Wednesday, April 22, 2009

Failure failure failure...

I find myself often ignoring the idea that a stock moped is a dependable moped and a souped (suped?) up moped is likely to be faster but exponentially more likely to break. Why do I do this? Because I'm an idiot that's why. Get off my back, what have you done lately?

Since slapping the Pinto together I have had moments of glory within ages of pure chagrin. Lately, the quest for glory has been to install the new cdi that treats has recently come out with. So far I have spent about a week dicking around on it, timing it, trying various cdi controllers, installing a proper kill switch, etc. I have managed to get it running, however, the incredible performance increase that I was hoping for has actually manifested itself as a mediocre performance decrease. I get about 5-8mph less top speed than I did before and my low end is worse. Hmmm.... I don't think that the fault lies within the unit itself, I suspect that I'm probably doing something wrong and have lately been considering a full breakdown and build up of this bike from scratch.

One major performance issue has been a top speed surging. When I hit the top of my power, rather than it just sort of hanging out there, the bike surges and loses power until I lay off on the throttle a little bit. It was exhibiting this same issue in L.A. and I thought that it was perhaps an issue with the Tillotson carburetor. However, Michael Mike, the mechanic whose example I usually follow, has not seen this problem in the nearly identical setup that he built so now I search for the root of the issue.

A) Fuel Flow
Perhaps I am just not pushing enough fuel through my carb. My petcock is fairly janky and so maybe when I hit the top speed I'm simply not getting enough fuel pushed through the carb. I had a little fuel pump kicking around my shop so last night I thought I'd throw it in there and see if anything improved. I tied it in to the pumper line on the bike and also tied in the fuel line and it didn't seem to effect anything negatively... until this morning when I couldn't start the bike at all. I suspect that over night the carb drained dry and now I need to prime the carb prior to starting it so that I have some suction. Lame. The problem is that I couldn't prime the carb and start it in place because I munched my pedal chain tensioner and had no pedal chain. The fuel pump also didn't seem to effect the surging issue so for now I'm thinking it may not be the fuel flow. Unless it's the petcock that is causing issues...

B) Dented up header on the pipe
My pipe is in pretty bad shape. Not so horrible that it won't run, but it certainly isn't helping things.

C) Seized up blued up kit
My 64cc polini has treated me pretty well if you don't consider the three times it's near-cataclysmically exploded on me. I've replaced the piston once, and the rings twice. It CAN go fast sometimes, but I feel like when you are making fine adjustments on a every other piece of equipment and the main hunk of metal that produces the power looks like it's been chewed by truckasaurus... it might be time to throw in the towel on ol' polini power and buy a cheap kit that I can hack on. "Rosanna, I need to buy a new kit. Do we really need to eat this month?" Probably will not happen for a while.

I think my issues come down to this truth that Responsible Jon so eloquently stated, "Kitted mopeds are only reliable if you are willing to replace EVERYTHING. Even the things that are sort of still working." Essentially, if I want to continue using this crap bucket as a daily rider, I'm going to need set it aside, ride my stockers to work and back and spend time and money slowly on the super bike, taking my time to figure things out instead of plugging the sieve holes one at a time.

I'll illustrate this post with photos of my blued up parts later.


  1. So that's what you've been doing all this time. Failing. Cut. It. Out.

  2. Never forget that 2 identical 'suped up' bikes will run so vastly different nearly no comparison can ever be made. Most of these machines are a far cry from an exact science. If they were we would all be screwed. Or jet-engine mechanics.

  3. Good luck to ya, don't get blinded with science!

  4. i've been having the same problem (the surging at high speed) on my puch polini. it started in la as well. nate thought it could be the reeds fluttering strangely at a certain rpm. i'll be installing and testing the performance reeds this week to see if it helps. i'll let you know what i find out.
    - gabe

  5. hey joel, just a heads up. i replaced my points and that fixed the surging problem i was having. did the cdi fix that problem for you?

  6. gabe, nope, the cdi didn't change it. When I get my Cali tax return I'm putting a new kit on there and maybe we'll see a difference?