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

> Eric Migliorino Wrote:

> How did you break in the Polini kit? The manual states not to go over

> 3/4 throttle the first 500km which is a little over 300miles. Seems

> sort of excessive but maybe I’m wrong?

>

To break in the kit I just let it heat cycle a few times. Fire the bike up, let it idle, get up in temp to around 180*F, then shut it off. I did that maybe 3 times. For the few days after that id take it around the block, more or less lugging it, keeping the bike under 15mph. After a couple days of cruising around the neighborhood I took it along the beach after work every other day (25mph speed limit) and ran it from 15 to 25mph trying to vary the speed. You're right the break in period is 500-600km I don't remember which. It seems the kit gets more powerful with every ride, and the cylinder head temps have dropped almost 20*F since installing.

>

> Are you getting mid 30’s with the tiny LB50 stock carb??? I couldn’t

> get my LB50 to work well with the stock LB50 carb, Polini kit and MLM

> pipe combo. Didn’t spend much time trying to re-jet and time since I

> had an LB80 carb I knew I put in it.

>

Yes that speed is with the stock LB50 carb, Polini kit, "hi compression head" and a modified stock pipe. I have to go back and look through this thread but I believe I settled with a 72 Jet. It's maybe a little on the rich side by a jet size or two, sustained wide open pulls will never go above 330*F. The Chinese PW80 clone carb I got yesterday from amazon measures 15.2mm in the center of the Venturi. The slide measures a hair over 17mm so I have room to open it up and not bleed around the slide which is what Im going to do this weekend. I was hoping this carb would have a throat closer to the 19mm stock LB80 carb, but 17mm will have to do for now until I can get ahold of an LB80 carb or a clone carb with a bigger throat. 15 to 17mm is a good start anyways, almost a 30% increase in area. That would work out to a nice boost in performance assuming the velocity in the Venturi doesn't fall off at low speed. We will see. I will report back here and on youtube with any findings, I'm most interested in boosting acceleration.

>

> Let us know how the PW80 carb works out. Does the stock carb/frame

> cover work with it? Did you need to re-jet? It should come with a 120

> main jet. I have an older LB80 carb up-jetted to a 95 jet in mine with

> the Polini kit. And when I say older style, it’s the LB80 carb that

> comes stock with a 65 main jet and has the single black plastic float.

>

Im not sure yet but my first impressions would say yes it fits under the plastic trim. Thats my top concern. I would have splurged on the VM20 intake and carb but I want to keep it mostly stock appearing. My clone carb jet isn't marked but I will post final jet size (micro bit size) when I settle on one.

> Are you keeping the oil pump hooked up or running premix? I was

> thinking of pairing a PW80 carb with the PW80 oil pump, thinking the gas

> to oil output we be in line with what the Yamaha engineers originally

> developed.

>

Im still running the stock injection pump with yamalube 2S. Judging by smoke alone, this pump is more than adequate for this application. Like I said above cylinder head temperatures are relatively low during sustained wide open pulls. It appears from both my Chappys, the bikes are over oiled. Its my understanding Yamaha squirted a little extra dinosaur juice to ensure a long healthy life.

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

> Hunter Skiff Wrote:

> Yes that speed is with the stock LB50 carb, Polini kit, "hi compression

> head" and a modified stock pipe. I have to go back and look through this

Hunter, i'm curious about your stock pipe mod. did you open it up and drill it out? if so what was the design like inside?

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

The stock pipe is separated into 2 sections with a wire mesh. The only way exhaust can move from one section to another is a single approx 1/2 size hole. As exhaust leaves the second section it makes almost a 90* turn and exists through the spark arrestor. upon the removal of my spark arrestor, the 90* ebow I mentioned was almost entirely plugged with thick oily carbon. My only modifications to the stock exhaust was removal of the spark arrestor and I drilled a few holes in the mesh divider between the two separate sections of the pipe to aid in airflow. The bike picked up power everywhere, but most noticeably around 25mph it starts to pull like it has an actual powerband. Then theres a lull from 32-36, then a second power band to 40mph or so. Ive attached some pictures showing the exhaust before and after the modifications. I will try and video document the LB50 this weekend

IMG_1020.jpg
IMG_1019.jpg
IMG_1021.jpg

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

awesome pics. this could be a way to pick up a little extra puff! i love the way the oem muff fits into the frame and i'm reluctant to lose that.

