Got my LB80 going, has a small petcock leak at the moment, going to remove it and get a simple on and off one.

 

anyways, my max speed is 35mph, I plan to change the gearing (sprockets) but need to know if anyone has done this route before, I want to get a bigger sprocket in front and smaller one in the rear. What size can I fit in the case without using the dremel?

 

cheers!

also, what is the stock gearing of the LB80?

 

I read somewhere it was 14 front 32 rear..

Hi AJ 

         just a quick word of advice      - you can change the gearing by changing the sprockets , but not the power output of the engine .And that's what matters if you want more poke. You won't gain much advantage  by changing the gearing, perhaps a few more mpg if you are sitting at a steady 35 .You won't get a much higher top speed (F=ma) unless you put in some more power,which means a bigger engine.  And please don't take a Dremel to it. Unless you like walking home.    (   Myself and a pal took 2 identical 125 cc bikes to the Hebrides, one with stock gearing ,the other modified.   There was no difference in the performance of the bikes,and hardly any in the fuel consumption.  Moral - want more power? Get a bigger bike.   ...and don't tamper.)

(this was not meant to sound condescending ,I just hate to see people wasting money and potentially knackering their bikes) 

 

 

lol I wont take it as that, but I don't care about the MPG, I want to go faster. So I was thinking of changing the gearing to go faster.

 

and it sounds like I should only change the rear sprocket, not the front

 

 

I don't want to dremel anything I don't have too!!

OK AJ ,and all the best, but you missed my point.  -  More speed needs more power, not more gearing. You will not  get more  speed by changing the gearing.  What you will get is a lower-revving engine providing the same top speed.Or a higher-revving engine that can climb hills better (but slower) You can't get more energy by changing the gearing ,all you are doing is changing the leverage of the engine. 

My advice remains the same  - want more performance: get a more powerful engine. (and stay away from Dremels .No good ever came of using a Dremel .My teeth have never been the same since.)

 

 

AJ mate, as above really you can have fast acceleration and lower top speed or slow acceleration and slightly higher top speed BUT at best your gunna get about 5MPH more for a shit load of wasted time and money, if you want to go faster the only real way is a bigger bike, sorry mate some things just are..!

Sorry people but 35mph from an eighty?

It doesent need modifying it needs fixing. Something is off, that bike should be good for 50mph.

it revvs out quickly! has tons of power, that's why I am stuck at the 35 mph thing also.

I understand the more powerful engine portion and I appreciate the patience you all have with me haha!

I wish I could put a Tachometer on her to see what the RPM's are at full throttle. Its the automatic 2 speed (2 speeds in Drive, 2 in Low Range) if this helps at all.

I found a rear sprocket that is a 25T compared to what I have now, a 30T rear sprocket.

 

Oops.

Ok. I thought they were 4 speed like the yb. Its got that 2 speed box with a high low option. Top whack IS listed as 35mph but with an experienced pilot wheelies are not a problem apparently.

As to sprockets changing the rear needs more teeth and affects the wheel ratio. 

14:32  2.15 to 1

14:25  1.8 to 1

Thats a 17% hike. Or around 7mph if your engine can cope with the gap between gears.

7 mph would be great! 35 just limits my street use (:

I ordered a 25T one online, they also sell larger front sprockets, but I will try this one out first!

 

 

On another note, I have another Chappy with that 4 speed manual.. I cant get her to start though, any way to swap trans?? or better just have it rebuilt...

 

cheers!

Yeah I can vouch for this, my chappy is good for 35/40 on the flat if I make myself small. 

JT sprockets used to provide a list on their website of sprockets, usually plus or minus 2 teeth each side. 

So, for more top speed you could go a tooth larger on the front and one smaller on the back, or keep the front the same and go two smaller on the back, chop and change until you find one you're happy with. 

Bear in mind though, even as an 80cc the chappy was never really designed to go fast at all, it's only a 2-speed auto. (4 speed manual rarely), how fast do you really want to go on a small tube frame with laughably small drum brakes and iddy biddy tyres?. 

As for the non starter, why not? Got spark? Fuel? Ignition?. 

Take the side cover off, clean and gap your points and spin it up on a drill, it might just need a bit of encouragement to get things moving if it's been stood a while. 

I installed a 25T rear sprocket and I can go 40MPH no problem now! its perfect, however when nearing the top RPM, it cuts out like it has lost all fuel. Then will recover if put choke on. Its odd. When I stopped the other day, I noticed it was leaking gas, everywhere.. I took apart the carburetor and everything was working fine (so I could see) but I think the float is not shutting off the fuel some times, and possibly shutting it off when it needs to be on, (at high RPMs) I sprayed carb cleaner in there to clean it really well but no luck.. what do I do?

 

 

as for the non-runner, the cap on the side has been off for a few years and the stator is all rusty, *see pic*

I would assume that once its cleaned off it should spark, I bought new points for her just in case.

here is how the bike sits currently

 

 

Could be fuel level dropping in the bowl, check your tank and lines are flowing good and your float height is correct. 

A decent set of points should have your red one going, there's no CDI or electronic magic, just points, a primary winding and the ignition coil, if all of those are in good shape it should run. 

I had a yellow one when I was working in the US, got caught trying to smuggle it home on a C-17... It's still at NAS El Centro as far as I know. 

how do I know what level my float should be at?

 

you are a crazy bastard! too bad it didn't make that trip!

1 hour ago, ajbrooks1 said:

 

you are a crazy bastard! too bad it didn't make that trip!

Yep... Had it all packed up in a couple of big boxes ready to load, then it got found out, ah well. 

I've got a Haynes manual in my room somewhere, I'll dig it out tomorrow and see what it says

 

legit my friend!

 

thank you

Just a brain fart, but ive been drinking so it's to be expected. 

Try lifting your carb needle up a notch, should help the top end, if it feels worse you can always drop it down again 

the carb needle.. where is that in the carb? are you talking like the jet?

I removed the oil tank and plugged the inlet tube from the pump so that there is still oil in the pump, but nowhere for it to go. (so it doesn't burn out or something)

 

I am now mixing my gas at a ratio of 40:1

 

I am at practically sea-level, what size jets should I go with?

Where the slide goes into the top of the carb right on the end of the throttle cable, it has a little brass needle that sticks down through the carb, it's a bit fiddly to get to but if you can unscrew the cap on the top of the carb where the throttle cable enters it you should see what I'm on about. 

Ok, I will check it out.

 

over the weekend, I pulled the carb off to check the float, I swapped the float out for one out of the other Chappy. I also noticed that there was what seemed like two jets in one part?

there is a main jet (the bigger one right?) and then another right by it. It is smaller, I was able to remove it to clean it but on the other carb from the non running chappy, there was a jet that screwed way down in there, then another that stuck out about 1/8 of an inch .... I wish I would have taken a picture! what is this jet?