Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

I pulled that old gasket out and the recessed area where it sits is still all intact which is good.

Is there anyway to clean or possibly burn out the crap inside the exhaust to clear it out while I have it off? I’ve read a few posts about burning it and another about using oven cleaner which I could see working.

E21F77EF-5248-4257-97DE-16A8DE024C69.jpeg

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

I've tried the burn method , but , I like oven cleaner a lot better .

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> P D Wrote:

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

> I've tried the burn method , but , I like oven cleaner a lot better .

Ok great yeah Im going to try oven cleaner and see how much I can get out.

Stupid question.. on the qt50 should the rear brakes be on the right and front on the left like a mountain bike. This one has the rear on the left which seems backwards to me.

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> S C Wrote:

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

> > P D Wrote:

>

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

>

> > I've tried the burn method , but , I like oven cleaner a lot better .

>

> Ok great yeah Im going to try oven cleaner and see how much I can get

> out.

>

> Stupid question.. on the qt50 should the rear brakes be on the right and

> front on the left like a mountain bike. This one has the rear on the

> left which seems backwards to me.

Both front and rear brake controls are on the left .

Anytime you have a question on part placement , consult the parts diagrams .

https://www.partspitstop.com/oemparts/l/yam/5004263af8700209bc7884e3/1984-yamahopper-qt50l-parts

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> P D Wrote:

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

> > S C Wrote:

>

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

>

> > > P D Wrote:

>

> >

>

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

>

> >

>

> > > I've tried the burn method , but , I like oven cleaner a lot better

> .

>

> >

>

> > Ok great yeah Im going to try oven cleaner and see how much I can get

>

> > out.

>

> >

>

> > Stupid question.. on the qt50 should the rear brakes be on the right

> and

>

> > front on the left like a mountain bike. This one has the rear on the

>

> > left which seems backwards to me.

>

> Both front and rear brake controls are on the left .

>

> Anytime you have a question on part placement , consult the parts

> diagrams .

>

> https://www.partspitstop.com/oemparts/l/yam/5004263af8700209bc7884e3/1984-yamahopper-qt50l-parts

Yeah for the brake drum. What I’m saying is the actual brake lever for the rear brakes is on the left and front brake lever is on the right side handlebar which I suppose is not much different than the road bikes and dirt stuff I ride. Difference being the rear brake is normally a foot brake on other stuff.

Got the new crank seals yesterday so hoping to get the crank case right side opened up and swapped out in the next few days. Still waiting on the right side gasket and will need to order one for the left. Is there any issue leaving it open without oil for a few days?

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

I see . Yeah , these little bikes can be set up differently .

And , there shouldn't be a problem leaving it open for a short . All parts likely have a coat of oil on them . Just to keep things cleaner , I usually will drape a big rag or towel over until I can get back to it .

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

Got the right side crank seal swapped out with the new one. Not to difficult, only pain point was the screw holding the plate over the seal under the small gear.

On that small gear, its two pieces and inside the gear itself are little black spacers. Does it matter which way those are in there? Meaning should there be some free play left to right on that small gear when installed like 1/2 inch?

Pics below of new crank seal installed and gear in question above.

2A74CB24-30A2-4A70-A46D-5DD942928EAE.jpeg
A28FF9B5-D412-4F4F-BC8E-377F163E42FE.jpeg

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

Found the below pictures online so I’ll back it off and make sure I have those rubber dampeners installed the same way assuming its correct.

A1629BD8-E86B-4483-AB4E-962FF634956A.jpeg
055D9DD9-B356-4E6D-A997-63DD9D4BBA8E.jpeg

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

welding a pipe on instead of fixing a broken bolt is totally something i would do

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

Got the crank seal replaced, new crankcase gasket, exhaust gasket, and grade 8 bolts instead of screws, cylinder/head all new gaskets and plug replaced. Also switched out the carb and made some adjustments to it. It cranks on first kick now and idles well. Have yet to run it due to storms to see if it loses power.

This bike came without the stock airbox installed. Does anyone know how the hell those go back on? Is it over the axle and between the back wheel and frame? There’s a brake line, oil line etc in that same spot.

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> Yeah for the brake drum. What I’m saying is the actual brake lever for

> the rear brakes is on the left and front brake lever is on the right

> side handlebar which I suppose is not much different than the road bikes

> and dirt stuff I ride.

I can tell you on my yamaha chappy the layout is the same (rear left, front right).

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

I bought a 60cc. Kit off of eBay. It has been great so far. I noticed more power but nothing crazy.

I just put a uni filter and 90degree boot. Im running a 90 main jet and it pulls great. 4 strokes a bit up top all the way WOT, but with it slightly less throttle it keeps pulling well past , 30 MPH on my Champ.

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> S C wrote:

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

> I pulled that old gasket out and the recessed area where it sits is

> still all intact which is good.

>

> Is there anyway to clean or possibly burn out the crap inside the

> exhaust to clear it out while I have it off? I’ve read a few posts about

> burning it and another about using oven cleaner which I could see

> working.

https://www.mopedarmy.com/wiki/Cleaning_the_muffler

Re: 1984 Yamaha QT50 - smokes a lot and loses power on ride

> Brian F wrote:

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

> > S C wrote:

>

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

>

> > I pulled that old gasket out and the recessed area where it sits is

>

> > still all intact which is good.

>

> >

>

> > Is there anyway to clean or possibly burn out the crap inside the

>

> > exhaust to clear it out while I have it off? I’ve read a few posts

> about

>

> > burning it and another about using oven cleaner which I could see

>

> > working.

>

> https://www.mopedarmy.com/wiki/Cleaning_the_muffler

Did this last weekend and it burnt a lot of crap out. Used the old charcoal grill approach and let it sit for maybe an hour before no more smoke or fire was coming out. Once it cooled off I heated it up with the propane flame thrower for about 2-3 minutes until it got red and no smoke or fire was coming out.

After cooling down, blew the ashes out with compressed air. Hung it in a tree with a coat hanger and painted it with black grill spraypaint.

Put it all back on the bike and let it idle for about ten minutes. Haven’t tried it on the road yet due to weather. Hopefully this week.

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