kurt t
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| posted on 1/2/07 at 10:48 AM |
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R1 carbs 1600cc honda
Hi, I am running a set of 99 r1 carbs on my 1600 cc twin cam honda engine with pipe across air filter . I have built a custom manifold and have been
running this set up for about 3 months.
I started out with the stock r1 carbs and they ran way lean so i took the factory 1.3mm main jet and drilled it out to 2 mm in a lathe .The engine
pulls very strong up top now and over all I am happy but i think Ican do a lot better on my midrange and over all mixture .
I am from Australia and the carbs havn't been setup by Bogg Brothers all I have done is drill the main jets. I started to read some post were
people are using main jets aroud the 1.65mm mark so i drilled another set to that size but now the car feels very flat.Is there an air jet that needs
to be blocked ?
Any tips on what the bogg brothers do to the r1 carbs would be great as I am on my own with this project in Australia.
Oh and another question . Has anyone had any problems with there r1 carbs sticking a little . As in the throttle dosn't want to return to idle
all ways and some times sticks at around 1500rpm. A quick blip of the throttle fixes it and I am sure its not the cable sticking .
 
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Peteff
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| posted on 1/2/07 at 11:19 AM |
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Bike carbs are operated by a twin cable system so you might need to put a good return spring on where the second one came from.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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bricheun
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| posted on 2/2/07 at 02:41 AM |
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You got a similar setup as me..though mine is a 1600 SOHC Honda engine running ZX6R carbs.
My carbs are tuned by boggs too, blocked main air jet and used 165 mains. Though I am running a 272 duration cam in mine.
Sticking throttle is also happening to mine too, I might try a stronger spring but I think a hanging "idle" is either an air leak or idle
mixture too lean. Try turning the pilot screw out.
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kurt t
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| posted on 2/2/07 at 05:36 AM |
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Bricheun , The main air jet from what I know is on the front of each carby looking down into the carb. There seems to be about 3 holes there what one
is the man air jet . Do you have a pic or could you explain which one it is?
Thanks, kurt
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bricheun
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| posted on 2/2/07 at 04:31 PM |
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Steve bogg said the main air jet is the one in the middle directly inline with the main needle.
Do you get a gurgling/stumbling from 1500 to 3000 at 50% to 100% throttle?
Does it pull low down?
Mine only takes off at 3000rpm and nothing below 3000rpm...strange.
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kurt t
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 posted on 2/2/07 at 10:51 PM |
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With the 2mm main jet and needle clip on the lowest setting the car was strong but I allso needed a little more rpm befor smash down on the gas
peddle. I think this is because there is no little fuel booster plunger that gives a shot of fuel when you hit the gas like in most car carbys. I
think some of the later bike carbs imparticular dirt bike carbys started to use one this.
I am not sure what hp mine is putting down but I was able to run a 14 second 1/4 mile at 98mph. With the EFI same engine and car was about a
15.6.That said my car is only 750kg.
I am running factory zc cams and it pulls ok down low streatable below 3000rpm but nothing to write home about. I think that with our little 1600cc
engines all though they breath well up top they struggle a little to pull enough velocity through the carbs at low rpm. 40mm carbs are good for the
track and drag strip for all out hp but I am starting to thing somthing a little smaller would be better for a street car.
As for my throttle sticking I think some of it has to do with the design of the carbs they have the throttle cable linkage up one end of the 1st carb
with a big mouse trap spring and on the 4rth carb there is a tiny spring with very little pressure to close the butterfly.So when the first carby
closes and the spring forces the other 3 carbs closed there is a tiny bit of slack between each carby and the last carby dosn't have nice
positive spirng pressure to close it. A lot of the other bike carbys tend to have the throttle linkage in the middle of all the 4 carbys. I think
this is a more even way to go about it to insure all 4 carbs get the same return spring pressure.
That said they seem to work well on the r1 bikes.
A lot of people tell me to fit a retun spring on the likage to creat a push pull setup like on the bikes. But this wont help as even pulling back on
the carb linkage with my hand won't bring the idle down when it sticks. The only way to do it is to ether snap open the throttle and let it
return fast of put some pressure on the linkage for the 4rth carby .
All that said wont be rushing out to buying a set of 32 mm honda cbr carbs, as this is only a toy car and I love the top end the r1 carbs give and
couldn't be botherd tig welding a new 32mm stainless steel manifold.
keep me posted on how you get on with your setup.
Kurt.
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bricheun
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| posted on 3/2/07 at 03:53 PM |
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Hi man..nice to hear about your experiences with the honda + carbs. I have finally sorted most of the problems out.
1) 1000-3000 no power = unbalanced float levels + blocked main air jet + improper settling of the needles + unbalanced carbs. (alot of faults)
Fixed it by making sure every float was at a 17mm height, double checking each time. Drilled out the plugged main air jet (leaned it out to be more
favourable and it also helps vapourizing the fuel). Don't need to do this unless really required (for our type of engines anyway)
Balanced the carbs my using a 1.5mm drill bit so that everyone of the throttle plates opened at the same time.
The slides - hmm..maybe when I removed them to check out the needles the first time I put the needle holder plastic in wrong. There are grooves on it
which allows it to press against the needle when properly fitted, otherwise the needle holder will be about 5mm too high allowing the needle to move
about quite alot.
Missing O-ring in the pilot jet, don't know how it got lost but I managed to find a small one in a spare rebuild it for another carb.
Tuned the idle mixture on each carb so on snap throttle it does not die (too lean) and not too much so that it hangs alittle (too rich). But it does
change after a hard run, maybe because of the engine bay temperature. The higher the temp, the richer the mixture and worse the idle.
The AFR is around 12-13 idling (varies so much), light cruise is around 12.5-13.2 (2500-3000). On larger throttle 50%-100% 3000-7000 goes from 9.8 to
11.8 (much to rich). Though there is power it seems like the symptoms on too rich, it does not feel as lively as could be.
So the next step for me is to in 1 step smaller jets 155 or use some spare 145, but I am afraid it might be too lean higher up with the 145.
Oh, the ignition is advanced quite alot more without picking and gaining some responsiveness. This could well be the richer mixture throughout the
rpm.
Note, my carbs did not come with any air funnels or airbox, using some cheapo brillo pad wrapped in fine mesh stainless steel net at the moment to
stop bits falling in. Should be coming next week the new ones and hopefully the funnels will improve the performance more.
My carbs are 4 X 36/37mm Kawasaki ZX6R carbs and seems plently big enough. I can pull in 5th gear around 2500rpm full throttle no problem, though my
camshaft does not start to perform until around 3000rpm to about 7200rpm. The biggest diffference between the standard 2X34 carbs and 4X36/37 is from
3000--->7500rpm where it pulls alot more and more effortlessly...
Now to get some tuning done and experiment with some jets/ drilling the slides etc... keep me informed how you got on.
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