Valve adjustment

ninjaryda · April 3rd, 2013, 10:05 PM

So I looked through the tutorial and did a valve adjustment on my 2007 250r. The exhaust valves were all tight (couldn't even fit a .002 gauge in there). All but one of the intakes were like that too, but they out of spec. I bought the bike used from the original owner, but I don't he ever had the valves adjust.

The process wasn't so bad. I went with a closer to minimum spec for each (intake and exhaust), as the wiki stated that this effectively gives valve overlap range and effects the power band. Before, the bike didn't wake up until 8k and really didn't hit the power band until closer to 10k. It felt like the bike had power all the way until 14k (the hard cuff or limiter, I assume) and would keep pull higher if not for breaking up. I also shimmed the needles in the carb with two washers (though they measured .300 instead of the wiki suggested .400 thickness).

It pulls harder in the mid range now (coming in around 5-6k), but the top end dies out about 12.5k now. It doesn't pull as hard in the 12-13.5k range. Matter of fact, I can't even hit 14k now. It breaks up at just pass 13.1k.

The only performance mods so far is a full exhaust/headers with a 1.75 CD pipe and a 13 inch muzzy can. I'd really like to get that very top end back. Is it possible going with pod filters and a matching rejet will get me some more top end? If not, I think I'm gonna go back and readjust the valves to something a little bit tighter.

Lychee · April 3rd, 2013, 11:12 PM

bigger main jet

ninjaryda · April 4th, 2013, 03:27 PM

Yeah, gonna do a jet kit. Need to get a better air filter setup first.

Question though, a 2" OD pipe would flow more and scavenge more, right? What about larger header pipes?

Lychee · April 4th, 2013, 04:07 PM

The carburetor is really finicky and your jetting will need to change to match every flow upgrade that you add. If you want it to run well now, change jetting now. Otherwise wait until you buy and install all the flow upgrades first and then rejet once, but know that it will not run well until you rejet.

I don't think this bike has a rev limiter. If it is running out of power at the top I have a feeling you are over revving the motor. You may get some gains from your flow upgrades, but don't expect a huge power increase. It is still a 250 after all.

I've read on this board that changing to pod filters really sucks. The air box does a pretty good job of stabilizing the air flow into the carburetor. You may end up rejetting and rejetting and never find a good setting because of the inconsistency of the air flow around the pods.

Are any top end gains from the tighter valve clearances worth the extra maintenance?

ninjaryda · April 4th, 2013, 04:22 PM

Quote:

I don't think this bike has a rev limiter. If it is running out of power at the top I have a feeling you are over revving the motor. You may get some gains from your flow upgrades, but don't expect a huge power increase. It is still a 250 after all.

Yeah, what was there - wasn't a huge difference to begin with. But I did want to get it back. I read on some ninja wiki that the original 250s had a rev limiter at 15k, then dropped this down to 14k starting with 2005 models (if I remember right). It definitely felt like a rev limiter when I hit 14k before (one spark plug is cut out), where as now at 13.1k - it just breaks up slightly (like not enough fuel, which makes sense given the new change in the valve overlap and not letting the headers scavenge enough in the cylinder to pull in more fuel/air mixture).

Quote:

Are any top end gains from the tighter valve clearances worth the extra maintenance?

If it means I have to check it every 2-3k miles, then that's fine with me (it wasn't that bad). Although I'm gonna try a few other options first.

Quote:

I've read on this board that changing to pod filters really sucks. The air box does a pretty good job of stabilizing the air flow into the carburetor. You may end up rejetting and rejetting and never find a good setting because of the inconsistency of the air flow around the pods.

I've read this too. Which why I was kinda of reluctant to do this. But Pod filters (or maybe dual K&N filters) are cheap enough. I could always revert back if I need to.

I kinda wish this engine had hydraulic lifters for the cam. There was cheat/trick you could do on car engines where if you ran a large overlap (which normally killed your low end because of the rapid bleed off at lower RPMs), you could use rapid bleed down lifters. Which effectively gave you a dynamic cam profile. The lower RPMs would cause the lifter to bleed out faster and thus close the overlap some. And at high RPM's, they wouldn't so you'd get the full overlap of the cam profile. Oh well :/

Lychee · April 5th, 2013, 12:18 AM

Quote:

Originally Posted by ninjaryda

Yeah, what was there - wasn't a huge difference to begin with. But I did want to get it back. I read on some ninja wiki that the original 250s had a rev limiter at 15k, then dropped this down to 14k starting with 2005 models (if I remember right). It definitely felt like a rev limiter when I hit 14k before (one spark plug is cut out), where as now at 13.1k - it just breaks up slightly (like not enough fuel, which makes sense given the new change in the valve overlap and not letting the headers scavenge enough in the cylinder to pull in more fuel/air mixture).

I recommend shifting up. Or at least using 50w engine oil. Good Luck man.

ninjaryda · April 6th, 2013, 06:02 PM

Update: I think it's just the carb being flakey (I need to tear it down one of these days and chem dip it. Probably when I get the re-jet kit).

I took the bike out on about 8 passes at Gates Pass full loop (Tucson) and it didn't break up at 13k. I was able to take it to the the rev limiter no problem (14k), every time. The sound of the muzzy exhaust sounds much better now too. The sound is more even now and less lawnmower-ish. The engine RPM scream/sound from 11-14k is pure sex, after this adjustment. Maybe it's just my imagination, but sounds a little bit louder in the mid range RPMs too.