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

It made a noticeable gain in performance, mostly on the big end. I would have loved to have tried the modified pipe on a bone stock LB50, as in my case I had already installed the polini kit. None the less the stock modified pipe is a happy medium as it provides performance and keeps the original look. As soon as the MLM People's pipes are back in stock I plan on picking one up to see if further performance can be gained. Other people in this thread have suggested it actually kills power, so this will be interesting to test.

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

Eric Migliorino /

Hunter,

I did exactly what you wanted to do and filmed it. Just need to edit and put on YouTube. I did test - bone stock LB50, modified stock exhaust and MLM pipe.

Results as follows:

Stock pipe - 23mph, decibels at idle ~70 and decibels rev’d up ~100

Modified stock pipe (no spark arrestor and think the muffler is hollowed - bike came with pipe already modified) - 27mph, decibels at idle ~ 100 and decibels rev’d up ~130. Obnoxiously loud but best pick up.

MLM pipe - 28mph, decibels at idle ~75 (close to stock) and decibels rev’d up ~110.

Was a little louder than stock but not obnoxiously loud plus it sounds nice and throaty. Pick up seemed about the same as modified stock maybe a hair less. Power band seems a little more tuned, meaning it takes off as the engine rev’d higher. The modified stock just created less back pressure so not as noticeable power switch in the higher rev’s.

If it weren’t so obnoxiously loud, I’d consider saving some $ and keeping the stock look with the modified stock pipe .

Eric

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

good feedback eric. i'm gonna crack open the oem muff myself and take a poke around. maybe there's a way to not quite gut it, something more like what hunter did, to get a middle ground. i wonder if we can swap out the arrestor for a proper glasspack?

on a different note, has anyone replaced the rear spring shocks on their chappy? if so what did you go with and what are your thoughts? i think the oem KYBs have just about had it and i'm getting too much bouncybounce for my tastes. there's a plethora of 280mm options (including those blingy chromed ones on treats) around so i'm interested in 1st hand experiences.

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

Jack Rutherford /

> Eric Migliorino Wrote:

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

> I took a closer look at the two stators. The key difference between the

> two (other than the stator plates being slightly different) is that

> there are 3 wires coming off right hand coil on the LB80 - yellow, green

> and green with red stripe wires, plus the 4th black wire coming from the

> condenser. The LB50 will have 2 wires coming off the right hand coil -

> yellow and green with red stripe plus the third wire is the black coming

> off the condenser.

>

>

> 2. Making changes to the LB50 stator. Disconnect the right coil from

> the left coil (Small black wire connecting right coil to left). The

> left coil wire attaches to the bottom screw holding the coil to the

> stator. The wire coming off the wire winding on the right would tie

> into the extra green wire you have. Just closely follow what you see on

> your LB80 coil and do the same to the LB50 coil. Also use a multimeter

> to test for direct shorts (no resistance = Short). This will hopefully

> avoid burning out any of your wire windings.

>

> Hope this helps, keep us posted as to how things work out.

>

> Eric

Eric, I've taken a closer look at what you wrote above and I think I'm going to give it a try. My lb50 stator is slightly different than your description of yours. Let me get some pics and post.

lb50stator1.jpg

shows black wire attaching two coils and lighter wire going to condenser

lb50stator2.jpg

just shows black wire attachment to rear of left coil (edited)

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

Jack Rutherford /

In thinking about this some more, are you sure I should cut the black wire attaching the two coils together. Wouldn't I be cutting power output in half by doing so? Maybe I should just splice the green wire in there somehow and not disconnect the two coils or am I misunderstanding? I'm not too familiar with stators but they seem fairly simple. (edited)

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

90% done with the PW80 carb swap. Just have some fine tuning to do, as well as hook up the factory choke mechanism. In general it has been an overwhelming success. I have decided to postpone my youtube video slightly until I can re-gear the bike. The bike currently has 13/28 gearing, and can now EASILY pull off 14/28, but I may go as far as 14/25.

