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187 Alpina EATING thru plugs

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Hello everyone. I have a 187 Alpina 250.....It’s completely restored. It runs great except I need to carry extra spark plugs with me because after about 45 minutes of riding The bike starts to sputter Lose power and eventually stall. It’s rather disheartening because I have to replace the plug every 45 minutes. Once the new plug goes in it runs beautifully until the same thing happens again. Occasionally the throttle sticks a little bit and I can smell a little bit of something “burning”.... just in general. No horrible burning. I am running 32 to 1. The dead plug comes out golden brown but apparently is completely deceased! Has anyone ran into this or is there something I am missing? I’m guessing the plug is being fried somehow. I highly doubt I got a whole batch of bad plugs!  running champion RN12YC

 

If anyone could help I would be very grateful

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What ignition system? What plug gap? What fuel? What premix oil? What does the spark look like? Are there any whiskers on the used plugs? Did the fuel type get changed recently?

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I also have a 187 and plugs are never an issue.  I run the stock femsa points and use a NGK B8ES plug.  I do run belray mc1 at 50:1....... maybe a little lean on oil for long wide open throttle but it works just fine.    I’d try a little less oil in the fuel mix. Maybe 40:1 and see what happens.  

Steve 

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RN12YC is a soft resistor plug.

I use for trials riding N11YC (ignition Electrex World). No problem at all after 3 years and the same plug. For trail type of riding I probably try a cooler plug like N9YC (or N7YC)

Also use for trial 1,5% (1/67) oil. I guess that harder riding need more oil. Perhaps 2% (1/50).

Carl

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I had the same problem a few years ago, I changed from Champion to NGK and the problem vanished. (bike was running a motaplat ignition)

I was reluctant to change as I got the Champion plugs for free from work!

it was only one bike that had the issue with the champion plugs, all my other bikes ran fine on them 

Edited by suzuki250

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Four things comes in mind:

- carb proper adjusted with the right jets.

- after the engines smells burned are may be the crank seals not proper sitting thus gear oil get burned.

- ignition is set correctly,

- less oil 1:50 is very good and sufficient, then oil with low burning point, also best fuel you can get with as little as possible ethanol.

Depending how you ride you might go to a hotter plug as the engine might not produce as much heat you neet to start the self cleaning process, thus I would recommend to try a hotter plug (carefully), I have had great experiences with hotter plugs (going down from NGK BP 5 ES to NGK BP 4 ES to my Sherpa and my SWM TL.NW) which now work proper for years while the colder plugs had to replace frequently, the named NGK is too without internal resistor which helps too.

Edited by pschrauber
Clearifying

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Had this with my ty250 mono's.

Turned out to be a dud HT coil.

Fine when cold, 30 mins of running = dead plug.

replaced the coil - bingo - never a problem since.

oh and +1 on Champion plugs - they are inconsistently crap.

NGK are far more reliable.

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Thank you everyone for rapid assistance.....I will employ the suggestions..... I will report back on the curative measure(s).....

 

thai mentioned bad coil...... if coil bad and plug dies after 30 min will new plug immediately fire up??

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On 7/27/2019 at 5:05 AM, stevem75 said:

I also have a 187 and plugs are never an issue.  I run the stock femsa points and use a NGK B8ES plug.  I do run belray mc1 at 50:1....... maybe a little lean on oil for long wide open throttle but it works just fine.    I’d try a little less oil in the fuel mix. Maybe 40:1 and see what happens.  

Steve 

The standard Bultaco Alpina plug is a NGK BP5ES or BPR5ES.

 

Edited by model80

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