I can't tune my Mikuni VM20 and need help

Ahamd Bahrami /
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Hey everyone!

Once upon a time I was going through some shit so I built a moped cause it made me feel good. Well, here is where I have come. And yes before the sharks come to feast, I am a noob! So I built this E50 magnum that has a non ported non case matched k star with one base and one head gasket, stock clutch, vm20 with MLM intake and foam/mesh air filter, Simo pipe, 16x40 gearing, timing is 16 degrees from TDC.

I know that the kstar with a simo pipe isn't very wise…. And I wasn't wise when i paid for it because I didn't know any better than a 5 star rating on treats and liking the way it looked.

So now, I am having a horrible time tuning it. It is constantly 4 stroking as soon as I hit the throttle. I have ran through almost every jet size from 185 down to 115 mains and 17.5-22.5 for idle. The thing idles ok but boggs and four strokes as soon as the throttle is touched, I did get it to break 30 mph with what I believe was a 140 main jet but as soon as I added my heavy chain in my bag the thing would not move and just 4 stroke.

My concern is:

-Is there some major problem I am missing? I have checked for leaks. Could it be some leak the bottom end of the E50?

-Should I try a different needle jet? The bike idles fine and the main jet was small enough that the motor cut when I went straight into full throttle. The issue is constant 4 stroking anywhere in the middle throttle range that worsens with load

-If I get a low end pipe will this problem will go away??

A couple side notes:

The motor did soft seize on me once.

The bike 4 strokes at more throttle positions as you increase the load. When its on its stand, it 4 strokes less.

I am 230lbs

I have been trying to figure this out for a while and have been getting frustrated so I appreciate all the feedback.

IMG_0841.jpg
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Subject Written By Posted
  I can't tune my Mikuni VM20 and need helpTopic by: Ahamd Bahrami Ahamd Bahrami 05/25/19 04:14PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Stephen Simmons Stephen Simmons 05/25/19 09:34PM
  Re: I can't tune my Mikuni VM20 and need helpRe: iskra chornia iskra chornia 05/25/19 10:22PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/25/19 10:29PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Russell Huddy Russell Huddy 05/26/19 12:26AM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/26/19 01:06PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Daniel '' Daniel '' 05/26/19 12:06PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/26/19 01:17PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Overpriced Parts Overpriced Parts 05/26/19 05:15PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/26/19 07:42PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Daniel '' Daniel '' 05/27/19 12:38PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/27/19 01:20PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Daniel '' Daniel '' 05/27/19 02:03PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/27/19 02:33PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Daniel '' Daniel '' 05/27/19 03:39PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/27/19 03:42PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/29/19 03:47PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Full Tuck Full Tuck 05/30/19 07:46AM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/30/19 04:11PM
  Re: I can't tune my Mikuni VM20 and need helpRe: D dB D dB 06/03/19 01:19PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Tri-ped Dave Tri-ped Dave 05/30/19 04:52PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 05/30/19 08:36PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Tri-ped Dave Tri-ped Dave 05/31/19 04:06PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Aaron Blair Aaron Blair 06/01/19 07:01AM
  Re: I can't tune my Mikuni VM20 and need helpRe: Ahamd Bahrami Ahamd Bahrami 06/01/19 03:07AM
  Re: I can't tune my Mikuni VM20 and need helpRe: alex ganz alex ganz 06/01/19 10:38PM
  Re: I can't tune my Mikuni VM20 and need helpRe: Bryan Colliver Bryan Colliver 06/04/19 11:44AM

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