Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /
chappy.jpg

I've got to up jet this thing for the pipe. What kind of jets does it take? same as qt50 by chance? or am I wishful.

Re: The Official Yamaha Chappy (LB50) Thread!!!

What year is that , Jack ?

Re: The Official Yamaha Chappy (LB50) Thread!!!

Looking Sweet!!!!! You'll like that pipe, nice boost in performance everywhere. Ive been eyeballing that MLM rack for sometime, and no that I see it on your bike I NEED IT!!

As far as the jets I don't have a set of QT50 jets to compare. I will say they're unlike any Mikuni jets I have.

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

Just got it today. 1977. That rack is solid. What size main jet is standard on the lb80? I guess I can take carb out and look.

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

ok qt50 jets are round and probably a different size. These look like they are hex jets.

btw, the title says 1976 so I'll check on the bike later for the year to see if they correspond. (edited)

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Jack Rutherford Wrote:

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

> Just got it today. 1977. That rack is solid. What size main jet is

> standard on the lb80? I guess I can take carb out and look.

Not sure, I used a micro drill bit set to upjet mine. Only went up one size, 0.001 with pipe

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /
chappyjets.png

Whaddayaknow? I bought these jets for a pw80 carb and I believe they are the same ones for the Chappy. they must share the same carb. stock main jet on a Chappy lb80 seems to be an 85. So I got a 95 that should be close.

Hunter, sounds like you went to a 90 then. I'll try the 95 and report back. (edited)

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack ,

Here's a list of the models that use the same main jet as your LB50 :

ASSEMBLIES WHERE 127-14143-13-00 IS USED

1976 LB802AC - Carburetor

1976 LB80IIHC - Carburetor

1977 LB802AD - Carburetor

1978 LB50PE - Carburetor

1978 LB802AE - Carburetor

1979 LB50PF - Carburetor

1980 LB50PG - Carburetor Lb50pg - Ph - Pj

1981 LB50PH - Carburetor Lb50pg - Ph - Pj

1982 LB50PJ - Carburetor Lb50pg - Ph - Pj

Looks like you already found that^ out . ;) (edited)

Re: The Official Yamaha Chappy (LB50) Thread!!!

Here's a pic of that^ type main jet . The pic is of a 75 , where that stock is 65 :

(edited)

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

so stock main jet on an lb80 is 65?

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /
gianelli.jpg

found a pic of the Gianelli exhaust others have mentioned in the past

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Jack Rutherford Wrote:

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

> so stock main jet on an lb80 is 65?

Stock for LB50 is 65 , according to the parts fiche .

And , a 1977 LB80-3D supposedly uses a 95 main jet . That differs year and model .

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

right. So I just pulled it out. the plot thickens

chappyjet.png

If I go to babbittsonline.com and look up 1976 lb80. I can choose between a LB802AC model and a LB80IIHC model. I chose the first and then if I click on carburetor, I can choose between the following three choices -

carburetor with standard stock main jet of 65;

carburetor LB80IIAD with standard stock main jet of 90; and

carburetor LB80IIAE with standard stock main jet of 90.

I apparently have the version with the 65 main jet.

just for giggles, I chose the LB80IIHC model as well and have jet offerings of 65, 70, and 75 and all three are listed as standard stock main jet.

Anyhow, mystery solved as to my model which is too bad that I already have 95-105 jets. I'll order a 70 and a 75.

Re: The Official Yamaha Chappy (LB50) Thread!!!

Dirty30 Dillon /

LB80 with a pipe, you may have good luck with a 95.

I pulled apart my Polini'd LB50 and figured out why it had lack-luster performance.

IMG2114379515688142077.jpg

Enlarged ring gaps, not sure if the PO installed off sized rings or what. Honestly surprised it ran. I have 45mm FG rings waiting to go in.

And here's a general shot of the very large ports.

IMG5381351353611694917.jpg

I was running a slightly janky SHA on the stock intake but will be upgrading the carb in the coming weeks.

Re: The Official Yamaha Chappy (LB50) Thread!!!

kevin Smellaflange /

is it easily possible to put a 80cc motor in a 50cc yamerhammer?

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Brent Eaton Wrote:

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

> is it easily possible to put a 80cc motor in a 50cc yamerhammer?

I think this is easily done

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

maybe they sent the wrong sized rings to the previous owner

Re: The Official Yamaha Chappy (LB50) Thread!!!

Dirty30 Dillon /

The LB80 motor swaps right in place. Same as the 3speed semi 50, the 4 speed manual 50, etc

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

so qt50 jets are so close. Other than they are round instead of hex jets, the only other difference appears to be that the threads are different. Damn, that would've been sweet.

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Jack Rutherford Wrote:

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

> so qt50 jets are so close. Other than they are round instead of hex

> jets, the only other difference appears to be that the threads are

> different. Damn, that would've been sweet.

