|
|
Post by 50cc on Oct 22, 2012 3:24:54 GMT -5
Hi guys,
I was wondering which are the most common factory main jet sizes installed by the Chinese factories in our scooters (50cc only please), so I decided to make this poll.
You may also share some further details in the comments below such as engine type, what type and size of carb you got your new scoot equipped with and if it's a 4-stroker or a 2-stroker.
Thanks again for your input!
|
|
|
|
Post by leonsavage on Oct 22, 2012 8:46:22 GMT -5
We are having no luck at all getting new Peace scooters to run right without changing the tamper resistant stock carburetor. It is not worth shop time, so we just replace them will a decent new carburetor. I have not been to the shop in a couple of days, but my count was 17 of 18 scooters got new carburetors during PDI to have acceptable performance. The new carburetors are re-jetted to 80 before installation.
|
|
|
|
Post by 50cc on Oct 22, 2012 9:26:11 GMT -5
We are having no luck at all getting new Peace scooters to run right without changing the tamper resistant stock carburetor. It is not worth shop time, so we just replace them will a decent new carburetor. I have not been to the shop in a couple of days, but my count was 17 of 18 scooters got new carburetors during PDI to have acceptable performance. The new carburetors are re-jetted to 80 before installation. Do they come with CVK clones or with real Keihin? How many mm's? I was lucky my Qingqi came with an original Keihin (it's a 2006) and I recently removed my 18mm aftermarket CVK clone that ran so-so with a 88 MJ and installed back my 16 mm original Keihin. Took some parts from the 18mm (like the float I accidentally broke) and noticed most of the parts are interchangeable except for the diaphragm of course. Anyway, the pilot and the main from the 18mm didn't work good with the 16mm, so I kept the original pilot, stuck a 95 MJ and.. VOILA! It works much better with the 16mm. I guess 18mm is a bit too large for 50cc and 16mm is more or less the best deal you can get for a stock 139QMB with only a free flow filter. Also, I find the acceleration much better with the 16mm. The funny thing is the smaller carb required a bigger jet to run properly... I guess because of the more intense air flow in the tighter venturi. |
|
|
|
Post by millsc on Oct 22, 2012 9:41:01 GMT -5
95mj on a stock 50cc? sounds way big i dont even run that with a 50mm bbk, exhaust and uni and other numerous mods. Seems its better to run an 18mm carb with an 80 jet on a stock 50cc your using way to much gas with such a big jet and 16mm carb, by the way where you buying these 16mm carbs?
|
|
|
|
Post by skuttadawg on Oct 22, 2012 9:43:17 GMT -5
My Magnum a 2T came with a 19mm TK carb with a 68 MJ and 40 IJ
|
|
|
|
Post by 50cc on Oct 22, 2012 9:47:28 GMT -5
95mj on a stock 50cc? sounds way big i dont even run that with a 50mm bbk, exhaust and uni and other numerous mods. Seems its better to run an 18mm carb with an 80 jet on a stock 50cc your using way to much gas with such a big jet and 16mm carb, by the way where you buying these 16mm carbs? Yeah, surprised me as well. And the 16 Keihin came with my scooter, I don't know where you can buy one, but I can take pics of it together with a ruler in mm so you see it's a 16 if you don't believe me. And idk how much more gas it'd take, but will test and report. |
|
|
|
Post by millsc on Oct 22, 2012 9:48:01 GMT -5
I believe you just never seen one before
|
|
|
|
Post by 50cc on Oct 22, 2012 9:55:09 GMT -5
I believe you just never seen one before Yeah, the finish is great, the logo "Kei (something like star) Hin" thing is there, the "JAPAN" thing is there, looks very fine polished (no edges), bowl sticks like glue and wouldn't leak a drop even with the float all the way up, responds faster, copper parts (jets and such) are from a darker (read REAL) copper, the AF mixture srew is different (sharper top) and wouldn' fit a clone, also the float needle is a bit shorter, etc. Levels above the clones. Worked great with my QT engine, now works with my BT just as good. I got 2,4 L / 100km with my airbox and my old engine with 5g weights. Idk how there mumbers might change with the free flow. Btw, my scoot is branded as "REX RS450" here in Germany if this matters. When he read about it in a forum, a guy from the Netherlands wanted to buy it from me for 60 EUR.. and that for a scoot carb with broken float and without a main jet. I'm so glad now I didn’t sell it. |
|
|
|
Post by redbullf1 on Oct 24, 2012 3:15:51 GMT -5
its pretty easy to open up factory carbs i did mine had a 79 main jet installed and i replaced it with an 81 runs way better next i am adding a 35 idle jet
|
|
|
|
Post by stiv625 on Oct 24, 2012 7:08:41 GMT -5
Mine was a #75 from the factory and actually ran decent at low rpms (really heavy rollers came with it too) but would have exploded at higher RPMs. 4g rollers, intake & exhaust mods and now im happily running an #85 MJ  |
|
|
|
Post by 50cc on Nov 14, 2012 10:51:57 GMT -5
Thanks for the info everyone, it's much appreciated from people like me who got a second-hand, already modified scooters.
|
|
|
|
Post by chops on Nov 14, 2012 11:43:34 GMT -5
Mine runs an #84mj as standard.
|
|
|
|
Post by 50cc on Nov 14, 2012 11:57:51 GMT -5
Mine runs an #84mj as standard. At what elevation? I run #85 now @ 34m (112 ft) above sea level. |
|
|
|
Post by prodigit on Nov 15, 2012 9:26:32 GMT -5
Small question:
For a similar engine size, does a 2stroke have a different jet size than a 4 stroke?
|
|
|
|
Post by 50cc on Nov 15, 2012 11:43:10 GMT -5
I always wanted to know that too, but from the forums I read I notice the numbers are pretty close for the similar air filter / carb size configurations.
|
|
|
|
Post by 50cc on Feb 7, 2013 13:44:18 GMT -5
up
|
|
|
|
Post by slopongen on Feb 13, 2013 11:37:24 GMT -5
On my Qingqi qm50qt-6 it was 79 i change it to 82 but it doesn't help. My adwise is if the standard is 79 or bigger don't mess With it.  |
|
|
|
Post by 50cc on Feb 13, 2013 14:59:02 GMT -5
On my Qingqi qm50qt-6 it was 79 i change it to 82 but it doesn't help. My adwise is if the standard is 79 or bigger don't mess With it. My last engine was the same Qingqi 139QMB and ran #85 stock. That's what I'm running now on the Baotian engine also. |
|
