Bike carbs...
#1
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Bike carbs...
Who knows a bit about bike carbs?!
Fancy at some point converting my Escort to run on bike carbs, for the fact its something a bit different, its currently a carb fed 1.6 cvh anyway, so its not as if there are ecu's and sensors to worry about, however my question really lies with what size of carburettors should i be looking at, choke size, how to jet them correctly etc etc.
I dont personally know anyone who has already done this conversion to any vehicle, but obviously being able to speak to someone first hand would be much easier, but am after gathering as much advice as possible before i actually attempt it.
Fancy at some point converting my Escort to run on bike carbs, for the fact its something a bit different, its currently a carb fed 1.6 cvh anyway, so its not as if there are ecu's and sensors to worry about, however my question really lies with what size of carburettors should i be looking at, choke size, how to jet them correctly etc etc.
I dont personally know anyone who has already done this conversion to any vehicle, but obviously being able to speak to someone first hand would be much easier, but am after gathering as much advice as possible before i actually attempt it.
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Give Boggbros a call. They will tell you most of what you need to know or do. Yamaha R6 38mm carbs & fuel pump work well. You will need to make or buy a manifold to suit, jets can be drilled out but there's a bit more too it than you might think regards the fueling.
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Heard that name mentioned a few times, will give them a try. Would the mechanical fuel pump already on the car be up to the job of feeding the bank of carbs you suggest?
The biggest thing i am worried about to be honest, is with the jets not really having a good idea what size to start at, i dont want to start drilling them out, going to far, making a hash of the job then having to start over again!
Manifold im not overtly worried about, im sure me dad can fabricate something to a drawing at work.
Thanks for your help chap
The biggest thing i am worried about to be honest, is with the jets not really having a good idea what size to start at, i dont want to start drilling them out, going to far, making a hash of the job then having to start over again!
Manifold im not overtly worried about, im sure me dad can fabricate something to a drawing at work.
Thanks for your help chap
#4
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Id go for some 38mm carbs from a gsxr600 or simular, jets will need drilling to 1.1 to 1.2mm, Id get a fuel pump from a bike as there self priming and cut off when a certain back pressure is reached, I have r1 carbs and fuel pump on a zetec in a mk2 xr2 and they sound and perform mint
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best to run them with the correct bike pump and bogg bro are the guys to speak too
would be interesting to see how they perform on the cvh
would be interesting to see how they perform on the cvh
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R1 carbs being 40mm are well suited to a 2ltr zetec I hear. R6 plenty big enough for a 1.6cvh lump. Had a mate with R1 carbs fitted to a 1.8 RS fiesta lump & it went realy well. Not wishing to start an argument but I have a pdf file saved to my pc stating that the jets should be drilled to around 1.65mm for a 1.6 motor & 1.8mm for a 2ltr ? I could do with hearing from someone who has actually done it all themselves as I am in the process of doing the same thing. I sold my 1st attempt (R6 carbs & home made manifold) thinking I was fitting a zetec to my my mk3 but things have changed again (bought another bike) so I will stick with cvh for now.
If you make the manifold from steel I would advise clamping it all to your head before you weld the inlet tubes to the base plate. I did mine in a vice & the whole thing bent to buggery bollox from the heat. Remember when making your manifold that bike carbs, when fitted to the bike are almost pointing straight down & not horizontal as you might think.
Anyone know how I can post a link to this PDF file I got ?
If you make the manifold from steel I would advise clamping it all to your head before you weld the inlet tubes to the base plate. I did mine in a vice & the whole thing bent to buggery bollox from the heat. Remember when making your manifold that bike carbs, when fitted to the bike are almost pointing straight down & not horizontal as you might think.
Anyone know how I can post a link to this PDF file I got ?
#7
Hi guys
just wonderin if you did nany more about the bike carbs ,have a set of 38mm keihins ready to fit to my 1.6 cvh,am curious to know what jets i will need,can see in some posts that 1.6-1.65 are recommended but just wonderin if any one has actually completed this job and what jet sizes ended up bein used,spec if requiredc as follows:
86 ,1.6cvh sm6090 head ported and polished,cvh33 kent cam,megajolt 3d elec ignition with escort coil pack.............any help appreciated
just wonderin if you did nany more about the bike carbs ,have a set of 38mm keihins ready to fit to my 1.6 cvh,am curious to know what jets i will need,can see in some posts that 1.6-1.65 are recommended but just wonderin if any one has actually completed this job and what jet sizes ended up bein used,spec if requiredc as follows:
86 ,1.6cvh sm6090 head ported and polished,cvh33 kent cam,megajolt 3d elec ignition with escort coil pack.............any help appreciated
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I am first and foremost a biker, just pop in to this forum now and again for help with girlfriend's Fiesta.
