New Motron owner with a few problems...

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New Motron owner with a few problems...

Postby rac421 » Thu May 24, 2012 8:23 am

Hi all, just bought my first moped and am trying to get it running. It has only 1400 miles on it but still is over 30 years old ('79 Motron Classic with the V1). Checking the timing with a meter I see that it is set up to fire at 27 degrees BTDC - this is four degrees more advance than the recommended 23 degrees. Would four degrees advance keep it from running correctly? The bike is from Denver (the mile hi city) and I thought maybe they had advanced it for the altitude.I can get it to fire and run for a few seconds at a time but that's it. Compression is 95 lbs, which I thought was good. Points are set correctly and providing a good spark to the new plug. I have gone through the carb but I'm still not sure it is getting proper fuel. I'm suspecting an air leak in the case - is this common around the peddle shaft? There does seem to be some oil around the right side shaft. All in all it's in great condition and I would like to do a full restoration if I can get it running right.

Thanks
rac421
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re: New Motron owner with a few problems...

Postby silverfox » Fri May 25, 2012 11:44 am

Any leaks around the pedal shaft will noe effect the running as the shaft passes thru the gearbox, not the crankcase.

If you squirt a little fuel directly into the carb throat does it fire?

Minarellis are known to have the crankshaft seals dry out if the engine has not run for a long time.
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re: New Motron owner with a few problems...

Postby rac421 » Fri May 25, 2012 11:49 am

Thanks so much for that information - can you replace the crankshaft seals without splitting the case?

Thanks
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re: New Motron owner with a few problems...

Postby rac421 » Fri May 25, 2012 11:55 am

Might mention that I have reset the timing to factory specs. The dpo rounded off the flywheel nut sometime in the past and it was a real bear to get off. I will have to get a new nut before continuing the testing. squirted a little Marvel Mystery oil in the cyl. and it must have loosened up a ring or something as today I'm getting a bit over a 100 lbs of compression on the gauge. Does that sound about right for a V1?

Thanks
rac421
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re: New Motron owner with a few problems...

Postby silverfox » Fri May 25, 2012 3:45 pm

I think that the oil that you squirted in the cylinder just made a hydraulic seal on the rings like the oil normally does.

Back to basics:
Do you know the history of the unit? i.e. When did it run last?

If it has spark it should fire and run if it is getting gas thru the carb.
Have you cleanrd the idle air passage? Take a look at the attached photo to see where it is.

The crankcase seal on the right hand side is behind the clutches and gears so as a minimum you have to take all that off. The left hand side seal is behind the generator so you have to take that off also. Looking at my parts list it looks like the crankshaft seals pn4790 can be accessed without splitting the crankcase, but I am not 1000 percent sure of this.

WORD OF WARNING!!!!!
There are a bunch of shims in this engine. They have to go back in the same place where they came from. Be very careful when you take the parts off as the shims tend to stick to the face of the gears, etc. Then when you are cleaning the parts you will find a shim in the bottom of the pan and say to yourself, "Where did the f**k did that come from"

You can down load the parts list by going to the Moped Repair section at the top of this page as well as the repair manual.

If the engine has been run recently, I would only dig into the engine as a last resort. Take the carb off and drizzle a little fuel into the inlet manifold and crank away.
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re: New Motron owner with a few problems...

Postby silverfox » Fri May 25, 2012 3:47 pm

Oops, I forgot to attach the photo:

Here it is:
You do not have the required permissions to view the files attached to this post.
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re: New Motron owner with a few problems...

Postby rac421 » Fri May 25, 2012 10:11 pm

I'm not sure when the engine was run last, but it did have several problems that I found in the early stages of my attempt to get it running. A loose ground wire coming out of the Magneto was making only intermittent contact, and a small piece of flashing metal loose in the float chamber - along with the advanced timing. I did go through the process of cleaning the fuel tank which had some rust , but is good to go now. I have ordered the new flywheel nut and as soon as I get that in I will get back on the project.

I did clean the idle port pictured but only because I had found that same picture in the archives, otherwise, I would never have seen the hole as it WAS clogged almost completely up. Again I won't know if any of this is helping until I can get that nut and get the machine back together. If I can get this thing to run at all I some very effective seal conditioner that I have used with good results in the past. So might give that a try as well - I do hate to get into the engine unless absolutely required. I used to restore vintage sports cars (yes mostly Italian :)) for a living so do know a bit about mechanics ...but these mopeds are totally new to me and I really appreciate the pointers.
rac421
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