250R NA Build - Ultimate

[tubarney]

Thanks but my tuner doesn't think thats the problem, a mechanic also said it don't matter. I'm going to put in the stock cams, airbox and the brt and take it down again by the end of the week. I am waiting for a head gasket atm.

By playing around with the brt we should be able to figure out if I have enough comp. Also he thinks that the cams may be the problem because they have been designed for a stock engine.

[mgentz]

My #1 carb took a poop. So I got a sweet used set off ebay for $130. Best I can tell....one of yhe horrible backfires I received killed it as all new jets and a full cleaning did nothing. Every now and again it cuts in but I'm not going to count on it.
@tubarney how is your stuff coming? Don't you love being pioneers?

[tubarney]

I received the head gasket today. The stock cams are in and the timing is set. I just got to check clearances. Should be ready for dyno on Friday.

[mgentz]

Sweet. My carbs should be in fri or over the weekend. I hope to dyno after a few test runs.

[tubarney]

I had to order shims. I'll have them tomorrow. Dyno will have to wait till Monday morning, unless he going to be open on Saturday.

[tubarney]

Turns out my tuner has shims. I'll be there tomorrow, just finished putting it together. Will post the results.

[mgentz]

So after getting new carbs and rebuilding everything again, I come to find out that my Takai coil failed. WTF?

I have the stock coils in and she runs fine and #1 is hot again. However, she is now a bitch to start again? How can it be easy to start on one cylinder and then when I get the other running it is hard again?

boy this is something....

[tubarney]

why did your coil fail? its probably hard to start because your jetting is wrong.

I couldn't get to the dyno today. I will have to go Monday morning.

[mgentz]

my jetting is as follows right now"

40 pilot
115 mains
FP needles 3rd clip
air screw set to 2 turns out

I have to start the bike with no choke and the idle screw (what moves the plates and changes RPM) set at a point where I get 4000 rpm on setup.

I assume that the large need for air means I need leaner jetting, but I was running 40 pilots at 2 turns out before....? I have also retarded my timing back to 10 degrees BTDC which is the same as stock and the BRT units.

Any thoughts on the jetting I should be at? I am returning my coil for warranty evaluation....but I will run them when I get it back.

[mgentz]

@tubarney have we lost all interest in this thread? Maybe its because it is taking too long to fine tune and pioneer this level of tuning on a 250? Or maybe it's because of this and that we have not posted the dyno sheets yet that everyone wants to see?

The best I can tell my jetting should have been just fine, but obviously it is not. It seems really weird to me that it would start better on one cylinder with the takai coils then it does on 2 cylinders with a stock set of coils.

Does anyone want to weigh in?

[subxero]

^ i wish i could help but i am probably in no position to offer advice,

But IMO your jetting should be fine for starting the bike unless it is way to rich....which it should not be. I was running my stock engine with pod filters more rich than your current setting and it started just fine. Only trouble i had starting my bike ever was when my pod filter got so wet that it was not pulling any air. Is your vacuum working correctly?

My only thought is that you still might have something electrical hiding somewhere, might explain the bad coil. Have you tried each cylinder individually? If so does one start much easier than the other? IDK

Just trying to throw some idea's out there. Good luck

[lgk]

How are your plugs?

[tubarney]

I think the problem is that we have so much to the engine that no one can really help us. There are too many variables in the equation.

Also the time it's taken to get these bikes on the road is a joke. Im starting to wish I just left it alone.

As far as my nightmare goes, I swapped in a stock set of cams and now my engine makes a ticking noise not like before. I think its the cams because they are out of another engine or cct.

I'll swap the beet cams back in a see if it goes away, if not it's either the chain or cct.

Then I will put the stock cams from my engine back in. Long story why I didn't put them in the first time.

[tubarney]

Originally Posted by mgentz

my jetting is as follows right now"

40 pilot
115 mains
FP needles 3rd clip
air screw set to 2 turns out

I have to start the bike with no choke and the idle screw (what moves the plates and changes RPM) set at a point where I get 4000 rpm on setup.

I assume that the large need for air means I need leaner jetting, but I was running 40 pilots at 2 turns out before....? I have also retarded my timing back to 10 degrees BTDC which is the same as stock and the BRT units.

Any thoughts on the jetting I should be at? I am returning my coil for warranty evaluation....but I will run them when I get it back.

Try leaning your jetting up. Drop down to a 110 main and put the needle on the first clip. They will effect it at idle. If you have to play around with your screw than its the other jets that are the problem.

