Bike Carb Conversion - Dummies Guide :)

Sooooo last week I did my motorbike carb conversion. This is on a MK2 Scirocco fitted with a 1.8 16v KR engine. Here is what I did.

I did a lot a research on this, reading these forums and speaking to people etc.

Got all my bits;

GSXR 750 Carbs jetted for my 16v
RamAir filters
Custom stainless Manifold
Facet Silver top fuel pump
Filter King Fuel Regulator
fuel pressure gauge
Oil Catch can
Universal Choke cable kit
2 x solder-less nipples
1 x 8mm T-Piece
Couple of meters of 8mm fuel pipe
Lots of small jubilee clips and some big ones.





Engine bay before I started;



It looked cool but fuel injection isn't for me + all that inlet manifold / intake pipe was taking up too much space for my liking.

So, I started by removing anything to do with the fuel injection / air which was basically the inlet manifold, injectors, airbox and fuel matrix. If you un-bolt everything it all pretty much comes off in one.




This is what I was left with under the bay;



I then started by jacking the back of the car up and removing the old fuel pump. Not being technical I have to look at a manual and have a chat with my bro as basically the facet pump is very basic. It has fuel in, fuel out and a live where as the old pump had a live, earth and had fuel in, fuel out but this also then went into something else that split the lines in two...... anyyyyywaayyyy to cut a long story short the current engine had a fuel return reservoir which was now no longer needed.

So remove you old filter /reservoir. Mount the new pump using one the the bolts where your old pump was. I also at this point nipped the end of the earth cable and attached a eyelet so I could bolt this to the body when attaching the pump. Run the pipe coming from the prime pump (square white plasticy looking thing) into the fuel in. Use on of the lines running into your engine bay and connect this to the fuel out on the pump. You may need to use some new fuel line for this bit. I then block off the fuel return line that goes into the prime pump with a big bolt and jubilee clip. Then I connected the live up to the pump.

Once that was done I then moved into the engine bay.

First of all I fitted the manifold. I used my old gasket as I forgot to order a new one. If you do this then make sure you use some instant gasket too so you don't get any air leaks. Ideally though just remember to buy a new gasket.

I then mounted the carbs to the manifold using some rubber pipe and jubilee clips. I'm not sure on the diameter of the pipe as I got all of this with the carbs already BUT just make sure it won't collapse when being sucked.

I then mounted the fuel regulator. I mounted mine down where the air box used to be (as there were already some little holes) using a little custom made mount (basically a flat bit of metal with some holes drilled in it.

I then worked out which line I connect the pump up to under the car. This was easy as I knew i had used the old fuel feed and I knew which pipe originally went into the fuel metering matrix. If you don't know this then you can just turn you ignition on and see which one is ****ing out fuel.

I then connected the fuel line to the fuel regulator which I did using some fuel line and jubilee clips. The fuel lines i had coming into the bay were copper so I had to use rubber fuel line to make them reach to the regulator. Nice and easy.

I then ran a line out of the regulator into a fuel pressure gauge (this is needed so you can set the pressure right. You can buy regulators with these built in but again I got all of mine with the carbs for cheeps ) I then ran a line from the gauge to the carbs.



The carbs have two fuel lines going in so you will no need to fit a T-Piece to split your line in two. I then fitted some more fuel line to the T-Piece and ran them into the carbs.

I then needed to attach the accelerator cable. I read few different mays of doing this like running a push bike brake cable etc but dont bother. Simply cut the end off your current cable and attach a solder-less nipple. It takes 10 minutes and fits much nicer. The lad I bought the carbs off had made a little bracket to sit the accelerator cable in so it sat nice on top of the engine. He just made that from the bracket that used to hold the cable and bent it to fit;



It's a nice cheap, simple bodge but looks tidy, mounts easily to the back of the block where it used to mount and does the job perfect.

