KDXRIDER.NET

Ok, so...

I have spark (also tried replacement coil and plugs for the sake of it)
I have fuel (removed carb, blasted out with compressed air, reset floats)
Reeds are fine
Engine has good compression
Exhaust is not blocked
Checked the stator, in correct position
Cleaned all connections and checked continuity
Rings look fine through exhaust port

The bike is just not running, we got it going from a bump start down a hill yesterday, it ran incredibly well but below 3/4000rpm just died, since then, hasn't started.

Anybody got any ideas? I stuck a multi-meter on the signal wire from the CDI and every rotation it gives a change in reading (indicating spark signal is being given), but could it possibly be giving it in the wrong position? I cant seem to see where the actual pickup is on this bike, I'm going to try a new plug 2moro and some easy start just to get at least 1 ting out of the bloody thing!

So... once again... anybody encountered anything similar? When it went I was riding along and the spark became very intermittent, no idle, and only firing for a few seconds at high revs... many had CDI trouble?

"engine has good compression"??....... did you check it with a gauge? if you had to bump start it, then its either a clogged pilot jet, bad plug, or ??

Last I heard you were milling the head and dremmeling the cylinder. How long did it run post-surgery? Have you popped the head back off to have a look?

Ive had bikes that were a bitch to start but we could get em started pushing it down a hill.

For me it has always turned out to be water in the gas

I agree, how old is the gas? I did this before and did all kinds of checking and cleaning before I thought of it. Now fresh gas is always on top of my list when the bike starts crapping out.

I haven't fitted the milled head yet, and the petrol is fresh (i had refueled and ridden a couple hours before it started playing up).

Haven't used a compression gauge sheerly because I don't have one to hand, but I've had many bikes and know what good compression feels like, even if it was slightly less than spec it would still fire!

got this email back from a handy website i found

"Sounds like a bad connection at the stator coil. Tighten all connections and maybe even resolder the solder connections.
To check the stator coil: use a cheap Radio Shack voltmeter, set it at 100 or more volts maximum AC voltage, connect it to the two wires coming out of the stator going to the CDI, tape the voltmeter to the bike so you can see the dial pointer while pushing the bike, push it and then dump the clutch, voltage should be no less than 75 volts. If lower then replace the coil.

Yes I can send a KDX200SR CDI to the UK for $55 total."

will give that a try l8r! (bearing in mind I wound the bastard myself.... worked for weeks though)

not one to argue................but you said you had spark in the very first sentence. compression has nothing to do with spark. if you have fuel, and spark............but have no idea what your compression is, then your wasting time. low compression will make one hard to start. thats why with a low compression engine, you can push start them to get them to run.

not saying this is YOUR problem, but you cant just say you have good compression by sticking your finger over the sparkplug hole, and calling it good. we rebuild our motors when the kicking compression is below 135psi. they will still run at this, but not as good. anything under 125psi is most of the time a dog to ride.

I'm going to agree with KDXManiac. Also, hooking up a voltage meter and trying to read voltage from the stator coil seems counter-productive. In my experience, you would be looking for resistance, not voltage. Good luck getting a reading while trying to bump start the bike too!!

Low compression also fits in with running well at higher RPM, but dying at low RPM.

When it went I was riding along and the spark became very intermittent, no idle, and only firing for a few seconds at high revs... many had CDI trouble?

I guess I would look first to an electrical issue. Did you mention that you had rewound your stator? That would be the place to start, checking resistance while fiddling with the wiring. You might do better checking stator output with the bike on a stand, plug out, in gear, grab the back wheel and spin the motor.

The CDI is a pretty durable part. I haven't heard much about them failing.

The key way is not sheared in the flywheel?

I vote that you re-check your pilot jet. Use a piece of fine wire, and run it thru the hole. It's cheap to check and non-destructive

Aren't you the one with the olympic swimming pool sized
engineering facility at your disposal ?
How come your staff of personal engineers don't have that broken
down thing fixed yet ?
Oh yea, your the one bashing R&B mods too!
Sure you didn't do the nasty and grind away on those intake ports
but just don't have the gonads to fess up ??
Seems like you tell two different stories all in one post.

