Light WOT Hesitation?

[JMcDonald]

Hello. I recently found this forum and have been lurking. I am impressed at how much information I've been able to find searching! However, my problem seems to be relatively uncommon:

Sorry, I did try to search, but all I found were threads about idling issues, and one thread where the guy had the wrong spark plugs and changing those fixed the problem.

Relatively soon after I got my bike, I noticed a higher-RPM hesitation at WOT. The end result now is that I can't go faster than about 90-95 indicated (depends on wind, slope, etc), whether the throttle is at 3/4, or fully pegged. Some times I feel no hesitation at all, and the only indication something is wrong is the low top speed. However, a lot of times I will feel hesitation occurring during this, even if it is slight.

One night my speed cap was about 75 indicated, which was extremely annoying.

I had the spark plugs changed at the 6k-mile maintenance, and nothing changed. I have a decent amount of experience with carbs (dirtbikes, RC cars, and my old Suzuki Samurai), and if it isn't an ignition / electronic issue, it really seems like a lean condition.

I am pretty mechanically inclined (I've removed and reinstalled a good half-dozen engines in cars). However, the main problem is both that I find troubleshooting intimidating, and that being in school, working almost full time, and with this being my only personal transportation, I don't have time to dig too far into it myself, nor do I want to take the risk of the inevitable "ah, crap" moment that will keep me from getting it back together in time.

Are there any simple fixes I should try? I inspected the air filter a couple thousand miles ago and it really didn't seem bad, but I suppose I could give it a clean this weekend. I have looked into shimming the carb needles, but I'd rather get it running correctly before modding it (I can understand the cold starting issues, but I can't imagine the tune would be so off it would only make like 80% of its power...).

I hope you guys can help me!


Also, I am 99% sure I have the CDI Issue, but I am not sure if that affects more than the tach reading.



Thanks!

[want1sobad]

welcome!

[dubojr1]

CDI concern IS only the display reading. Clean that filter for sure if there's doubt. You may also want to try some seafoam prior to tear-down. There's been some members here who have had good results with it.

[JMcDonald]

Ah ok thanks for clearing up that CDI issue! It is annoying, but not $300-or-several-hours-at-the-incompetant-dealer annoying :P .

I will try the air filter, probably tomorror, and might look into the snorkel mod while I've got it all apart! I'll report back what I find.

And thank you for the welcome . I bought this bike with the intention of upgrading quickly. However, it has been growing on me more and more as I get better at riding and get a better idea of the type of riding I like doing .

[dubojr1]

Remember you said no mods till it's running correctly. You don't want to do the snorkel mod yet either cause it will lean the top end more.

[kkim]

J-

sounds like it might be rich to me. can you explain exactly what happens at WOT/max speed?

make sure you have a clean air filter when you do this and have no air leaks around the carb intake boots while troubleshooting/jetting the mains.

to test whether it's lean or rich right now, pull the choke open when at WOT... if the bike runs better w/ the choke on, you're lean... if it starts to slow down or bog even more on the top end, you're too rich.

before you do any of this though, do a WOT run then, pull and read the plugs to get a visual baseline for troubleshooting purposes.

how long have you had the bike and did you buy it used? if used, did the PO do any carb work to it?

[JMcDonald]

I bought it used a few months ago, with about 5600 miles on it, and now it has a little less than 8000 on it. I bought it from a good friend of mine, and I do not think he did anything more than take it in for the routine maintenances. He bought it new.

I will take in on the highway in a few minutes and see how it does playing with the choke at WOT!

[randomwalk101]

Originally Posted by dubojr1

CDI concern IS only the display reading.

Don't know about that....

[dubojr1]

Originally Posted by randomwalk101

Don't know about that....

Please clarify. It is my understanding the CDI issue most members complain about is only that the display needle mis-reads from one occurance to another.

[JMcDonald]

Ok, went on the highway, and the engine begins to bog / stops accelerating at WOT when the choke is fully applied.

I just removed and cleaned the air filter and am going to put it back. However, it did not seemed clogged by any stretch, and hardly looked different from one side to the other. It looks pretty much just like when I checked it a couple months ago.

I won't be able to get to the plugs til prolly tomorrow since I don't have my tools with me, but it does now seem very like like it is running rich.

I'll see how this works out.

[kkim]

sounds to me like you need to go one step leaner on the main jets and retest.

http://faq.ninja250.org/wiki/How_to_...roper_main_jet.

[JMcDonald]

Ok, the air filter didn't do a lot (not enough to even know if it was just me or if there was an actual difference). So, I pulled the snorkel just to see what it did. First, it sounds way different! I never wounda thunk it.

But, I immediately turned around and reached 100mph indicated on the speedo, with it still climbing (well, for a 250:P ) before I had to slow down!

