Mikuni Jetting & Ignition for 82 Maico 490

[michida]

I have an 82 Maico 490. The motor was recently rebuilt by Woody Graves in Geneva Florida of Woody’s Vintage GP and
Florida Vintage MX, not sure if you have heard of him.

It was missing the Bing Carb when I got it so I bought a VM38 Mikuni it has a #330 Main jet and #30 Pilot. I am trying to get some ball park jetting so I can get it to run then tune it in. At this time it attempts to fire, kick back good, but will not start. I bekieve I am getting enough fuel due the plug is wet and I can smell gas at the spark arrestor
I am in Gainesville Fl.

I also am concerned that I am not getting spark when kick starting it. If I have the Spark plug out and I kick start it I get a nice white spark and it triggers my timing light. When I try it with the plug in I do not seem to be getting spark on a regular basis, it will ocasionally light up the timing light.

Any help would be much appreciated. Thanks

[Big Maico 393]

I think I can help you on the timing it should be 2.0 mm +/- .2 BTDC

Don't know which model you have a Mc/Motocross or a GS/Enduro, need to know to be sure on the timing if you have the MC & internal rotor motoplat or the External Motoplat the timing above should be good.

If you have one of the SEM ignition's I'll have to ask a friend.

You need to look up the Maico Motorcycle group for all kinds of information.

[Only registered and activated users can see links. ]

[michida]

Originally Posted by Big Maico 393

I think I can help you on the timing it should be 2.0 mm +/- .2 BTDC

Don't know which model you have a Mc/Motocross or a GS/Enduro, need to know to be sure on the timing if you have the MC & internal rotor motoplat or the External Motoplat the timing above should be good.

If you have one of the SEM ignition's I'll have to ask a friend.

You need to look up the Maico Motorcycle group for all kinds of information.

[Only registered and activated users can see links. ]

It is a GS with the external Motoplat Thanks Bruce

[michida]

It is a GS with External Motoplat

[Big Maico 393]

Bruce:

Do you have a dial indicator? if so it's easy to time a 490, just find TDC & back off until you reach 2mm BTDC +/_ .2

I use to get to that point & then loosen the stator mounting screws just enough to where I could move it by hand with a little resistance, then put the rotor/flywheel back on & ajust until I could put the alignment pin through the hole in the flywheel with the hole in the stator. then go back & tighten the screws.

Then I would recheck the timing, that should do it for you!

[Big Maico 393]

Bruce:

I forgot to post this!

[Only registered and activated users can see links. ]

Toby Opferman's site has a electronic manual for your 82'

[michida]

I do have a dial indicator, Hope this does it. I tried Opferman Motor site and it would not come up will try later. Thanks for your help. Hopefully someone will answer the carb question. I think it is close and should be getting enough fuel for it to fire up.

By the way what Premix ratio do you use. I am using 32:1 with Yamalube-R.
Thanks, Bruce

[Big Maico 393]

Bruce:

I just switched from Bel-ray H1R to Maxima 972 Castor, as the bottom ends on the 490's tend to run a little dry, you should be Ok with Yamaha lube @ 32:1

[michida]

I checked the timing it is at 2.2, Maico manual states 2.1 so it is close to the 2.0 +/- .2.
I get spark when I do not have a plug in it. Have put a timing light on it to show spark as well. When plug goes in and kick is under compression I am not generating a spark.
I believe this is my problem. Any suggestion. Could I have a weak generator?
Bruce

[Big Maico 393]

Originally Posted by michida

I checked the timing it is at 2.2, Maico manual states 2.1 so it is close to the 2.0 +/- .2.
I get spark when I do not have a plug in it. Have put a timing light on it to show spark as well. When plug goes in and kick is under compression I am not generating a spark.
I believe this is my problem. Any suggestion. Could I have a weak generator?
Bruce

Bruce:

I know that you are thinking no spark from the motoplat is the problem, but it's not a motoplat problem. it's that the 490 Maico's have a long stroke motor & you must get the motor to really turn over to generate a spark, easy to do with the plug out & no compression.

Here's the way I start my 490's, I stand on a crate & get above the kick starter & then bring the piston to just passed TDC, Pull the compression release & kick the kick start lever hard through the stroke. I'm trying to get the motor to turn over quickly & cycle more than once. which is hard to do on a Maico as the kick start gear ratio is too small & you have to fight the compression!

Think of trying to start an old 500 four stroke single & you get the idea. The motoplat requires that the crank is moving at a good speed to generate a spark. that's why most Maico's don't like to idle !

[michida]

No matter how hard I try or what technique I use I can not get it to create a spark under compression. Out of fifty full kicks just after TDC I got one spark and that was a kick back. I have my timeing light on it so I can see if it is creating a spark.

Is there a test I can do with a VOM meter on the Motoplat ignition.

What is the thread size on Flywheel so I can get a Flywheel puller.

Is there anyone in North Florida I can take this to to help me work this out?

Thanks, Bruce

[Big Maico 393]

Bruce:

You are using the compression release & holding it open until the motor starts Right?

Another trick you can try, is to lay the bike over to one side until gas flows out of the overflow on the carb. make sure that you have the throttle open , so some gas will flow into the motor. then put the bike in gear & rock it back & forth with the compression release pulled to make sure that you get some gas in the motor.

Try It & let me know.

BTW:

I'll ask the Maico Group if any is in north Fla, what part of North Fla?

[michida]

Yes compression release is down all the time when kicking starting . I have a 50 pilot and 360 main in Mikuni VM38 I believe I am getting enough fuel but I will try your suggestion. Unless I am being fooled by the timeing light I am not getting spark under compression, but as I said before with the spark plug out I do get spark 90% of the time when I kick start it.

I am near Gainesville Fl.

Thanks for the Motoplat info. Bruce

T