GASGAS MC 125 Questions

Atkinson
Profile picture for user Atkinson
Posts
92
Joined
5/7/2014
Location
ID US
Atkinson
Im going to be picking one of these up in the spring and am curious what would be a good setup as far as pipes and carb setup. Im leaning towards doing a FMF Factory Fatty pipe with the Powercore exhaust, is there something else that works better on the Austrian 125s though?
Im also thinking about doing a Lectron carb, has anyone run one on a 125? Mainly would be riding around 5000 feet, but if I ride in mountains at all would be around 8000, that why I'm kinda leaning towards a Lectron.
Any advice or tips on these bikes would be appreciated.
|
Bruce372
Profile picture for user Bruce372
Posts
6329
Joined
4/1/2008
Location
US
Bruce372 1/27/2022 7:55pm
1/27/2022 7:55pm
Best thing you can do is just leave it stock and dial the jetting. There is a good thread here. For Mx, the lectron is a downgrade and for trails its ok, but no better than dialed stock, although they have a new billectron.

A lot of the aftermarket parts are no better, or don't fit right or both.
3
Rickyisms 1/28/2022 6:00pm
1/28/2022 6:00pm
I believe stock pipe with pro circuits shorty on it made some of the best power, but like Bruce said get jetting dialed and play with your power valve setting and springs. Go from there.
2
Bruce372
Profile picture for user Bruce372
Posts
6329
Joined
4/1/2008
Location
US
Bruce372 1/28/2022 7:30pm
1/28/2022 7:30pm
Rickyisms wrote:
I believe stock pipe with pro circuits shorty on it made some of the best power, but like Bruce said get jetting dialed and play with...
I believe stock pipe with pro circuits shorty on it made some of the best power, but like Bruce said get jetting dialed and play with your power valve setting and springs. Go from there.
Yep. The PC shorty is one of the few silencer you can buy that don't make it worse, at least on the 150 with the 125 being slightly more forgiving.

It's amazing how great they are dialed jetting stock, two ring piston thats nice and reliable and goes a long way on a top end. And it's amazing how many trick parts that make it less reliable but marginal gains if not make it worse.
1
macz400
Profile picture for user macz400
Posts
1388
Joined
8/20/2013
Location
League City, TX US
macz400 1/29/2022 7:19am
1/29/2022 7:19am
Back when I had my 18 150sx, best thing I did to that bike was drop the Mikuni and run a Keihin. Bike ran crisp and clean. Didn’t have to fool with jetting changes like I did on the Mikuni. Shorty silencer also helps
1

The Shop

See All »
Sandvik74
Profile picture for user Sandvik74
Posts
341
Joined
5/20/2021
Location
Larsmo FI
Sandvik74 1/29/2022 7:58am
1/29/2022 7:58am
macz400 wrote:
Back when I had my 18 150sx, best thing I did to that bike was drop the Mikuni and run a Keihin. Bike ran crisp and...
Back when I had my 18 150sx, best thing I did to that bike was drop the Mikuni and run a Keihin. Bike ran crisp and clean. Didn’t have to fool with jetting changes like I did on the Mikuni. Shorty silencer also helps
+1 on that, swap out the Mikuni for a Keihin PWK Airstryker and you will be happy. You get a lot more out of your engine with a dialed carb than a Lectron carb. Espacially if you buy the H-series Lectron, for mx that carb ain’t worth shit unless you dont care much how crisp it runs and don’t know how to jet.
2
wiedeman
Profile picture for user wiedeman
Posts
111
Joined
6/19/2021
Location
Osceola, WI US
wiedeman 1/29/2022 9:09am
1/29/2022 9:09am Edited Date/Time 1/30/2022 10:08am
Best thing you can do is a Keihin PWK 38, then get the STIC metering block. I have it on my yz 125 and love it.
Sachmo831
Profile picture for user Sachmo831
Posts
252
Joined
10/7/2015
Location
South Bend, IN US
Sachmo831 1/29/2022 12:09pm
1/29/2022 12:09pm
Has anyone ran both the shorty and standard length pc silencer? Seems like everyone goes straight to the shorty
sandman768
Profile picture for user sandman768
Posts
8087
Joined
3/21/2014
Location
Saratoga Springs, NY US
sandman768 1/29/2022 12:53pm
1/29/2022 12:53pm Edited Date/Time 1/29/2022 12:55pm
Sachmo831 wrote:
Has anyone ran both the shorty and standard length pc silencer? Seems like everyone goes straight to the shorty
I have not done back to back comparisons, as I still have the stock pipe & silencer on my 22 125sx. Generally a shorter silencer enhances throttle response & low end performance while giving up some top end over rev, think arenacross type tracks, tight, short straights. The Standard length silencer will offer better top end over rev. Think outdoor Mx, longer type tracks…after doing the carb mods as per AJ & Diggers jetting thread, nothing else really needs to be done, the bikes pull clean from idle to redline…. I have been wanting to buy a pipe & silencer combo, just to have spares……
2
wrc777
Profile picture for user wrc777
Posts
3196
Joined
5/21/2020
Location
Greenwood, IN US
Fantasy
115th
wrc777 1/29/2022 2:04pm
1/29/2022 2:04pm
I bought a used 150sx that has the pc exhaust and lectron on it. Here is what I have found. Get the jd jetting jet block gasket and just change it when you get the bike home and put in the recommended jetting for your temp and altitude. I think you will like it pretty well just doing that. I have ran the lectron. It seemed to give up some power everywhere.