I know I didn't do a great job with the scientific method, largely due to time constraints, but at least you guys helped me discover whether it was lean or rich!

I will look into leaning out the carbs (or adding an exhaust...) .

Thanks a bunch, guys!

[kkim]

yep, leave the snorkel off and add a full exhaust. I recommend an Area P quiet core.

with snorkel removed and a full exhaust, the 98 main jets are just about perfect for street riding.

also, if you're going to leave the snorkel off, you should shim the needles to richen the low and mid range as the bikes, stock, come jetted too lean in this area.

[dubojr1]

And may I suggest...

http://www.ninjette.org/forums/showthread.php?t=53242

Good deal on the Area P!

[JMcDonald]

Thanks guys .i am also considering making my own exhaust, too. But we'll see heh.

Heh ive almost found a new love for the bike! I never realized how much this issue affected my percepton of it.
Posted via Mobile Device

[kkim]

Originally Posted by JMcDonald

Heh ive almost found a new love for the bike! I never realized how much this issue affected my percepton of it.
Posted via Mobile Device

heh, heh, it gets even better... much better.

[JMcDonald]

Ok so yeah I can tell the low end / midrange could use some adjusting, so I will try to get to those shims this weekend. However, while the low end and midrange does have a noticably reduced thrust, the top end is exactly opposite! I eating now, but im gonna go out and see what she'll do .

[randomwalk101]

Originally Posted by dubojr1

Please clarify. It is my understanding the CDI issue most members complain about is only that the display needle mis-reads from one occurance to another.

Cdi control sparks which is dependent on rpm. If cdi sees rpm differently than that of engine (actual), spark/timing will be off thus you see crappy acceleration etc.

[randomwalk101]

Originally Posted by dubojr1

Please clarify. It is my understanding the CDI issue most members complain about is only that the display needle mis-reads from one occurance to another.

I had this issue before replacing with tis brt.
Not only rpm displays is off, accelleration is crappy...it's like you loose power all the sudden compare to before.

[JMcDonald]

I shimmed the needles today, using two 3mm washers on each needle. Working on this bike is so easy compared to cars, lol. But yeah, the low-end is now about like it used to be before removing the snorkel, though I still have that little bit extra top end power .

I took off the muffler just to see how it sounded... I was gonna ride it around but it was a bit too loud for my neighborhood so I put it back away heh. But, I will probably get on building a full exhaust within the next couple of weeks .

[dubojr1]

Originally Posted by JMcDonald

I shimmed the needles today, using two 3mm washers on each needle. Working on this bike is so easy compared to cars, lol. But yeah, the low-end is now about like it used to be before removing the snorkel, though I still have that little bit extra top end power .

I took off the muffler just to see how it sounded... I was gonna ride it around but it was a bit too loud for my neighborhood so I put it back away heh. But, I will probably get on building a full exhaust within the next couple of weeks .

And we will expect pictures of that...

[JMcDonald]

Oh there will be! I am going to go pretty minimalist with it, too. I am kinda tempted to go strait pipe and have it exit basically where the head shield is, but I am worried that might get a little old (maybe...my last MR2 had a 3" strait pipe, and I drove for hundreds of miles with nothing but the downpipe on my previous one... so I don't mind a few decibels out of the exhaust :P ). But, an even bigger concern would probably be its offense to law-enforcement :P .

If anything, though, I will probably try to wedge a small bullet muffle underneath there and still put the exit in the same location just after the first mounting bolt.



You know we're working with a helpful bunch of guys when a guy can go from asking how to fix his bike, to planning future mods, all in the same thread .

[kkim]

Originally Posted by JMcDonald

Oh there will be! I am going to go pretty minimalist with it, too. I am kinda tempted to go strait pipe and have it exit basically where the head shield is, but I am worried that might get a little old (maybe...my last MR2 had a 3" strait pipe, and I drove for hundreds of miles with nothing but the downpipe on my previous one... so I don't mind a few decibels out of the exhaust :P ). But, an even bigger concern would probably be its offense to law-enforcement :P .

If anything, though, I will probably try to wedge a small bullet muffle underneath there and still put the exit in the same location just after the first mounting bolt.



You know we're working with a helpful bunch of guys when a guy can go from asking how to fix his bike, to planning future mods, all in the same thread .

please don't do that.

http://www.ninjette.org/forums/showthread.php?t=52566

[dubojr1]

I knew your were going to catch that kkim...

[JMcDonald]

I wouldn't have done it for any perception of increased safety. It would have only been to make the project simpler, to save a little weight, and for the look (just personal preference). But, I will see if I can't find a muffler small enough to fit under the frame before going strait-pipe, and even then I might just make a small muffler to put under there.