81 - 490 Carb

[chev350]

Hi there
i need to get a new Carb for my 81-490 piston port what would be the way to go
1) Bing with what jetting for coastal area and +- 25-30 Deg
2) Mikuni 38mm round slide with what jetting
which would be the better way to go
thanks

[090]

I really think a Mikuni is the way to go. Nothing like a new carby. I have fitted a 38 to mine and has been bored as well. I will try and remember to check my spec's for both carbie's when I go down the shed tomorrow night. bing's are great but are getting long in the tooth and the slide wears.

[East Coast Maico]

i would go with new bing..

I really think a Mikuni is the way to go. Nothing like a new carby. I have fitted a 38 to mine and has been bored as well. I will try and remember to check my spec's for both carbie's when I go down the shed tomorrow night. bing's are great but are getting long in the tooth and the slide wears.

[paul]

maicos love bings

[chev350]

thanks for  the replies but just made me more confused on which one to get Maico only in UK recommends that i should get a Mikuni and nearly every one else says a Bing
place in the States also said should go for the Mikuni
It a lot of money to spend on a Carb don't want to go the wrong way

Thanks

[090]

i would go with new bing..

I really think a Mikuni is the way to go. Nothing like a new carby. I have fitted a 38 to mine and has been bored as well. I will try and remember to check my spec's for both carbie's when I go down the shed tomorrow night. bing's are great but are getting long in the tooth and the slide wears.

How much is a new Bing?

[chev350]

A new Bing 160 Pounds from UK and a 38mm Mikuni is 170 Pounds

[Turtle.Inc]

Keep in mind the airbox boot on the Bings and the Mikunis are different. I just switched to a Mikuni for ease of parts just in the past couple of weeks  after having a Bing for last couple of years and noticed a remarkable improvement in starting, tuning etc, mind you the bing was worn and found harder to get parts for. Bings may flow better at high rpm but i havent noticed any difference really by running the mikoni. There are also a couple of Mods need to be done to the mikuni regarding jetting sizes and slide conversions

[090]

Well I should have looked a bit harder for a new one myself. Heaps of people say the Bing is better up top. I have a Mikuni on my GS490 and it goes well. The main difference is that a Mikuni is a 38mm and the Bing is a 40mm. I had my Mikuni taper bored . I think I will struggle to feel a difference.
Mikuni is cheap as well. And yes, new inlet and airbox rubbers needed and probably throttle cable as well.


http://cgi.ebay.com/ebaymotors/38mm-Mikuni-Carb-AHRMA-Husky-Can-Am-Maico-Penton-CZ-_W0QQcmdZViewItemQQhashZitem2eb3bd2c69QQitemZ200584014953QQptZMotorcyclesQ5fPartsQ5fAccessories

[East Coast Maico]

Bing type 55  Mag bodied work really good. Taper and oval bore them.

[colmoody]

Think 090 has nailed it on this one. If you are chasing horsepower/top end the Bing is the way to go. For ease of tuning and a few less dribbles give me a Mikuni.

[JohnnyO]

A good condition Bing with the right jetting works perfectly on a 490, i tried a Mikuni then put the Bing back on with a new slide, needle jet and needle fitted and the Bing was better for me.. more power and strong all the way through the revs.
My bike was no easier to start with a Mikuni, the problems i've had with hard starting on the 490 have been ignition related.

[chev350]

The Guys that are using the Mikuni is it the 38mm round or 38mm flat slide and may ask what jetting you running

[090]

Round slide. I will check on jetting today and edit this post. 360 main from memory. Either way you go they will both be a good choice. 350 and 45 pilot. I have put a 360 in to see if that works. Better to be safe than sorry.

[Bruno1969]

Hi Chev,

Opinion seems to be pretty split amongst what carb to go with.

Crabman on edirt runs a Mikuni on his 81 490 but he always seems to have hassles with jetting - not sure whether that is a reflection on the Carb or an indictment on his ability to jet properly!

I run the slightly worn Bing that came in the box of pieces that was my bike, and my 82 490 runs beautifully. Starts easily, idles, doesnt bog when snapping the throttle open and makes good clean liner power all the way through the rev range. Plug is a perfect tan colour and I run Motuil 710 at 30:1.  I can't really imagine a Mikuni improving anything.

My jetting - bear in mind that I am nearly six thousand feet above sea level;


main jet 190
pilot jet 45
Needle number 6L2
Needle Jet Block 280-2 

Cheers