Former lurker here with some tech questions...

[sickopsycho]

So I've been lurking here since I bought my 2007 ninja 250r a couple months ago. I have no idea about the maintenance history and this is my first bike- so I decided to do the responsible thing and do EVERYTHING on the maintenance schedule before I go out on my first (true) ride. I put it in the back of a pickup and carried it home, then unloaded it a few blocks away and rode (like a squid- no helmet, jeans t-shirt) home. That was my only ride so far. So- I have read that there isn't MUCH variation between the entire ninja 250 series... so I've basically been following all of the wikis I found online, mostly from this forum. I did not realize that almost all of them are for the 2008+ models. So I ordered my handy dandy spanner wrench so I could adjust the rear preload... it feels a little soft. I go to insert said wrench... and I cannot find an adjustment on the shock. Have I lost it, or is there no adjustment on these older bikes? My second question was about carb syncing. I performed an oil change- it came out clean looking with a new looking K&N oil filter, the same I was replacing it with. That made me happy as at least someone has taken some kind of care of it... afterwards I did a valve adjustment. I ended up adjusting 1 intake and 1 exhaust valve per cylinder- the other was in spec. I swapped plugs, #2 looked to be running a little lean (#1 has a good amber burn on the electrode, #2 was more towards the white side). I decided to perform the poor mans carb sync where I had a clear piece of 1/4"ID tubing running between the 2 carb vacuums with a small amount of engine oil in the middle. When I cranked the bike up, even though I had followed the directions and sealed all of the vacuum ports I disconnected when removing the fuel tank... almost all of my oil got sucked into one of the carbs. This, of course, cause the engine to run extremely erratically and I couldn't perform a sync. Any suggestions on this? Am I supposed to crank the bike and then attach the hose? I don't see how this would be possible as a gross air leak wouldn't allow the bike to run properly... Let me know please- I leave this in your very knowledgeable hands!

[alex.s]

no preload adjuster on the pregen shock.

sounds like you setup the carb sync wrong.

[sickopsycho]

Originally Posted by alex.s

no preload adjuster on the pregen shock.
*dammit*
sounds like you setup the carb sync wrong.

So I put the two ends of a probably 5ft hose on the two nipples on the air/fuel side of the carb. One of the vacuum lines went to the shutoff vavle on the fuel tank... the other one went to... I cant remember. These two nipples were right on the top on the inside (cylinder side of venturi, not the seat side) and I had the hose running out and hanging down to the ground with approximately 12" of 10w40 motor oil in the center. As soon as I cranked the engine, the oil started going crazy. It went everywhere. I though, heck this might just be part of the process, so I cranked again- it started and sucked half the oil out and started running like crap. There was no way I could have accurately adjusted anything at this point, I was playing with the choke just to keep it running even though I had warmed it up for 20 minutes of running. Normally the bike will start with a half second crank in warm weather and no choke at all. Hope this gives some insight. I'm pretty sure I capped off the vacuum lines that were disconnected- one was a vapor line from the base of the fuel tank, the other was... again I don't remember. There were 2 though that I capped off. Perhaps the hose wasn't tightly sealed on the carbs? I made sure to get 1/4"ID tubing as the wiki called for...

[Ghostt]

Here's a link to one of best WIKI on the PreGen Ninjette

http://faq.ninja250.org/wiki/Ninja250_Howto


As far as your sync problems goes , read my write-up on the subject


You can sync with the carbs in hand. Back the idle adjustment off to close that carb then match the second carb to it with the sync screw. You can then turn the idle adjustment up while using a thin feeler gauge (maybe .002") between the throttle plate and the throttle bore, adjust to just fit, and then check the second one and adjust to match. If you have good feel for this it will run fine once installed.

It would do folks well to take a minute to review and understand what a sync tool does, how it works. And take another minute to look at the carb linkage and sync adjustments available to fix irregularities that might occur. It can help take some of the mystery out of this as well as stop unnecessary carb sync screwups.

Meaning, that the carbs were right once, the butterflies were matched and it performed well, but then changed. Undecided And the problem somehow occurred in the butterfly direct shafts, or the sync screw turned or wore that pad that it rests on, or the carburetor pairing/ bridging brackets twisted in relation to each other, and enough so that the butterflies no longer operated in sync, such that performance noticeably suffered. And a fix will be accomplished by changing the butterfly position, the only thing the sync adjustment does. Hmmm. Really? Undecided

Meanwhile, the tool measures vacuum at each individual runner. That's all it does, how it works. And vacuum is effected by a huge list of things, butterfly position being only one of them, and the only one addressed with that tool while turning those sync screws. The rest of that list includes, valve adjustment, jetting, float level, compression differences between cylinders caused by wear as well as factory CC differences in the head, intake runner, as well as flow by port variations, etc. Variations in cams, wear or factory tolerance. Then there's the potential big one, pilot jets and pilot screw mixture settings. All of those effect the vacuum and will be read by the sync tool, accurately identifyng the difference that exists, and with the only adjustment being used to "correct" the problem, move the butterfly relationship, one to the next.