Good to know

Re: The Official Yamaha Chappy (LB50) Thread!!!

Dirty30 Dillon /

> Jack Rutherford Wrote:

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

> so qt50 jets are so close. Other than they are round instead of hex

> jets, the only other difference appears to be that the threads are

> different. Damn, that would've been sweet.

If they have the wrong head and the wrong thread... are they actually close at all?

Jetrus.com has great prices on OEM style jets

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Dirty30 Dillon Wrote:

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

> > Jack Rutherford Wrote:

>

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

>

> > so qt50 jets are so close. Other than they are round instead of hex

>

> > jets, the only other difference appears to be that the threads are

>

> > different. Damn, that would've been sweet.

>

> If they have the wrong head and the wrong thread... are they actually

> close at all?

>

> Jetrus.com has great prices on OEM style jets

Close expect for everything that makes them different lol

Re: The Official Yamaha Chappy (LB50) Thread!!!

> Dirty30 Dillon Wrote:

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

> > Jack Rutherford Wrote:

>

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

>

> > so qt50 jets are so close. Other than they are round instead of hex

>

> > jets, the only other difference appears to be that the threads are

>

> > different. Damn, that would've been sweet.

>

> If they have the wrong head and the wrong thread... are they actually

> close at all?

>

> Jetrus.com has great prices on OEM style jets

I've used and recommended jetsrus .

http://www.jetsrus.com/a_jets_by_carburetor_type/a_jet_kits_a_selection.htm

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

yep jetsrus.com is the only place that seems to carry those jets anymore

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

> Dirty30 Dillon Wrote:

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

> > Jack Rutherford Wrote:

>

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

>

> > so qt50 jets are so close. Other than they are round instead of hex

>

> > jets, the only other difference appears to be that the threads are

>

> > different. Damn, that would've been sweet.

>

> If they have the wrong head and the wrong thread... are they actually

> close at all?

>

> Jetrus.com has great prices on OEM style jets

The difference in the head doesn't matter. I'll check my die set on the threads.

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

well it's probably easier just to buy the right jet.

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

> Dirty30 Dillon Wrote:

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

> SO:

>

> I opened up the trans on my Chappy for the first time, looking to eek

> out the issues I was having, which included the floppy kickstart, bad

> clutch engagement/sticking etc.

>

> For all those wondering, these trans' are very overbuilt, with huge

> gears and really large, robust clutch pads.

>

> As you can see it takes continuous springs like a ZA50/Tomos A35/55. My

> first experiment is going to be cutting these down a bit on the first

> gear to see if it solves my sticking clutch issue. Barring this, Tomos

> springs are actually only about 3/4" shorter... so maybe the stock

> replacements stretched, or the aftermarket stiffer springs will work

> well.

>

> As for the KS lever sag: This was actually a really easy fix. The KS

> shaft has the ability to rotate with out the spring attached. When

> disassembling, it is easy to lose orientation and therefore, spring

> tension. When putting it all back together, rotate the KS shaft

> clockwise until the gear stops itself, and then pull the spring over and

> hook it on the tab that's cast into the case. Excuse my lack of

> pictures, but just remember: all the way clockwise, and then make sure

> the spring has tension on it when idle.

>

> Another common problem I read in this thread and other is the second

> gear shuddering/grinding.

>

> This is most definitely caused by the failed one-way pawls in the second

> gear main assembly pictured below.

>

> While the center, splined chuck is removable and maybe replacable, I am

> thinking that if you have this fail, the best option is probably to weld

> that sucker. Although I am curious whether this means that you lose bump

> start, or the bike now won't roll backwards either...

>

> I am going to attempt to shorten the stock springs and see how that

> changes my first gear clutch engagement. IF positive, I may grab a Tomos

> blue spring and enhance from there. I found that even the way it is,

> second gear kicks in at a good RPM range, so I may leave second gear

> clutch the same.

Very helpful. any report on the 1st gear clutch springs. I'd like to delay the shift to 2nd gear a little longer. I'm shifting right around 20 mph and rpms drop off too much when it shifts.

by the way m10/14 Mikuni main jets are the same as the 127-14143 jets and can be found on ebay. (edited)

Re: The Official Yamaha Chappy (LB50) Thread!!!

Dirty30 Dillon /

Shortening first gear helped take off for sure, but you would need to shorten/change the second gear clutch to delay engagement.

I'm waiting in my intake to arrive and I will be able to get a better feel for the change now that I have proper rings in there

Re: The Official Yamaha Chappy (LB50) Thread!!!

Jack Rutherford /

Right. Spring on 2nd gear.

How much did you shorten 1st gear clutch spring? 1/4"?

Re: The Official Yamaha Chappy (LB50) Thread!!!

Thanks for all these informations

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account