|
|
Jul 31, 2006 11:49:38 GMT
|
Is their anything about on this? There are formulas for getting the jetting roughly right on Webers, etc. but I'm all new to bike carbs so need a little help I could just send them off to Bogg Bros but I'd prefer to do it myself
|
|
|
|
|
street
Posted a lot
6.2 ft/lbs of talk
Posts: 4,662
|
|
Jul 31, 2006 16:58:57 GMT
|
Trouble with things like this, it seems, is the people who know what jets work best for what engine like to keep it to themselves for some reason. I find the same sort of secrecy with Dellorto 40's jetting- someone who has a well sorted set-up wont give away what jets they are using, so you end up doing it the expensive way with trial and error and/or a rolling road. Most frustrating. How available and cheap are the jets for bike carbs?
|
|
|
|
|
|
|
Dunno, they turn up on ebay but I think it'll be the pillar drill and vice method
|
|
|
|
|
|
|
There MUST be a (complicated) calculation to work this out? Engineering types wanna help?
|
|
|
|
phatphord
Part of things
Scorpilow
Posts: 674
|
|
|
at the risk of sounding the obvious,if you're running a larger displacement engine than the carb/tb donor engine,then the likelyhood is that you're gonna have to jet up. I guess using the donor power output as a guide for what you may be envisaging could have some use,but limited. cylinder head volumes may also be useful to know? There are kits known as 'dynojet kits' in 3 stages for bikes,stage one being just a mild change of jets,stage 3 being used if you are fitting individual filters,free-flowing pipe etc. Stage 7 kits are available for a few bikes,but they're really aimed at full-on tuned engines. I've drilled out main jets before when tuning bike engines,and also fitted dynojet kits,and they do work well. Dunno how they work out against weber parts costs,but a dynojete kit costs from £80 upwards. Just a thought.
|
|
1994 Ford Scorpio Lowrider um...and some bikes...
|
|
B-8-D
Posted a lot
down to one car!!
Posts: 4,038
|
|
|
bike carbs can be "tuned" quite easily like said.. dynojet for the needles.. jets are about a quid each and there is a massive range.. different spring rates and drilling the slides is all methods used.. your best bet is to upjet the mains a bit and lift the needles a few stages just to get it running (trial and error..) then take the car along to a rolling road, also take a bike tuner (someone who has experience on setting up bikes on the dyno) and let them play.. some car dyno's have experience with bike carb setups, but most are still learning and so a bike tuner would have more of an idea and so would save a bit of dyno time.. si
|
|
|
|
|
|
|
Speak to Allens performance in Nottingham For all things Bike carb related there really is no substitute for rolling roading it, but a lamda sensor in the exhaust is another way of getting it pretty close Bike carbs are not that difficult to set up, certainly easier than webers make sure you balance them properly though I still Fancy a Bank of Keihin FCR`s..... fantastic Flatslide Carbs and about as sophisticated as fuel metering gets before you go injection, a doddle to set up as well and tuneable throughout the rev range as well The fact they sound fantastic at Idle and howl like nothing else is a nice bonus
|
|
|
|
|
|
|
I still Fancy a Bank of Keihin FCR`s..... fantastic Flatslide Carbs and about as sophisticated as fuel metering gets before you go injection, a doddle to set up as well and tuneable throughout the rev range as well The fact they sound fantastic at Idle and howl like nothing else is a nice bonus I'm weighing up the FCR option for my A14 Race engine,.. the cost of that + (simple) manifold vs. cost of Webers + Tomei Manifold + shipping... I notice some people also using MSR bike carbs,.. what are they from??