It's that clear understanding that has me of the opinion and long time practice to not touch the sync screws on a set of carbs that were right once and were never dismantled from the rack. And jet cleaning as well as float needle changing doesn't require that they be dismantled. And further, if I DID dismantle a set of carbs, I just matched the butterflies on the bench at assembly, using a feeler gauge, and then never touched them again, never gave them another thought.

That method, properly executed, will have THAT portion of the complete equation, balanced flow to each cylinder in a multi-cylinder/ carb application due to butterfly position, satisfied entirely adequately. And in fact, it has worked for me every time I've done it on every bike (as well as individual runner/ butterfly V-8 intakes, all eight) that I've ever owned or any that I've fixed for others. And the times I fixed for others was usually after an attempt by others to sync the carbs, chasing a problem, or sometimes not even chasing a problem, but one they created wth a sync tool, chasing a problem from that list, that was never a butterfly position change problem. Those linkages are so direct and simple that they don't know how to screw themselves up. Not enough to care about.

I'm sure this will start a lot of controversy so I won't argue it, just offering it for those who understand the whole picture that I outlined and might make good use of it. It is what I've done, on every engine I ever worked on, including blue printed racing engines as well as regular old, high mileage street stuff. I've had at least four, four cylinder bikes with over 100,000 miles that ran quite well, the whole time, and never had a carb sync performed. When they did finally get a total disassembly, this is how I set them up, on the bench. Over the years I've straightened out at least a half dozen messed up ones, probably more, and on the bench, after fixing the original problem which was fouled pilot jets.

I only posted this because it seems like its coming up fairly often, especially with problems from a sync gone bad. One I would suggest was never a sync problem to begin with. A big or sudden change in performance is NEVER a sync problem. NEVER. Remember that. Cool If there is a problem, and you connect the gauges? YES, there will definitely be an imbalance indicated. But because that hole has a problem that is from the rest of the list. A bad plug, a plugged pilot jet, a screwed up float, a bad valve or setting, etc. Every one of them effecting the vacuum in the intake but NOT from a sudden move of a butterfly position, a sync adjustment.


-

[sickopsycho]

Originally Posted by Ghostt

Here's a link to one of best WIKI on the PreGen Ninjette

http://faq.ninja250.org/wiki/Ninja250_Howto


As far as your sync problems goes , read my write-up on the subject


You can sync with the carbs in hand. Back the idle adjustment off to close that carb then match the second carb to it with the sync screw. You can then turn the idle adjustment up while using a thin feeler gauge (maybe .002") between the throttle plate and the throttle bore, adjust to just fit, and then check the second one and adjust to match. If you have good feel for this it will run fine once installed.

It would do folks well to take a minute to review and understand what a sync tool does, how it works. And take another minute to look at the carb linkage and sync adjustments available to fix irregularities that might occur. It can help take some of the mystery out of this as well as stop unnecessary carb sync screwups.

Meaning, that the carbs were right once, the butterflies were matched and it performed well, but then changed. Undecided And the problem somehow occurred in the butterfly direct shafts, or the sync screw turned or wore that pad that it rests on, or the carburetor pairing/ bridging brackets twisted in relation to each other, and enough so that the butterflies no longer operated in sync, such that performance noticeably suffered. And a fix will be accomplished by changing the butterfly position, the only thing the sync adjustment does. Hmmm. Really? Undecided

Meanwhile, the tool measures vacuum at each individual runner. That's all it does, how it works. And vacuum is effected by a huge list of things, butterfly position being only one of them, and the only one addressed with that tool while turning those sync screws. The rest of that list includes, valve adjustment, jetting, float level, compression differences between cylinders caused by wear as well as factory CC differences in the head, intake runner, as well as flow by port variations, etc. Variations in cams, wear or factory tolerance. Then there's the potential big one, pilot jets and pilot screw mixture settings. All of those effect the vacuum and will be read by the sync tool, accurately identifyng the difference that exists, and with the only adjustment being used to "correct" the problem, move the butterfly relationship, one to the next.

