Author Topic: New Carb vs old carb  (Read 952 times)

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Offline calebdmin

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New Carb vs old carb
« on: January 25, 2019, 04:17:05 PM »
I just bought a new vm38mm carb for my 465 I've noticed a few differences from the new to the old like it has an extra half inch on the air intake, and it is missing the third hose connection on the bottom. I know nothing new is going to be an exact fit but I'm just wondering if this will make a big impact on the way it functions I've ordered the right jets and such. I was thinking that if the carb is still essentially the same could I just shave off the extra half inch? because it physically won't fit.

Offline calebdmin

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Re: New Carb vs old carb
« Reply #1 on: January 25, 2019, 04:19:38 PM »
another pic

Offline killindini1

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Re: New Carb vs old carb
« Reply #2 on: January 25, 2019, 08:15:14 PM »
Removing a bit of the flange shouldn't make a big difference, just cut it to the same overall dimensions as the old one.
Have you unscrewed the top yet?  My bet is that you are going to have to drill and tap your slide so you can use the original throttle cable and top hat.

Cheers
Steve.
Beer is more than just a breakfast drink

Offline T.RexRacing

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Re: New Carb vs old carb
« Reply #3 on: January 26, 2019, 03:56:11 AM »
Yeah Yamaha had the carburetors made to their specifications and they are not quite the same as an off the shelf Mikuni VM. I'm curious what slide cutaway does it have?
Whatever you do will be insignificant, but it is very important that you do it.
- Mahatma Gandhi

Offline Devondan

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Re: New Carb vs old carb
« Reply #4 on: January 26, 2019, 09:07:01 AM »
All my new mikunis had the holes already tapped in the slide.

Dan
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Offline fatterhatter

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Re: New Carb vs old carb
« Reply #5 on: January 26, 2019, 08:44:55 PM »

  The chinese are copying lots of carbs atm. I bought a chinese keihin 39mm for my aprilia rs125 road bike. I paid about ?25 posted for a complete new carb, and about another ?20 on jets. After a bit of plug chopping and changing jets i got the bike running really well with 36bhp on a dyno at 12,250 rpm.
  Some mikuni's and lots of keihins are cheap on ebay, some are better than other copies, the chinese carb i bought works well.


http://www.ebay.co.uk/itm/KEIHIN-PWK38-38mm-PWK-Carburetor-Carb-For-ATV-Dirt-KTM-250-250SX-250EXC-96-99/163406087429?hash=item260bc30505:g:2LgAAOSwhexcNHRH&redirect=mobile

Offline T.RexRacing

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Re: New Carb vs old carb
« Reply #6 on: January 27, 2019, 02:26:31 AM »
I do not like buying from companies that steal the R&D of others.
Whatever you do will be insignificant, but it is very important that you do it.
- Mahatma Gandhi

Offline fatterhatter

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Re: New Carb vs old carb
« Reply #7 on: April 06, 2019, 08:10:57 AM »

The Germans pioneered 2 strokes, and MZ after the war improved on prewar designs. The Eastern Soviet Block was very restrictive and Suzuki managed to persuade Walter Kaden to elope and give them MZ designs and secrets. Nearly every Japenese 2 stroke is a copy (a mirrored design so MZ had the sprocket on the left, the japs on the right, same with the kickstart.).
All designs from day one are a copy of what has come before, the japanese moved production of many parts to china in the 1980s onwards to cut costs. I always try to buy the best product available, why pay more for a product that could have many parts made in China ?

Offline gripper

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Re: New Carb vs old carb
« Reply #8 on: June 30, 2019, 01:34:47 PM »
Exactly, I did a job for and old German guy who used to work at Maico in the 60?s.
They go very exited when the Japs came for a factory visit, thinking a big order was likely.
The Japs bought 2 bikes, took them home, pulled them apart, and started copying. The rest is history.