How am I doing with this rejetting?

[headshrink]

This is an excerpt from the email I sent to Factory Pro, and am wondering if there is also feedback you all may have.

"I’ve installed a new engine in my 250r, returned it to MOSTLY stock configuration, and am currently re-jetting with the Factory Pro kit. I hope you don’t mind answering a couple questions so I can get this dialed in. I’ve read the included instructions over and over, but still find it difficult to get right.

CURRENT ENGINE CONFIGURATION:
Stock exhaust, airbox & filter.
Snorkel REMOVED.
+1 tooth on counter-sprocket.

Before starting with the FP kit, I tested the bike with stock equipment. And the bike was unrideable…. It was so bad I thought the new engine may have been blown. This is when I tore down and completely cleaned my carbs for a second time, and installed my old Factory Pro kit. Things have been improving since, and the bike is much more rideable. It’s still extremely sluggish from a stop though.

MAIN JET: I started with a #92, but chose the #88. The difference was slight, but I THINK it was a little better up top WOT. Mid was slightly smoother too, but I understand we aren’t looking at that yet.

NEEDLE SHIMS: I started with the 3rd clip position, which seemed a bit flat in the mid-range, and kept adding shims to test at ½ positions. 4 had decent mid, with some flat spots, and 4.5 seemed to smooth out transitions (although my log shows no real boost in mid power). I’m not sure if having the needle this high indicated the main should be higher or not, but I kept it at 4.5 and moved on.

FLOAT HEIGHT: I started with 17mm (Discovered this when I went to adjust. It was WAY to lean from a past project). I lowered the floats to 16mm, 15mm, and finally to 14mm (stock). Each change improved lower RPM response and smoothed out the overall power curve.

FUEL SCREWS: I started with the suggested 2 turns out, which seems to hold a consistent idle, and neither hanged or dropped below idle when blipped. The only problem is how slow it starts moving from a dead stop. It doesn’t begin to make power until it passes 4K+ RPM. I added a quarter turn to compare, but when I blipped the throttle the RPM would fall below idle, so I returned to 2 turns out without testing on the street.

PILOT JET: #40

I feel I’m getting somewhat close, but suspect something is off. Since the fuel level was changed by so much, do I need to start over? With the needles giving better performance with so many shims, does this suggest I should be one main jet higher? I appreciate any feedback you can give."

[ducatiman]

Originally Posted by headshrink

Before starting with the FP kit, I tested the bike with stock equipment. And the bike was unrideable….

Is there an underlying problem somewhere? describing a stock '08 250 ninja as "unrideable" is hardly normal. I'd like to read further particulars leading you to make that summary...also interested in F Pro response (I trust you'll post)

[Ghostt]

[HoneyBadgerRy]

I would try the richer main and 3rd clip again.

[headshrink]

Originally Posted by ducatiman

Is there an underlying problem somewhere? describing a stock '08 250 ninja as "unrideable" is hardly normal. I'd like to read further particulars leading you to make that summary...)

I was trying to be succinct, but basically the bike responded very lethargically across a majority of the power-band. IIRC, the unrideable part refers primarily from a stop to about 9K-ish RPM. From idle to mid it was so slow I estimated someone with a brisk power-walk could possible move faster (literally, not figuratively). I could tell cars behind me where waiting patiently for me to get moving. The 250r is a very capable bike, and although it had been a while since I used it as my commuting beast before my 500, something was clearly wrong with it. As I mentioned, the old beast started to show signs of life again when I started rejetting.

[headshrink]

Originally Posted by HoneyBadgerRy

I would try the richer main and 3rd clip again.

Good to hear you say that. This confirms both my instincts, and what FP seems to be saying.

Here's the official word from FP:
"The float height affects the main a bit - so if you change the other lower settings a lot, you need to slightly trim the mains to compliment."

The original instructions also mention that if the fuel level is changed significantly you need to start over. I guess that is what I'm doing.

