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

unicorn sighting!

https://www.cycletrader.com/listing/1976-Yamaha-Chappy-5008659435

alas too rich for my blood... :(

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

Jack Rutherford /
chappy.jpg

Near Cleveland, Ohio

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

Jack Rutherford /
gryelchappy.jpg

for sale Cedar Lake, Indiana

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

still testing things, but i have to say that the clutch characteristics are remarkably dependent on the tranny oil.

like dillon, i've been annoyed by how quickly 1st gear grabs especially once the cases are nice and toasty after summer stop and go traffic, bogging down hard on launch. in my case it also happened during the upshift to second, getting stuck in the no-mans-land of sub 4k rpm.

first i tried a "grippier" oil by topping off with a bit of pennzoil synchromesh MT fluid. unsurprisingly it made the problem worse.

i drained and refilled with mobil1 5w40. a bit better than the syncromesh blend, the multiweight synthetic didn't change characteristics with case temperature as much, but still got too rapid clutch engagement.

i did a partial drain and added some (about 4 oz) STP engine oil treatment. the bottles i had were from the 90s so it was the high ZDDP formula that they used to use (i hear the current off the shelf version has less zinc). it's very thick stuff, almost molasses, and is primarily a viscosity booster.

long story short it made a tremendous difference in shifting characteristics. now 1st gear grabs very gradually from a stop and i don't get the quick RPM drop as before. not only that, it actually winds 1st out and then i can feel second start to ramp up. it almost feels like there's a variator for those few seconds of transition where rpms are steady around 5k but speed is increasing. then second is fully engaged.

i did note a slight drop in flat out, probably due to the increased viscosity and fluid losses, maybe 1mph on top. i have been watching for excessive slippage at lower speeds and haven't noted any yet.

being thicker i'm not sure if this will be a good colder weather mix but time will tell. the bottom line is that the bike became a lot less stressful and more fun to ride in this warm weather with some small changes in tranny lube.

ken

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

had a 40 mile day yesterday (route on Google maps) and did some math after topping off the tank, netted 57mpg. not bad considering how many minutes were at wot.

also finally got my hands on a 10 and 12.5 pilot jet. swapped the 15 that was in there for the 12.5. the 15 was 3 turns out and wanted more. the 12.5 sits perfect at 1.75 turns out. tiny throttle adjustments while coasting have cleaned up. that just happened this afternoon and I've only got a few miles logged but so far im pleased.(edited)

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

Eric Migliorino /

What tires does everyone use on their chappy’s? I have the stock 4.00 x 8 tires.

Does anyone use the thinner 3.50 x 8 tires? Any reason to go with the thinner tires? I would think the slightly wider tires would be more stable.

I have a set of Shinko white walls - 4.00 x 8 tires but need to mount them. Anyone else have good luck with these tires? Obviously cheaper than stock tires.

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

> I have a set of Shinko white walls - 4.00 x 8 tires but need to mount

> them. Anyone else have good luck with these tires? Obviously cheaper

> than stock tires.

i've been running those WW shinkos for a little over 1k miles now. they're a bit taller than oem tires so speedo reads about 8% low. run 15psi front/30psi rear. tread life is good, traction is good. little slippy in wet but what isn't? biggest pita is keeping the rear sidewall clean since the white shows everything.

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

Eric Migliorino /

Anyone use the Michelin s83’s?

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

finally got my hands on a 28t rear and slapped it on last night. combined with the 16t front the FD ratio is 0.571. oem on the lb50j was 13/32 which is 0.406. total ratio change is 41%.

compared to what i was running before today (16/32, 0.500, 23% taller than oem) i jumped up 14%. in theory picking up 5mph top speed. didn't have road to test flat out during the commute this morning.

however i have geared up too far imo and acceleration is now too sluggish for my driving patterns. maybe if i had more long stretches it would be worth it.

it's easier to swap the front sprocket and i have 13t, 15t, and 16t available. i'm going to stay 28t in back and drop back down to 15t in the front which will give me 0.536, (32% taller from oem and halfway between today and yesterday).

i also bit the bullet with the treats sale and grabbed a MLM PP, so a lot of this fucking around will probably have to be repeated.(edited)

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

Ken,

Your gearing experience seems to be consistent with mine as well as Jack's. My LB80 has 15/28 gearing. Only modification is the MLM people's pipe. The gearing is just ever too all, even down here in south florida where its all flat. I think 15/30 gearing would probably be ideal. Not much is gained in top speed by changing from 14t to 15t (other than lower cruising RPMs) . so maybe 14/28 would be better if your commute has hills. I want to say on these bikes +1t in the front is equivalent to +3t out back. Keep us posted with your findings.

-Hunter

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

slapped the 15t front on and pickup is much better vs 16t. treats won't be in hand until Thursday so I might mess around some more and try the oem 13t in front w/the 28 rear.

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

went back to oem 13t in front with the 28 in the rear. this is shorter (0.46) than I was running for a long time (16/32, 0.50) and an even bigger change from what I was last on (15/28, 0.53).

as expected rpms went up, acceleration went up. top speed changed less than expected... with 0.53 I could sit at 45mph on a long stretch. with 0.50 it was around 43, and with 0.46 it was 41.

I've found as it sits my motor doesnt appreciate sitting past 8k5 or so. I felt the slightest hint of a seize coming on during some sustained pulls with the lower gearing. since i have the sudco adjustable main I immediately richened it up but then at 8k5 it was just starting to 4 stroke. anything past that and it got worse. so when richer speed was limited by 4 stroking, but leaner was too hot. (this is at 20:1 too.)

at this point it's starting to seem like 0.50 is a sweet spot in terms of revs/top speed. to that end I just snagged a 14t front off Amazon and I'll go back to that to compare.

getting pretty quick at these front sprocket changes now... lol

« Go to Topic — end of thread

Want to reply to this thread?

We'd love to have you join the discussion, but first you'll need to login (or create an account).