You won't harm it by going lean or rich.

[Racer x]

Don't give up guys.
This stuff is not easy and everything does not just work because you bolted it together.

Mike when the engine starts on one cylinder . Which one? Did you swap the coil side to side?
Do you use starting fluid to start it?
When did it first do the no start thing?

[mgentz]

#2 started right up. #1 was cold. Switching changed this.

Actually I used no starting fluid and she fired right up and that just seemed odd. It has been hard to start all along. I think I will lean out the mj and tighten the air screws .5 and go from there.

[tubarney]

is it possible for an new gen cam chain to stretch?

[mgentz]

Yes. Any chain can stretch. That is what originally started me on all this since the case has to be split.

My chain and cct are both new now.

[subxero]

the main jet has next to nothing to do with start up and idle

Your idle screws, pilot and needle taper in relation to needle height are primary, The only way the main jet should affect the engine at start up and idle is if your needle is messed up, and or way to high.

Are the other needle jets in the carb good? Not the actual needle but the 2 circuits that are directly above the main jet, the cylinder part and the piece that sits on top of it?

[mgentz]

I had this problem with my carbs and still with my "new" ones with only 1500 miles. I don't think its the carbs but the jets. The question is where to start? I too think that I need help in the starting circuit but wonder which way to go...

[mgentz]

I will turn my pilot screws in to 1 turn out and .5 and 0 and see what happens. My theory is that I am pulling more air (volume) through the same size venturi therefore increasing velocity and actually getting too much fuel. Will post results....

[subxero]

since you can start with no choke, and choke makes it works, it makes sense that you are to rich on start up... but why. You are either not getting air flow through filter through carbs or that is fine but you are just getting to much fuel.

I would play with screws initially just to see if any adjustment could be noticed. If leaning it out helps then i would set screws back to 2.5, change pilot jet and look for changes. Again adjust idle after look for more changes then adjust pilot accordingly if necessary.

I see you have FP needles, i moved to the FP needles after awhile, I started on the 4th clip position which is pretty rich. I ended up on the 2nd clip position with a shim and it is just barely lean 1/8th-1/2 throttle in cooler temps. I probably should be running 3rd clip position it is literally .012" higher on the needle than my current position but it makes a noticeable difference in my bike

[cuong-nutz]

Your starter jets were not clogged?

http://www.ninjette.org/forums/showthread.php?t=123000

Hook back up the stock CDI if you haven't and see how the bike runs.

How do your spark plugs look? Any fouling?

Are you positive that throttle plates are not stuck slightly open with the MP throttle?

Choke plunger isn't sticking?

[mgentz]

Originally Posted by cuong-nutz

Your starter jets were not clogged?

http://www.ninjette.org/forums/showthread.php?t=123000

Hook back up the stock CDI if you haven't and see how the bike runs.

How do your spark plugs look? Any fouling?

Are you positive that throttle plates are not stuck slightly open with the MP throttle?

Choke plunger isn't sticking?

Between the two sets of carbs and hours spent with cleaner and air I thought I would have gotten those clean but maybe not. How did you clean yours?

[mgentz]

@tubarney I wonder why our jetting is so different? What feet above sea level are you?

[cuong-nutz]

Originally Posted by mgentz

Between the two sets of carbs and hours spent with cleaner and air I thought I would have gotten those clean but maybe not. How did you clean yours?

compressed air and cleaner may not be sufficient at cleaning it out. It's a possibility you could have just packed it in. I had some 22 gauge speaker wire laying around and used a few strands. I twisted it in and out removing the crud slowly each time.

[mgentz]

Would that have made me rich?

[mgentz]

okay here is the report: it started with the pilot screws all the way in. However I still need to have the idle adjustment at about 3000 rpm. The choke, any choke at all, made it die. therefore I think I need at least 38 Pilots if not smaller.

[mgentz]

Ok...38 pilots helped but its still not perfect. I think I will need 35 or smaller. See my post #581....

Given this I may need to stay around stck jetting. Crazy. And I have no restrictions on the amount of air coming in. I think the motor is just pulling that much more.

[rojoracing53]

Originally Posted by mgentz

Ok...38 pilots helped but its still not perfect. I think I will need 35 or smaller. See my post #581....

Given this I may need to stay around stck jetting. Crazy. And I have no restrictions on the amount of air coming in. I think the motor is just pulling that much more.

If those pilots get any smaller they're going to plug up during gas stops

[mgentz]

I know right, but the results don't lie

[tubarney]

I had 40 pilots, 3 washers and 115 main. It would bog and stall. It needed no choke. Choke would make it stall.