|
|
|
|
|
|
|
I still Fancy a Bank of Keihin FCR`s..... fantastic Flatslide Carbs and about as sophisticated as fuel metering gets before you go injection, a doddle to set up as well and tuneable throughout the rev range as well The fact they sound fantastic at Idle and howl like nothing else is a nice bonus I'm weighing up the FCR option for my A14 Race engine,.. the cost of that + (simple) manifold vs. cost of Webers + Tomei Manifold + shipping... I notice some people also using MSR bike carbs,.. what are they from?? Never heard of MSR Carbs ? Mikuni do Flatslides as well , but FCR`s are just superb If you are buying new then you need to speak to www.sudco.com as the £/$ rate at the moment makes it stupid to go elsewhere, make sure you have the port spacings to tell them and the base engine spec, as they will be able to supply them with pretty accurate Jet and needle settings...... Still reckon an ECU and those R6 TB`s will work out a better and cheaper option though ;o) Carbs are not a cheap option anymore
|
|
|
|
|
|
|
Never heard of MSR Carbs ? Mikuni do Flatslides as well , but FCR`s are just superb If you are buying new then you need to speak to www.sudco.com as the £/$ rate at the moment makes it stupid to go elsewhere, make sure you have the port spacings to tell them and the base engine spec, as they will be able to supply them with pretty accurate Jet and needle settings...... Still reckon an ECU and those R6 TB`s will work out a better and cheaper option though ;o) Carbs are not a cheap option anymore I've seen Mikuni's on A15 engines before so thats an option.. the MSRs are apparently "Matsuoka MSR" carbs ... that shed any light on them?? ECU is definatly tempting still,.. but there is no way I'm going Megasquirt,.. and Emerald, DTA etc. are beyond my means at the moment.
|
|
|
|
|
|
|
|
I'm going to have to read what it says on the side of my carbs, they're from a manufacturer I've not heard of. oooo, it's like a voyage of discovery They're off a late 80s Honda CBR1000 FH
|
|
|
|
|
|
|
They look like Keihin CV carbs, but Mikunis look very similar Either way Allens will be able to sell you jets and needles to get you somewhere near HW: Never heard of MSR ? Stick with stuff you can get parts for Set of FCR 41s will be upwards of £300 s/h Manifold £150 Maybe some new jets/needles/gaskets etc £30 - 50 You already have the Throttle bodies..... Manifold £150 ECU..... £350 - 400 maybe.... not a lot in it and thats before you start adding in the recurved distributor you`ll need with the carbs Fuel pumps needed for both, but EFI one is now easier to find scrap yard wise than a Facet (£50 off the bay) Your call but I personally would (and did) spring for the ECU as whatever you do to the engine later, you are only button presses away from a fuelling and spark solution, with conventional carbs and dizzy you are spending more money again I have a good contact who can supply most ECU setups and will pass on the Trade savings to me if that helps you ;o) Cheers Dom
|
|
|
|
philly
Part of things
Posts: 159
|
|
|
just wondering
ive heard that munki YZF-R1 carbs are not as adjustable as some of the other bike carbs out there. is that true? anyone else heard that?
just that i came accros a set the other day- very cheap so could not refuse!
|
|
spaceframe mini project, bmw 635csi, mx5
|
|
|
|
|
I have a set of Mikuni 40s... attached to the bike engine! Apparantly they sound great although I've never heard the engine running
|
|
1997 TVR Chimaera 2009 Westfield Megabusa
|
|
|
|
|
Top marks!!!!! They are indeed Kaihins. It ses VG on the side dunno what that means though
|
|
|
|
|
|
|
Mmm - this is all very interesting stuff, I have been looking at ways to pep-up the performance on the Derby, as a kind of way to learn about engines. I ran a 19.2 sec quarter last year in it & it would be a personal achievement to knock at least a second off that time. I was going to fit a twin choke DGAV carb that I have, but I like the idea of fitting bike carbs - Since Autohausdolby is fitting his carbs to a very similar engine I am following your progress with great interest R6TBs sound interesting aswell
|
|
|
|
|
|
|
What engine has the Derby got? Is it one of the old "outside bolt" 1.3s where the back row of head bolts is outside the rocker?
That 19.2 is a respectable time for a stock Pizzle - I got a best of 20.1 out of mine at Big Bang but it's only a 1.0 litre and that was before we put it on open headers ;D
|
|
|
|
|
|
|
What engine has the Derby got? Is it one of the old "outside bolt" 1.3s where the back row of head bolts is outside the rocker? That 19.2 is a respectable time for a stock Pizzle - I got a best of 20.1 out of mine at Big Bang but it's only a 1.0 litre and that was before we put it on open headers ;D Its the 60hp 1272cc HH engine - looks like this.... Goes very well TBH - but would be nice to get it going even better The main thing it could really do with though is a 5 speed box
|
|
|
|
|
|
|
I know the feeling well - there seems to be a bizarre shortage at the moment. 80 mph in 4th on open headers is loud
|
|
|
|
|
|
|
I know the feeling well - there seems to be a bizarre shortage at the moment. 80 mph in 4th on open headers is loud Geez - I can imagine BTW is running your car on open headers wise - surely you have removed the important back pressure that a tuned length exhaust would provide?
|
|
|
|
|