy with the way it’s coming together, I’m going to take my time the beat I can and do this thing up right. Over the winter I am going to tear an engine all the way down. Have the cases blasted outside, powdered silver, and have a really good looking ride. I need to find or modify some other metal fenders for this.

Any suggestions. For metal fenders? I guess plastic would work. I’d rather have sheet metal though.

Re: Rebuilding an 84/79 QT50

So although I’d cleaned the engine very well apparently I didn’t do it good enough. So I put new gaskets and a cylinder and head as well as engine covers back on, put the oil pump back on as a seal and will be steam cleaning tomorrow.

I found a tiny tiny chip just where the right side engine cover meets the case toward the front of the bottom. I’m going to get this repaired, don’t need any air leaks or oil leaks(it was holding oil fine so it may not be much to it but I’m going to investigate more.

Re: Rebuilding an 84/79 QT50

Is it wise to powder-coat the head on an air-cooled engine? I would tend to worry about reducing the rate of heat radiation. A black head would radiate heat best, which is why heat radiators in electronic devices are black anodized, but that's not really a coating. Is a powder coating thick enough to prevent good heat conduction?

Mark Kinsler

Re: Rebuilding an 84/79 QT50

I had this exact conversation with the powder coated guy(very large operation) and he said it just depends. My final choice was to not powder coat the head or cylinder. I don’t think it’d hurt a dang thing but it could hold a couple more degrees.

The main issue is this.

On a strictly air cooled 2 stroke like most any of us are running you Produce to much heat, apparently powder coat begins to break down(maybe get soft) at 300 degrees. There is some high heat stuff out there in black.

We talked about this for a while because I was going to go all the way with it but figured I’d ask I’m first and sure enough.

Re: Rebuilding an 84/79 QT50

I haven't seen powder coating used in high temperature applications, now that you mention it. You're supposed to use an oven to set the stuff. I will readily admit that old, overheated, oil-stained bare aluminum is not the most attractive finish we could wish for, but cylinder heads on air-cooled engines lead a difficult life.

Mark Kinsler

Re: Rebuilding an 84/79 QT50

They do, Harley engines take powder well but they run in the 280s Im told, been a while, and that sounds low to me but the powder guy told me thats the case... Our bikes get HOT.... possibly running up to 400 degrees is hell on powder.

Re: Rebuilding an 84/79 QT50

The cylinder head temperature on a properly-running Volkswagen Beetle air-cooled engine (40 hp, 1970) was 410 degrees F, according to the instructions on the cylinder-head temperature gauge I bought from JC Whitney around 1978.

As John Muir said in his iconic VW repair book, it is necessary to cool the burning heart of the beast that bears you.

Mark Kinsler

Re: Rebuilding an 84/79 QT50

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.

Mock up

Re: Rebuilding an 84/79 QT50

Long long way to go, but I like where it’s going

Re: Rebuilding an 84/79 QT50

So I got some really good looking cylinders in today.

I have got to get the drive train(shaft and rear axle) portion for my second bike still.

But I took a few photos around the motor just to see what it looked like again. I’ve got a $350 Treatland order and a $215 EBay order of parts coming tomorrow and can’t wait, should have big things happening this weekend.

No real reason for the photos below but I wanted some frame of reference from where I am now to where I am next week. I’m in the market for a VM18 and MLM Intake it turns out.

Trying to decide color on next bike, yellow seems to be popular, but I think I’m going to do something strange and different. God I wish I could run 20” wheels and tires on these damn things.

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Re: Rebuilding an 84/79 QT50

I had this little issue and the seal went in to far on the right side, but my sleeve allowed me to fix it up.

Thanks to some awesome members here, you both know who you are, I changed both crank seals, honed my bore, set my ring gap, and have my carb ready to go.

I apparently have to purchase an impact screw driver.... then I can do my intake and reeds. But I’ve got a hell of a lot done in two days of work over two weeks(powder coat took some time.

Thanks PD, Thanks Again Jack

Far far from done but I am getting there.

How do you time these damn things?

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Re: Rebuilding an 84/79 QT50

> Jack Rutherford Wrote:

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

> Return the yt60 knockoff top end. That will only fail miserably. Get the

> malossi kit or get Yamaha oem yt60 top end.

^

Re: Rebuilding an 84/79 QT50

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Almost there

Re: Rebuilding an 84/79 QT50

Jack Rutherford /

Timing is set with woodruff key.

Re: Rebuilding an 84/79 QT50

> Jack Rutherford Wrote:

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

> Timing is set with woodruff key.

So if everything went back in smoothly after the seal change, I’m solid?

Re: Rebuilding an 84/79 QT50

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Fresh lube for the trans....

Re: Rebuilding an 84/79 QT50

(edited)

Re: Rebuilding an 84/79 QT50

You can hear the fuel/oil tank ring(no bolts still got to run the harness), sounds like motor noise it isn’t.

Need wheel bearings brakes, a new single throttle cable the choke kept causing grief so I removed and capped the cable inlet for now. I’m happy with it. Huge improvement over how I got it. Tires. Got to get tires. (edited)

Re: Rebuilding an 84/79 QT50

So I got a great engine(this far out of this rebuild)and the stuff all came back good from powder coat.

But now that I’m reassembling all the different components which I broke all the way down s well, I seem to be getting a very good idea of the utter torture this machine must have been run through. Things like brake lines, kick stand springs, hell a brake spring..... Even taking a good look at the tires and seeing the flat contact patches. No wonder I have a set of 99% condition Oem QT brake shoes, the first owner pinched the rear brake cable so hard it never worked again nor is it repairable with any amount of heat or beating, I did try some oil but realized I was wasting my time.

Either way I had to try it out so without brakes of any kind or a twist throttle, I ran some 60lb mono fishing line down the carb slide, tied it off and ran it to the handle bar where I made a crude pull throttle. I went for a little ride. The jets, port cleaning, and exhaust really did give it a good upper midrange boost in power. I used the old show against the front tire for a brake trick. There were no wrecks but I’m pretty impressed.

I took the drive shaft apart to paint the tube housing today, sure was a lot of chewed up black rubber coming out from the pinion shaft..... is there a seal inside that backwards hex key fitting I need to get changed right on out?

Re: Rebuilding an 84/79 QT50

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