coozer
|
| posted on 21/6/11 at 11:04 AM |
|
|
Have you checked the slide operation? All move up and down correctly?
Stupid Q? but what state are the air pipes that come out betwix 2&3 and 3&4? Not blocked? free to air?
1972 V8 Jago
1980 Z750
|
|
|
|
|
David Jenkins
|
| posted on 21/6/11 at 12:59 PM |
|
|
One previous question you didn't answer (I think!) was - "Is the engine running properly at the moment, ignoring the smell of
petrol?"
The reason for asking is - if the engine's running well then the state of the jets may be irrelevant and the problem's elsewhere.
However, if it's running rough, using petrol like there's no tomorrow, or similar, then maybe fuelling is a problem.
You could try checking the colour of the plugs - get the engine nicely warmed up, give it a bit of welly here and there, then on a quiet road floor
the clutch and turn off the ignition. Once you've stopped whip out a plug or two (hot, hot, hot!) and check their colour. This is a crude and
unreliable test, but if the electrode is black and dripping with petrol you are undoubtedly over-fuelling. If they're a nice biscuit colour
then you're roughly in the right ball park.
A couple of dumb but basic questions
- are there any signs of fuel dripping from the carbs when the engine's stopped but the ignition's on? I'm thinking of stuck
and/or dirty float valves that aren't shutting properly when the chamber's full.
- is your passenger compartment fully sealed off from the engine compartment? You might be smelling normal engine fumes that you wouldn't if
everything was screened off.
(I'm working on the principle that it's worth trying the simple solutions before getting onto the tougher, more expensive solutions!
|
|
|
40inches
|
| posted on 21/6/11 at 01:20 PM |
|
|
Have the carbs been stripped before? Float level OK?
|
|
|
Craigorypeck
|
| posted on 21/6/11 at 06:18 PM |
|
|
Easily the best thing to do is get an afr hooked in... if your gonna home tune.
can get a complete second hand set up off ebay if you keep an eye, or new if you wanna spend 150-170 quid,
I went with the innovate lc-1, quite fiddly to wire up, the uego one looks simpler..
Anyhow- it takes all the guess work out of tuning carbs, idle is easily set then get the main jet right at wot redline and then work back ways through
the revs by adjusting needle height.
I too have ZX9R carbs, C1 jobs, on my 16v 2.0, I have 135 mains with ACs blocked, lift holes reduced 1mm, afr is spot on at all revs. I'm
running red top and filterking with no issues.
Make sure they are positioned at the right angle too... Also just noticed you have a bike pump? They are interrupter type (unlike most fuel pumps
which just whirr away all the time) which means they only tick when the carbs need fuel. So with the engine off and pump working it shouldn't be
ticking at all, if it is there is a leak somewhere.
[Edited on 21/6/11 by Craigorypeck]
|
|
|
scoop
|
| posted on 21/6/11 at 06:29 PM |
|
|
The car is running okay otherwise as far as i know. The sierra pedal box ive fitted has left a way for the engine fumes to get into my footwell.
The carbs are only two years old from Bogg Bros and went back to them in march this year for a clean up. Ive only done 350 miles! Everything moves
smoothly and the needles are on the lowest setting barr one. They will insist on setting them with the mixture screw turned out 2 1/2 which is far too
rich.
I think its got to be the jet size from all the information everyone has gratefully passed on.
Rather than guessing what i need ive come to the conclusion that i'll leave it all to the proffesionals and book it into Frosties next week
weather permitting.
|
|
|
scoop
|
| posted on 21/6/11 at 06:34 PM |
|
|
Craigorypeck, what do you mean when you say lift holes redused by 1mm?
I changed the plugs yesterday and the ones i took out were more blacker than brown. I will go out and check the new ones now though.
|
|
|
David Jenkins
|
| posted on 21/6/11 at 06:48 PM |
|
|
quote:
Originally posted by scoop
Rather than guessing what i need ive come to the conclusion that i'll leave it all to the proffesionals and book it into Frosties next week
weather permitting.
If you're seeing blackish plugs then you are probably overfuelling. I think you're right - a trip to a rolling road is your answer.
Who is/are "Frosties"?
|
|
|
scoop
|
| posted on 21/6/11 at 08:25 PM |
|
|
Frost Motors in Ipswich. He used to work at Scole Engineering im told. Hes got the only rolling road and the skills in Suffolk to do it im told. Have
a look at www.fmsauto.co.uk
I forget who mentioned that the midrange was basically controlled by the level of the floats and mine did seem hesitant about 3 to 4k so i raised them
a notch and have just been out again. It is improved
The plugs still dark brown/black.
Thanks everyone for your help.
|
|
|
norfolkluego
|
| posted on 21/6/11 at 09:45 PM |
|
|
quote:
Originally posted by scoop
Okay. Now we're getting somewhere. I understand that webber jets fit these carbs. Which ones do i get, DCOE?
[Edited on 21/6/11 by scoop]
Buy proper bike jets if you need them, way cheaper than Weber, they'll be available from any motorbike shop.
|
|
|
scoop
|
| posted on 22/6/11 at 05:46 AM |
|
|
Cheers for that. The webbers are only a couple of quid each so i look forward to the lowercost items
|
|
|
Craigorypeck
|
| posted on 22/6/11 at 06:52 AM |
|
|
quote:
Originally posted by scoop
Craigorypeck, what do you mean when you say lift holes redused by 1mm?
It reduces the speed at which the slides lift, i had overfueling at lower revs when throttle was applied. this helped a bit. TBH I'd need custom
needles made but doubt that will happen anytime soon.
Check out post 17 in this link, it has good info,
http://www.turbosport.co.uk/showthread.php?103402-X-flow-on-Yamaha-R1-carbs
[Edited on 22/6/11 by Craigorypeck]
|
|
|
mcerd1
|
| posted on 23/6/11 at 07:34 AM |
|
|
scoop's pics
 
