Big fat 40mm Carbs

[Steptoe]

Sorting through my parts today and i found a carrier bag with pair of pre 1980 40mm Carbs inside ..

Where did they come from, i had no idea i had them tucked away

 

[solidstate100]

Sorting through my parts today and i found a carrier bag with pair of pre 1980 40mm Carbs inside ..

Where did they come from, i had no idea i had them tucked away

Ahh there they are - left them at yours ages ago. Stick em in the post to me would ya? Thanks!

 

[Kenny]

Proper man's carbs !

 

[Beemerboff]

A Vincent Black Lightning achieved almost 150 MPH on 1 1/8" or 28.6 mm carbs, and some guts are getting 110 hp out of bikes with 32 mm carbs so just why anyone ever thought 40 mm carbs were required is a mystery.
If you do the sums 28.6mm is actually close to optimum for a road going air head too, revs a bit higher than the Vincent but has a shorter stroke which evens things out.

 

[Weekday Rider]

I have a Mikuni 40mm pumper carb on my XR650R. It works fine thanks .

 

[flytoolow]

Sorting through my parts today and i found a carrier bag with pair of pre 1980 40mm Carbs inside ..

Where did they come from, i had no idea i had them tucked away

So are you cleaning them, flogging them or just posting for your W&nKB&nk?

 

[Rob Farmer]

I have a Mikuni 40mm pumper carb on my XR650R. It works fine thanks .

Do you really know that it does? Perhaps you'd have loads more torque if it had a 32mm

 

[Weekday Rider]

Do you really know that it does? Perhaps you'd have loads more torque if it had a 32mm

This is my second XR650R the first one was standard. The response from the pumper carb is definitely more instant but as the bike is far from standard I can't say if the carb alone is responsible for the extra power it has. Stage one cam, full race exhaust, modified air box and the 40mm pumper carb together definitely give more power as proved on a dyno. Correct setting up of the carb also worked wonders.

 

[markjackson]

This is my second XR650R the first one was standard. The response from the pumper carb is definitely more instant but as the bike is far from standard I can't say if the carb alone is responsible for the extra power it has. Stage one cam, full race exhaust, modified air box and the 40mm pumper carb together definitely give more power as proved on a dyno. Correct setting up of the carb also worked wonders.

That sounds like a big red pig of fun!

I wish I still had my XR650. It pulled like a train, wheelied everywhere and even did corners brilliantly too!

 

[Florence]

That's a cracking photo Mark

 

[markjackson]

Ta.

I lost a class win by 2/100 of a second that day, and got told off by the officials for having sparky sliders, but it's worth it for a good piccy!

 

[Rob Farmer]

This is my second XR650R the first one was standard. The response from the pumper carb is definitely more instant but as the bike is far from standard I can't say if the carb alone is responsible for the extra power it has. Stage one cam, full race exhaust, modified air box and the 40mm pumper carb together definitely give more power as proved on a dyno. Correct setting up of the carb also worked wonders.

I reckon it would still have more midrange torque and better throttle response with a 32mm carb. You need both on a dyno

 

[Steptoe]

So are you cleaning them, flogging them or just posting for your W&nKB&nk?

All that and more .