Next was attaching the brake servo line to the side of the manifold which I did by using some of the pipe i had removed when taking all the manifold / airbox off. This again was nice and simple.

I then mounted my oil catch can near the radiator and ran the oil breath pipe to it. You can add an extra pipe on the catch can with a filter or something but for me personally I am only using it so the **** doesn't go directly onto the road.



So with all that done this is how the engine bay now looked;





Everything was now in place meaning I could try and fire the old boy up. Here is the first start...... remember what once your fire up you will need to adjust your fuel regulator to 3 psi (below is a video, just click it) ;

http://s49.photobucket.com/user/jambutties/media/2013-09-30132040.mp4.html

You can hear it sounds bit funny but that was because it was sucking in air from where the carbs were mounted plus it wasn't really setup.

Here is how it looked with the filters on;







Here it is just ticking over later that night (below is a video so just click it);

http://s49.photobucket.com/user/jambutties/media/2013-09-30190251.mp4.html

I still need to go over everything yet tide it up, like cut out all the old electrical bits that are in the bay and insulate them under the dash. Fit the choke cable (not essential but if I want to drive it in winter I will need it) and generally tidy it up and go round making sure everything is nice and tight etc.

I have read a few forums etc and people are always asking about the ECU / dizzy etc. All your ECU is now doing is controlling your spark so only attaches to the dizzy. I think i may need to adjust my timing slightly but thats it you don't really need to touch any of that.

At the mo I think it is still sucking in air as it aint quite running right BUT it runs.

We did set it up ourselves but I am going to take it on a rolling road and have it done properly and see what bhp it's at.

I must say though, off the mark it is something else, it's sooooo responsive it's unreal =)

Once it's all setup I will post some more video's of the sound and let you now the BHP etc.

[REMEMBER PEOPLE I AM 100% AMATEUR SO DON'T KNOW LOADS BUT IF YOU ANY QUESTIONS THEN FIRE AWAY AND I WILL TRY MY BEST TO ANSWER]

 

Your video links aren't working :-( well-not on iPhone :-/

After some tidying up and tuning job ll be a gooden :-)

Only thing I would be worried about is air temp of intake :-/ I should imagine on a warm day in traffic taking air from the top of the radiator isn't going to help. Are you plumbing a better intake in?

Although as always with things that look and sound the nuts there are always issues to get use to.

 

cheers for this very helpful

 

Hopefully the links will work better now?

As for the air intake stuff. Tbh I'm not 100%.

I know a lot of people do this conversion and have it setup like this and nobody has ever really mentioned there being an issue with it. It will just have to be something I trial lol.

 

I have a very similar set up at the mo. R1 carbs though. Ive never had a temp issue in the summer. Not yet anyway! Im going to get omex 200 aswell. Have a look into it.

 

That's good to know I didn't think there would be a problem really.

When you say omex 200 I am guessing your talking about the ECU?

 

Air expands as it heats up, which means hot air contains less oxygen than cold air :-/

Surely on a hot day in traffic this must have. Knock on effect on combustion and engine temperature :-s or am I just over analysing it :-@

 

Yes mate. Its basically the same as megajolt, but apparently better. Well worth looking into if you intend to keep your carb set-up. Might be worth giving northampton motorsport a ring. Or someone local to you. Like you, Im a newby, I can understand how it works when told, but cant quite explain it lol

 

No, your right. But I personally have never had any problems whilst sat in traffic on a hot day. I havnt heard of anyone else who has either. Maybe its different with an airbox and manifold etc. I know I wouldnt go back to k jet again. And my set up hasnt even been fully optimised yet.

 

Just a thought, I noticed you have several outlets on your manifold for the brake servo. You only need one of those. Block the others off. I have heard that using all 4 can cause pulsing or something. I have a bogg brothers manifold and that only comes with the single outlet for the brake servo and it works perfectly.

