need help

crassius

crassius

Well-Known Member
got 6 kits in and just built one

kits have new rubber spark boots on the CDI & mags are all the 450ohm type (that are measuring 480 - 510)

fired it up & ran for 4 min - stopped it for a while to cool - fired it & ran 30sec & died with backfiring

spark looked weak & mag tested OK, but high, so put on a new CDI - ran 2 min & died

replaced mag with a 350ohm & both CDIs were still no go - put on yet another rubber boot CDI & so far is running OK on the 350 mag

so, anyone using the 450 mag with rubber boot CDI? any problems?

side note - took off mag & saw fuel running out 4 mounting holes!! - made sure to file backside really smooth to seal that

got a good deal on kits, but if I need to replace mag & CDI on each, it will be a problem
 
I have one kit that came with that CdI off eBay, it has ran flawless since February. I haven't ohmed mine because it has worked from the start, mine has the molded boot on the cdi and no white wire on the mag.
 
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yeah, putting in a 350 mag I have a rubber boot CDI running now (but only have maybe 45 min on it)

the 450 mag has more windings and more power, but not sure if it is just a current boost, or voltage too - need to find out if they are all going to blow out on the bigger mags
 
update: rubber boot CDI is still running OK on the 350ohm mag

supplier offered to send 2 replacements, but I told him to hold off till I get a chance to do more testing next week

no one else having trouble with those CDIs hooked to 450ohm mags?
 
did testing on bad CDIs

bizarre intermittent spark at normal revs & timing is off when it does spark - got a faster drill motor for the CDI tester, and at very high speeds the CDIs will spark at the right time (but there is no way to pedal the bike that fast to start it)

same type of CDI is still running well after I replaced 450ohm mag with a 350ohm mag

just ordered some 350ohm mags, but hoping I won't have to replace a bunch to get these running (maybe it was just a factory screw up on that particular pair of CDIs)

kit seller is being good about it & sending 3 new ones to replace the two bad ones - nice to have kits on the shelf that I can sell cheaper than they can buy on the net, but not so good if the CDIs fail

anyone else running rubber boot CDIs with 450ohm mags???
 
Just got a package from supplier - he sent 3 CDIs to replace the two bad ones.

All replacements are the plastic boot CDIs, so I still don't know if the rubbers are too weak for the 450ohm mags : (

I'm going to pull all the CDIs out of the kits & replace with plastic boot CDI's (lucky to have enough on the shelf) and use the rubber boot ones only with 350ohm mags.

still no one else with problems??
 
third new CDI blew out this week - really seems a problem between rubber-boot CDIs and 450ohm mags

no one else seeing this??
 
Well whenever I bought my first kit it ran fine for about 200 miles then burned up the mag wich tested at 450 or more ohms then bought a new mag wich tested at 350 ohms where it should be at.But when I got my new mag they sent me a piece of paper with it that said on some there mags they were making had some kind of epoxy coating on it and where the ground wire on the mag bolts on the epoxy was keeping the ground wire from making a good ground causeing the mags to burn up so I got to looking at my old burned up mag and sure enough you could see a little tiny wire that is soldered to the mag from the coil and it was burned up.So they told me on that piece of paper to make sure if you get one of those epoxy covered mags to sand the epoxy off where the ground wire bolts to the mag hope this help.
 
I've seen that often with some mags, but all these have held up well - it is certain CDI units that may be having problems with the 450 mags, but with only three failures, it could still be just coincidence. When they blow out, my supplier has free new ones here 2nd day, but I'd rather they didn't fail in the first place.
 
FWIW, crassius, I'm seeing this. I'm sure others are, too. We just don't have the answer.

But we'll definitely be interested in what happens next.

Best of luck to you.
 
all fails so far are CDIs with long, dull colored rubber boots - some replacements with short, shiny rubber boots are not failing - not sure yet if that is significant
 
bumping this thread

seeing a crapload of posts about bad CDI units now, many of which run only a few minutes & then present with a weak spark that will run the bike if started at about 20mph, but will not start bike normally

my supplier is sending replacements for dead ones, but it makes all 2-stroke kits look bad

I originally though it was just rubber boot CDIs, but now it seems more like the 480ohm mags may be the problem.

any thoughts?
 
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