Description
 
Description
 
Description
-
|
|
|
scoop
|
| posted on 25/6/11 at 10:03 AM |
|
|
Just rung Bogg Bros and they tell me the jets are drilled to 1.65mm not 1.8 so seems strange that my carbs are overfuelling?
|
|
|
Bowers919
|
 posted on 13/7/11 at 11:38 PM |
|
|
bike carbs on 1600 x-flow
I have 1600 xflow engine running bike carbs, fitted them and ran them with facet fuel pump and regulater, but it would not rev straigh out.. it
stuttered at 4,700rpm when you put the pedal to the floor, so i took the regulater out and still had the same problem :-s
ive tryed putting a small storage tank just before the carbs to see if its the lack of fuel at high revs but it only made a slight change, it would
stutter at 5,500 rpm then harsh accelerating.
the only time it revs out straight is if u accelerate steady but thats no fun :-(
any idears?? :-/ :'( thanks
|
|
|
britishtrident
|
| posted on 14/7/11 at 06:36 AM |
|
|
"Smell of petrol" isn't so much a clue as a flashing illuminated sign ----- the float bowls are flooding.
Getting the jets a bit wrong won't cause a smell of petrol in the engine bay.
|
|
|
David Jenkins
|
| posted on 14/7/11 at 06:52 AM |
|
|
I had a very similar effect when I first fitted bike carbs - accelerating quite well but losing power massively at anything over 4k. When I finally
got an air-fuel ratio (AFR) meter onto it I found that the mixture was far, far too rich at wide open throttle (WOT). After reducing the jet size
from 1.6mm to 1.3mm the AFR was near-enough perfect when accelerating hard (slightly rich).
But it would be wise to get your car onto a rolling road, rather than just try this out, as your problem may not be the same! At least get an AFR
meter and a mate to watch the readings as you go down the road.
quote:
Originally posted by Bowers919
I have 1600 xflow engine running bike carbs, fitted them and ran them with facet fuel pump and regulater, but it would not rev straigh out.. it
stuttered at 4,700rpm when you put the pedal to the floor, so i took the regulater out and still had the same problem :-s
ive tryed putting a small storage tank just before the carbs to see if its the lack of fuel at high revs but it only made a slight change, it would
stutter at 5,500 rpm then harsh accelerating.
the only time it revs out straight is if u accelerate steady but thats no fun :-(
any idears?? :-/ :'( thanks
|
|
|