 

Haha good spot. For some unknown reason the guy I bought the bits off had drilled and topped the other outlets. at the mo I have jus got a pip running from one to the other and am using the one on the side for the servo. I have actually been speaking to a family friend today who very conveniently works for a company that manufactures Brauns f1 parts he has said he will get the holes welded up for me for free which is a plus

I also had a good look at all my work today to see why it isn't running as well as I hoped. I seem that a lot of clips i had fitted (even though they were new) were just goosed so i have replaced all them to get them nice and tight. I also noticed the clips / rubbers holding the carbs to the manifold seems to have moved and it was basically sucking in air. I removed and refitted again then took for a test drive, needless to say it ran sweet as a nut and sounded great. I then drove home for find it was popping and farting again. When i got home I checked the rubbers again and it appears one has slipped off again meaning it was sucking in air.

AGAIN the rubbers i had were supplied by the guys i bought the carbs off so seemed a bit bodged. I have not ordered some nice new silicone rubber tubes and clips which should solve the problem

In regards to the OMEX 200 etc and having it properly setup. I live in Cheshire and have heard that a place called Mikeanics in Congleton is brilliant with these conversions and will set it up nice. Alternatively we also have PSI tuning in the same area.

 

Might be worth while buying the original carb to head rubbers and having your friend put the correct grooves into your manifold too. That would stop any leaks and also hold the carbs on firmly. From what i gather, the silicon pipes tend to work loose over time because of bumps etc in the road.
Glad your looking into omex. Will be interesting to see how you get on. Alot of people tend to shy away from bike carbs, but if done correctly, the results are pretty good. I like mine and have no intention of scrapping them. I have just got my engine block and parts back from the machine shop. Cant wait to put it all together and get it in the car. Just need to find a little time. Keep us posted. Its good to see someone else going the bike carb route.

 

I was thinking that about the original rubbers actually however, they are proving to be a little difficult to get hold and the ones I have seen have been staggers with two rubbers being shorter which I am guessing was to fit them in the bike frame.

Has anybody ever had their carbs welded to the monifold? Wondering if that's worth while seeing as the manifold is made specifically for the carbs?

Funnily enough though me and my old man are just about to start up an online business selling motorbike / scooter service spares etc and have just got our catalogues through from our suppliers. Fingers crossed I might get lucky and find some rubbers in there cheap.

Just from the short drive I have had in my car with the carbs I definitely wouldn't go back to fuel injection. It's so much more responsive and sounds great. It will be interesting to see how it goes on the Dyno at some point.

In regards the Omex stuff. I will probably look into it but looking at the price I don't think it will be a route a look at for a while as I have Many other things I want to do.

Keep us posted on your build too. I'm always interested in reading other peoples wins and loses, it's the best way to learn I think.

 

Haha, bit of a science lesson going on here.

In regards to the welding of carbs to your manifold...... I was put straight by my brother. You can't really weld two different metals together, especially stainless and aluminium. Plus it wouldn't be recommended anyway as it would be mare trying to service your carbs.

Also in regards to the comment made about using the original rubbers that were used on the bike this can't be done either. On the bike the rubbers basically bolt straight to the engine in place of the the manifold meaning they just wouldn't work with a car engine.

 

who made your manifold for you. looks like a nice bit of kit.

 

You are using jubilee clips for fuel lines - swap for proper fuel line clips.

Also if using silicone don't use jubilee clips they will wreck your expensive pipe and don't seal evenly (which is why you may be having issues) Use proper silicone hose clips.

PS: well done - I hope it goes well for you.

 

Just added R1 bike carbs to my ABF, WHICH EXHAUST YOU USING, AND WHAT JETS ?

 

Nice to see some home building!, I work on bikes for a living and heatsoak affects efi bikes far worse than carbed ones.

Properly setup you should have no bother sat in traffic with a hot engine bay.

Some people cut the bonnet for colder air intakes but you also get water problems as well if it's not garaged.

 

What air filters you using ???

 

What distributor did you use and what part of the loom did you use ?