Sorry if posted already i have searched and can not find anything.
I am having real issues with my 998 hs4.
Yesterday I took the carb apart and cleaned it. Upon doing so I identified the piston cushion was over 1.6mm, so I reduced this to the recommended 12 thou.
I then tried ro base line the carb by winding the mixture in and then down 12 flats.
The car wont start at all now. It has had the odd run for a few seconds very lumpy then stalls out.
The plugs are dry but have gone very black.
Im at a loss as to what's happening. Do I need to re install a oversized cushion?
There is fuel in the float bowl and fuel in the jet when I lower the jet down.
I am getting spark at the plugs.
Setting Up A Carb For Baseline Running.
Started by
Earley86
, Oct 03 2026 08:59 PM
4 replies to this topic
#2
Ethel
-
- TMF Team
-
- 26,802 posts
..is NOT a girl!
- Local Club: none
Posted 04 October 2026 - 09:19 AM
Has the float lid got a vent pipe? Blowing (gently) down that should show if there's a restriction or blockage on the fuel side.
You haven't obstructed the communication port(s) to the piston chamber - filter elbow gasket?
Wouldn't hurt to crank it over with the plugs out to confirm they spark.
#3
Earley86
-
- Noobies
-
- 28 posts
Passed Test
- Location: Liverpool
Posted 04 October 2026 - 11:11 AM
So the saga continues, the needle is a ADL in a standard 998. So I assume it will never fire with the baseline settings.
I dont knkw if to try and continue but with a leaner mixture setting as the csr did run great previously.
Or get the correct needle.
The coil has failed now, assuming after all my cranking and failed starts.
I dont knkw if to try and continue but with a leaner mixture setting as the csr did run great previously.
Or get the correct needle.
The coil has failed now, assuming after all my cranking and failed starts.
#4
timmy850
-
- Members
-
- 3,608 posts
Up Into Fourth
- Location: NSW, Australia
- Local Club: MITG
Posted 04 October 2026 - 08:08 PM
The majority of needles have much the same profile at the idle end, and the adjustment in the jet means they should all start and idle fine
Is the choke and fast idle cam set up correctly?
Is the choke and fast idle cam set up correctly?
#5
68+86auto
-
- TMF+ Member
-
- 1,482 posts
One Carb Or Two?
- Location: Brisbane, Australia
Posted 04 October 2026 - 10:11 PM
So the saga continues, the needle is a ADL in a standard 998. So I assume it will never fire with the baseline settings.
I dont knkw if to try and continue but with a leaner mixture setting as the csr did run great previously.
Or get the correct needle.
The coil has failed now, assuming after all my cranking and failed starts.
If the coil has truly failed, it will be unrelated unless you had the coil lead disconnected at some stage while cranking.
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users
