a_robotham wrote:I'm no expert but I believe your CDI is not allowing the spark to advance all the time. Sounds similar to what a car will do if the ignition does not advance. Try finding a cheap CDI and swap it out.
I have wondered if it is sparking incorrectly due to a fault in the electrical system (like the CDI, rectifier or ignition coil). I don't know much about the electrical system though; Is there any way to test these parts with only a cheap multimeter?
Also, would I be right in thinking that the CDI is the coils & stuff behind the round crankcase cover on the left hand side of the bike (when viewed sitting on it)? I'm only asking as I'm relatively new to bikes and the CDI seems to get referred to a lot in forums as a box/unit (ie. one piece) but it doesn't look like a box, and it is made up of several bits (2 coils and a few smaller bits). Have I got it wrong?
I've had a look for replacement electrical parts to try in the bike but can't find any for a price I can afford at the moment, I will keep looking though.
supercub wrote:What is your compression? If it is a variated transmission, is it going into top gear ratio when it goes 18mph, or is revving wildly?
200/1 mix is way too low. I would think 32/1 is closer to what it should be but there are people here that are more familiar with the bike.
I'm not exactly sure of the compression as I can't find my compression tester, but it seemed ok when I last tested it after the last time I took the engine apart. I'm pretty sure it's single speed transmission, not variated. I know what you mean about the 200:1 mix, it sounds far too high but when I had it at 50:1 the bike seemed to run even worse; this was before I cleaned out the exhaust though, so I will try lowering the mix back down to see if this helps.
jayel wrote:the QT's came with about a 74 main jet for break in purposes needs about 68/70 to run good, check your main jet size and check that the choke (enricher) is workng right it may be holding open resulting in a overly rich condition
I checked the choke and it's ok. It still has the same main jet that came with the bike when I bought it 4 years ago, and it had done around 8,000 miles when I got it. Also the bike worked ok for the first 300 miles or so. I will have a look at the jet to see what size it is though.