yfm200 moto 4 issues

[keith krawczyk]

I have a 1985 yfm200n moto 4. I have just rebuilt the Carb and now anytime I start it up it will run fine at idle but bog when given throttle throttle. It has a new air filter and I adjusted the valves but still boggs when given throttle any help would be great!

 

[speedyslyder]

i think member @tbrooks gots one of these.
2 types of bogs /lean/rich.
it could be starving for fuel or starving for air or too much fuel..ect
compression test /correct plug/gapped correctly.
fresh gas

 

[tbrooks]

I have a 100. All I did was clean the carb, change plug and oil and mine ran. Sound like its prob carb related. Did u clean the carb thoroughly and set the floats?

 

[Awk08]

you completely disassembled all jets, cleaned and blew them out with compressed air ?

found this in a google search..............

if the carb # is Mikuni VM22SH ID # 52H-00, then the stock main jet is a 115, the needle jet position is # 3, and the pilot screw turns out 1.5 turns. If your carb # is Mikuni VM22SH ID # 1NU00, then the stock main jet is 117.5, the needle jet setting is the same, and the pilot screw is 2 turns out. Valves would not make it do this. Sounds like you're not getting enough fuel. But for the record, valve clearances are: Intake - 0.05-0.09mm Exhaust - 0.11-0.15mm


float level set/checked ?
looks like it should bve at 25mm ?
http://www.allensperformance.co.uk/vm22-133.html

 

[keith krawczyk]

Im going to pull the carb back apart a re check all my jets. Then go from there

 

[keith krawczyk]

Ok i check the jet sizes and the main jet was wrong So i removed it and placed a 117.5. i checked the float and it is adjusted correctly correctly. It will allowing to throttle up higher now but im getting some back firing and it is still wanting to bogg down

 

[Awk08]

Ok i check the jet sizes and the main jet was wrong So i removed it and placed a 117.5. i checked the float and it is adjusted correctly correctly. It will allowing to throttle up higher now but im getting some back firing and it is still wanting to bogg down

if you're confident the carb is now correct ?
how bout that fuel screw ?

time to check some electrical, new plug, check plug cap and wire and all connections.

 

[tbrooks]

Back firing is a sign off too much fuel or timing off or bad connections as said^^ The float must be dead on within range, and measured exactly as specified, a mm off can make a big difference

 

[keith krawczyk]

She is running like a champ now! Took out the crappy champion spark plug and went and got the NGK that yamaha said was factory installed then after some fine tuning of the pilot screw shes runs like brand new! Thanks @tbrooks and @Awk08 for the help

 

[tbrooks]

Glad to hear it