Author Topic: Continental.GT 535 converting to Mikuni Carburetor  (Read 1440 times)

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JVS

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Reply #30 on: January 14, 2020, 10:06:42 am
Bess_GT

Once you confirm that the carb is a VM32 or equivalent, you need to contact Hitchcocks to see what jets they supply with their carb kit for the Conti 535. They will most likely tell you this even though you haven't purchased a kit from them. Contact them at info@hitchcocksmotorcycles.com

They reply promptly.

For the 500cc UCEs, they supply a VM32 and have jetting supplied for a freer-flowing configuration (exhaust + air filter) around sea-level. Their 500cc Mikuni kit comes with the following jets:

25 Pilot jet,
Q6 Needle Jet,
6DP17 needle,
185 Main jet,
Needle clip in 3rd position (middle),
Slide cut-away 3,
Float height 23-24mm.

You need to at least start around those jets if you're at sea-level. Secondly, you need to ensure that your idle air-screw mixture setting is correct. This is done after the bike is warm. If this is not set properly, your bike will run like crap, no matter if your other jetting is relatively correct.

You can have a look at the following videos on how to adjust the idle air screw or follow the instructions in the VM tuning manual as posted by ace.cafe, (section 5.3 on page 10 of the manual).

https://www.youtube.com/watch?v=67Nb3DI-B3s
https://www.youtube.com/watch?v=q5pFOBSkMX0

Or follow these steps as highlighted by ace.cafe in other posts:

Quote from: ace.cafe
The usual procedure is(before you start the engine) to turn the air-bleed screw in until it stops all the way in.
Don't jam it. Just turn it in until it stops.
Then turn it out 1.5 turns, as a basic starting point.
Then, start the engine,and set a somewhat fast idle with the big-headed idle speed screw.
From your basic starting point of the little air-bleed screw at 1.5 turns out, the entire range of turning available on that screw is only 1.5 turns in or out.
You can turn it in or out from your starting point of 1.5 turns out, untll you can find your highest idle speed that the air-bleed screw can give you.
When the bike is warmed-up.
Then after you find that spot, use the big-headed idle speed screw to lower the idle to a steady reliable idle speed.
That should do it.

The hiccup off idle was probably nearly eliminated by cleaning the pilot jet and pilot circuit orifices, and getting it fairly closely tuned in with the air-bleed.
The air bleed adjustment can make or break your idle and low-speed running with just 1/8-turn of the screw. It is pretty sensitive.
So, once you find the highest idle with the air bleed screw, you only want to fine-tune it very little in the direction that might help out your hiccup. And you don't know which direction until you try it. Although, my guess would be that turning it in very slightly would be the direction in your case, IF you need to do anything after you get it set properly at highest idle when warm.


Remember not to unscrew the air bleed screw more than 3 turns. If you're close to 3 turns out, you might need one smaller pilot jet size (e.g. 22.5).

This should get you very close.
« Last Edit: January 14, 2020, 10:18:33 am by JVS »
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