For starters, I bought a clone replacement carb for a PW80 off amazon, so keep that in mind as your milage may very. To make the factory throttle cable work you're going to need to make a sleeve, as the factory carb uses a brass tube with adjustment nuts. I was able to make one out of a stainless rod (see attached photo) and mimic the factory bend. This was not only important to make the throttle work, but to allow the factory plastic cover to be used. I had to also modify the plastic insert that came with the carb. The one that slides over the intake. It had to be made slightly thinner, easy work with a Dremel tool or similar. Thats about it. Although I have not looked it up yet, the choke mechanism seems to be a direct swap so thats a relief.

The motivation for this swap was to boost performance of my LB50. I remember in the early pages in this thread it was stated that the stock carb bore size was 15mm. However, my stock carb measured 11mm (see attached). This explains the terrible transient response that comes with modifying other aspects of the bike while retaining the stock carb. My PW80 clone carb measured 15.2mm, but I proceeded to work the throat and was able to increase the bore to 17.6mm (see attached, its much smoother than how it appears in the photo). Your slide diameter is the limiting factor here so you cant go too big.

Jetting is still being dialed in but HOLY COW what a change. Acceleration is MUCH improved. The bike takes off like a rocket, hardly falls on its face after the 1-2 shift, and screams right up in RPM. As I said above I am going to try taller gearing as the bike can definitely tolerate it at this point. This carb has really complimented the Polini Kit and Modified stock exhaust. (edited)

IMG_1244.jpg
IMG_1252.jpg
IMG_1208.jpg

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

Jack Rutherford /

nicely done!

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

Eric Migliorino /

Hunter,

Thanks for sharing! There are many of us that want to upgrade our carburetors while still keeping the stock carb/frame cover, plus having something we can easily source. LB80 carbs are hard to source and even harder is finding one in good shape. Not all parts are available to replace, so it’s hit or miss when you buy one used.

How did you bore the carburetor throat? Did you use a drill press? What size bit? Any other tips like using pipe thread oil? Did you need to smooth out what you drilled and how?

Once you get jetted properly, what jets and air filter set up do have?

BTW - Treats has a 20% off coupon but the MLM pipe is still out of stock. Thinking they want to get rid of the more expensive Scorpion pipe. Thinking we should come up with a standard pipe mod too!

Thanks again Hunter.

Eric

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

Eric,

For enlarging the throat I use the standard fare of carbide bits for my dremmel tool to get the bulk of the material removed. I spray WD40 every minute or so just to keep the bits from gauling with aluminum. After the shape is roughed in, I go in with a 100 grit sand disk, then finish with a 400 grit (the finest I have). Its tedious work but its easy. Maybe practice on a spare junk carb you have lying around. If it is your first time I would make a guide out of a wooden dowel. Basically just a little stub of wood the final size you want the throat to be. It'll help gauge your progress as well as ensure the Venturi is still round. As mentioned above youre limited to widening the throat by the size of the slide. Going larger than the slide and you'll bleed air around the slide and the carb is practically junk. Take your time and it'll turn out okay.

I would like to stress though, that assuming your stock carb measures 11mm as mine did, the PW80 clone carb off amazon measures 15.2mm. This alone would be a huge step in the right direction even in its stock form. I want to say the carb was $23 shipped, and appears very well built compared to come other clone carbs ive bought in the past. Hope this helps.

~Hunter

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

>

> BTW - Treats has a 20% off coupon but the MLM pipe is still out of

> stock. Thinking they want to get rid of the more expensive Scorpion

> pipe. Thinking we should come up with a standard pipe mod too!

>

Send Benji over at treats an email asking for some more of the MLM people's pipes! I emailed him several weeks back and he informed me that he would put an order in for some more, but they have yet to materialize. Some pressure and emails showing interest in what's probably an otherwise seldom used pipe might get them back in stock sooner!

