| [ Total Views: 770 | Total Replies: 13 | Thread Id: 105240 ] |
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 baja_01
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 posted on February 27th, 2014 at 06:32 PM |
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44mm jetting?
Hi All
Need some advise on my motor, 78x69(2007cc), 044 heads, w120 cam, 9.1 CR and 44mm HPMX carbs.
Motor starts fine but pops and backfires thru the carbs. Jetting is:150 mains,F11 emulsion, 200 airs, 50 Idles and 36mm vents.Any suggestions on where
to start greatly appreciated.
BTW freshly built motor with all new parts. Can't even run in cam because of all the popping and carryon...........
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Craig Torrens
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| posted on February 27th, 2014 at 06:58 PM |
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PM sent re jetting 
Oh and I think you mean 78x90.5, not 78x69 !
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baja_01
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| posted on February 27th, 2014 at 07:38 PM |
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Bugger stuffed that up ................PM received
thanks........
Frustrating after nearly 12mths building this........Maybe do the EFI caper soon..
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BiX
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| posted on February 27th, 2014 at 08:24 PM |
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Are you sure the leads are on correctly and the timing is right? I think this would be more of an issue than jetting.
I have no sympathy for my car, only the wallet that pays for it!
Go hard or go home!!!!
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vwo60
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| posted on February 28th, 2014 at 02:21 PM |
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50 idles are a bit small try putting a set of 55's, check that you have no vacuum leaks also, here is a good site, takes the guess work out of it
when you start off, gets you close but still will need a bit of adjustment.
http://www.aircooled.net/vw-carburetors-jetting-102/
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baja_01
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| posted on March 4th, 2014 at 05:57 PM |
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Okay......found my set of 60 idle jets(some 55's coming). Runs without popping thru carbs just need to fix a couple of oil leaks now
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baja_01
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| posted on April 23rd, 2014 at 05:00 PM |
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Hi All
Got my jetting set up as suggested by CT. Idles great seems to free rev smooth but when driving you go to accelerate and it coughs splutters then
clears. Seems to help if you give it a big bootfull.Idle jetting still a bit off maybe?
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 Bizarre
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| posted on April 23rd, 2014 at 05:31 PM |
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are you sure the carbs are synched (perfectly)
They are opening equally
Bogging like that on acceleration I found to be more one carb opening earlier than the other
Futue te ipsum!!!
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baja_01
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| posted on April 23rd, 2014 at 05:56 PM |
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I set them up with the sync tool. I'll check it again as the idle is a little high too.
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Bizarre
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| posted on April 23rd, 2014 at 06:02 PM |
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Just make sure they open equally
They can be sync'd at rest but as you go to open, one may move before the other
If you have the hex bar - they can do this by having slop in the drop arms or the cams
Watch as you apply the slightest pressure on the cable connection
Futue te ipsum!!!
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baja_01
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| posted on April 23rd, 2014 at 06:28 PM |
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No hex bar, I'm using a centrepull setup......
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vwo60
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| posted on April 23rd, 2014 at 06:56 PM |
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What size chokes are you running and what is the cam. 36mm chokes might be to large, what are you looking for with the engine, were do you want to
make the power and how do you drive.
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fish26
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| posted on April 24th, 2014 at 10:37 PM |
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IMO 36mm venturi is too big, but if you choose to use them my set up would be 55 idle, 155 main, 180 air
Few things:
044 heads, std valves? ported? chamber work?
Intake manifolds? match ported to head and carb? gaskets?
Any intake or exhaust leaks?
44 HPMX, cleaned and set up or out of the box? fully synced?
bitten by the bug..........several times
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baja_01
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| posted on April 28th, 2014 at 05:55 PM |
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Thanks for the replies
Motor was built to have a little more oomph than standard, not drag racing. Heads and manifolds just smoothed a little , nothing flash. 40mm 35mm
valves if I remember correctly. I do have a set of 32mm vents that I can try?
When I get time I'll double check the float level and set them up from scratch...........
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