As stated above, you must remember that carbs on sportsbikes point almost straight down into the engine. This is so that the space available on a bike is put to the best use, but I also think there are meant to be some performance gains to it. Here is a google image to show that:
However, not all bikes are set up that way. Lower performance bikes would look more like this:
ie, with the carbs at a flatter angle. I don't know if running "downdraft" carbs in a "sidedraft" configuartion gives any issues, but I would guess it'd be easier to start with sidedraft carbs, like eg. from that bike as shown, which is a comparitively low-tuned 1300cc 16v air/oil-cooled engine. It's an XJR1300, in case that helps!
Bike carbs, particularly sportsbike carbs, can be very fussy about having the right volume airbox and the right length velocity stacks. Later-model bikes (particularly Kawasaki) often used ram-air, and if the pressure on the carbs isn't right, your carburetion will be all to shyt, so avoid Kawasaki carbs. Carbs for muscle bikes are typically more happy to run with individual sock filters on.
One other thing to remember about bike carbs - they will need to be kept synchronised. On a bike it is a once every... err... every so often type of job, I don't know if it would be better or worse for intervals on a car. Some bikes are better and worse for it, but most benefit from a check and synchro every 15 or 20k miles.
Yes, I would use a bike fuel pump for the reasons above.
Worth noting bike carbs will typically use two throttle cables - one to push and one to pull. They are much thinner than car throttle cables, and possibly not durable enough? Sure that can be got around, but it's worth considering. They are usually joined as a bank on a long bracket, and for the skilled fabricator you could change the spacing, but generally it'd be a PITA. I have to guess the bank will be too narrow, maybe you can account for that by using bendy eg. silicon tube connectors between your manifold and the carbs.
The sound and performance gains from having individual carbs are real, otherwise sportsbikes wouldn't have bothered, as it obviously costs lots more to make 4 than 1 or 2 carbs. I reckon it'd be pretty cool to have that kind of induction roar from under a car bonnet too!
Meh, maybe there's something useful in there
As stated above, you must remember that carbs on sportsbikes point almost straight down into the engine. This is so that the space available on a bike is put to the best use, but I also think there are meant to be some performance gains to it. Here is a google image to show that:
However, not all bikes are set up that way. Lower performance bikes would look more like this:
ie, with the carbs at a flatter angle. I don't know if running "downdraft" carbs in a "sidedraft" configuartion gives any issues, but I would guess it'd be easier to start with sidedraft carbs, like eg. from that bike as shown, which is a comparitively low-tuned 1300cc 16v air/oil-cooled engine. It's an XJR1300, in case that helps!
Bike carbs, particularly sportsbike carbs, can be very fussy about having the right volume airbox and the right length velocity stacks. Later-model bikes (particularly Kawasaki) often used ram-air, and if the pressure on the carbs isn't right, your carburetion will be all to shyt, so avoid Kawasaki carbs. Carbs for muscle bikes are typically more happy to run with individual sock filters on.
One other thing to remember about bike carbs - they will need to be kept synchronised. On a bike it is a once every... err... every so often type of job, I don't know if it would be better or worse for intervals on a car. Some bikes are better and worse for it, but most benefit from a check and synchro every 15 or 20k miles.
Yes, I would use a bike fuel pump for the reasons above.
Worth noting bike carbs will typically use two throttle cables - one to push and one to pull. They are much thinner than car throttle cables, and possibly not durable enough? Sure that can be got around, but it's worth considering. They are usually joined as a bank on a long bracket, and for the skilled fabricator you could change the spacing, but generally it'd be a PITA. I have to guess the bank will be too narrow, maybe you can account for that by using bendy eg. silicon tube connectors between your manifold and the carbs.
The sound and performance gains from having individual carbs are real, otherwise sportsbikes wouldn't have bothered, as it obviously costs lots more to make 4 than 1 or 2 carbs. I reckon it'd be pretty cool to have that kind of induction roar from under a car bonnet too!
Meh, maybe there's something useful in there
Last edited by a_morti; 27-10-2010 at 05:19 PM.
#13
startin to gety abit worried,seems to be gettin a bit more hi-tech than i first imagined,anyway talked to chester sportscars today and they actuall supply a complete bolt on set up ready to run,manifold ,jetted and balanced carbs everything that i need and also at a reasonable price (i think anyway) so am goin off to rethink my next move............
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