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

shayne zroback /

We need this

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

Eric Migliorino /

Jack,

My thinking was to disconnect black wire attaching the two coils and using that wire off the left coil to tie into that extra green wire. The wire on the right coil would need to tie in somewhere. I’ll take another closer look between the two stators I have, one being from an LB50 I have in pieces and the other for an LB80 I have in pieces.

If you have a flywheel puller and an impact driver with Vessel JIS tips, you can easily pull your LB80 stator and mimic LB50 stator to be like the LB80 stator. Remember the extra wire is because the 3 position key switch - off, run without lights and run with lights. The LB50 it off or run with lights on.

Eric

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

Chappy PW80 Carb Swap and Ride

The first half of the video shows off the performance of the LB50 with the polini kit, modified stock exhaust, and jetted factory carb.

Second half of the video shows off the same LB50 but with the PW80 carb installed. Hopefully the change in performance is as dramatic on video as it is in person. Next stop, taller gearing!!

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

Awesome video, very helpful. Will be applying these findings to my (2) LB50s!

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

Jack Rutherford /

> Eric Migliorino Wrote:

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

> Jack,

>

> My thinking was to disconnect black wire attaching the two coils and

> using that wire off the left coil to tie into that extra green wire.

> The wire on the right coil would need to tie in somewhere. I’ll take

> another closer look between the two stators I have, one being from an

> LB50 I have in pieces and the other for an LB80 I have in pieces.

>

> If you have a flywheel puller and an impact driver with Vessel JIS

> S tips, you can easily pull your LB80 stator and mimic LB50 stator to be

> like the LB80 stator. Remember the extra wire is because the 3 position

> key switch - off, run without lights and run with lights. The LB50 it

> off or run with lights on.

>

> Eric

Don't kill yourself over it. I really think my buddy should just buy the correct stator. I've pulled the stator several times so it's no big deal. I even changed the left side crank seal on my bike while I was at it. My last attempt involved taking the lb50 stator and just connecting a 'Y' in the wiring from the yellow stator wire to the green and yellow wires coming from the bike. No go. And who knows if the lb50 stator I have is any good. Coil could be bad.

For future reference, Yamaha made several bikes that used this or a very similar stator - FS1, QB50, GT50, GT80 and it appears the Champs stator is similar but 6 wires.

I think I've only had the lb80 and lb50 stator side by side once or twice. I would probably need to pull both stators and get them side by side again. At this point, we know my buddy's bike runs with my stator which is probably good enough. He knows the bike runs well and can get the correct stator and headlight and other parts and take it from here. (edited)

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

Jack Rutherford /

Damn, that pw80 carb woke that thing right up! Do the lb50 and 80 share the same stock carb?

Must not be - I see completely different part numbers comparing 76 lb80 to 78 lb50.

btw, many of you probably know this but if you just search on ebay for seal dimensions, you can usually get a way better deal than some places. For example, left side seal is 20x35x7 $5.81 shipped off ebay vs. $12 and shipping elsewhere. (edited)

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

> Jack Rutherford Wrote:

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

> Damn, that pw80 carb woke that thing right up! Do the lb50 and 80 share

> the same stock carb?

>

> Must not be - I see completely different part numbers comparing 76 lb80

> to 78 lb50.

>

Jack,

They are not the same. It was stated early in this thread that the LB50 and LB80 carbs were 15 and 19mm respectively. My LB50 only measures 11mm at the throat. Not sure on my LB80 because it never occurred to me to measure, but I would say its NOT 19mm, and probably something closer to 15 or 16mm. If that were the case there might be some room for improvement on the LB80s without swapping intakes, and retaining the stock plastics. This might be a future project.

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

> Michael Blank Wrote:

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

> Awesome video, very helpful. Will be applying these findings to my (2)

> LB50s!

Michael,

Thanks! let me know if you have any questions with the swap when you get around to it

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

THEY'RE BACK IN STOCK! NOBODY PANIC!

