FFFF'ING MOLKT CARBS!!!!!Best carb replacement?

Mini Dirt Bikes & Pit Bikes Forum

Help Support Mini Dirt Bikes & Pit Bikes Forum:

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
Issue:

Posted up a while back, big long issue that thought I had solved. Quick recap--->

Engine: 160cc YX Piranha
Carb: Molkt carb 26mm, new large float style.
pilot:30, main 110, middle clip. Float set to 6.5mm from flange(parellel, level) Not a jetting issue, Bike runs great with this setup, when carb works properly.
No big mods, stock engine.

Overall issue was gas not getting into combustion chamber, ie. float sticking randomly.
It can happen at anytime. Bike will run amazing one day, park it overnight and then just will not start at all the next day. No gas getting into chamber. Cross checked gas tank venting, inline filter, all good. Somehow the float needle gets stuck. I've try to blow through the gas line once tank and filter are removed and I'm not able to, it's blocked. If I take the carb off and blow while tilting it, it unsticks.....Did this with Molkt carb 1.....
tried another brand new Molkt carb.....same issue. Once I pop the float back open, I can install the carb and bike will start and run like dream, then a few rides later, randomly it sticks again. I'm stumped........I think I'm done with Molkt carbs. Any suggestions for the YX160?

J
 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
Ya, that settles it. I'll get the OKO 26. Was always trying to save a few dollars with Molkts, and my old one with old style float works great. Havn't got one of the new one's to work so F it. Thanks for the assurance. Best place and prices to get the OKO? what kind of jets do the OKO's use? what size jets are recommended for the YX160, few hundred ft. sea level. Humid summers, cold winters.
 

my67xr

Miniriders Legend and Master Spanner Spinning Mode
Joined
Jul 29, 2010
Messages
11,982
Reaction score
79
Location
South Australia
with your Molkt,
i've heard a common problem with them is sticking floats, try removing the float from the carby and sit it into the fuel bowl.
is there enough clearance to the sides

maybe post up a couple of pics of the float from different angles, it may have a slight twist in the metal plate ?
 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
The floats all good, even without opening it up, all I have to do is blow in the inlet line and tilt it once it's off the bike and I here it click open. It's almost like there is negative pressure created in the float bowl and the float needle suctions closed, but that can't be due to the drain holes etc. I'm stumped and don't care anymore, going for a VM26 or an OKO flat. If anyone has any suggestions for jetting on those carbs, let me know...
 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
Ok, so I picked up a brand new VM26, put it on and the bike started beautifully, never heard it idle or run so well. Ran it out for a bit then shut it off to cool down to try to see if it would start again. F me, looks like it is having the same problem as with the molkt carb, no gas getting into the chamber, looks like the float is sticking again, even with brand new VM26. To me, there is some kind of vacuum created by the motor that's locking the flow of gas. I need the experts to weigh in, really weird problem here. If it were my gas tank vent, it wouldn't have started at all in the first place, when it gets started, it runs like dream. I think I'm done with this motor, I have the exact same setup using an old molkt carb and it works awesome. This motor is just F'ing cursed I'm going to fing throw it through a window. So tired of dealing with it.
 

8r3nd0

Sinister 50's
Joined
Jan 27, 2012
Messages
2,382
Reaction score
17
Location
Australia
How do you know that fuel isn't getting in, from reading each post I'm more inclined to say that it might be a timing or electric problem. The Cdi, coil or plug might be shot.
You sound switched on so am I right in saying that you've check for leaks ie manifold and exhaust.
 

my67xr

Miniriders Legend and Master Spanner Spinning Mode
Joined
Jul 29, 2010
Messages
11,982
Reaction score
79
Location
South Australia
do you have some clear hose that fits over the drain barb ?
fit it on and hold it up higher than the top of the carb and open the drain screw.
the level inside the bowl will be the same as in the hose on the outside

 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
How do you know that fuel isn't getting in, from reading each post I'm more inclined to say that it might be a timing or electric problem. The Cdi, coil or plug might be shot.
You sound switched on so am I right in saying that you've check for leaks ie manifold and exhaust.
No as you'll read below. Usually a timing issue will let the bike run atleast. Usually symptoms of a shot CDI or Coil is sputtering, missfiring, cutting out, overreving, pinging etc.
______________________

With the Molkt carbs after running for a bit, then shutting off and trying to restart, it would not restart, ever, after 100+ kicks, nothing, no pops, nothing. Pulled the plug and dry as a bone. That tells you gas isn't flowing. To re-inforce that, I'd blow into gas line, stuck float, pull carb off and tilt, blow hard and float pops open gas spills out. re-install it and would start then after a short run and shut off, would not start again, stuck float. Conclusion, something screwy with the Molkts floats...


