mjfriesen

I have a 247 with a 26 MM mikuni on it. Jetting is: pilot - 30 main - 130 needle jet - O-2 needle - 5f21 slide: 2.5 float jet: 2.5 It starts well and runs well, but is a little too abrupt at just off idle, kind of like having a fast-turn throttle, even though I have a slow amal throttle fitted. It is a spigot-type carb, and it has an aluminum adapter between the cylinder and the rubber carb mount. There is also an adapter for the mouth of the carb to mount to the airfilter boot. I have another 247 with a rebuilt amal (replaced all jets and needles, had the body straightened and the slide sleeved last year), and it is MUCH nicer at low throttle. It comes on smooth and linear, instead of on-off like the mikuni. I would love to have another amal... I have verified the jetting with a reputable dealer, and although I have tried different pilot jets, needle jets, and needle postions (don't have another slide with a different cutout) i can't seem to improve it. That's because i am not very good at 2-stroke carb tuning. Good Luck! The 247 is a great bike!

sounds like it was running way too lean and over heated, causing the bike to "diesel", i.e. run even without the benefit of a spark. I had this happen to me once when i was chasing a friend on an atv on trails he knew very well. my old bike did not like going ~45 mph continuously. it actually got so hot i could only stop it by shutting off the gas - should have thought to block the exhaust, but oh well! It may be that lowering the needle is causing it to run lean and over heat, or maybe the needle is a coincidence. i would check it out, and see if it is dangerously lean. hope you sort it out!

I have a couple cota's of the same vintage, and the tanks have all been treated with Caswell sealer. Caswell Plating I did not experience the brown goo problem, so i can't say if that is the problem. All of my montesa tanks were getting soft and leaking at the seams. Love the Caswell epoxy sealer, and have never heard of any problems with it (unlike kreem...)

I guess that is the beauty of the internet!

I don't doubt that it can do that, but i would remove the old condenser. One way a condenser fails is to go into a "high leakage" mode, which can allow more of the ignition energy to leak out to ground instead of being used in the coil to produce a nice big spark. I would imagine that having 2 condensers in the circuit increases the total amount of leakage possible (i have not tested this, but am just guessing. I should dust off the oscilloscope and try to remember how to use it...screw it ). When one of the 2 condensers fail (goes into high leakage mode) the second condenser is not going to help you. I am just a hack that a number of years ago was a pretty pathetic physics student, so if i have misstated anything, someone please correct me!

I don't have any pics, but it is not too different from the pics of the bultaco, and TayId's description is great. Just about any small engine capacitor/condenser will work. I bought one from the local Lowes Hardware for a lawn mower. It had the wire lead on it and a mounting tab that made it easy to mount right next to the coil.

i think most people prefer a slow action throttle for trials. better control and smoother power delivery are easier with the slow throttle.

Belews Creek, which is between Stokesdale and Winston-Salem. Beautiful land, great terrain to ride on.

We should have taken some action shots, but i guess we were all having too much fun riding! Or maybe it was exhaustion from kicking the late 247 to much.