single carburator?

Has any one found a single carb adaptation for a xj650. mines an 81. I saw one post where somebody made a cool 4 into 1 manifold, but I cant find the post and was wondering if he actually got it to work? Any help would be appreciated.

 

DKS. I've been thinking about using 2 Edelbrock oval bore pumper carbs. They have external jet adjustments and the main jet is an external changeable metering rod. May be just the ticket for a daily ridden, weekend warrior. Try Edelbrock Off road dept.. (the motorcycle dept is just about all Hog heads).

 

maybe two larger carbs... like 2 650 dualsport carbs...

 

One 41mm flatslide would be plenty to feed all 4 banks. the whole point is to ditch the junk CV style carbs and let your wrist, not your engine's vacuum, control the revs.

 

Exactly, I want ONE carb. No problems. a 41 mm flatside eh... Has any one had success with this?

 

you can. I'll help ya.

 

Ok, this thread just got added to my favorites. I'd like to see how this goes. Please post pics and detailed info? Thanks.

 

i to want to see this done, how about a weber carb with 2 barrels like that on a toyota truck.
i'v seen the fuel injected version, how bout carburated...?

 

Something like this???

 

I love Europes style that is bees knees.

 

Apologize, this isn't really XJ related. A friend of mine had an older Goldwing (1100). He bought a kit that had just 1 weber carb and 4 into 1 intake manifold. His bike ran GREAT after the change over...

skillet

 

I think you are going to have fuel distribution issues unless you are very good at setting up the manifold.

 

Introducing our new carb system:
Thru years of experience we have taken into account velocity, atomization, carb size, fuel to air ratio, distance from the cylinder head, etc… And developed a carb system that we are proud of. The development of the manifolds was not rocket science. No computer generated images. No elaborate Nasa space shuttle testing facility. Just experience and determination. (“Persistence wears down resistance.”) The manifolds were lengthened, opened, angled, shortened and everything you can imagine. We knew we must get the intake runners equal length. Then we had to test quite a bit to get the intake runners the perfect size. (Inside diameter.) Not to big. Not to small. They had to flow like water. Flow like water? Yes, bigger is not always better. Just like cylinder heads, velocity and direction of the flow means everything. Think of the intake flow like a garden hose. If you squeeze a garden hose the water moves faster. If you have a great big garden hose the water moves slowly. We knew we could gain a lot of torque and some streetable horsepower if we pushed the carbs away from the head a little, but we also knew that the carbs had to feel a signal, or pulse from the motor at low rpm. Some of the carb systems we have seen in the past have a long intake tube or something with the carb or carbs attached to it .We have found this theory impossible to work in the real world. All the carbs feel is vacuum at low rpm, not a signal or pulse. Remember, carb tuning should be done from the bottom up. (The main jet is last.) We tested 30, 32, 34, 36, 38 and 40mm carbs. Bigger carbs made more power on top rpm, but we were determined to build a system that worked at all rpms. Because we wanted to build a system that covered all possible applications, (Custom frames, pipes, air filters and altitudes.) we were not focusing on high performance. After testing, testing and more testing, it was time to DYNO test the bike. Mainly for proper fuel to air ratio. When we check fuel to air ratios, we like 12 or 13 to 1 ratios for good power. Sometimes with lower cooling abilities we like 10 or 13 to 1 ratios for cooling. (Richer). We never make lofty horsepower claims because there are so many variables involved to achieve max horsepower. (Exhaust, cams carburetion, ignitions, etc…) Lets just say, if you have your fuel to air ratio correct your motor has reached its potential and the horsepower is there. Once again, we like to leave exaggerated horsepower claims to bar stool mechanics, but if you want to have some horsepower facts here you go.

Our test bike went from 51 to 58.8 hp. (Rear wheel) The bike gained significant torque. We were pleased, because it does not hurt to have extra power. This carb system took us about a year to develop. (Yea right.) Because we also have a full service department. Honda high performance engine program, custom frames, and other custom stuff. The carb system was put on the shelf now and then. There seems to be a lot of speculation on how this system makes power and how this system actually works when so many other systems have failed. Lets think about a couple of theories. Webster’s Dictionary says: “THEORY [The principles of an art or science rather than a its practice][A conjecture, a guess.” 4 into 1 exhaust systems work well because as a cylinder fires the exhaust helps pull exhaust gases from the other cylinders, so the cylinders are working together extracting exhaust and pulling fresh fuel in the cylinders. With that in mind lets talk about the intake system we have developed.

You will notice there are two separate manifolds. One manifold is for number 1 and 2 cylinders and the other manifold is for number 3 and 4 cylinders. Lets talk about number 1 and 2 cylinders. While number 1 cylinder is pulling fuel in the cylinder, number 2 is not pulling fuel. We feel just like the 4 into 1 exhaust theory, by number 1 cylinder pulling fuel in the cylinder this helps number 2 cylinder with a waiting incoming charge of fuel almost pressurizing the intake manifold. This almost makes you think that a 4 into 1 intake manifold might work also, but do not forget, you must jet the carbs from the bottom up. And the carbs must feel a signal. Seems to me there is also a lot of speculation on which is better. One carb per cylinder or an intake system like ours. I believe at very high rpm, maybe one carb per cylinder might make more power, but Honda sohc motors do not rpm that high. Before you go spending money for a carb system, remember this system is not a cure all solution for other problems. You will also need basic skills to install and possibly tune the carb system. Consider the power triangle procedure we at Cycle X perform on all ill running motorized vehicles. Motor must be in sound condition. (Compression, valves adjusted, etc…) Stretched cam chains will affect your performance.

