Stock 2HP Magnum Tuning issues

john cervini /
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1980 MK2 With the 2hp za50. Stock bing 12/323 carb. 60 main jet. New pucks. 2nd speed clutch not flipped. Stock airbox and exhaust. I have cleaned and gapped the points, greased the cam lobe and adjusted timing. My stator plate was all the way to the right as seen in the picture. My issue is that it revs up quickly and seems like first is slipping alot. Gets up to 15mph and won't shift unless I blip shift and it four strokes before it shifts. Tops out at 23. It just spins the clutch trying to get up my driveway too. Clutch pads look perfect. The only way I can get it to not 4 stroke is with the air filter screen removed. The needle was initially on the 3rd notch down. I've tried bringing it up each notch. Currently at the top with no improvement. Any ideas?

Re: Stock 2HP Magnum Tuning issues

Drop the main jet down one size and put the needle on the second clip from the top (as it is oriented in the carb, so the the tip of the needle being the bottom)

Re: Stock 2HP Magnum Tuning issues

john cervini /

I'll have to see if I have any jets. According to the wiki 60 is the correct jet for this carb.

Re: Stock 2HP Magnum Tuning issues

Is this the magnum in your profile pic? Stock pipe?

Re: Stock 2HP Magnum Tuning issues

john cervini /
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Negative. Wish I still had that one. This is a silver mk2.

Re: Stock 2HP Magnum Tuning issues

Overpriced Parts /

Stock jet is 60 with 212a atomizer but you need to have the small size plastic snorkel inside the airbox not larger size that’s on a magnum XK

You must have a perfect unmodded stock exhaust with no holes in it !

If you don’t have the correct snorkel or no snorkel and you don’t have a complete in modified exhaust or if it’s blocked your bike will be more than a turtle then it was stock,

I mean a huge motorcycle looking bike that barely does 30 mph, why bother but I did have a stock lo mi magnum that did 31-32mph stock with ok take off but I Took out the trimmed the stock white snorkel that was in air box and put a longer one from a 1,5 maxi in it,

I’ve had a few dozens of magnums go through my hands and most people drill holes all through the exhaust knowing nothing about anything when all you need to do to get good gains is to throw that junk airbox in the recyclable bin, put one 5/16 hole down low and one more through the endcap,

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Then Run a metal mesh filter and you go 40 mph with upjet (if needed) with stock gearing like this,

You could have dragging bearings or brakes on the recalled snowflake mags they put on those bikes, and I know how to detail those also !

Shame you don’t live closer John! We could have your bike figured out in a afternoon!

Re: Stock 2HP Magnum Tuning issues

john cervini /

Thanks again Ken. I had an exhaust leak and didn't realize that tube in the airbox was so important. It's running great now and hit 32 on a flat. I Also opened up the point gap to .20

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