I switch up to 2 washers and 110 main. I could ride it and start like normal.

Main jets and washers effect idle and low throttle settings.

keep the 40, change the main and needle position.

[tubarney]

I'm trying out a different cct to see if that fixes the noise. If not I will switch the cams back because it was fine before.

It sounds like this.
http://www.youtube.com/watch?v=WWvtRoj_iHU

[mgentz]

when I switched down to the 38 Pilots I also changed the main jets to 100. It does seem to start better but I still need to give it a little throttle end turn up the idle rpm adjustment just a tad.

[tubarney]

Originally Posted by mgentz

when I switched down to the 38 Pilots I also changed the main jets to 100. It does seem to start better but I still need to give it a little throttle end turn up the idle rpm adjustment just a tad.

That jetting has probably made it lean. i bet it's going to be somewhere in the middle. If the engine is working fine mechanically, just take it to the dyno and get the tuning fixed.

I found my problem, timing was out.

[tubarney]

That solved that problem. Now I can put in the airbox and get it to the dyno on Tuesday. I am busy Monday.

[subxero]

Originally Posted by mgentz

when I switched down to the 38 Pilots I also changed the main jets to 100. It does seem to start better but I still need to give it a little throttle end turn up the idle rpm adjustment just a tad.

Again, the main jet has next to nothing to do with start up and idle. Sure you might get a minor effect but you are using the wrong jet to tune the idle circuit. I went from 118's down to 115's, 112's and finally ended up at 110's while running a #40 pilot. At no point did changing the main effect my start up or early position throttle. It will effect your 1/2 throttle and beyond though and you will have to adjust needle height to compensate, needle height will then effect early throttle position which will then need fine tuned in the end

You need to be careful as the main jet primarily controls 1/2-WOT throttle and right now you have not had a chance to run your bike with the throttle in those positions therefore you are making changes to a circuit you know nothing about yet Not saying the 100's will be to lean but i would rather be a little cautious as the results of being to rich are not near as dangerous as being to lean the first time you actually crack the throttle wide open.

the pilot jet and idle screws are intended to tune Throttle position from idle - 1/8th throttle with some tiny overlap from the actual needle, needle height and it's taper. The needle when set correctly keeps the main jet almost entirely out of the equation at those throttle positions. The needle essentially plugs the main jet circuit and does not unplug that circuit until the throttle is cracked and the needle is lifted. The higher wider parts of the needle control the throttle at 1/8 - 1/2 throttle, the high angle quick taper controls 1/2 - 3/4 throttle and then the straight thin part to the tip works with WOT.

I do think your jetting is not perfect obviously for how your bike is currently running but i also think it is potentially the secondary problem. Something else is not working properly and changing the jetting is simply compensating for that problem.

^Just a guess because i can't imagine the bike would be so hard to start otherwise.

I think you are running pods filters, right? Did you soak them with filter oil or anything which might prevent air flow?

[mgentz]

I have a panel filter in a modified airbox.

[subxero]

Originally Posted by mgentz

I have a panel filter in a modified airbox.

ahh i c

yeah in that case your jetting will be closer to stock but it still doesn't explain why it is so damn hard to start

[mgentz]

Originally Posted by cuong-nutz

Your starter jets were not clogged?

http://www.ninjette.org/forums/showthread.php?t=123000

Hook back up the stock CDI if you haven't and see how the bike runs.

How do your spark plugs look? Any fouling?

Are you positive that throttle plates are not stuck slightly open with the MP throttle?

Choke plunger isn't sticking?

And the winner is....holy ^@$&

So based on this tip I plugged back in my stock CDI. She fired up without a hint of issue. Thank you @cuong-nutz

Lessons learned on this:

1) don't trust what a "tuner" puts in for a map. The maps loaded by jetting pro had WAY too much advance for idle rpms
2) my "ticking" was actually pinging at idle, this explains why it only went away up at stratospheric rpms


Now she runs, starts and sounds like a champ...but I have to fix my jetting so it's back to:

40 pilot
2 turns on the screws
112 mains

@tubarney of all those BR-Tis maps you posted, which one are you using?
@Racer x which one are you using or what would be a good map?

I cannot wait to see how she runs now that I am finally getting to the bottom of all this crap. However, I really do hate working on the carbs while they are in the bike and yes I have special tools. Those CR carbs with the cap on the bottom would sure make this easier. Hmmm?