Screen Shot 2019-07-03 at 10.52.04 AM.png

oem exhaust modifications

so over the last week or so i've been playing around with the oem muffler.

first things first, bust out the cutoff wheel. opened up fully, the guts look like this:

20190627_164007.jpg
20190627_163954.jpg

one thing i noticed was the strange inlet to the chamber:

20190627_164042.jpg

so the divergent/expanding neck section leading up to the chamber is really just additional chamber volume. it is not in any way a diffuser, which was surprising based on it's outside appearance.

(post continued for additional attachments...)

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

the transition from the header looks odd also:

20190627_164056.jpg

that's basically a step change down to the inner tube diameter. after thinking about it, i considered that it may contribute to a high rev VE bump, but based on the overall design i do not think it's likely. (i haven't done any measurements or calculations to figure out what RPM it would have any effect.)

i do not particularly want an overly loud and noisy ped, so i took a path of making incremental modifications. to that end i'm planning to pull out that step change and small diameter inlet tube at a later date and see what happens (if anything).

meanwhile while i had the main chamber open i chucked up my unibit and made the "cross chamber" orifice bigger. i also made a number of smaller holes directly from the first chamber into the spark arrestor inlet, basically shunting the entire rear chamber:

20190627_165315.jpg

then i did a quick hack stitch with my $90 hf and went for a spin.

20190702_172711.jpg

first, without any flame arrestor it was quite a bit louder. too loud, in fact, for my tastes. so i slapped the arrestor back in and to my surprise it was barely louder than stock! so the arrestor was doing quite a bit of attenuation. in bone stock form the arrestor seemed to make little to no difference, so i attribute the "shunt holes" as contributing heavily to the overall SPL.

i left the arrestor in for a few more days of commuting to work.

(continued...)

Re: oem exhaust modifications

Kenneth,

Very Cool! Interesting you have that tube on the inlet side. My exhaust did not have that. Its almost like a header extension since the pipe does not follow the diverging shape of the exhaust housing. Assuming it acts in principal like a header extension, it's my understanding that longer headers shift the power band to lower rpms? I think I like your placement of the holes (the ones by the outlet) better than what I did. Interesting enough my exhaust was completely plugged in that region. I suspect years of unburnt oil and carbon packed in behind the spark arrestor. I am curious to hear about your findings in terms of performance gains. Awesome job!

~Hunter

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

the arrestor guts look like this:

20190709_154238.jpg

basically looks like a dyson setup where the exhaust stream creates a vortex and centrifugal force causes carbon bits to fling to the outside where they are retained. the entire stream has to fit through the 4 small channels at the top of the arrestor, which is pretty restrictive.

browsing treats i came across this and the gears started turning...

a few days later and i had one in my hands:

20190709_154246.jpg

looks like a pretty good match!

20190709_154321.jpg

(continued...)

Re: oem exhaust modifications

Dirty30 Dillon /

The header length is the easiest way to modify your tuned length, which changes the resonance to either a lower or higher RPM response.

Longer tuned length = better resonance at lower RPMS, and shorter at higher RPMs.

The treats pipes have a shorter tuned length than the disco'ed Gianelli and Polini Pipes for Chappy. This might explain some peoples mid-shift deadspot

Re: oem exhaust modifications

i needed to find a way to retain the perforated tube in the arrestor housing. i considered hacking the arrestor guts but i poked around the spare parts bins and came up with an old axle nut from my subaru that had a washer flange of the right diameter, and a threaded portion that was a close fit to the perforated tube.

20190709_154336.jpg

after the corners of the nut were eased a little bit, it slid right into the arrestor housing:

20190709_154354.jpg

things started coming together!

(continued...)

Re: oem exhaust modifications

now i had to retain the tube in the nut. my first thought was just weld it together, but i wanted to make it easy to repack/service if necessary. back to the parts bin for a big enough fender washer, and a couple of spot welds:

20190709_160625.jpg

then ream it out to just slightly smaller than the tube dia:

20190709_160849.jpg

looking good!

(continued...)

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