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Advice On Testing Regulator/rectifier

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#1
Hi everyone,
I am trying to test the regulator/rectifier on my 1993 KDX250SR.
My workshop manual doesn't have any information on how to test this unit, and any youtube videos deal with units with one or two plugs.
My unit has:
3 yellow wires in one plug
1 red wire in a plug
1 brown wire and 1 black and yellow wire in one plug

Could anyone give me a heads up on how to test the reg/rec with a digital multimeter?

More info on the bike:
It was not starting and kept backfiring.
I have: cleaned the carburetor, cleaned the air filter, redone the top end; new piston / rings/ small end bearing / KIPS valves, new reed valves, repacked muffler, new spark plug.
The bike starts and revs fine, but bogs down/loses power when I try to ride it.
I had a similar problem many years back and a mechanic fixed it with a new reg/rec unit.

Any information/advice would be very much welcome.




 

jaguar

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#2
I don´t see how the rectifier/regulator has anything to do with how the engine runs.
They work off of the lighting coil which is separate from the stator coil which produces voltage for the CDI which affects how the engine runs.
Check for crankshaft seal leaks if changing the jetting doesn´t help.
 
Likes: PaulKDX250SR
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#3
Thanks Jaguar. I'll pull the carb today and check and clean it thoroughly once again. Then, I'll take it to a mechanic to have the engine pressure tested for leaks.
 
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#5
Jaguar, thanks for taking the time with your advice.
The bike won't start prior to the top end rebuild. It just backfired. I had many thousands of k/ms on the piston and reed valves.
I got to wondering if the new Boyesen reeds had effected the jetting. I pulled the needle and set it to the 2nd notch from the top as opposed to the middle and the bike is running much better now. It is still 'hanging' a little, that is, it is not calming down to tick over quickly.
I took the bike out for 20 minutes and it still feels a little 'boggy' down low.
I pulled the kips cover to check shaft lever movement and it's moving correctly.
I am still running in the top end so I don't want to open her right up yet.
I did do a plug chop though and the plug is; whitish-brown.
 
- a d v e r t i s e m e n t -

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#7
try raising the needle by lowering the clip position. that will enrichen the mid range jetting.
you can do it without removing the carb.
Hi Jaguar,
I was adjusting the airscrew yesterday and it's pulling smooth from 1/2 throttle on up, but I am still not happy with off-the-throttle-response.
As you recommended, I'll raise the needle up a notch today and see how it responds.
Thanks for your help bro.
 

jaguar

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#8
adjust the idle air screw till it idles the fastest and then blip the throttle and listen to how fast the engine picks up revs. then adjust the idle richer until you like the off-idle acceleration. screwing in the idle screw makes the idle richer. If it likes less than 1 full turn out (from being screwed completely in) then you have to enlarge the idle jet hole with a micro drill bit or buy a richer idle jet. Amazon sells micro drill bits. do this whole procedure after a high speed run that brings engine temp up to its normal high range.
 
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#9
adjust the idle air screw till it idles the fastest and then blip the throttle and listen to how fast the engine picks up revs. then adjust the idle richer until you like the off-idle acceleration. screwing in the idle screw makes the idle richer. If it likes less than 1 full turn out (from being screwed completely in) then you have to enlarge the idle jet hole with a micro drill bit or buy a richer idle jet. Amazon sells micro drill bits. do this whole procedure after a high speed run that brings engine temp up to its normal high range.
adjust the idle air screw till it idles the fastest and then blip the throttle and listen to how fast the engine picks up revs. then adjust the idle richer until you like the off-idle acceleration. screwing in the idle screw makes the idle richer. If it likes less than 1 full turn out (from being screwed completely in) then you have to enlarge the idle jet hole with a micro drill bit or buy a richer idle jet. Amazon sells micro drill bits. do this whole procedure after a high speed run that brings engine temp up to its normal high range.
Jag,
Spent three hours trying to dial the jetting in today. I ended up taking the easy way out and bolted on a carb I have from a 220: #6 slide, 38 Pilot, 158 Main, clip 2nd from top. The bike is picking up smooth with a strong pull through the rev range.
I have 60,000 k/ms on the old carb. I am going to replace all the parts and have the float level checked by a mechanic, and then see about trying again in Spring. In the meantime I am going to see how I get on with the 220 carb.

Cheers Jaguar.
 

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