Bored out standard carbs - at least 15% more flow.

[Brock@BDK]

Just to let you know that we've just bored out some standard KR1S carbs for a customer.

We measured the standard carbs at just under 28mm with a fairly significant step inside the bore and managed to bore them out to 29.6mm which have to be bored offset.

We've calculated this to give just under 15% extra square area and with the smoothing of the bore this will probably translate to around 18-20% improved flow.

This isn't as substantial a gain as fitting 35 or 38mm carbs, but it does have the advantage that you don't need to make / adapt or replace the fuel tap, engine mount rubbers, airbox, airbox rubbers or throttle cables.

No doubt we will work towards providing those in the future, but we have a lot on at the moment (as always).

Anyway if this is of interest to anyone then they are quite welcome to get in touch with us.

A couple of pictures of the finished work shown below.




All the best,

Brock@BDK
01508 481713

[500bernie]

Nice work =D>
Do you want to post the price, or is it on request?
I think the owner of those carbs is a member of the forum, he will be pleased with them
Cheers
Bernie

[gary]

Hi, well happy with the work bdk did on my carbs , first class work, good price and quick turnround, looking forward to adding them to my other engine yupgrades , and getting the bike on the dyno.

[JanBros]

and may we know what it costs ?

[falconman]

I can verify it works. I did that on my KR and it improved by going from around 139 to 143 at Bonneville. Should be around 145 to 147 range at El Mirage. =D> Do it if you can. I had to since the rules require that I run stock carbs.

[500bernie]

Hi Falconman,
Did you have to go up quite a bit with your jetting to suit the increased volume of airflow?
Cheers
Bernie

[falconman]

I think it was an average of one main jet size. It is hard to tell since the DA changes every race and I always rejet for each race. The idle jet and needle stayed the same.

[500bernie]

Thanks, its nice to have an idea of where to start from.
Cheers
Bernie

[headcoats]

Thought about getting this done but was worried there isn't enough metal up the sides and if you put the slide in,you can see daylight through it

Is this a problem ?

[Brock@BDK]

Hi guys,

Sorry for some reason it never sent me a notice that replies had been made to this post.

The cost for the conversion is £80 plus VAT (where applicable) and carriage.

There is sufficient meat in the side of the carbs with the groove staying intact all the way down.

Can't remember if I mentioned but we offset the bore so that there isn't a gaping hole at the bottom of the carb.

In some ways I wish it weren't so busy here - really struggling to get jobs finished for Christmas, but we hope to be making a start on the 35mm adaptors early in the New Year - we have already been talking with the injection moulders over stubs for the KR1R or KR1S conversions that would look as original.

Anyroadup thanks for the interest, must do some work though now

Brock