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Discussion Starter #1
I am currently trying to save a 1987 CBR250R MC17 that I found in a dark storage shed in the west of Finland. Was very dirty and unloved but hopefully I am well on the way now.

I have a question regarding test resistance of the pulse generators. I cannot find the workshop manual for my exact model, so I am using the RR manual. This states that the pulse generator resistance should be 315-185ohms at 20'C. Mine measure 430ohms, both the same, is this OK or should I be looking to replace them?

I have no sparks so I'm eliminating as I go. Coils seem to measure OK. Kill switch, fuses, all good. I have ordered a CDi which are relatively easy to get, but the pulse generators are pretty few and far between, and I don't want to bid and buy something that another CBR250R owner might need, if mine are OK.

Any advice would be appreciated. And I will be posting some picks soon . . . . when she finally fires up.

Thanks in advance.
 

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I could test my working MC19 for you. Looked up 'cbr 250 pulse generator' on da googz and a faded service manual page came up. It said the spec was 315-385 ohms, not down to 185. It also said to remove the "left cover". Is it talking about the fairing, or the actual engine cover?
 

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Discussion Starter #3 (Edited)
My bad typo

I could test my working MC19 for you. Looked up 'cbr 250 pulse generator' on da googz and a faded service manual page came up. It said the spec was 315-385 ohms, not down to 185. It also said to remove the "left cover". Is it talking about the fairing, or the actual engine cover?
Sorry. I meant to put 315-385, trying to type in the dark, asking for trouble.

My resistance was 430ohms on both. So question is, do I buy replacements or are mine OK. I thought that maybe since they haven't been used in 20 years there may be some variance in the resistance, due to cold or lack of use.

What d'ya reckon?

G

BTW. You would have to remove the engine cover and change the gasket, there will be oil, maybe not much. Best to test the connectors that come from the generators. White/Blue to Blue and White/Yellow to Yellow.
 

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Mmmm, yeah, wouldn't really want to pull it apart, possibly leak oil and have to change a gasket, especially for a grey import bike. You said the kill switch is OK, did you just measure it or did you bypass it and try to start it anyway? My VFR 400 NC21 wouldn't start due to a bad kill switch, and a jumper wire in the right spots was enough to get it running. Have you tried push starting, in case its just the electrical system not being strong enough to turn the engine over AND produce a spark?
 

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Discussion Starter #5
I only have the engine in place with wiring, not at the push start stage yet. I measured 12v and the primary coils and I've tested the coils and these seem OK. According to the wiring diagram if the fuses or the kill switch is the problem, I should not get a voltage there. So I seem to have the coil part ok, which leaves either the CDi not processing the pulse, or the pulse generator not pulse generating. I have ordered a new and an old CDi to replace, but do I bid on pulse generators, more rare, more expensive.

So the question remains, is 430ohms too high and an indicator of faulty pulse gens?

Help appreciated . . . . muchly.
 

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I only have the engine in place with wiring, not at the push start stage yet. I measured 12v and the primary coils and I've tested the coils and these seem OK. According to the wiring diagram if the fuses or the kill switch is the problem, I should not get a voltage there. So I seem to have the coil part ok, which leaves either the CDi not processing the pulse, or the pulse generator not pulse generating. I have ordered a new and an old CDi to replace, but do I bid on pulse generators, more rare, more expensive.

So the question remains, is 430ohms too high and an indicator of faulty pulse gens?

Cant help you with the answer to that question but i do have a PDF copy of the manual in Japanese which confirms the 315-385 numbers. I also have a manual that is covers the R and RR in english. I Can send a copy if you are interested.
 

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While going thru the same tests you are doing, I sat a bare bottom end (crank in) along side my race bike & plugged it's pulse generators into the bike, and spun the bare engine with a drill, the result was a fat blue spark at the plugs, so I swapped the pulse gen's over and tested again,,,with the same result
It became apparent my starter motor was dragging too many amps (in the race engine) which put the battery cranking voltage into the too low range, low voltage = no spark.Engine turnover below 500 rpm = no spark, it seems there is a minimum cranking speed before the CDI will work.
Even using a BIG battery the cranking speed was too slow, voltage too low.
After replacing the starter motor , everything worked as it should
Always remember to "look outside the box" , especially when playing with electrickery
Tiny
 

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Discussion Starter #8
Thanks. what unexpected and brilliant information. I have so meticulously rebuilt everything that to not get a spark has been a bit of a kick in the teeth. Last night I found a set of pulse generators for a CBR 600 Hurricane from 1987 on Ebay and I managed to get them at a great price, so now I have coils, ht leads, CDi (original and derestricted) and now a starter motor so I am hoping that swapping out these bits one at a time with bring it back to life. If not then I have a great set of standby parts in reserve for when I find the culprit.

Sometimes I'm grateful for these problems, there is usually a lot to be learned along the way, and that can never be a bad thing. Just hoping that my well abused and aging brain is capable of retaining this stuff so I can help others in the future.

I'll start writing everything down I reckon, safest.

Thanks again. I'll start posting some pics soon.

I also have the rather tricky task of registering it here in Finland, without original Japanese registration papers it might be a long process/

G :)
 

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Discussion Starter #9
Forgot to say, any copies of manuals would be great. I can't find exactly CBR250R (H) MC17. Thanks in advance.

G
 

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I am currently trying to save a 1987 CBR250R MC17 that I found in a dark storage shed in the west of Finland. Was very dirty and unloved but hopefully I am well on the way now.

I have a question regarding test resistance of the pulse generators. I cannot find the workshop manual for my exact model, so I am using the RR manual. This states that the pulse generator resistance should be 315-185ohms at 20'C. Mine measure 430ohms, both the same, is this OK or should I be looking to replace them?

I have no sparks so I'm eliminating as I go. Coils seem to measure OK. Kill switch, fuses, all good. I have ordered a CDi which are relatively easy to get, but the pulse generators are pretty few and far between, and I don't want to bid and buy something that another CBR250R owner might need, if mine are OK.

Any advice would be appreciated. And I will be posting some picks soon . . . . when she finally fires up.

Thanks in advance.
 

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Hey guys my mc17 for rough idle..i changed cdi rectifier ignition coil spark plug battery..not fixed my problem..today ill check my pulse genarator 1st coil 472ohms other coil 478ohms..and 1.4 cylinder good heat and 2.3 cylinder not good heat its why..But 4cylinder working.carburetor is good .plz help me?
 
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