I installed an 80cc kit on my 49cc 4 stroke dykon. Everything went really well and everything is setup correctly. Valves are adjusted to .004 With timing at TDC. I have a aftermarket high flow air filter On my original carburetor with a # 90 main jet. The scooter runs really well until I go down a long hill. When going down the hill it Feels like it totally runs out of gas in the bowl. It will run perfect uphill and on level surfaces. When i go downhill it acts like it has no gas or no fire for a split second then goes back to running and then does it again and again on and off but only for a second and always down hill. It will have the same problem when hitting a bump in the road, but only for a second then fine until the next bump or hill. I have a jetting kit with a bunch of main jets I have went from #88 all the way to #95 in one # increments. I have also tried taping up the high flow air filter Starting small and going down the length to see if too much air flow was the problem but that didn't help either. Iv run out of ideas. Any help would be greatly appreciated.
Downhill i would say you are hitting the rev limiter. As for it dying for a second or two over bumps, you have a bad electrical connection, probably ignition related
Thanks for your reply. I will definitely check my connections. I believe my cdi isn't limited, it's that blue one off ebay: Here. Maby change my plug. Could it be failing at higher rpms? Has to be spark or air gas mix right? A buddy said it may be too much pressure in the crankcase... does that make any sense? Stock exhaust to restrictive? Stock carb to small? Checking connections tomorrow will keep updated.
Ok. So I checked for loose connections especially on the ignition end, replaced the cdi and coil i think (goes to the spark plug) with back ups I had laying around. Still had the same problem. I then started to decrease the size of my main jet from #90 to #88... Some improvement. I then went from #88 to #87 with a good deal of improvement but the problem was still there. Here is the funny part, I pulled up in my yard after the test trip w/#87 main jet and noticed the bike sounded different at idle. I left it running and looked it over. There was a lima bean size hole near the muffler mount. This was new I know from the change in sound. I then took it back out and problem solved... Must have been too much pressure trying to flow through the exhaust, causing it to blow a hole in the muffler casing thus solving my downhill problem. LOL. Thanks for the help guys.
