[ricekrispy]

ricekrispy,



Thanx for the info! If you're saying that a 27.5 is still too lean on your 140 then it should be really lean on my 150 cause of the bigger cc's right? This of course is assuming that both bikes are under the same conditions and elevation. So if my theory is correct then I should probably start with buying an assortment of #30-#40 like you did and start with the 30 right? What kind of airfilter and pipe are u using on yours? U r tuning with the air filter on right? What do you guys think?....Manuel

Hey man, I'm in North West Ohio and it's winter here, temps in the lower 30's. I think your jetting situation will be all different, but I can tell you that the #27.5 pilot was still too small, so I jumped to a #35-42.5, I will be tunning tomorrow starting with the 35. I chose to skip the 30-32.5 due to them being so close in size to the 27.5. My bike is also using the IRK, and I have heard that some of the 150cc bikes using the standard ignition haven't been affected by this problem. I'm switching to the standard ignition as well.

I tried using a UNI dual stage filter but that let in way to much air and leaned the bike out so much, so I went back to the stock round filter for now.

Hope this info helps you out, but it seems like trial by fire is the only clear way of fixing this problem.

 

[OLDSCHOOL]

Kevin I think a 25 pilot and a 110 main is a good starting spot are you gonig to run it at the MOM race

well the weather is getting nasty up here and it all depends on if I can get it broken in....but getting the jets should not be a problem....



I just like to get a base line but without any numbers on the ones that come stock I could be there for days....

I have my other bike I can run if I dont get it to run real decent



thanks for the info



you going to be at the race?

 

[micro75]

Yes I am going looking forward to it no bike though

 

[foespilot]

I too just got an 08 Pitster x4r 150. It too has carb. issues, 'bout nearly killed me today. Im learning a lot reading these forums, thanks to all. Hope someone has the answers... Its kinda pricy to run like crap.

 

[magiksc]

.... use the oko 26mm carb, john will atest they are way easy to dial in compared to the vm26.

I agree, the Oko is a great carb and easy to work with. I have played with that Molkt and while it ran great on my wife's 140 here in Utah, when we wen to the Texas Nationals I junked it for a 26 mm OKO. Now I run the Oko on her 140 and my 150. The jetting for me here in Utah is in the low 40's on the Pilot and around 105 on the main (the weather is changing here so it will be time to rejet). I've been hearing some rumors of some new versions (bigger) of the Oko being released but until I see more its all rumors for now, I'm wanting to move to a 28mm carb but not sure yet.

 

[gixxerguy6]

I'm posting about ricekrispy's carb issue. MOLKTZ 26mm



42.5 on the pilot still a slight stumble off idle, 105 main with UNI filter 3/4-1 out on the AF screw. Warm here in the 50's but raining and lots of moisture. Went riding in the woods bike did great through the tight slow stuff no stalling, no stumbling from slow to full on 'lets get going' throttle. Riding on the road the bike performed great, reved out good through all the gears.



All this was checked after swapping out the IRK to the stock flywheel.



Small changes will have to be made when the temp drops back down or the moisture isn't present but we'll check that this week sometime.



I hope this information helps someone with these carbs.

 

[65fsbk]

Update:



So I got the new Pilot jets yesterday and the first one I installed was the #30 and there is no backfire at all now and very responsive from idle to 1/2 throttle. So I figured that is the right pilot jet, now it's time to go to the main jet tuning.



The first main I installed was a #140 and after 1/2 throttle it would nose over badly and fall on its face with lots of sputtering. So I figured it was way too rich. I installed a #110 main and it definetly felt better through 3/4 throttle but it would sputter ocasionally and felt like loss of power at WOT. I bumped it down to a #100 and it wasn't much of a change from the #110. I bumped it down to a #95 and it seemed to loose more power and sputter more. After that i went up to a #120 and it didn't feel much different from the #110.



Could the needle position make a difference at all up high? Currently the clip on the needle is on the slot second from the bottom.



When i say it feels underpowered, I'm saying that I would think that a 150cc in a CRF50 would put me on my back at anytime with a roll of the throttle. Maybe I'm expecting too much, I mean I am 6'2" 210 Lbs.



The gearing I'm running is a 15 Tooth sprocket on the front and the stock CRF sprocket in the rear whatever that is if that helps diagnose the issue.



Another question, does the location of the pickup magnet on the IRK make a huge difference? I currently have it in the center of the slots with it gapped the width of a business card from the rotor. Will moving it up or down do anything performance wise? If it does which way should I move it with the symptoms I'm having?



