Upgraded and now it won't start

Discussion in '2-Stroke Engines' started by Motocruiser, May 21, 2011.

  1. Motocruiser

    Motocruiser Member

    So I just recently got all of my upgrade parts in. Includes: SBP expansion chamber, pirate cycles 44 & 36 tooth sprockets and hub adapter, jaguars CDI, a CR-80 coil and Dellorto SHA 15.15 carb. It ran fine a couple times down the street then died. I unhooked my kill switch, no fire. I replaced the spark plug and plug wire, no fire. Took the CDI apart to check internal wires, all fine replaced, no fire. Next step is to go through all of the wires to make sure they aren't grounding out somewhere. If that fails I guess I'm gonna order a new magneto. Any other suggestions from anyone?

  2. adrian101

    adrian101 Member

    I'm guessing if you got a new CDI and placed it on your bike it may be the problem. Check if you matched the colors correctly. (blue to blue)(black to black) and the two coming from the kill switch can go in either of the left over holes from the CDI. If you mess up the (blue to blue)(black to black) you can destroy your CDI unit.

    Might sound silly but also check for air leaks, carby Inlets, exhaust outlets and the carby itself. basically where air could get in or out that you dont want it to. makes your engine cut out and you mistake it for a sparky fail or wiring mistake

    here is a trouble shoot guild for the standard CDI which may help:

  3. Motocruiser

    Motocruiser Member

    I appreciate the reply. I had the wires correctly hooked up as it ran previously. I don't have a stock CDI so the video isn't going to help. I have a modified KDX200 CDI by a forum member Jaguar. Not thing I'd different in the setup except the exhaust and carb. So I suppose I should go back to stock to see if that was the problem.
  4. srdavo

    srdavo Active Member

  5. SlugMan

    SlugMan Member

    I bought (pirate cycles) the same carb as you and installed it over the weekend on my 66cc grubee engine. I'm pretty sure I know whats wrong! Hehe
    The mixture is to rich for the engine. I'll tell ya my experence.
    After the install, the bike would not start, you could tell it wanted to. After thinking a couple of min's, I took out the air filter and removed the carb cover ( Give it more air). It started without the choke on!! Now this told me the engine was running WAY to rich!
    The engine needed more air, and I had a stock exhaust on it. I took off my stock exhaust and had an extra straight pipe laying around (Stock exhaust with the muffler cut off). After switching exhausts it took off like a rocket! Still won't start with the choke on, which tells me it's still running rich.
    I went online the other night to a moped site that sold these carbs and it warned not to install this carb unless you have done MAJOR mod's (Intake, exhaust, piston, etc)... You need to lean out the mixture. (Probably)

    Good luck :)
    Last edited: May 22, 2011
  6. SlugMan

    SlugMan Member

    I missed the part about no spark... Well, maybe it's not the carb. I did get my CDI from Jag the other day, but have not installed it yet. I would like to know how it works out for ya.
  7. Motocruiser

    Motocruiser Member

    The CDI worked fine. Its a subtle change but I never had the opportunity to try it with lower gearing or my SBP expansion chamber because it stopped working. I then returned the bike to stock and it still won't run.
  8. Al.Fisherman

    Al.Fisherman Active Member

    People take warning......

    Only install one mod at a time and test run between mods/upgrades
    Last edited: May 23, 2011
  9. SlugMan

    SlugMan Member

    Good Point Al,
    I installed my carb, then made sure the bike started. I didn't care if it ran like **** at that point. Then I installed my high compression head. Next, I will install my new ignition parts, then my expansion chamber. Then fine tune the carb.
    I learned the hard way about doing one thing at a time. I used to fix old tube radios. When I first started, I would change multiple parts, then plug it back in. One time, I did this and the radio didn't power up.... Wow, what a pain-in-the-neck it was trying to figure out where the problem was! I ended up taking it to a more experience person, and he told me the same thing... One part @ a time! And he fixed radios for a living :)
    I wish you the best of luck figureing out what the problem is...
    Gas/Air , Spark & Compression = Varoom!
  10. motorpsycho

    motorpsycho Active Member

    this allows you to backtrack easily if you run into a problem after installing an upgrade or high performance part.
    plus, it will tell you if that part is actually giving you a performance gain or loss.
    if you bolt on a bunch of stuff, and then lose 5 mph, now you have to try and figure out exactly which part is causing the loss.
    one part at a time and then a test run in between each part will tell you exactly what that part is doing.
    if you put on an expansion chamber and gain 5 mph....good.
    put on a high flow air filter and gain 1/2 mph ...good.
    put on a high compression head and gain 3 mph....good.
    put in a champion spark plug and lose 5 mph.....take the plug out and go back to what was in it before.
    put all those parts on at the same time without a test run in between, you will never know exactly what's going on.
    Last edited: May 24, 2011
  11. Motocruiser

    Motocruiser Member

    I didn't change anything electrical. Everything ran fine stock. I returned the engine to stock minus the rag joint drive sprocket. I seriously doubt the upgraded drive sprocket is causing the no spark issue. It also doesn't explain why when I coasted to a stop the engine died and I couldn't start it again when it was running fine seconds earlier. It doesn't explain why neither the upgraded or stock CDI are working. Not that I don't appreciate any help. But putting on an expansion chamber and carb should not cause a no spark response. Sluggish power, bogging, performance gains yes. Not the latter.
    Last edited: May 24, 2011
  12. Motocruiser

    Motocruiser Member

    Well, after replacing the CDI and magneto. I've decided I'm giving up on this engine. I'm well over $2k into this bike and I can't afford to keep throwing parts at it.
  13. hey see if your magnet is weak i went through the same bull sh** and find out it was a $5.00 magnet :idea:
  14. BoltsMissing

    BoltsMissing Active Member

    Try the basics,
    No Kill switch and no blue and black wire crimps.
  15. Motocruiser

    Motocruiser Member

    Just an update. I received my new engine June 3. The engine fired right up with my CDI's that was though to have shot ****. Still not sure what was wrong with the old engine but this next winter should give me plenty of time to tear it down and rebuild. In the mean time I'm going to enjoy the engine that is running.
  16. srdavo

    srdavo Active Member

    good for you!!
  17. cpuaid

    cpuaid Member

    Had a similar problem with a high performance carb upgrade. Bike ran fine with new carb but it was hard as heck to get started sometimes. A few weeks later the bike wouldn't start at all, not even with using starting fluid. Disabled kill switch, no start. Drained out the gas tank and replaced with fresh gas. No start. Swapped out plugs, no start. Swapped out spark plug cable, no start. Swapped out CDI, no start. Swapped out magneto, no start. Took apart and cleaned out new carb, no start. Let the whole thing sit for over a year because I was so frustrated. Swapped back to my old stock carb and the darn thing finally started up again. A week later and she still starts right up again with the stock carb. Go figure.
  18. one way to fixe the problem