2 STROKE WORLD .net

The 2-Stroke Garage => Turning Wrenches => Topic started by: Joe6v6 on May 05, 2024, 09:10:22 PM

Title: 28mm Mikuni - What are these lines
Post by: Joe6v6 on May 05, 2024, 09:10:22 PM
I assume these are the stock carburetors,77 RD400, what are the inlets in the middle. Are they overflow for the float bowl? What are the other 2 smaller diameter inlets? Where should I run these lines to. Seems very difficult to find a diagram of all the lines that come off these carbs. 
Title: Re: 28mm Mikuni - What are these lines
Post by: SoCal250 on May 05, 2024, 11:14:53 PM
Joe,
The two large upward angled nipples on the inboard side of the carbs are bowl vents. They were originally connected with a hose to the airbox. I just connect a short piece of hose to mine and let them hang down. Some people who are running a Y-boot instead of the stock airbox drill holes in the bottom of the boot, add nipples, and run hoses to them. A third option is you can remove the brass ball in the bottom of the bellmouth covering the airjet, clean the jet, then block off the vent tubes. Do not block the vent tubes unless the airjet has been unshrouded.

The two smaller nipples on the bottom of the bowls are fuel overflow for the float bowls.
Title: Re: 28mm Mikuni - What are these lines
Post by: LMS on May 06, 2024, 06:50:46 AM
On another note, you might want to think about getting pod filters that don't have the end caps.
Title: Re: 28mm Mikuni - What are these lines
Post by: m in sc on May 06, 2024, 10:56:43 PM
yup. ditch those filters. either get all foam unis or a y boot. correct info on lines above
Title: Re: 28mm Mikuni - What are these lines
Post by: Joe6v6 on May 08, 2024, 09:14:32 PM
Thanks for the info, whats the issue with the filters with the capped ends? do they restrict air flow? Or do they not filter well?
Title: Re: 28mm Mikuni - What are these lines
Post by: SoCal250 on May 09, 2024, 12:38:01 PM
The flat hard back of the filters can cause reversion waves and interrupt the intake signal. This can lead to flat spots and tuning/performance issues.
Title: Re: 28mm Mikuni - What are these lines
Post by: racerclam on May 09, 2024, 01:35:49 PM
K&N filters are junk , they pass as much dirt as the do air. Use Uni filters
Title: Re: 28mm Mikuni - What are these lines
Post by: Joe6v6 on May 16, 2024, 01:22:35 PM
Quote from: racerclam on May 09, 2024, 01:35:49 PMK&N filters are junk , they pass as much dirt as the do air. Use Uni filters
Consider it done - Thank you