I also have the pc shorty and pipe. Stock vs pc pipe i can’t tell a difference. Shorty vs stock the shorty has better throttle connectivity at low rpm. Top end felt the same but that was with the lectron. I need to try it again with the stock carb since the lectron falls off on top a lot worse than the mikuni.
1
Johnnydirt
Profile picture for user Johnnydirt
Posts
246
Joined
4/23/2021
Location
NY, NY US
Johnnydirt 1/29/2022 3:15pm
1/29/2022 3:15pm Edited Date/Time 1/29/2022 5:33pm
I have the stock pipe with PC shorty, JD jetting Keihin PWK 38 and rktek head insert on my 21 125xc. Running 110 cut with 91 ethanol free for practice and VP T2 for racing. Love the bike rips for a 125!!
1
Rickyisms 1/29/2022 4:19pm
1/29/2022 4:19pm
Johnnydirt wrote:
I have the stock pipe with PC shorty, JD jetting Keihin PWK 38 and rktek head insert on my 21 125xc. Running 110 cut with 91...
I have the stock pipe with PC shorty, JD jetting Keihin PWK 38 and rktek head insert on my 21 125xc. Running 110 cut with 91 ethanol free for practice and VP T2 for racing. Love the bike rips for a 125!!
Are you changing jetting for race day for the T2? Or just run it fat on practice days?
Johnnydirt
Profile picture for user Johnnydirt
Posts
246
Joined
4/23/2021
Location
NY, NY US
Johnnydirt 1/29/2022 5:31pm
1/29/2022 5:31pm
Rickyisms wrote:
Are you changing jetting for race day for the T2? Or just run it fat on practice days?
I go +1 on the pilot jet +2 on the main with the T2.
FGR01
Profile picture for user FGR01
Posts
6095
Joined
10/1/2006
Location
AZ US
Fantasy
954th
FGR01 1/30/2022 6:47am
1/30/2022 6:47am
Sachmo831 wrote:
Has anyone ran both the shorty and standard length pc silencer? Seems like everyone goes straight to the shorty
Not exactly the PC units, but I've tried multiple shorty and standard length back to back. As others have stated, you give up overrev for a perceived increase in bottom response with the shorty. I prefer the standard length as the end result is less shifting on most normal MX tracks. With the shorty, the power is punchy but then falls on its face rather dramatically, forcing you to shift sometimes soon before a corner or jump.

On the carbs, I'd guess everyone recommending a Keihin never rode an Austrian 125 with a Mikuni using the Digger/AJ jetting from the other thread. The myths of the Mikuni being hard to jet or temperamental requiring constant changes for conditions are not true. But the key is you have to change the slide and the needle jet tube. You will never get there using the chart in the manual because the slide is just too rich.
Atkinson
Profile picture for user Atkinson
Posts
92
Joined
5/7/2014
Location
ID US
Atkinson 1/30/2022 4:40pm
1/30/2022 4:40pm
Thanks guys, some great information here, gives me a good idea on what way to go with it.

Post a reply to: GASGAS MC 125 Questions