Engine Idle too high around 3000 is it correct

G

Geeky

Member
#1
#1
I have massimo mb 200 and I did a mod of adding filter, new carburetor, torque converter, and 0.038 main jet. I had series of issue with original carburetor so bought new twice. First one had a lot of jerk and used to turn off. Now bought different one and put the 0.038 main jet. The RPM is too high. I tried setting the idle screw and air fuel but not getting right adjustment. Governor is there.
While adjusting I do smell fuel could it be normal that bike haven't run a lot so engine is being adjusted.

Plus the speed is slower than original know.

Made this video if anyone can help. Please turn the volume low and gradually increase to see if you can catch something.

http://imgur.com/a/1pSMWvm

I regret doing mods and buying this china bike. Have spent a lot of money and trying to get it to work rather enjoy ride. Last thing I want to do is buy a new predator engine.
 
Last edited:
Colemanman

Colemanman

Member
#2
#2
theres no reason to buy a new motor. The jet they give you in the jet kit doesnt always turn out to be the right size jet the motor needs. Pull the spark plug and if its black its to rich if its white its to lean. You want kinda of a brownish color. make sure you dont have a vacuum leak due to bad sealing gaskets on the carburetor. Theres 3 of them. I believe the idle is supposed to be around 14 to 1600 rpms. Also make sure no debri or dirt are inside the main or pilot jet as well as the emulsion tube. The pilot jet is the black thing under the idle screw. Pops out easily with a screw driver. Get a a few more smaller and bigger jets so you can properly tune the engine. Also your pilot jet may need to be changed to accommodate the different main jet. Also if your jet came with a gx140 emulsion tube you need to run a few sizes smaller main jet than you would with a stock emulsion tube. Its the tube right above the main jet. Ignore that statement if you still have the stock emulsion tube. also pilot jets. They control idle as well as idle transition to about 1/4 or so throttle. The right pilot jet keeps the motor a little richer on the bottom end to achive peak acceleration. Then at full throttle when its the main jet is the jet only supplying the fuel, your right size main jet will allow your motor to hit the highest rpm when your at full throttle and your engines under load. Too fat on the top end and it wont rev out as high under load and running slighty leaner on the top end will help it fully rev out to its max potential. So the pilot jet has to be the right size as well as the main. Not every engine even if its identical engines with identical parts will take same jets to run properly. Some like bigger and some like smaller. Also when tuning the idle the air bleed screw on the side of the carb affects idle air fuel mix only i believe. Youll have to adjust when you change jets too.Its really a involved process to tune a motor properly but it will gain you the max performance. And a good idle quality. Sorry about the long post just trying to help. Feel free everyone else to let me know if i was wrong on any information. Im learning just like everyone else.
 
G

Geeky

Member
#3
#3
Colemanman said:
theres no reason to buy a new motor. The jet they give you in the jet kit doesnt always turn out to be the right size jet the motor needs. Pull the spark plug and if its black its to rich if its white its to lean. You want kinda of a brownish color. make sure you dont have a vacuum leak due to bad sealing gaskets on the carburetor. Theres 3 of them. I believe the idle is supposed to be around 14 to 1600 rpms. Also make sure no debri or dirt are inside the main or pilot jet as well as the emulsion tube. The pilot jet is the black thing under the idle screw. Pops out easily with a screw driver. Get a a few more smaller and bigger jets so you can properly tune the engine. Also your pilot jet may need to be changed to accommodate the different main jet. Also if your jet came with a gx140 emulsion tube you need to run a few sizes smaller main jet than you would with a stock emulsion tube. Its the tube right above the main jet. Ignore that statement if you still have the stock emulsion tube. also pilot jets. They control idle as well as idle transition to about 1/4 or so throttle. The right pilot jet keeps the motor a little richer on the bottom end to achive peak acceleration. Then at full throttle when its the main jet is the jet only supplying the fuel, your right size main jet will allow your motor to hit the highest rpm when your at full throttle and your engines under load. Too fat on the top end and it wont rev out as high under load and running slighty leaner on the top end will help it fully rev out to its max potential. So the pilot jet has to be the right size as well as the main. Not every engine even if its identical engines with identical parts will take same jets to run properly. Some like bigger and some like smaller. Also when tuning the idle the air bleed screw on the side of the carb affects idle air fuel mix only i believe. Youll have to adjust when you change jets too.Its really a involved process to tune a motor properly but it will gain you the max performance. And a good idle quality. Sorry about the long post just trying to help. Feel free everyone else to let me know if i was wrong on any information. Im learning just like everyone else.
Click to expand...
Thank you for the reply! It is a brand new carburetor I just bought and just replaced the main jet. Sorry I mentioned wrong I changed the main jet not pilot jet
 
Last edited:
Colemanman

Colemanman

Member
#4
#4
To a certain extent yea you can. But if you turn it too far out you risk the spring not having enough tension to hold the air bleed in. Best performance would come with the right pilot jet. But in your sisituation id just put it where in runs the best for you
 
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