 

Uh-oh..he's flipped his lid and stretched his cam chain.

 

I've seen weber 2 barrel 38mm double pumper carbs before, I dont really think that mocking up a manifold and cables would be that hard. good luck!

 

Skillet: what did the manifold look like on the Gold wing? does it have 4 intake ports ike the XJ?
How about a manifold like this one from "look ma, no carbs"?
Any other success stories out there?

 

That's another amazing Custom Fabrication Job that should be featured in the Bike Mags.

I think if that Job sees wide publicity, somebody will take the idea and have kits on-the-market.

Sure, they'd be made by starving, orphan-slaves in a Hong-Kong sweatshop, ... but, for $245.95 ... they'd sell like Hotcakes!

 

what if you replace the hitachi 34's with mikuni 30's
their 23% smaller but the don't have the throttle plate in the bore,their highly tunable, brand new, not a CV carb and a set would cost about 180$
all you need is a flange to pipe adapter and some kind of throttle cable setup
and a fist full of jets
don't know what kind of hit you'd take on performance though, maybe not that much

 

The configuration of the Goldwing engine is such (2 cylinders per side) that the manifold sat right in the middle, distance from carb to head was equal on all 4 cylinders. This is one of the problems that would have to be taken into consideration for XJ style bikes. Way over my head ...

skillet

 

Ahhhh, I see (as the light bulb goes on over his head)...

skillet

 

looks expensive...

 

Okay, I know it has been awhile, anyone still on this thread. i looked around and found some interesting stuff on an xs 650 site. joewiseguy.com has had success with a 2 into one intake.... soooo I am going to try a Mikuni 36 vm with 200 main and 25 pilot. mounted up to a custom 4 into 1 intake with the intake length as close to equal as i can get it, but the consensus is, it isn't that critical. I know what some are gonna say, but since I am not looking for performance or milage gains like manufacturers are it will only be small losses in performance and milage. Thanks to those of you who were supportive and I will try to keep you posted.

 

A bit off topic, but any attention is good attention. What is a Honda TL? Is it a trials bike? The 1970's are a bit hazy for me.

 

i like this thread. always interested in ditching stuff off the bike

 

I don't see, the photo's gone...


Rickkk!!!

 

psalten, a 25 pilot? waaaaaaaaaaay too small. 200 main, prob too big

 

Dw what size carb did you use for your 400? I think I remember you said it was a dirt bike?

 

Danno, yea TL's were trials bikes, i have a 125 and i think there was a 250 also
geared so low there was no hurry to get on till second gear
great woods bike, trails were optional just go where you wanted

 

Yep, I ride vintage trials with AHRMA. It is great fun. lots of old bikes and cool people.

 

35mm roundslide. i am feeding 200cc jugs each though

 

I was thinking about this as well... I was just wondering if a straight 4-1 could be used, or is a 4-2-1 would have to be used... I dont know if the middlecylinders would be running richer... or if the engine vacuum would pull equally..

 

Ya, kinda unrelated to the topic of the xj carbs, but I was wondering because I have a 400 Honda twin I'd like to set up with one carb. I will look around for something such as that. Was it hard to dial in?

 

not really, not if you have any clue on how to read a plug and listen to the engine exhaust note...

 

i think this winter i am going to put an FCR41 on the bike. its the carb i run on the race quads.

 

Thats what the guys at joewiseguys choppers are are doing and they say it works great on xs 650s... so with equal displacement it should work, me thinks..

 

Hey has anybody been working on this. I have! I have some steel pipe and some elbows and I've been cutting and welding... I am going for a 4-2-1 configuration. I post some pics soon.

 

dwcopple: Whats the brand on that 41mm flatside carb? N where can I buy it?

Thanx

 

Mate of mine has an XS 1100 with a single twin barrel 45mm weber carb on it. Uses a simple 4 into 1 manifold. After a bit of re-jetting he got it to run ok, but not great. It doesn't flat spot but the power is around the same as he had before (hasn't been on a dyno). He likes it because it's easier to maintain.

 

you must mean 35mm. Its a Keihin from a CR125R Honda.

 

ok youre going to think im crazy but, what if you take a corvair manifold and mod it so that it will mount up, and use a 1 barrel corvair carb. i dont know the flow on one but i do know the motor is a 2.7l and they run two carbs on the 110 motor?

 

K thanx now will that fit n work on a 750?


Thanx

 

KEIHIN has a Web site.

The Flat-sides that fit XJ-Bikes are the ones that fit the KAW KZ Models.

Close to $900.00 for a rack of four including the Dual-cable Throttle.

 

Hi,

I've been lurking round here for a while, I've got an XS1100 which is close enough that there are crossover areas.
I registered to post these pictures of my 1-3/4" single SU conversion coz I thought some of you might be interested.











It doesn't run right yet due to some ignition problems which have led to a complete rewire.

Cheers

Tink

 

Odd looking carb, seems to be upside down

 

...on that 650, ...a single carb of 35mm bore is going to be your best app. Larger/Smaller and you'll find tuning "issues". The Honda CR Mikuni carb mentioned earlier is popular, simple and works. I've put single carbs on many bikes over the years including CB's, XV's and XS's, GS's, KZ's and, until somewhat recently, have been building single-carb manifolds for Honda GL's (Goldwings).

 

It's an S.U. HIF44 and it is the right way up.

HTH

Tink