ALSO, since my problem area is low-early mid, I just REINSTALLED the snorkel The install was not as hard as I thought, just needed to remove the battery box and use a flat head screwdriver to jam the snorkel back in. Hopefully this won't take away a noticeable amount of power from the top end, but since this bike is mostly used for commuting I thought it best to get more usable power for all the stop and go's.

[RacinNinja]

Originally Posted by headshrink

Good to hear you say that. This confirms both my instincts, and what FP seems to be saying.

Here's the official word from FP:
"The float height affects the main a bit - so if you change the other lower settings a lot, you need to slightly trim the mains to compliment."

The original instructions also mention that if the fuel level is changed significantly you need to start over. I guess that is what I'm doing.

ALSO, since my problem area is low-early mid, I just REINSTALLED the snorkel The install was not as hard as I thought, just needed to remove the battery box and use a flat head screwdriver to jam the snorkel back in. Hopefully this won't take away a noticeable amount of power from the top end, but since this bike is mostly used for commuting I thought it best to get more usable power for all the stop and go's.

My 250 with the snorkel installed produced 31 HP peak. As you can see, it's a nice steady consistent climbing curve all the way to the top.

Dyno graph below, snorkel still installed.

[headshrink]

Originally Posted by RacinNinja

My 250 with the snorkel installed produced 31 HP peak. As you can see, it's a nice steady consistent climbing curve all the way to the top.

Dyno graph below, snorkel still installed.

That's pretty impressive for the old 250r. After reading in another thread the other day how CV carbs are more sensitive to vortexes in the air coming in, I began to understand a little more why the this might be a good thing. I'm going to try it anyway.

[RacinNinja]

Originally Posted by headshrink

That's pretty impressive for the old 250r. After reading in another thread the other day how CV carbs are more sensitive to vortexes in the air coming in, I began to understand a little more why the this might be a good thing. I'm going to try it anyway.

I do have a full exhaust system and K&N air filter.

Still, proof in the pudding that the factory airbox isn't as restrictive as people think it is.

[Ralgha]

An 88 jet is REALLY lean, stock is 98, mine's running great on a 95 with the stock air box and a full AreaP exhaust. What altitude are you at? If you're anywhere near sea level, I'd try the 98 jet and see what happens.

[headshrink]

Originally Posted by Ralgha

An 88 jet is REALLY lean, stock is 98, mine's running great on a 95 with the stock air box and a full AreaP exhaust. What altitude are you at? If you're anywhere near sea level, I'd try the 98 jet and see what happens.

FP recommends as a starting point 88 if stock exhaust, and 92 for full exhaust.

It's currently now at 90, 3.5, 14mm, and 2
intake and exhaust are 100% stock.

Still working on it, but it's probably within the ballpark.... I hope.

[Ralgha]

Originally Posted by headshrink

FP recommends as a starting point 88 if stock exhaust, and 92 for full exhaust.

It's currently now at 90, 3.5, 14mm, and 2
intake and exhaust are 100% stock.

Still working on it, but it's probably within the ballpark.... I hope.

Yeah, I remember that from when I did my FP jet kit. I read that and was like...nope! I know they're the experts and all, but come on guys. My bike ran fine stock at sea level, there's no way I'd start with an 88, I could tell already that it would be too lean. I started with stock (98) and went down. My butt dyno determined that 95 was the best, and the real dyno confirmed it later.

[Ghostt]

What did the exhaust gas analyzer say?

[Ralgha]

Originally Posted by Ghostt

What did the exhaust gas analyzer say?

Mine? I don't recall, I posted the chart here awhile back, I'll see if I can find it.

[Ghostt]

Originally Posted by Ralgha

Mine? I don't recall, I posted the chart here awhile back, I'll see if I can find it.

I can assume the fuel/air ratio was fine then?

[Ralgha]

Yep, found it, per the dyno guy's advice, I enriched the needles one clip after this run:

[Ghostt]

This is exactly why I say jetting without access to an exhaust gas analyzer is just a best guess scenario.

[RacinNinja]

Originally Posted by Ghostt

This is exactly why I say jetting without access to an exhaust gas analyzer is just a best guess scenario.

Amen.