HOWEVER! it did the same general thing with the VM26 but I kind of jumped the gun with my post, I didn't pull the plug to see if it was a gas flow issue so I'm mistaken in doing that. Turns out I went back to start it, took a while, had to crack throttle wide open but it started, mind you it was a biatch to get going.....on top of that, checked plugs a few times after stop and restart and there's gas flow.....so this tells me that for the VM26 it's simply a jetting issue...gonna play with the jetting and see if it works so stay tuned. At this point it's still a B*** to start but I know it's getting gas so the chemistry is there. Gas(fuel) and spark will always produce some kind of response, it's just a matter of tweaking jetting to get it metering properly. Where as before, I was getting no response due to spark but NO fuel to chamber........a weird situation. My hunch is, I should be able to get it rock'n ballz. Jet kit in mail.

I appreciate the replies. Will update.
 

my67xr

Miniriders Legend and Master Spanner Spinning Mode
Joined
Jul 29, 2010
Messages
11,982
Reaction score
79
Location
South Australia
the China copy Mikuni's i've played with, seem to like a #20 - #22.5 Pilot jet, and depending on engine a #100 - #107 Main jet
 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
Hey guys,

So played with jetting today. Good times :(

stock jets were 22.5 pilot, #190 and middle clip, Air screw 2-3 turns out. Had issues starting with this setup.

Went to 27.5, #180. Had issues, air screw 3 turns out, too far. forget exactly but wasn't quite right.
Went back down to 25, #190, air screw 2.25 turns out. Started like a dream, literally could have started it with my hand. Problem was cut out and sputtering at 1/2 throttle on. Couldn't figure out if it was lean or rich bog.

So tried, 25, #190, air screw 2.25 turns but moved clip up for richer mix. Same problem.
Then went same as above but moved clip even further up for richer mix, Same issue, stall sputter on full throttle.
Then went opposite on the clip, so still on #190 but clips set to lean it out. Seemed to help a bit. Since I was topped out on the clip. Went to #180:

So, 25 pilot, #180, clip set 2 from....(**** can't remember, anyway, set second from top or bottom) hehe.
Air screw 2.25 turns out. Went for a good rip, bike is 95% there, just the slighest slightest flatness on the top end when full open. I can remember it pulling a slight bit harder through to top end wide open before. But otherwise, very rideable. Only thing is, seems to have trouble starting unless the throttle is held wide open, no choke. Just trying to figure out what this indicates with regards to jetting. So to repeat, bike runs good with this jetting setup, just starting it required holding throttle wide open, will fire right up after a few kicks like this, otherwise it's hard to start if you don't hold the throttle open. I know this means something. Anyone.....
 

DHXrider

Well-Known Member
Joined
May 9, 2009
Messages
62
Reaction score
0
Location
Outaouais region, Canada
Ya, that's all theory though, a great general guide. In my experience, real world jetting can be slightly different. a #20 would be too low, I can probably try stock #22.5 and just see what happens. I'll have to wait though, ripped a gapping hole in my tire today ). I'm already 2.25-2.75 turns out on the #25 so logically I should be able to drop it down a size, we'll see.
 

my67xr

Miniriders Legend and Master Spanner Spinning Mode
Joined
Jul 29, 2010
Messages
11,982
Reaction score
79
Location
South Australia
yeah just takes a bit of playing around.
you have to love adjusting the mixture screw each time too, they are so easy to access ! lol
i reckon i can turn my mixture screw back about 1/2 turn, with each Pilot jet size i drop.
 

cooper1783

New Member
Joined
Mar 2, 2022
Messages
3
Reaction score
0
Issue:

Posted up a while back, big long issue that thought I had solved. Quick recap--->

Engine: 160cc YX Piranha
Carb: Molkt carb 26mm, new large float style.
pilot:30, main 110, middle clip. Float set to 6.5mm from flange(parellel, level) Not a jetting issue, Bike runs great with this setup, when carb works properly.
No big mods, stock engine.

Overall issue was gas not getting into combustion chamber, ie. float sticking randomly.
It can happen at anytime. Bike will run amazing one day, park it overnight and then just will not start at all the next day. No gas getting into chamber. Cross checked gas tank venting, inline filter, all good. Somehow the float needle gets stuck. I've try to blow through the gas line once tank and filter are removed and I'm not able to, it's blocked. If I take the carb off and blow while tilting it, it unsticks.....Did this with Molkt carb 1.....
tried another brand new Molkt carb.....same issue. Once I pop the float back open, I can install the carb and bike will start and run like dream, then a few rides later, randomly it sticks again. I'm stumped........I think I'm done with Molkt carbs. Any suggestions for the YX160?

J
 

cooper1783

New Member
Joined
Mar 2, 2022
Messages
3
Reaction score
0
have any of use thought of drilling a small hole in the float and filling it with some water to add a bit more weight and put some hot glue over the hole so it wont stick i dont know just a thought
 

Latest posts

Top