Hi, i have had a GIO 250 atv for about 3 years now and it's been great, no problems.

Recently I bought a Minkuni carb and a high performance CDI box from GIO and now I can't get it to run properly.

It will start, idle and drive but when I open the throttle all the way, it feels WAY to rich and bogs, so i tried rejetting the Main Jet from a 102 to 95 and it's a wee bit better. If I remove the air filter (pod/foam) it will rev high, but when i put it back on it won't rev, so it's like it's not breathing.

So not breathing equals too rich right??
anyone put a high rev box on a GIO? anyone upgrade to one of their mikuni carbs?

Ideas?

thanks

 

Welcome to the forum aircube!

Removing the air filter leans things out (lets in more air). Id keep trying smaller jets..

What size Mikuni carb did you buy?

 

thanks for the welcome,

the ATV is a GIO 250cc Badboy Utility quad. The CDI is one of those blue aluminum Casoli racing hi/per CDI's that just plug in. The new carb is a 30mm Mikuni.

I was up till 330am last night trying to figure out the issue and I finally got it. I swapped back to the Orginal stock CDI and there was no change, so that ruled out the hi/per CDI.

I really did't want to have to remove the carb again b/c its a tight fit on the GIO 250, but I figured that perhaps the float was messed up or that it was'nt sitting level. Once i had it off and took the bowl off i found the source of the problem right away. Last spring when I installed the new CDI and carb I had gone back and removed the bowl w/o removing the whole carb a few times to try different jets. The bowl o-ring seal was so difficult to keep in place while i put the bowl on that I ran a bead of gasket maker in the o-ring ridge........well aparently some gasket maker (silicone) was floating around in the bowl wreaking all kinds of intermittent havoc. Can't believe i did't think of this earlier....

While i was in there I cleaned everthing inside just incase some of the silicone became lodged inside some of the ports/jets. I removed the 95 jet and re-installed a 102.5 Mikuni high speed jet (b/c i think it was the garbage in the carb all along) I bent the tab on the float so it sits horizontal, I installed a new rubber manifold, put the uni pod filter back on, reinstalled the hi/per CDI......and hit the starter, adjusted the low speed needle a bit and she runs very well....

Spent an hour or so this morning moving the clip around on the slide needle and it seems to like the richest position(clip on the bottom ridge)

pleased with the performance now, i am able to crawl around and the then hammer it and there's no stutter. The new Mikuni carb and the cdi eliminates the top end stutter as well. Super smooth and powerful from idle to wide open.

Wow, this thing has basically been out of commission for 4-5 months just because i did't realize i got some garbage in the carb..., oh well lesson learned and the thing is performing MUCH better than stock. Also have a few other mods, new gas/oil shocks front and back, 24" Maxxis Zilla's on the front and 25" Maxxis Zilla's on the back. Oh and dropped to a 14 tooth rear sprocket as well.

 

I have a Gio beast 200CC with the Mikuni carb and no-rev CDI box thing. I have a 102.5 main jet in it because I had it laying around, I can pop a wheelie quite easily now, I also have a different air filter. The only problem I have, which I think is a design flaw in the intake manifold is that if you let the quad idle for more than 20 seconds or so, it floods out when you hit the throttle. I think fuel pools in the intake while idling (which goes up 90 degrees for 4 inches or so right after the carb, then 90 degrees into the enigne, and it is metal), it can idle all day and be fine, but when you give it gas, it puffs out black smoke and wants to die, the longer you let it idle, the worse it gets. Adjusting the idle screw makes no difference in this, we have 2 of these quads, both do this with the stock carbs and the Mikuni's, so I just live with it.

 

well...... after having a GIO250 that ran perfectly all summer I let it sit for a week, went to start it, it started as soon as i hit the button. I started driving and its running REALLY rough, like the fuel keeps cutting out. its acting very much like it did when there was junk in the carb. So I take the carb off, dissasemmble it clean it like crazy with solvent and then blow it out. Put it back on, but NO change. End up killing the Solinoid, so start by arcing a screwdriver across it to start it, ended up killing the StarterClutch.

installed a new solinoid, starterClutch(sprag), and Stator and tomorrow i am going to give it another go. But before i fry another solinoid or spragClutch does anyone have any ideas why this thing would have been performing so well, then it sits for a week, then it sudenly is really difficult to start and runs very poorly at speed, cuts out and misses??

 

Try the original CDI one more time to see if it is related.
Try re-adjusting the carb at idle and see if there is an improvement.

 

well, i just got back in from cleaning the carb....again, putting all the parts back on and firing it up. All systems are go

Looks like the shotgun approach worked so I am not sure which it was really but I'm guessing it was the gunk in the carb again.

Heres a thought.... there were some metal chunks from the sprag clutch going bad in the stator housing area and I was wondering if some small chunks may have been sticking on the magnet on the pickup??

well either way, as long as its up and running. Now I can make use of the new mud zillas ( in the snow)