single carb

lar55 · New Member Joined: Jul 07, 2007 Posts: 9 Location: ill

Hey guys . Need to know were to get a single carb manifold for my 650 or how can I make one . And how much do you drill the jets out to make them work . I'am not looking for speed . Just something simple . Thanks Lar

royfisk · Posted: January 18, 2008, 6:46 pm Post subject: Re: single carb

I dont know of any comercially available manifolds for this purpose. And have not seen many customs done that way. The 2 that I did see were both useind s&s carburators. and homemade exhaust pipe manifolds. The s&s carb allows for needle adjusting screws and changeable main jets. They worked alright but not vm mikuni right.

mo650chopper · Posted: January 19, 2008, 10:05 am Post subject: Re: single carb

I have a question on how you would know the proper size carb. Even though your only drawing air through carb to one cylinder at a time I belive one 34MM would be too small but it wouldn't need to be twice the size either????

royfisk · Posted: January 19, 2008, 10:23 pm Post subject: Re: single carb

well mo the harley sportsters use to run just fine on 36 mm mikunis (VM) carbs. they were 900 and 1000 cc's . The smaller carbs will flow enough cfm to run these engines its the jetting that would get tricky. Just as our beloved 650's will run fine on all 3 size mikuni's . My guess would be a 38 mm mikuni jetted properly would run both cylinders fine, I also dont think there would be major jet changes. where the trick would be is getting a manifold that would distribute the fuel evenly, That too may not be as important as I think cause Ive seen some pretty trick intakes on bikes before and runners were not always even. but my main question is what would be the purpose of this? What is expected to be gained?

mo650chopper · Posted: January 20, 2008, 12:14 am Post subject: Re: single carb

People do alot of things to motorcycles without much purpose in mind other than being differnt or adapting something they have laying around just to make it work. Being an old Harley guy I just like having to mess with one carb instead of 2. Kinda like a V8 4 barrel on a smaller scale. I've got my 80 XS running good on a couple 78 carbs so I'm good for now. Who knows what crazy idea or parts I'll come up with in the future. I doubt there would be any performance gain.

funranger · 650Rider Supporter Joined: Feb 18, 2005 Posts: 18

I have seen triumph and BSA kits to use one carb may want to look there.

pumps · Posted: January 20, 2008, 2:08 am Post subject: Re: single carb

xs650temp.proboards29....593&page=3

Some pics way down.

xsjohn · Posted: January 20, 2008, 5:36 am Post subject: Re: single carb

You could never balance the cylinder temperatures........

John

Shannon60 · Posted: January 20, 2008, 10:32 am Post subject: Re: single carb

Q for you xsjohn why are the cylinder temps uneven?

royfisk · Posted: January 20, 2008, 11:06 am Post subject: Re: single carb

triumphs, bsa's, nortons, ALL had single carburator models, now that I think about it they also used same bore carburators. little differant jetting. Now if you were to desire crazzy ness why not dual carbs, and manifolds going around the cylinders so air is comming in from the front of the engine. COLD AIR . scrad effect, forced air induction. My neighbor has a goldwing with a 400cfm holly four barrel on it. Been useing it now for onward 10 years . He had carburator problems and for those who havent been there goldwings are a royal pain in the a___ to work on. I once was playing with the idea of making up a manifold for a buddy of mine to adapt 8 mikuni 34mm vm carburators to his 350 chevrolet street rod. More for a trick look that neither of us have seen done before. After many of beers and finding obsticals that we would incounter such as enrichinr linkage, throttle linkage, manifold manufactureing, etc ( before I had welders, and pipeing knowledge) we parked the idea. But I still think it would be trick looking on a 32 ford open cowel street rod with 8 air filters . So I guess this single carb thing is not as crazzy as it first souds. think your haveing problems now syncrhonseing 2 carbs try 8.

mo650chopper · Posted: January 21, 2008, 10:09 am Post subject: Re: single carb

Maybe a couple hilborn fuel injectors like my buddy had on his 341 CI Desoto Hemi, 11.7 second quarter mile times, That was a cool engine.

On a more serious option maybe a CV 40MM HD Keihin from a 883 sportster? Should be easy to find one cheap I would think. The stock carb was always one of the first parts I'd remove when I had HD's.

mo650chopper · Posted: January 21, 2008, 10:28 am Post subject: Re: single carb

Kinda intrigued by the dual carb idea Roy being with the stretch I have on my bike gives me a lot of room to work with in that location. Wouldn't the long runners required, probably a foot or so long, make tuning tough?

xsjohn · Posted: January 21, 2008, 10:34 am Post subject: Re: single carb

Have we been forgetting the hot right cylinder......or just ignoring it...does keep you from getting down the road farther....been trying to stay out of this but it is getting harder.......FI would be cool on each cylinder if they could be individually mapped......at least for me.....

John

lar55 · New Member Joined: Jul 07, 2007 Posts: 9 Location: ill

Thanks for all your in put however I have gotten no closer to a manifold . There was a guy bob scogin who made one and had good luck with it . He also moved the back bone back a little . I guess I 'am not looking for speed . I would like something I can depend on and start easy. I love the look of the old trimph. 500 with one carb and what a nice bike to ride. The main reason for a manifold is I have no carbs now . I thought I would start over with something different, Thanks Guys . I think I will try to make one .

xsleo · Posted: January 22, 2008, 5:17 pm Post subject: Re: single carb

with fuel injection, if you had a system for each side, injector, o2 censor, brain. you could have them auto tune. that way each side adjust to what each side needs. it would cost alot ,but might work.

xsjohn · Posted: January 23, 2008, 1:00 am Post subject: Re: single carb

Can do that with 2 carbs too...........

John

xsleo · Posted: January 23, 2008, 1:30 am Post subject: Re: single carb

true, but when you change pipes, air filters, cams, head work,poor gas, altitude, hot, cold , most any changes the system would tune accordingly. it would make changes alot easier.

xsjohn · Posted: January 23, 2008, 1:35 am Post subject: Re: single carb

May end up with a Goldwing before that's over with.....
xsjohn

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