Author Topic: Replacement for XBR500 carburettor  (Read 313 times)

richardeblack

  • Full Member
  • ***
  • Posts: 126
Replacement for XBR500 carburettor
« on: July 06, 2021, 01:31:49 PM »
Hello All,
Anyone fitted a non-CV carb to an XBR?  I am having so much trouble getting one of  my XBRs to run right.  Seems ok on the carb from my main XBR but even with all the internals from my road one, none of my other carb bodies seem to work properly.  Nothing obvious, cleaned them all out thoroughly etc.
Main reason for asking for help is that I'd like to fit a simple carburettor on it. 
Has anyone fitted a concentric?  They are so simple if a little crude.
I am Thinking of a 40mm carb.
If anyone has any ideas I would be very grateful.
Thank you.
Richard.

TB

  • New Member
  • *
  • Posts: 4
Re: Replacement for XBR500 carburettor
« Reply #1 on: July 07, 2021, 01:33:55 PM »
Hi Richard,
Not considering how much you would like to spend, this is what you should get:

http://mainjet.de/nws/product_info.php?info=p61_vergaser-mikuni-tm-40-kpl--mit-adaptern.html

Bolt on modification, no more idle stalling and runs great.
Had it on my old XBR and now on my GB.

Br TB

welland99

  • Full Member
  • ***
  • Posts: 127
Re: Replacement for XBR500 carburettor
« Reply #2 on: July 07, 2021, 07:13:38 PM »
I think I've seen that model of carb advertised on eBay before.

SteveC#222

  • Hero Member
  • *****
  • Posts: 1876
Re: Replacement for XBR500 carburettor
« Reply #3 on: July 07, 2021, 09:21:40 PM »
I know that if you are tuning an XBR for more speed/power they generally use a Mikuni TM40 flat slide carb. Quite expensive though.
Growing old is inevitable, growing up is optional!

themoudie

  • Hero Member
  • *****
  • Posts: 4095
Re: Replacement for XBR500 carburettor
« Reply #4 on: July 07, 2021, 10:59:50 PM »
Aye Richard, the TL is very nice, but at ~£350, not cheap. An alternative could be the VM38 as used on GoldStars, G50 and SR500.

My friend who has made many Mikuni single carb conversions to Norton Commandos recommends this supplier, Motocarbs. So, here is the link to their website:

Motocarb_Mikuni_VM38

I hope this helps.

Good health, Bill

TB

  • New Member
  • *
  • Posts: 4
Re: Replacement for XBR500 carburettor
« Reply #5 on: July 08, 2021, 07:04:21 AM »
It's in Euro's so ~£300.  :)
/TB

richardeblack

  • Full Member
  • ***
  • Posts: 126
Re: Replacement for XBR500 carburettor
« Reply #6 on: July 08, 2021, 01:54:45 PM »
Hi Richard,
Not considering how much you would like to spend, this is what you should get:

http://mainjet.de/nws/product_info.php?info=p61_vergaser-mikuni-tm-40-kpl--mit-adaptern.html

Bolt on modification, no more idle stalling and runs great.
Had it on my old XBR and now on my GB.

Br TB

Thank you very much for that.  Indeed it is a little expensive for me considering I didn't pay much more than that for my main XBR.  I might consider it on one of the XBRs I am planning to put together but I am not interested in outright performance on my road one.  Do you know if it has an adverse effect on MPG please? Also, do you know what jetting your carb is set up with please?  A friend has an old VM40 which I might try although it is probably fairly worn and I suspect the jetting will be very different for the flat slide one.
Thanks Bill, I emailed  MotoCarb about the VM38 as it might be a better option for me considering I rarely use more than 5000 rpm.
Thanks also to SteveC and Welland99.
Cheers,
Richard

blew

  • Full Member
  • ***
  • Posts: 181
Re: Replacement for XBR500 carburettor
« Reply #7 on: July 09, 2021, 05:01:44 AM »
My XBR carb was running slightly rich (probably worn needle/needle jet) so I fitted a carb of identical size (39mm) off a bigger model.I can't remember now if it came off a 600 or 650,but it runs fine and idles perfectly.

mthee

  • Hero Member
  • *****
  • Posts: 1491
Re: Replacement for XBR500 carburettor
« Reply #8 on: July 09, 2021, 10:58:39 AM »
Here's a link to a catalogue download with loads of detail on the Mikuni carbs. I used it before moto63 very generously sent me the flat slide he had replaced. The TM40 comes with a 230 main jet as standard 👍

http://www.sudco.com/sudco_catalog_vol_38.html

Fear of the unknown does not mean the unknown needs to be feared