Thanx in advance for the feedback!!!...Manuel

 

[micro75]

Try putting the needle in the middle and try that first the timing will make a big diffrence the gap should be ok with the business card moving it up will retard the timing down will advance it try the needle the try retarding it a little and see if it helps

 

[65fsbk]

micro75,



What does the movement of the needle actually do? In what way does this affect the performance. Does moving it up richin it or lean it, or does it do something completely different? Thanx!

 

[OLDSCHOOL]

micro75,



What does the movement of the needle actually do? In what way does this affect the performance. Does moving it up richin it or lean it, or does it do something completely different? Thanx!

NEEDLE JET: Your carbs needle affects throttle settings from 1/4 to 3/4 turns lucky you dont have to replace the needle to adjust. Start out with the clip in the middle setting make a couple of runs, then change the clip down two positions. This is the quickest and fastest improvement you can make to the bikes jetting. Dont be afraid to move the clip up..LEANER or down..RICHER. You spend most of your time riding in this range.

Try all clip positions on the needle see what runs the best.... If you find your clip position at the very top or bottom. then you need to go back to your main jet and pilot jet and make a different setting...

When all is done your clip should be in one of the three middle notches.





Micro75 suggested that I start with a #25 pilot and 120 Main and im at sea level, (Stock Flywheel and rev box) (Temp at 35 degrees) and it runs real good

 

[65fsbk]

OLDSCHOOL,



Thanx for the feedback! Did u remove the IRK or did it come without it?

 

[OLDSCHOOL]

OLDSCHOOL,



Thanx for the feedback! Did u remove the IRK or did it come without it?

The motor did not come with it. I believe its comming as an option with the complete bikes.



Ive been using IRK for a few years and I dont care for them in the Dirt...

 

[mathis]

Finally:



Molkt 26mm:



what jets to use on Lifan 140cc?

What jets to use on YX/GPX 150cc with IRK?



Thanks

 

[foespilot]

What brand of jets cross over to use with the molkt carb?

 

[OLDSCHOOL]

What brand of jets cross over to use with the molkt carb?

Read the thread its mentioned a few times

 

[MPE]

Hi Guys.

Just a bit of ineresting info to add to the Molkt carby jetting issues.

We had a customer get back to us with similar problems with his Molkt carby setup on a new 150cc motor. No matter what he did with main or pilot jets would sort out the crazy 1/4 to 3/4 mixture problems.We had the guy bring his bike into our workshop to diagnose the problem and as soon as we pulled the top off the Molkt carby and looked down inside the slide there was the culprit no retaining washer locking down the needle assembly.The needle was floating up and down freely inside the slide causing the bike to run erratically one second lean next rich.

We fit a new Molkt retaining washer in place,screwed the top back on the carby and Voila instant sweet running engine from idle to WFO Smiles all round this end.



Moral of the story dont take it for granted that the little Chinese "Mechanic" Cough Cough ! has assembled the carby correctly at the factory !!



Perhaps there are a few more Molkt carbies out there missing a vital needle retaining washer as well !!



Ps.We had another customer today with identical situation with poor running with the Molkt carby..This carby had the retaining washer fitted ..But it was fitted under the needle circlip rather than above thus causing the same erratic engine running scenario.The fix was to remove the slide assembly and refit the Retaining washer above the needle circlip reassemble the carby and problem solved.....Braaaaap !



Cheers

 

[mattmoto441]

i thought i would dig this thread up on this carb just because it has a lot of good info in it and i have also found a issue with the carb that has not yet been brought up. What i have found is that the needle bottoms out and holds its self up just a little bit. So i am no carb guru but this could be the main problem with the carb to where it is giving the dead bog that you get around 1/2 throttle. Some people have jetted around this but you get yourself to where the bike runs rich down low and lean up top, or vice versa. So could the needle be copied off something different then the main jet ?? Like i said IM no carb guru but i think that if you get a needle that would match the main to where it don't bottom out inside the carb that could fix 90% of that hard tuning issues there are with this carb. .If you put the needle in the middle it just barely bottoms out, but if you have the clip one or two up then it bottoms out and holds the slide open? This isn't on just one carb, i have 2 of them that the needle bottoms out

 

[CCSRacer197]

hey oldschool now i know why those vm26's are always so much nicer to have. personally i was thinking of going with a keihin PE26-28. little more expensive then the vm but i would like to try one. any ideas?

 

[OLDSCHOOL]

hey oldschool now i know why those vm26's are always so much nicer to have. personally i was thinking of going with a keihin PE26-28. little more expensive then the vm but i would like to try one. any ideas?

what are you running for a motor and break down of top end parts

 

[chiro972b]

I had someone else tell me to use the Keihin hex shaped mains like from a PWK, but it sounds like you guys are using the round sloted ones right?



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