25 replies to this topic

[Kurt]

As for the power output I couldn't say, I have spent some time online trying to find out as much as I can from others who have done bike carbs on cars.

I found that its big with the clubman -kitcar guys in the UK . There is a shop over there that do a lot of bike carbs on cars they offer a kit with custom manafold r1 carbys and that have been rejetted . and if you can get to the shop they will do an even finer tune on the rolling road .

I found some posts on a forum were people had a kit from this shop but they didnt give away to much on the jet settings or other mods and so on . I did read about one person using a 170 main jet.

On another forum I allso read that if you dont run an airbox bike carbs will run very lean. Another guy was talking about blocking off the air corection air jet so that the main jet pulls more gass and how if you intend to run no airbox you need to do this as the main jet hole that would be needed is bigger than the hole is screws into .

At this stage the car is running so lean that after a small underpwerd run up the road for 5 mins will have the car allmost over heat .

I am tempted to drill out the 1.3mm main to a 1.5mm or lager and just see how it runs, I need to find out more so i can get them in the ballpark.

[crazi-85crx]

This is what I like to see . Good work so far Kurt, and goodluck with the rest.

[CRXfanatic]

Hot damn! Now that's good quality work and information!!!!!

Cheers, Mate!

[Kurt]

I got off work a little early today so I had some time to drill out my main jets.The Stock r1 main jet is 1.30mm I went 2.00mm on my main jets and that realy cleared things up in the top end pulls much harder.I would say its drivable now but I still think there is a long way to go yet. As its still not as crisp as the efi.

For example if I was in 1st gear with the efi and hit the gass full to the floor the revs would swing to 7000rm the wheels would light up in a cloud of smoke and you would have to feather the gass to stop it hitting the rev limiter 7800 i think zc ecu.

If I do the same with the carbs there is a strong pull but a slower climb to 7000 rpm. and no tyer smoking action lol . The good thing with the carbs is that it just keeps on pulling after 7800 I stoped at just under 9000 and prob wount do that again in a hurry pore old ew bottom end. I gess it is ballanced and a stong bottom end but they all have there limits lol

I still miss that SNAP! that the efi had. I am realy thinking that because I am running no airbox is holding me back .

Other problems.

The bikes use two throttle cables. I gess it,s for safty one cable to open the throttle and the other to close it. Because of this the spring return isn't that strong and I am finding that the revs are hanging up some times.And a stab at the peddle dosnt fix it at least I think thats what is happening?

Over all the hardest thing with this project is all though I am not the first to do it it sure feels that way when trying to find good relavant infomantion. There is Plenty on bike carbs but not much on what to do with them when thay are hanging of the side your civic engine lol.

Anyhow guys I will be doing some cleaning up of the hole installation and tinkering with settings this weekend and with a bit of time and luck in the daylight I just might get it sorted out . I will Keep you all posted.

Kurt.

[crazi-85crx]

Sounds like your having fun lol. FYI The lack of throttle response is most likely due to the runners on the manifold being so long. In an EFI setup the fuel injectors are mounted close to the head (within a few mm's), and now the carb jets are mounted about 8" from the head, so the fuel/air mixture must travel that much farther before the engine notices the change. However, the long runners is probably what's giving you such a nice high rpm range.

[Kurt]

Just a little update on my bike carbs. Today I did some thinking, measuring and experimenting with airboxes, filters and so on. I tried running the car with the factory R1 airbox. It's a big bugger of a thing, and I had to take my hood off to use it. So it was a quick blast down the road before the boys in blue start asking questions lol.

The car had some real snap to it and pulled very hard up to the point where I pulled the pin at 9000 rpm. Got to get used to having no rev limiter. So there is a definite improvement with an airbox. Now because it just isn't going to fit, no matter what I do, I did a little bit of research online to find out about the effect of running with no airbox.

What I came up with was that sure you get more air into the carbs and that's usually a good thing for power - just add more fuel to the equation and you're laughing. Most people have to jet up their carbs because of this. The bad thing with cv carbs is you also drop the vacuum pressure in the carbs so the needle slides respond very slow and also can flutter a little. This leads to a slow progressive acceleration.

I have some strips of aluminium around 5mm thick by 100 wide and around 350 long. What I plan to do is trace out the 4 airbox holes that will be then cut from the aluminium so that the factory rubber clamps can be fitted. This will form a base plate that will sit just under the trumpets. A large foam filter will sit on top of the plate forming a small rectangular box. I hope with the amount of still air under the filter and the small restriction the filter offers will be enough to calm the needle slides down a little.

I also worked on the throttle cable today. The stock civic cable sticks up too high when on the bike carbs so once again you can't close the hood. The way to fix it is cheap and works well. All you need is a rear bicycle brake cable kit. I picked one up for $4 and cut my civic cable to retrieve the rubber spacers throttle pedal clip and plastic clip that fits to your fire wall. I then cut the bike cable to length, slipped on the civic hardware, then crimped the end - everything you need is in the kit. The bike cables are more flexible and don't stick up high, also very smooth to operate.

Tomorrow I will make a bracket for the electric fuel pump and if I get time, will sort out the vacuum advance and brake booster. I plan to weld little SS nipples into each runner and link them all up for the vac advance. The nipples can perform a second function as a vacuum port for each carb when you have the carbs sinked/balanced.
Brake booster will run off just one runner.

I will post some pics later.

Kurt.

[lilneedle]

I see u had more moto than I did...comming together now bro...good luck....what motor do you have???9000rpms????dam

[Kurt]

I run a hydra engine ew2 block with zc integra head. The bottom end has been fully ballanced, but even so I realy think 8000 is the max I would like to rev it to. I just over did it a little lol.Will have to install some kind of rev limiter.

[lilneedle]

or get a shift light and watch it glow....lol

[RFL85CRXSI]

Why dont you try an MSD or a Mallory Hyfire ignition? With your carb setup, a performance ignition can help get some of the "snap" like an EFI system. I ran a Mallory HyFire 6AL with a built in rev limiter on my Dx for a while, and I could tell a differance in acceleration.
Best of luck.

[lilneedle]

Yea get the box...AND BUY MY BLASTER COIL...HEHE