Help: PZ30 engine requires twisting throttle to start

AresROC · 11-26-2019, 05:39 PM

Symptom: Engine requires opening throttle to start, hot or cold

Conditions:

Without throttle, engine would start and then dies quickly
Cold starts on half choke. Would not start on full choke.
Idle is set to 1500~2000 rpm.
Fuel mixture screw tuned to 1/2 turn out for highest idle RPM
Pilot Jet 35 (Down from 40 & 38. Stock is 34)
Main Jet 110 (Stock 105, also tried 115)
Occasional backfire when closing throttle

Additionally, when engine is hot after WOT runs, engine would not quickly return to idle, and instead the RPM would only slow down gradually, indicating running rich?
It is the same problem with no choke also... Any ideas I can try?

ps. I think it might be my fuel mixture screw profile...

11-26-2019, 05:39 PM	#1
AresROC Join Date: Mar 2018 Location: Las Vegas, NV Posts: 193	Help: PZ30 engine requires twisting throttle to start Symptom: Engine requires opening throttle to start, hot or cold Conditions: Without throttle, engine would start and then dies quickly Cold starts on half choke. Would not start on full choke. Idle is set to 1500~2000 rpm. Fuel mixture screw tuned to 1/2 turn out for highest idle RPM Pilot Jet 35 (Down from 40 & 38. Stock is 34) Main Jet 110 (Stock 105, also tried 115) Occasional backfire when closing throttle Additionally, when engine is hot after WOT runs, engine would not quickly return to idle, and instead the RPM would only slow down gradually, indicating running rich? It is the same problem with no choke also... Any ideas I can try? ps. I think it might be my fuel mixture screw profile... __________________ BaShan BSR 250 DB-41H 2018 Red BS250GY-18D JFG Racing Exhaust . Adjustable Shock 320mm . Brozz Digital Gauge . Renthal Fat Bar . 428 17x46 Sprocket . Fender Eliminator . Wheel Truing . Fuel Tank Repair . Keihin PZ30 Main-115 Pilot-38 Needle-1Washer Fuel Mixture-1/2 BSR Chronicles - "Project leads to more projects!" Yamaha WR250R Suzuki GSX-R 600
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