jog clone everyday 40mph bike not wide open thrott

[atheos]

I bought a cheap jog clone a few years ago.  a crappy local atv speed shop over charged me ($1400) and modded it for me:  leo vance exhaust, 19 or 20mm carb, 75cc cylinder, carbon fiber reeds, incorrect and unknown clutch weights, and a stiffer spring for my 250lb self.  My brother fried the engine last year and i just got a new cylinder today.  What advice could anyone give me for setting up my scooter to make it an everyday riding bike at 40mph without wide open throttle.  I think that is how my brother fried the cylinder.  That or it was an improperly tuned carb.  Do you think i need to rejet, adjust screw settings,  or is the bigger carb sufficient enough.  Please know i am new to scooter tuning.  all previous tuning and modding was done by a mechanic i had little faith in and would like to do it myself from now on to save a lot of money.  He charged me $425 for parts and labor just for the cylinder, is that not ridiculous.  I will be starting work within the next couple of weeks.  I know i don't want to do any machining for 90cc, so 75cc is enough for me.

[atheos]

oh, yeah, i also have a cold air intake air filter where there used to be an air box.

[90GTVert]

Depending on the carb, I'd switch back to an airbox. It'll fit over some styles of carbs that size, like the DellOrto and Arreche. An airbox cuts back on noise and makes tuning and staying in tune a bit easier.

I would definitely check the jetting and adjustments of the carb. Even if you don't make any changes, just due to the fact that there was an engine failure. I always select the right main jet first, doing WOT runs. Then I set the mixture screw to get a good idle, but don't spend much time on it since I'll reset it for the last step. Then move to the needle and look for good throttle response. If you are unsure what's correct with the needle setting (or any setting for that matter) err toward rich. Then go back and fine tune the mixture screw to get the highest idle speed (not the idle speed screw) that will allow the throttle to feel responsive from idle to maybe 1/4 throttle. You also need to ensure the mixture setting is rich enough that your engine returns to idle. If it's too lean you may notice RPM hangs at a high idle when you let off the throttle.

Your setup should be capable of what you want, and in a safe manner as long as the carb and CVT are in a good state of tune.

[aznatama]

My scooter did about 35 stock, with the restrictor and not a WOT. you should be able to get to 40mph w/o WOT on a 70cc.

There's a lot of info on this site, and check out my 8pg thread about modding my x50i, there's lot of good links in there explaining about all the mods you already have on your bike.

[atheos]

I don't have the airbox anymore I lost it. Is the cold air intake sufficient enough or should I like for another one? Is there any recommdation for proper clutch weights? I will have pictures and updates when I start the rebuild.

[90GTVert]

As long as you're fine with it, you don't have to use an airbox. I'm just not a fan of the open filters. They work though.

My best recommendation for proper roller weights is to find out what you have now and figure out what you need. If you need more revs, go lighter. If you need less revs, go heavier. Go in small steps unless it feels way off. A set of cheap tuning weights is a good idea for experimenting, but once you find the weight that works you should buy a good set of roller or sliders. The tuning weights just don't hold up long. The stock variator should use 15x12mm rollers. Here's an example of a tuning set...
www.ebay.com/itm/MULTIPLE-ROLLER-WEIGHTS-MULTI-PACK-JOG-CE50-CG50-CY50-UNIVERSAL-15X12-ROLLERS-EZ-/271140694564?pt=Motorcycles_Parts_Accessories&hash=item3f213eaa24&vxp=mtr

Parts For Scooters or our other advertisers and many sites sell good rollers and sliders for more permanent use. Sliders are the toughest and usually last quite a long time.

[atheos]

I found a website scooterpartsexpresss.com and love it. It seems to have everything one could need. If there is a better one let me know. I am curious if I need that oval gasket for exhaust when putting a new cylinder on. I also don't know if I will need the metal circle gasket for exhaust as well. My new cylinder only comes with the gaskets for it's head and to the engine. The website I am looking at doesn't sell just the oval gasket so i am unsure of what i will need. Also what about new gaskets for carb, is there one there and will i need that one also?

[90GTVert]

Most of the Leo Vince exhausts use a stock style round crush gasket, and you should replace that with a new one. The carb has no gaskets to mount it and the bowl gasket should be fine without needing replacement through many jet swaps as long as you're careful with it.

[atheos]

so, after much internet searching, it turns out my scooter style is the hurricane style. I am now considering if there is anything else i should do at the same time as rebuild. this is the setup i have now or will have soon:

75cc bbk
20mm carb
carbon fiber reeds
leo vince exhaust (maybe mmg) (w/ expansion chamber)
cold air intake filter
100mm main jet

Here are my main questions:
is bigger jet enough adjustment or will i need to adjust needle? (don't know what jet is
on there now but am going to #100 because the cylinder overheated and seized twice
with only carb screw adjustments)
would i get a significant benefit from larger carb?
could i benefit from 14x31 trans gear?
what variator/clutch/spring setup would you recommend? (i am 250lbs.)
should i get performance clutch to grip better or is it possible stock is ok and i
should wait and see?

Also, i have to say how much i enjoy this website. it takes normal repair work on what used to be my only mode of transportation and turns it into an enjoyable hobby. Everyone here also seems very polite and helpful. Thank you everyone!

[90GTVert]

I'd suggest a selection of main jets. It's pretty rare, at least for me, to guess just the right jet on the first try.

You may need to adjust the needle. The main jet and needle have different functions. Mixture screw and pilot jet control up to about 1/4 throttle, main jet above 3/4, needle in between. There are other components, but that's the only stuff you should really need to deal with.

Carb size info...
49ccscoot.proboards.com/post/44367

Stock clutch will be fine. I'd suggest a tuning set of rollers and a kit with 1000, 1500, and 2000 RPM clutch and contra springs. You can get both on eBay. Prob 1500-2000RPM clutch springs will be best. Maybe start with 4g rollers and a 1000RPM contra.