My Derbi Gila build and fine-tuning questions
It lives! But first, some build pics.
Ground off the piston interfering nubs, all the way down. Smoothed the transfer transition into the case.
Used a metra performance crank, 4 lbs vs 4.5 lbs for stock. New bearings and seals.
Gila with the stud holes widened and a decompression hole drilled. Filing out the holes by hand wasn't as bad as I thought, still took a little while though.
Side by side with my old 65cc pyramid reed engine.
Now, the setup:
Gila 74cc cylinder
Derbi Metra head with decomp
Derbi Metra crank
20mm PHBG - 48 idle 98 main so far
Muffler Racing exhaust (had to bend the header)
Puch CDI modded for Derbi
TJT, heaviest weights
TJT clutch springs not yet installed
Hutchinson GP1 tires
The results and questions:
Pretty quick, fun bike but not yet what I'd expect from a Derbi Gila. GPSed at 51 mph, ok but I was hoping to touch 60. Acceleration is very good but no wheelies. My ignition advance right now is about 2.5 mm, maybe too much. Stock TJT variator weights might not be heavy enough, maybe its not opening all the way? My gearing is still stock. I think the jetting is ok but could probably use some fine tuning. Pulling over after doing 51 mph the cylinder exterior was about 225 F, plug looks pretty good. Any suggestions to get this into true ripping territory?
Ground off the piston interfering nubs, all the way down. Smoothed the transfer transition into the case.
Used a metra performance crank, 4 lbs vs 4.5 lbs for stock. New bearings and seals.
Gila with the stud holes widened and a decompression hole drilled. Filing out the holes by hand wasn't as bad as I thought, still took a little while though.
Side by side with my old 65cc pyramid reed engine.
Now, the setup:
Gila 74cc cylinder
Derbi Metra head with decomp
Derbi Metra crank
20mm PHBG - 48 idle 98 main so far
Muffler Racing exhaust (had to bend the header)
Puch CDI modded for Derbi
TJT, heaviest weights
TJT clutch springs not yet installed
Hutchinson GP1 tires
The results and questions:
Pretty quick, fun bike but not yet what I'd expect from a Derbi Gila. GPSed at 51 mph, ok but I was hoping to touch 60. Acceleration is very good but no wheelies. My ignition advance right now is about 2.5 mm, maybe too much. Stock TJT variator weights might not be heavy enough, maybe its not opening all the way? My gearing is still stock. I think the jetting is ok but could probably use some fine tuning. Pulling over after doing 51 mph the cylinder exterior was about 225 F, plug looks pretty good. Any suggestions to get this into true ripping territory?
My Derbi Gila build and fine-tuning questions
Sorry, you must log in before posting to this forum.