FAO: Those who have disconnected the choke

[dandragarth]

When i decided to go for the blanking off of the choke route simply because i thought the bike could do better on fuel.I ordered from Lings a pair of the caliper blanks.they arrived very quickly so off came the tank.Choke cables disconected,plungers free new spings blanks ready to blank.No good to small for the threaded hole in the carbs.So answer was take off the black plastic nut on the end of the choke cable and screw it in. But then silicone seal the hole.Result was it works perfect.My bike is the RD04.She starts up no problem and runs allot better.

[chronyx]

Mmmmmm, float heights - if they are low (which I doubt as it normaly takes something drastic to alter them such as a strip down of the carbs) it would explain why it needs to crank lots to start as the carbs need to fill up before the fuel starts getting drawn in, but it could also point to the non-return valve in the fuel line after the pump - if that's shot and letting the fuel drain back down then you have the same problem - but TBH with the amount of fuel a 'good' stock pump or an aftermarket type delivers its a matter of seconds to lift enough fuel to fill the carbs back up and not the lots of seconds we're on about. Its where I'd start though - check the valve is still a one-way-street and check the delivery rate from the pump - nothing to scientific, just make sure its giving a good surge of fuel at cranking. Then you'll know you've got carbs that are full within seconds of starting to crank and you (we) can go from there.....

Great info mate thanks.

Do you know if the coils earth themselves through the chassis via their mounting plates?

I ask as I had a possible brainwave - the chassis has been powder coated, the main earth point is clean but I just bolted the coils right back into place when I re-built it. I presume this could make the spark weak?

[stageonesimmo]

Oh dunno about that but it wouldn't hurt to pull a couple of plugs out and check that to be sure as weak spark certainly wont be helping with starting. Can't say for certain where the coils earth but if it is through the body then if the mounts aren't good clean metal then you'd be right to suspect that as a source of the problem........

[chronyx]

Cheers for confirming my suspicions!

[Mutley]

Repainting the frame can easily mess up the coils if not earthed properly.

A mate of mine recently bought a Husaberg cheap as it wouldn't run to find it had been powdercoated; a few minutes later, it was running fine!!

[chronyx]

Marry me nice one thank you, well that's one to add to the top of the list of things to eliminate!

[stageonesimmo]

Yip, right at the top.

Strange though, it was running fine for a while after it was powder-coated though right? Must just have been earthing down the bolt threads which have now got wet and corroded slightly if so..........

[chronyx]

Nope been dodgy since then, I just haven't used it much so assumed it was that, or something fuelling related! It was only something that was said at college (Sparky course) that made me think of earthing on the bike

[scarfacehugo]

Hello Tim!
Sorry just to have noticed this post now.

Here's my humble opinion:

A fine tuned engine should never start cold with the choke off. If the choke valves are there its for a reason.

At cold temperatures, the normal amount of petrol inside the carb doesnt vaporize , so we open the choke so that more petrol for the same volume of air is allowed into the engine.

If you simply rotate the grip you are not enriching the mixture to start it.

In all the engines and carbs I've tuned, I use as a starting point the "choke test". If it starts with the choke off, it's too rich, if it needs the choke on for too long, it's too lean.

I'm not sure how or why, but my guess is your carbs were using more petrol than the engine needed before I cleaned them. Maybe pilot screw, maybe something else. These symptoms you find in your bike are the exact same ones i find in mine. My bike would never start with choke off and it is now perfectly tuned.

Hope this helps, if you need anything else from me, please let me know.

[chronyx]

Alright mate, yeah I did wonder if it was too rich before, but it always ran to over 200 miles on a tank which I was happy with and seems to be pretty good from what I've read here. The main jets are all standard, the dyno operator said it was running rich on main but I don't mind that. Rather rich than lean eh!

I normally rotate the throttle just so the starter isn't fighting against total engine compression, it really is barely open

Another question though! (Sorry)

Is there any part of the carbs that can drain itself of petrol over night?

What I mean is, once I turn off the ignition, should the fuel normally stay where it is?

I wondered if fuel is draining further back into the system and taking time to get pumped through again the next time I ride.

Never noticed any petrol odour around the bike apart from right underneath up close and personal


Also I have noticed it's 'coughing' a lot when I blip the throttle to change down a gear from being on the over-run/engine braking. I can hear it through the airbox. Never backfires though!

However throttle response is instant and the idle is smooth once it's warmed up. Totally happy as far as that's concerned!


Thanks for all your replies by the way. Once I get this sorted I'll be so chuffed, I can get the fairing and brand new crash bars back on (Been riding it since the summer 'naked'!)