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Africa Twin RD04 - L
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Discussion Starter · #1 ·
Hello everyone,

I'm new on this forum though I already spent a fair amount of time reading topics on this forum. But I can't find an answer to this problem.

I own this africa twin RD04-L for now a couple of month it has an arrow exhaust and K&N filter. It has always been difficult to start it after it sat for more than 2/3 days. I'd have to wind it for 30 seconds until it slowly start, like the plugs has been fouled, bit of sputter and backfire. The idling is quite low like 900 rpm and it takes like 20min before the idling is getting up to normal (when the engine is hot basically). Also the idling is slightly holding at 1500 rev. Though it's running well when accelerating so nothing really bad but that doesn't satisfy me to have it like this.

I took the carbs off a couple of times already :
  • changed the choke cable but didn't help so I literally cut it next to the carbs to see if that was stuck somewhere but no luck
  • I did the carb sync
  • I checked any vacuum leak with a propane bottle nothing

Am I missing something? Could it be the spark plugs that needs to be renewed? Or is the spring for the choke cable is too weak to close properly?

I'm opened to your suggestion, I don't want to take it appart again without finding the problem.

Thanks a lot,
Tom
 

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Africa Twin RD04 - L
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Discussion Starter · #3 ·
So if the bike only sits for one day it is easy to start?
as weird as it sounds yes! Will start without choke. I’ll have to rev it a bit and that’s that. I forgot to mention it pops every now and then quite heavily.

Thanks
Tom
 

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Hmmm, something isn't right!

A few things to consider:
  1. if you are getting popping, your mixture might be off. Reset the air screws. Follow the manual's steps to figure out the right setting after the reset. Because you have an aftermarket exhaust and air filter, it is possible that you will need to change your idle and main jets.
  2. Starting easily without choke tells me that your mixture is off. If you are sure your choke cable is operating properly, then I would again try to play with your air screw.
  3. Hard starting after sitting for a few days could be fuel evaporation. The fuel pump has to get fuel into the carbs when you are pressing the starter button after the fuel has evaporated over a few days. That's why it takes so much time. Ensure that your fuel pump and relay are ok. Then, take a look at the fuel hoses between the carbs and fuel pump. Might be time to replace them.
  4. I don't suspect the spark plugs, but it cant hurt to swap them out for fresh ones.
  5. I think a vacuum leak is still a possibility. Double check to be sure.
Does the bike diesel at all? (take a long time to return to idle after being at speed)
 

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If the bike starts well after a few hours or day, but not after 3 days, you have the usual problem that was solved later with the RD07a. Basically, your carburator bowls are emptying thru evaporation and you need to crank a bit for the fuel pump to fill up the carbs. You will need to modify the carburators' vent hoses. They shall be longer and exit lower. This seems to keep fuel from evaporating. You'll need some silicone hoses and a few Ts...
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Africa Twin RD04 - L
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Discussion Starter · #6 ·
Hmmm, something isn't right!

A few things to consider:
  1. if you are getting popping, your mixture might be off. Reset the air screws. Follow the manual's steps to figure out the right setting after the reset. Because you have an aftermarket exhaust and air filter, it is possible that you will need to change your idle and main jets.
  2. Starting easily without choke tells me that your mixture is off. If you are sure your choke cable is operating properly, then I would again try to play with your air screw.
  3. Hard starting after sitting for a few days could be fuel evaporation. The fuel pump has to get fuel into the carbs when you are pressing the starter button after the fuel has evaporated over a few days. That's why it takes so much time. Ensure that your fuel pump and relay are ok. Then, take a look at the fuel hoses between the carbs and fuel pump. Might be time to replace them.
  4. I don't suspect the spark plugs, but it cant hurt to swap them out for fresh ones.
  5. I think a vacuum leak is still a possibility. Double check to be sure.
Does the bike diesel at all? (take a long time to return to idle after being at speed)
Nice! Thanks for your input, I am mechanically inclined but quite green with those fairly high tech carbs.

I don't have the workshop manual, it might be time to get one! On the top of my head, the mixing screw is 4.5 turns out.

Fuel evaporation could be a thing, I might just start to think about changing the hose system

I know that the rubber from the airbox to the air filter is cracked and fixed with some tape, I might wait beforeI invest £80 into a new one on rugged road. Though I didn't hear any change of the idling when passing the propane nearby this area.

It does diesel a bit from 1500 to idling. Not before, maybe I shall re-do my carb sync. I find it really tedious to be done on this bike as the screw is really hard to access.
 

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Discussion Starter · #7 ·
If the bike starts well after a few hours or day, but not after 3 days, you have the usual problem that was solved later with the RD07a. Basically, your carburator bowls are emptying thru evaporation and you need to crank a bit for the fuel pump to fill up the carbs. You will need to modify the carburators' vent hoses. They shall be longer and exit lower. This seems to keep fuel from evaporating. You'll need some silicone hoses and a few Ts... View attachment 166744
That's exactly it! I have to try to start for about 30 sec until it picks up.

You almost need a priming system. I'll wait a bit before I do this mod but thanks for the drawing
 

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The priming system I use on my '03 Transalp is to pull the vacuum tap hose off the rear carby mount and suck on it then block it with my tongue and count to 30.
Really.
 

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Agree with Lee on this issue. I have an RD03 and it does exactly the same, my solution is to bypass the fuel pump relay by bridging the connector under the clocks with a small bit of wire. This will then run the fuel pump when you switch on the ignition ( don’t hit stater button) you can then hear the fuel pump working and filling the carbs. Give it a few seconds and when it stops making a clicking sound hit the starter and bet it fires right up with the carbs full. With the relay not bypassed the fuel pump only works with the engine running hence it takes a lot of turning over before it fills the carbs again.
 
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