First you say you have spark:
"I have spark (also tried replacement coil and plugs for the sake of it)"
And why would you try a different coil if you have spark ?
Nothing better to do with your time ?

They You say:
"When it went I was riding along and the spark became very intermittent"

Were you riding along with a spark tester or an oscilloscope measuring
spark kv and duration on record mode that of course came from your
olympic swimming pool sized engineering facility ?
So which is it ? You do have spark ? You don't have spark ?
or it's intermittent ?


Here's your original post on your olympic swimming pool sized
engineering facility just to refresh your memory.........

moto_psycho wrote:got an engineering shop the size of an olympic swimming pool at my disposal thanks!

but yeah, seat of pants works well enough but sadly there isn't an international standard for measuring the SOP-Dyno

You think this could be the problem ?
You wound the bastard yourself ?????

moto_psycho wrote:got this email back from a handy website i found

"Sounds like a bad connection at the stator coil. Tighten all connections and maybe even resolder the solder connections.
To check the stator coil: use a cheap Radio Shack voltmeter, set it at 100 or more volts maximum AC voltage, connect it to the two wires coming out of the stator going to the CDI, tape the voltmeter to the bike so you can see the dial pointer while pushing the bike, push it and then dump the clutch, voltage should be no less than 75 volts. If lower then replace the coil.

Yes I can send a KDX200SR CDI to the UK for $55 total."

will give that a try l8r! (bearing in mind I wound the bastard myself.... worked for weeks though)

Wow, someones got a lot of time on his hands...

Engineering workshop - mechanical engineering, lathes, mills, electronic discharge machines/spark erosion units etc etc not motor vehicle diagnostic equipment.

Spark intermittent -engine still spinning at WOT, fired well for a few seconds, then stopped, then fired for a couple seconds, then stopped.

The head, I've machined according to A Graham Bell's information. (it is still sitting on my desk, not fitted yet, I was waiting for rings to become out of tolerance 1st)
Haven't touched a barrel yet cause I'm waiting for a spare to pop up on ebay just in-case I do destroy it.

I never bashed the R&B mods, I just wanted more information, dyno figures etc.

Talk about taking things the wrong way

It appears the resistance has become very low in my home wound stator...


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Here are your posts bashing R&B
And who is the F-nnnnnnnnn Wanker ??
You call everyone on this site a bunch of F-nnnnnnnnnn Wankers then come back begging for help..





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moto_psycho wrote:what are the actual mods he does on those carbs anyway?

It says right on his website what he does.[/quote]

Boring carb to 36 mm (gives you a better top end)
Installing divider plate (gives that low end response, like a smaller carb)
Modify slide (do not forget to send your slide with your carb)
Install new needle (gives the carb that personality)
Change jets (if necessary)
Modify jet block (helps with the over all performance)
Modify low speed circuitry This part of the modification along with the other mods really brings the air mixture screw into play. With only very small adjustments, you can keep your bike running at its peak as you change altitude or with weather changes during your ride.


wow, so informative. somehow i remain sceptical, unless specific details are given. i could scratch my name in the slide and call that modification :p[/quote]

You might need to pull the stator and double check that it isn't shorting. Also, before you do anything else, double check that all your ground connections are clean and tight.

wanker.

Check the loose nut behind the wheel too....

you mean the bars...

can we get back on topic please?

How about this...

IM SORRY! <---------

as for rb giving out specs on what he does............he is not going to give away his secret so everyone can copy his work, i wouldnt.

also, you cant bash everyone, or anyone on this site, and expect for all to just overlook what you said............some will, and some will hold a grudge forever. if you dont want oppinions, dont ask. i dont agree with eveyone, and everyone dont agree with me....but i dont bash them....thats why i ask questions, and make my decisions myself. just something for you to think about.

You seem to have this habit of pissing everyone off, and then expecting helpful comments from them anyway. You can't go around calling people "closed minded $#@&ing wankers", and then expect them to want to help you. I mean, really??

Yes, the resistance is low on your source coil. Probably a short in the windings. Did you insulate it with anything? I'm guessing not. Oops.