It's that clear understanding that has me of the opinion and long time practice to not touch the sync screws on a set of carbs that were right once and were never dismantled from the rack. And jet cleaning as well as float needle changing doesn't require that they be dismantled. And further, if I DID dismantle a set of carbs, I just matched the butterflies on the bench at assembly, using a feeler gauge, and then never touched them again, never gave them another thought.

That method, properly executed, will have THAT portion of the complete equation, balanced flow to each cylinder in a multi-cylinder/ carb application due to butterfly position, satisfied entirely adequately. And in fact, it has worked for me every time I've done it on every bike (as well as individual runner/ butterfly V-8 intakes, all eight) that I've ever owned or any that I've fixed for others. And the times I fixed for others was usually after an attempt by others to sync the carbs, chasing a problem, or sometimes not even chasing a problem, but one they created wth a sync tool, chasing a problem from that list, that was never a butterfly position change problem. Those linkages are so direct and simple that they don't know how to screw themselves up. Not enough to care about.

I'm sure this will start a lot of controversy so I won't argue it, just offering it for those who understand the whole picture that I outlined and might make good use of it. It is what I've done, on every engine I ever worked on, including blue printed racing engines as well as regular old, high mileage street stuff. I've had at least four, four cylinder bikes with over 100,000 miles that ran quite well, the whole time, and never had a carb sync performed. When they did finally get a total disassembly, this is how I set them up, on the bench. Over the years I've straightened out at least a half dozen messed up ones, probably more, and on the bench, after fixing the original problem which was fouled pilot jets.

I only posted this because it seems like its coming up fairly often, especially with problems from a sync gone bad. One I would suggest was never a sync problem to begin with. A big or sudden change in performance is NEVER a sync problem. NEVER. Remember that. Cool If there is a problem, and you connect the gauges? YES, there will definitely be an imbalance indicated. But because that hole has a problem that is from the rest of the list. A bad plug, a plugged pilot jet, a screwed up float, a bad valve or setting, etc. Every one of them effecting the vacuum in the intake but NOT from a sudden move of a butterfly position, a sync adjustment.


-

Hey thanks! I don't have an issue, and I don't know that the carbs have ever been messed with so I'll just leave it alone. =) The bike runs great... I just thought I'd check for fine tuning purposes. Thanks for the reply. =)

[Ghostt]

You can start with cleaning the spark plug caps/Renew the HT leads they are prone to cause issues, add a set of Iridium plugs and that takes care of that, you also might want to consider doing the CoPs conversation, it eliminates the coils, HT wires, and caps, plus they deliver a stronger spark.

After that I would personally recommend changing the clutch springs to a set of Barnett springs for the ZX600.

But the best bang for your buck is upgrading the suspension, and getting it dialed in.

Write-ups available upon request.

[sickopsycho]

Originally Posted by Ghostt

You can start with cleaning the spark plug caps/Renew the HT leads they are prone to cause issues, add a set of Iridium plugs and that takes care of that, you also might want to consider doing the CoPs conversation, it eliminates the coils, HT wires, and caps, plus they deliver a stronger spark.

After that I would personally recommend changing the clutch springs to a set of Barnett springs for the ZX600.

But the best bang for your buck is upgrading the suspension, and getting it dialed in.

Write-ups available upon request.

That's good info- and thanks to everyone for the input. I ended up saying Eff it and not worrying about balancing the carbs. I might end up taking them off before long and cleaning them out. The bike has 17k on it and IDK if that's ever been done. I have no idea about maintenance history other than the bike was never dropped (or if it was, they replaced everything that could have gotten any damage). The oil and filters were all very clean when I changed them. I changed brake fluid, coolant, spark plugs. I tightened 4 valves, 1 exhaust and 1 intake for each cylinder. I tightened the chain. As far as I'm concerned, the bike is road ready now. I'm from NC and the weather has been really nice since I've had it... on a really warm day I don't need the choke to start it, on a cooler day I can half choke it to start and kill the choke after about 1 min of idle. I'm extremely impressed with this bike- I think I'll keep it =) Regarding the coil over plug conversion... I'm not sure I'll go down that road. Honestly I am extremely interested in a fuel injection conversion and I think that would be my first project if I decide to do much modifying this one. I wouldn't want to get the $500 kit that they sell ready to go for the bike, though. I would probably either get a mega-squirt type setup or possibly even try to build one using an Arduino if that's possible. I have a background in automotive so I'm very familiar with how fuel injection works... I'm just not sure if an Arduino has enough flash memory to hold everything I'd need for a closed loop fuel map. eh- that's down the road. Thanks for being an awesome forum, I'm sure I'll be on here all of the time looking for answers to questions about my bike. =)