educate the newbie

[detonatortuning]

OK after some PM's with Brent and finally getting an engine swap up and running i have some questions.

we put a 90cc minarelli clone into a vento triton, that was the easy part. fighting with wheels and finally finding a 100/60-12 that let us use the stock 12" wheel in a short case was kind of a pain but worth it in the end.

now i have some refinement issues to pursue.

at idle the belt seems pretty loose, enough so that it's flopping around and dragging on the bottom of the cover some......? the whole variator seems to be real noisy with the cover off, normal.....?

the kicker mechanism on this engine is problematic and sometimes hangs up to the point that the variator fan contacts something enough to howl and grind on the vanes, though i have yet to be able to see what it's hitting ! we can open it up and put it back together and it will be fine if we don't use it or until it decides to be a pain again......?

we are using the stock vento 50cc, airbox, carb and pipe for this project, both seem OK, the thing max's the stock speedo, haven't checked that for speed with anything else yet. question here being, should i leave the carb as is for idle screw setting, it was 3/4 turn out from seated to begin with, OR .....?

any replies greatly apprec'd,

thanks,
steve

[90GTVert]

Thanks for the info on the tire size to fit a 12" on a short case. I'm sure that will come in handy for someone.

Is the belt riding all the way to the center of the front pulley, or close to it? If not, it's gonna be loose till the trans starts working. Check your belt size too. I imagine you'll want a 788. That's what I've used on all of my short and long case minarellis. Sometimes you get noise from the variator at idle, but check the condition of the guides on the ramp plate and make sure the rollers are the right size. It wouldn't hurt to check the splines to see if anything is worn there letting something bounce around.

Sometimes kickstart parts get a coating of belt dust and such and it can make the gears hang up. Otherwise, not sure. I hate kickstarts and curse them myself, sorry. lol

I'd adjust the idle mixture. Adjust it to find the highest RPM at idle (once the engine is warmed up), then turn it 1/8 to 1/4 turn in to err on the side of rich. Then readjust your idle RPM if necessary.

[detonatortuning]

thanks Brent,

that's a DURO 100/60-12 that's 16.75 tall when mounted on a stock vento 3.5 x 12 wheel, there's room to spare after you get it wiggled into place. there is a new MAXXIS 110/60-12 tire that is just over 17" in diameter mounted, that will probably be about the max for a 12 tire in a shortcase.

it looks like the vari plates are fully open and the belt is all the way down in there and just kind of catching in pulses at idle.

being a new engine i wouldn't have expected to have to look for screwed up stuff already. i'll check the belt #. how will i know if the rollers are incorrect ?

the whole kicker mechanism is balky and stiff on this thing. i myself like kickers as a back up, but i may have to really massage this thing because i don't like stuff that is dicey.

the carb adjustment is really bugging me on this thing. i think, the idle jet screw controls fuel not air, and is why i can kill the engine by turning it max "IN" or to the right, that leans it. "OUT" or to the left is richer.

i found a post by "FOX" that seems to line up with this and i'll try that and see what kind of results i get.

thanks,
steve

[90GTVert]

Forgot it was new, but still it never hurts to check if you feel the noise is a bit much. The rollers should fit kinda snug. Stock varis for most minarelli engines are 15x12, some aftermarkets use 16x13.

If the mixture screw is on the inlet side (filter) it should control air. If it's on the outlet side (engine) it should control fuel. Inlet side, in to richen (close off air). Outlet side, in to lean (close off fuel).

[detonatortuning]

and there you have it. i have another 2T that has the high and low adjustment screws on the outlet side and didn't know any different. it makes sense now.

the belt on there is some Green Elephant brand 17x790, the one from the vento is a 788, so i'll swap them and see what happens.

thanks,
steve

[detonatortuning]

BAH,

well the owner of this scooter had intermitent problems with the electric start in the past and it quit responding to the button so i jumped the relay and since it started i figured just replace it.

NO DEAL HOWIE still nothing. i guess i'll have to take it all apart to hunt it down. is there a fuse between the battery, the button and / or the key switch ? or any other thing i'm not thinking of ?

thanks,
steve

[90GTVert]

There's a fuse right by the battery usually. Not in the large wire that goes to the relay, but into the rest of the elctrical system that would power the starter button to trigger it.

Some info here that may be helpful...
49ccscoot.proboards.com/index.cgi?board=basicstuff&action=display&thread=647&page=1

[detonatortuning]

the fuse next to the battery is OK so...... i guess i'll start opening up the handlebar and control covers and see what's up. :spin: round and round and round we go LOL

thanks,
steve

[detonatortuning]

well................it took a while and some dead ends but it turned out to be in the switch that interups the start signal unless you have the front brake applied.

i guess it a good thing to prevent sudden, high throttle starts and resulting wheelie crashes, but it's nuts to track down.

now on to the belt swap and testing to see if we can get some smoother operation.

i found that the 90cc jog application uses the 787x 16.5x 28 belt so i'm pretty sure that this 790x 17x 30 belt is just what they had a pile of when it was assembled.

did a full throttle belt view tonight a found that the belt stays down about 3/16" from the outside edge of the vari, and i'm now sure that at rest the belt is not going fully down to the pin either.

more later,
steve

[detonatortuning]

OK we're rocking !!

got to the bottom of the kick starter issue. it was also the source of the variator rubbing.

this thing has a double wound return spring that is WAY more than it needs and also so tall that it will pull the kicker spindle past the spring clip on the outside of the case, jack the the kick shaft gear up and the spring then comes up between the gear and inside the case causing it to make contact with the vari fan.

so.....the fix was reposition the spring tang in the gear to reduce it's force, pull the spindle completely out as far as possible, use the washer and new spring clip, THEN use enough washers to take up the remaining room to the back of the kicker arm mounting so that no matter what it can't pull back in and cause more problems.

took it back to the owner today, he's really pleased with the smooth BIG power of the 90 compared to his old 50cc.

thanks for all the help on this,

steve

[90GTVert]

Glad it's all set and the customer is happy. Thanks for keeping us informed.