RPM needle wiggles with new slip-on exhaust

[adamcorley]

hello im new to the forum and would like to thank everyone for having me and all the usefull info i've gotten from here.

My issue is this...

I just recieved my hotbodies MGP growler slip-on exhaust 2 days ago for my 2009 ninja 250r and have noticed a few things im unsure about.

I like the slip-on it sounds great and seems to respond well but i wanna make sure i'm not gonna hurt my bike.

First is that when i start the bike i need to use the choke to get it going even when its warm outside (80*F+) I know that may be because i need the needles adjusted. It has alwasy needed to use the choke when cold or cool but it seems like i need it more so now.

Next is when the bike is idling is not totally smooth sounding and the RPM needle that usually is rock steady is wiggling a little (not much but noticable and you can hear it with the louder exhaust. When driving it also seems to be reving up a lil higher then i remember before. For example i can usually go 60-70mph in sixth gear and be at around 7-8000 rpms but now im at at 9000rpms at 60-65mph thats a fairly noticable difference to me.

It does also back fires a lil, but not much. I'm sure this has to do with the needles needing adjusting too.

Anyway maybe im being parinoid but id rather be that than have my bike blowup or slowly ruin itself. i hope someone can ease my fears and let me know what up and what i shouod or should not do. thanks

[k-os]

To answer the first question, installing the exhaust leaned out your air fuel mixture more than stock.

[M-Oorb]

1) Yup its a little leaner now, shim should solve this
2) Carbs could need syncing
3) Remove the Kleen air system and your good to go

[Momaru]

Welcome Adam! Might throw up a little intro for yourself in the new members section.

Originally Posted by adamcorley

First is that when i start the bike i need to use the choke to get it going even when its warm outside (80*F+) I know that may be because i need the needles adjusted. It has alwasy needed to use the choke when cold or cool but it seems like i need it more so now.

These bikes are normally cold-blooded as they're set up lean from the factory for better fuel economy. Now that you've opened up the exhaust a little, the bike 'breathes' better (aftermarket exhaust is less restrictive than stock), which has further leaned out your fuel setup. The choke is not an 'air choke' so much as a 'fuel enricher' on the ninjette, but accomplishes the same goal; richens the fuel mix. Working on your jetting should fix this, but given this is a slip-on I don't think you'll screw the pooch if you don't.

There's a bunch of DIYs about this in the sticky list I'd start with shimming the needles and adjusting the mixture screws. They're both relatively easy to do and just about free ways to improve the bike's response.

Originally Posted by adamcorley

Next is when the bike is idling is not totally smooth sounding and the RPM needle that usually is rock steady is wiggling a little (not much but noticable and you can hear it with the louder exhaust. When driving it also seems to be reving up a lil higher then i remember before. For example i can usually go 60-70mph in sixth gear and be at around 7-8000 rpms but now im at at 9000rpms at 60-65mph thats a fairly noticable difference to me.

I'm not sure on this one, but sounds like it might be your CDI. On some bikes as the CDI heats up it can raise RPM amongst other things. Can't find the original post right now but I know it's out there.

Originally Posted by adamcorley

It does also back fires a lil, but not much. I'm sure this has to do with the needles needing adjusting too.

This frequently happens with aftermarkets. Removing the kleen air system may help

Originally Posted by adamcorley

Anyway maybe im being parinoid but id rather be that than have my bike blowup or slowly ruin itself. i hope someone can ease my fears and let me know what up and what i shouod or should not do. thanks

A slip-on proabably won't mess anything up if you leave the jetting alone, but the bike will be happier with some richer tuning to help it balance out the increased exhaust flow.

[M-Oorb]

Also what is the bike idling at now? What about before? could be you just need to adjust your idle. Also, are you remembering to shut off your choke once the bike is all warmed up.

I once forgot to turn mine off until I noticed about 5 min into my ride that the revs were much higher then realized why

[tjkamper]

Originally Posted by Momaru

I'm not sure on this one, but sounds like it might be your CDI. On some bikes as the CDI heats up it can raise RPM amongst other things. Can't find the original post right now but I know it's out there.

That is what I was gonna say!

I would definately check the Sinc on the Carbs and Shim the needles, to see if that fixes your rough idle. But those things would not effect the TACH reading a higher RPM at the same speed.

The issue is probably the CDI. Espcially since it is getting warm out.

Good luck

Here is the CDI Link: http://www.ninjette.org/forums/showthread.php?t=21043