rough idle?

[DeusEx]

Hello everyone,
I recently removed the db-killers from my Leo's and noticed that it idles very rough when its warmed up.
I already tried to raise the idle to 1400 rpms but it didn't make a difference. It still sounds like a 2-cylinder.
When its cold and when I put the db-killers in, it idles smoothly...
I read a lot about backpressure and stuff but I like the way it currently sounds and I just want my smooth idle back...

 

[Motogiro]

Have you disconnected your battery so that the computer does a reset? Disconnect the negative lead for 1/2 hour. Reconnect and run the bike for a few cycles where the engine warms and cools. See if this helps. The ECU on the bike has volatile memory that can relearn it's sensors if there is a small change. Larger changes will have to be managed by an additional fuel management system. Does your bike have the OEM catalytic converter? Has it been removed?

There are many things that can add to rough engine idle when exhaust has been changed. Make sure you have good plugs and you may need the throttle bodies synchronized.

A question I have is because you said it feels like it's running on 2 cylinders is, is it actually running on 2 cylinders when you pull the inserts?

 

[degake]

Do a throttle body synchronisation.
It will definately help with the rough idle :thumbup:
Add a Power Commander and it will help even more

Grtz,


Degake

 

[TownsendsFJR1300]

I noticed after having my battery disconnected for several hours (doing some farkle re-wiring/routing) last week, that the engine loped some during a semi cold start up... NO other changes. It eventually, after several starts, stops/rides, ran as normal with a smooth idle (open Scorps with the CAT)..

I guess as Cliff stated, the ECU had to relearn the FI, timing etc...

Do a couple of days riding and see what happens.

BTW, I keep my idle at 1000 RPM's, its rock steady and there's not much back pressure. Its good now...

A throttle sync would never hurt either.. About a month ago I did do a throttle sync and got them within 2 mm's of each other.. Factory spec's allow 10 mm's between the cylinders...

 

[DeusEx]

@Motogiro, the bike has the catalytic converter still on. I've tried it in the past without it, but there was no difference, idle is still rough. Plugs are as good as new.

@TownsendsFJR1300, I have also replaced the stock air filter with a bmc. Do you use your stock or an aftermarket on your bike? Could that be the cause?

Could you please elaborate a bit further on the throttle bodies sync, I'm not familiar with this...

PS: A power commander is out of the question for the moment.

 

[TownsendsFJR1300]

@Motogiro, the bike has the catalytic converter still on. I've tried it in the past without it, but there was no difference, idle is still rough. Plugs are as good as new.

@TownsendsFJR1300, I have also replaced the stock air filter with a bmc. Do you use your stock or an aftermarket on your bike? Could that be the cause?

Could you please elaborate a bit further on the throttle bodies sync, I'm not familiar with this...

PS: A power commander is out of the question for the moment.

I have a the stock air filter in mine. As for the throttle sync, you need a manometer. I purchased a "Carb Tune" manometer as it has no liquids (SS rods) and was about $85.00 US $ delivered to my door in Florida from the UK.

To adjust, you lift the fuel tank.

There is a block on the left side of the bike with 4 adjustment screws. On each side of the bike(still under the tank) you'll find 4 vacuum lines, 2 on each side (one on each side has a white slash mark on it) , their right next to the frame itself.

All lines are plugged from the factory with a black plastic plug.

You remove the vacuum plugs and plug in the manometer.

The #1 cylinder (furthest to the left) is the base cylinder.

You adjust (after being warmed up and a strong fan blowing on the front of the bike to keep temps in check) the other screws to match the vacuum to #1.

Yamaha spec's allows for 10mm variance, I got mine adjusted down to 2 mm. Most dealerships won't get yours adjusted this close and charge more than $85.00 (I paid over $125 at the dealer for my FJR before I bought mine and it was in spec but not that close)..

I rev mine up to 4 k (for a second) and adjust accordingly. This helped me in eliminating 80% of the vibration of an in-line 4. It helps to have a shop manual, but that's it in a nut shell.

This is the unit I purchased: www.carbtune.com

Its top of the line and paid for itself many times over... Others have made their own, IMHO, I prefer not to gamble sucking fluids into my engine and pay $85.00...


***Note, there is a throttle sync adjustment screw with spring in the middle that SHOULD NOT BE ADJUSTED..

 

[SovietRobot]

I had a terrible lumpy idle and the only thing that actually fixed it was a new cam chain tensioner.
Not that you shouldn't adjust the throttlebodies and check everything else first though.