Not valve related, but I got to test the top end speed out today on a long stretch of small/low traffic highway. There was a slight down hill (maybe 2-3% decline) and couldn't say about the wind, but I hit 110mph. I didn't hit 14k yet (was coming up on other cars), so I could of hit near 115mph. Not that I need to go that fast, but nice to know what the bike can do (with my weight/height). Also did some first time riding on a regular freeway (I-10 four lane per side), it handled like a breeze. Even passing or riding around semi's.

I'm completely in love with this bike

April 3rd, 2013, 10:05 PM	#1
ninjaryda ninjette.org member Name: Rick Location: Tucson Join Date: Feb 2013 Motorcycle(s): 2007 250r Posts: 63	Valve adjustment So I looked through the tutorial and did a valve adjustment on my 2007 250r. The exhaust valves were all tight (couldn't even fit a .002 gauge in there). All but one of the intakes were like that too, but they out of spec. I bought the bike used from the original owner, but I don't he ever had the valves adjust. The process wasn't so bad. I went with a closer to minimum spec for each (intake and exhaust), as the wiki stated that this effectively gives valve overlap range and effects the power band. Before, the bike didn't wake up until 8k and really didn't hit the power band until closer to 10k. It felt like the bike had power all the way until 14k (the hard cuff or limiter, I assume) and would keep pull higher if not for breaking up. I also shimmed the needles in the carb with two washers (though they measured .300 instead of the wiki suggested .400 thickness). It pulls harder in the mid range now (coming in around 5-6k), but the top end dies out about 12.5k now. It doesn't pull as hard in the 12-13.5k range. Matter of fact, I can't even hit 14k now. It breaks up at just pass 13.1k. The only performance mods so far is a full exhaust/headers with a 1.75 CD pipe and a 13 inch muzzy can. I'd really like to get that very top end back. Is it possible going with pod filters and a matching rejet will get me some more top end? If not, I think I'm gonna go back and readjust the valves to something a little bit tighter.

April 3rd, 2013, 11:12 PM	#2
Lychee sail away Name: Jon Location: San Jose Join Date: Jul 2012 Motorcycle(s): gixxer (sold), ninjette (upgrade!) Posts: 964 Blog Entries: 8	bigger main jet __________________________________________________ Unregistered found this post helpful. Track Day Preparation Checklist 1. Financial 2. Mental 3. Physical 4. Gear / Bike

April 4th, 2013, 04:07 PM	#4
Lychee sail away Name: Jon Location: San Jose Join Date: Jul 2012 Motorcycle(s): gixxer (sold), ninjette (upgrade!) Posts: 964 Blog Entries: 8	The carburetor is really finicky and your jetting will need to change to match every flow upgrade that you add. If you want it to run well now, change jetting now. Otherwise wait until you buy and install all the flow upgrades first and then rejet once, but know that it will not run well until you rejet. I don't think this bike has a rev limiter. If it is running out of power at the top I have a feeling you are over revving the motor. You may get some gains from your flow upgrades, but don't expect a huge power increase. It is still a 250 after all. I've read on this board that changing to pod filters really sucks. The air box does a pretty good job of stabilizing the air flow into the carburetor. You may end up rejetting and rejetting and never find a good setting because of the inconsistency of the air flow around the pods. Are any top end gains from the tighter valve clearances worth the extra maintenance? __________________________________________________ Unregistered found this post helpful. Track Day Preparation Checklist 1. Financial 2. Mental 3. Physical 4. Gear / Bike

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April 4th, 2013, 03:27 PM	#3
ninjaryda ninjette.org member Name: Rick Location: Tucson Join Date: Feb 2013 Motorcycle(s): 2007 250r Posts: 63	Yeah, gonna do a jet kit. Need to get a better air filter setup first. Question though, a 2" OD pipe would flow more and scavenge more, right? What about larger header pipes?

April 6th, 2013, 06:02 PM	#7
ninjaryda ninjette.org member Name: Rick Location: Tucson Join Date: Feb 2013 Motorcycle(s): 2007 250r Posts: 63	Update: I think it's just the carb being flakey (I need to tear it down one of these days and chem dip it. Probably when I get the re-jet kit). I took the bike out on about 8 passes at Gates Pass full loop (Tucson) and it didn't break up at 13k. I was able to take it to the the rev limiter no problem (14k), every time. The sound of the muzzy exhaust sounds much better now too. The sound is more even now and less lawnmower-ish. The engine RPM scream/sound from 11-14k is pure sex, after this adjustment. Maybe it's just my imagination, but sounds a little bit louder in the mid range RPMs too. Not valve related, but I got to test the top end speed out today on a long stretch of small/low traffic highway. There was a slight down hill (maybe 2-3% decline) and couldn't say about the wind, but I hit 110mph. I didn't hit 14k yet (was coming up on other cars), so I could of hit near 115mph. Not that I need to go that fast, but nice to know what the bike can do (with my weight/height). Also did some first time riding on a regular freeway (I-10 four lane per side), it handled like a breeze. Even passing or riding around semi's. I'm completely in love with this bike