Installed Clarke 3.9, Bike won't go

I finished putting my new 3.9 on today. After I got every thing buttoned up the bike will fire but will not stay running.

As soon as it fires and kicks out the starter gear, it stalls.

Yes, the vaccuum line is hooked up and has vaccuum.

After much fiddling I was able to get the choke all the way out.


The bike is a new 06 400S (had it for about 2 weeks)so there shouldn't be any other issues.

I put a fuel filter between the petcock and carb for added insurance.

If by any chance a piece of dirt got into the carb where would it likely lodge first?


Did you wash out the tank first? All plastic tanks are very dirty inside from the maunufacturer. There is a fuel filter screen on the petcock so IMHO the additional fuel filter is not necessary. Sounds like it is starving for fuel...check all that...flush the tank and look at the petcock filter. Good luck :thumbsup:

Just as Ross said, plus make sure there is no air lock in the new fuel filter.

Neil. :thumbsup::thumbsup::confused:

There's lots of fuel getting thru.

I blew the tank out with air thoroughly and then swished it out with gas for good measure.

I unhooked the line at the carb and turned the petcock to 'prime' - fuel gushed out.

I suspect there might have been a piece of dirt in the hose after the filter - I forgot to make sure it was clean before installing it.

Could the pilot circuit be clogged?

Or what would the most likely carb issue be?


Leave the petcock on prime and see if it will run ...

Here's what happened-

I decided to take the carb off the bike and give it a thorough cleaning(even though it's new).

Getting the carb off and on is a lot(I mean A WHOLE LOT) easier if you remove the muffler/midpipe then remove the top bolt for the rear subframe, the bolt holding the overflow tank to the airbox and the bolt for the rear brake reservoir. You can then tilt the subframe back about 1-2" which gives you a lot more room to work.

Disassembled carb, thoroughly cleaned it with carb cleaner and air but I didn't find any evidence of dirt anywhere.

While I had it apart I replaced the factory pilot screw with a Keintech one that I got from TT. I set the screw to the factory setting of 3 turns out.

Reassembled carb and put it back on the bike. Reassembled the bike and put some fresh gas in it.

Opened petcock to 'prime', waited a few seconds and hit the starter button.

The bike still wouldn't fire. :thumbsup:

So I grumbled for a few seconds and thought 'let's see what happens if I turn that screw out a bit more'.

I turned it 1/2 a turn and tried again. It started right up! :thumbsup::confused:

Now I have my bike back!!


I've read that if you go more than 3 turns out that you might want to put silicone or something on the screw to hold it in place. Otherwise it might vibrate out.

You should check that out just to make sure.


I have also read that if your more than 3 turns out you need to go one size up on your pilot.

I have a DJ kit coming for the bike. It should be here in the next few days.

Should be able to take care of the factory jetting issues then.

The Keintech screw fits pretty snug so it seems OK so far. I'll probablly silicone it when I install the DJ kit.


I have a DJ kit coming for the bike. It should be here in the next few days.

Should be able to take care of the factory jetting issues then.

The Keintech screw fits pretty snug so it seems OK so far. I'll probablly silicone it when I install the DJ kit.


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