Bike Carbs

[Guest Leaner]

Hi all

I've adapted an injection manifold to hopefully suit the bike carbs I have got. I am running a point distributor and servo which I would like to retain as I like this setup.

I have made a pipe to link all inlets together so I can connect the dizzy and servo, does anyone see any problems with this.

[Guest Takumi]

I love it, ! bodging is always more satisfying than going the long way round!

 

my first bike carb manifold was using the pinto efi manifold chopped up, with plastic tubes, fiberglassed into the runners so I could attach some tubes to the bike carbs, worked fine for about 200miles, then started to crack around the fiberglass filler..

 

now ive got a straigh manifold and respaced the carbs..

 

manifold looks good,

 

atb

 

tak

Edited March 2, 2008 by Takumi

[Guest Leaner]

Hi Tak iv just left stubs on the manifold just long enough to clamp the hoses on to. Iv ground the inlet down inside to blend into the rubber hose to help with the flow of fuel /air mixture iv yet to builb up the courage to fit them yet i wont to kno iv got everythin ready for a straight swop !!!

[Guest stuart_]

hi, what sort of carbs are they?

 

As i will be doing my manifold soon.

 

thanks

 

stuart

[Guest Leaner]

Hi Stuart the carbs are Keihins i think they were of a yamaha but wouldn,t swear to it i didnt space them as i cut the inlet to suit , i think it worked well they have only cost me the price of the hose to connect them together so it is certainly done on a tight !! budget

 

 

Bernie

[Guest craig030774]

what hose did you use and where did you get it from

[Guest stuart_]

Have you picture of the manifiold you used?

 

stuart

[Guest Leaner]

Hi, i used the standard pinto injection manifold and cut off the bulk of it then kept trimming it until i was happy i could get my rubber hoses to connect to the carbs. I measured the distance from the cylinder head to the side chassis rail to make sure it would fit and make it as compact as possible. the hose is 48 mm i.d which i got from my local hydraulic company . I will try and post some pictures of my cut down manifold later.

 

Bernie

[Guest salty_monk]

I think you'll find that small hose on the front at the right is a vacuum hose designed to drive a vacuum petcock from a bike tank. (Fuel only flows when there is a vacuum). It will likely drive your vac advance on dizzy but I doubt it would drive a servo. If you don't use it you'll probably want to cap it.....

 

The only way you'll tell if your pipe works is to try it.... One question though, is it easily removeable in situ because you'll need those ports in order to vacuum balance the carbs, makes a huge difference to bike carbs when they are in balance.

 

This is one of the better balancers out there.... http://www.carbtune.com/

 

Dan

[Guest Leaner]

Hi Dan im not using that small pipe for my vacum advance and servo if u look at the top of the picture u will see I have made a pipe that links all the holes where the injectors used to fit so that the vacum for the servo and dizzy draws from each inlet so im hoping it will be a balanced vacum draw off. I wasnt sure wot the pipe u mentioned was for i was told it was probably a vacum so i was just going to fit them and then work out wot to do with it.

 

Bernie

[Guest salty_monk]

Hi Dan im not using that small pipe for my vacum advance and servo if u look at the top of the picture u will see I have made a pipe that links all the holes where the injectors used to fit so that the vacum for the servo and dizzy draws from each inlet so im hoping it will be a balanced vacum draw off. I wasnt sure wot the pipe u mentioned was for i was told it was probably a vacum so i was just going to fit them and then work out wot to do with it.

 

Bernie

 

Bernie,

 

Sure I see what you've done, just pointing out that it's a vac line & might be ideal for your dizzy or if not defo cap it off as it will upset what else you've done.....

My point about balancing & being able to access those 4 ports to do it is very valid too....

 

It's a good idea but just a couple of points.

 

I knew nothing about bikes till I bought one a year & a bit ago, now I can rebuild carbs with the best of them BUT jetting that type of carb is a black art (like an SU carb), there is a vacuum lifted piston "slide" for each carb body, a needle that can be one of a million profiles, main jets, pilot jets, float levels, air jets etc. All of them have an impact & you will likelly need to balance them when you've finished messing with them.

 

Good luck with it, my carbs are very similar (on the bike) so if I can give any pointers shout.....

 

I also have some good links to tuning pages etc for them & a diary of how to rebuild some Mikuni's that should be similar to those.

 

Dan

[Guest Leaner]

Hi Dan thanks very much for ur input on the subject and i will certainly keep you in mind if i need any advice , its gud to know theres plenty of lads an girls in the club that are willing to share their knowledge or ideas to help fellow members . A lot of what we do is trial and error or just guess work which for me makes life more interesting .

 

 

Many thanks Bernie

[Guest stuart_]

Hi bernie, where did you source the manifold from if you dont mind me asking??

 

thanks stuart

[Guest Leaner]

Hi Stuart its just a standard pinto injection manifold i had lying about and decided to see if i could cut it down to suit the bike carbs i had .It wont suit all bike carbs it depends on which ones you use , mine were ok without the need to space them out . hope this helps .

 

 

Bernie

[Guest salty_monk]

Bernie,

 

Thinking more about this today (dangerous huh! ) Are there four threaded ports on the carb bodies just before where you have attached your manifold?

If so they are the vacuum ports for balancing, if not then they are like mine & originally had them on the bike manifold (actually each one has a sort of collar that then bolts direct to the head).

 

I think you might need to add some ports if possible if you don't have them as I can't see how you can balance them without those.... I think the adapters that connect up the balancing kit have a 5mm thread. You just put a bolt in it when not using.

 

Dan