250R NA Build - Ultimate

[mgentz]

nothing has been found wrong so far. In fact everything they have checked they said I did it correctly. However they did say that I should've replaced the cam sprockets when I replaced the cam chain and that the cam chain was riding a little high on the sprockets due to this. Therefore I'm going to have them replace the cam sprockets but I don't think that's the issue its just preventative. We'll see what they come up with. They're going to keep working on it.

[mgentz]

They too wonder about the tight spots when turning the crank. They are looking into the bottom end.

[tubarney]

Originally Posted by mgentz

They too wonder about the tight spots when turning the crank. They are looking into the bottom end.

after putting mine together I would say that if there is tight spots without the cams installed than there is a problem. Before I installed the cams there wasn't anymore resistance anywhere.

[mgentz]

Do you think its possible that the valve springs given to me are too strong and somehow causing this? Any chance someone has stock cams they are willing to give or sell me?

So far the dealer has no definite idea. They will continue all day tomorrow again....

[tubarney]

Originally Posted by mgentz

Do you think its possible that the valve springs given to me are too strong and somehow causing this? Any chance someone has stock cams they are willing to give or sell me?

So far the dealer has no definite idea. They will continue all day tomorrow again....

Yes they could actually, I forgot about these. Maybe they are creating too much seat pressure for the camshafts to push them. Only 1 way to know for sure. Do you still have the stock springs? Take both to someone that does heads. They will have a spring machine that measure's how strong they are.

Try Ebay for camshafts, also you can find stock springs on there for cheap as.

I think I found my problem. Can anyone tell me if the smaller second hole faces the front or back of the bike. It is the vacuum piston out of the carb.

[subxero]

^ not sure how much it matters but the original larger vac hole is on the side closest to the engine, NOT the side closest to the airbox. Do you even have another hole drilled in the slide? i can't see it. But yeah, hole goes towards engine

[subxero]

Originally Posted by tubarney

the jetting is all over the place.

You need to give it a little bit of throttle to start it. It idles well after that with no throttle at 1400rpm. But as soon as you try and raise the revs and give it some throttle the revs only get to about 4k then don't go anywhere and it will stall. At least the thing starts and idles. Just the jetting needs fixing.

I'm guessing the pilot is good. Probably just main and washers need changing. 1/8 throttle will raise revs to 4k, but anymore throttle after that and it won't be happy.

I am going to pull spark plugs and check if I'm rich to make sure.

I think I'm just going to take it the dyno tomorrow and get it tuned. Will save me stuffing around with it.

if you keep blipping the throttle can you get the revs past 4k and then get it to stabilize with steady throttle at 1/2 or more one you get to a higher RPM?

What are your current jetting settings?

[tubarney]

I solved the problem. I think one of the boots was installed incorrectly.

The rings are sealed. It has stop smoking. I was a bit worried at first because it was smoking like crazy.

When you rev the bike, the revs drop below idle then return to idle after about 2 seconds. I spoke to my tuner today. I am dropping it off tomorrow to get it sorted. I'll post the dyno results along with a video.

[Racer x]

Drilling a second small hole next to the large one will make the slide move faster. It will only go in the carb one way.

The valve springs can't be causing a no start. Can they?

[tubarney]

Originally Posted by Racer x

Drilling a second small hole next to the large one will make the slide move faster. It will only go in the carb one way.

The valve springs can't be causing a no start. Can they?

I'm not sure if it was the boot. I also removed a washer from the needle. I'm thinking it's rich so I'm going to check the plugs and make some adjustments before I take it down to the dyno, cheaper that way. Its dropping below Idle after blipping the throttle so I think its rich. All I did today was pull the top of the carbs and removed a washer, then it was accepting throttle and reving like normal, only the revs were dropping below idle when i let of the throttle, a fair bit to, to the point were it would stall.

I don't think the valve springs are the problem with Mike's bike. I was thinking before that in theory I guess the camshafts would only output a certain amount of force. If the seat pressure created by the spring was higher then normal it could cause them to only open part of the way or not at all also causing the timing to be out.

But how would the camshafts spin if they could not open the valves.

I really have no clue why. If you have oil pressure, compression, correct timing and valve clearance, spark and fuel I have no idea.

[Racer x]

The thing about machines is. The answers always come.

[mgentz]

Originally Posted by tubarney

I'm not sure if it was the boot. I also removed a washer from the needle. I'm thinking it's rich so I'm going to check the plugs and make some adjustments before I take it down to the dyno, cheaper that way. Its dropping below Idle after blipping the throttle so I think its rich. All I did today was pull the top of the carbs and removed a washer, then it was accepting throttle and reving like normal, only the revs were dropping below idle when i let of the throttle, a fair bit to, to the point were it would stall.

I don't think the valve springs are the problem with Mike's bike. I was thinking before that in theory I guess the camshafts would only output a certain amount of force. If the seat pressure created by the spring was higher then normal it could cause them to only open part of the way or not at all also causing the timing to be out.

But how would the camshafts spin if they could not open the valves.

I really have no clue why. If you have oil pressure, compression, correct timing and valve clearance, spark and fuel I have no idea.

Yep...grasping at straws here but this is a mystery. Gotta think of everything.

[tubarney]

Originally Posted by Racer x

The thing about machines is. The answers always come.

will be very interesting to see what it is.

I have a question.I just pulled a spark plug and it black as all f***. How many Jet sizes should I go down if it is so rich that it stalls? 1 or 2. I can't even make it around the block.

I am running a 40 pilot and 115 main, 2 washer under each needle. I'm pretty sure when I removed a washer it help a lot. It idles well, just doesn't handle throttle.

I am thinking 110 main, back the pilot screw back 1 turn.

[Racer x]

110 for start

[mgentz]

could I be giving it too much fuel to start?

42 pilot
FP needle 4th position
118 mains
screws out 2.5 turns

[mgentz]

everyone told me to go richer....but I think it would still start....just run bad.

[tubarney]

Originally Posted by mgentz

everyone told me to go richer....but I think it would still start....just run bad.

It should start with the larger jets. Mine starts really easy.

Pretty much any mixture of fuel and air when compressed will explode and start the thing. If you tried starting fluid and it didn't start the jetting won't matter.

There's no harm in trying but. If you can get a 40 pilot and a smaller main then maybe try that and see if it works.

[bruce71198]

Originally Posted by mgentz

everyone told me to go richer....but I think it would still start....just run bad.

42 pilot is too big/rich. remember your port work and large bores have little to do with pistons moving at a slow speed. The amount of air the throttle blade allows in, at idle, is the same as on your stock engine while cranking to start.

[subxero]

Originally Posted by tubarney

will be very interesting to see what it is.

I have a question.I just pulled a spark plug and it black as all f***. How many Jet sizes should I go down if it is so rich that it stalls? 1 or 2. I can't even make it around the block.

I am running a 40 pilot and 115 main, 2 washer under each needle. I'm pretty sure when I removed a washer it help a lot. It idles well, just doesn't handle throttle.

I am thinking 110 main, back the pilot screw back 1 turn.

I'm no pro at plug checks and have only ever done them on my 2stroke dirtbike. And for that i was always taught that plug checks are really only good for reading main jetting and that in order to get a good reading, you need A) a brand new plug, and B) to kill the engine after your WOT run to prevent other circuits from having an effect on the plug after the WOT to get a proper reading for the main jet? On a dirtbike this is probably non issue but don't think it would be wise to kill the 250 at WOT? IDK

As far as your jetting again once you start changing one circuit others will run differently as well. I have practically a blog about my jetting over the past 2 weeks here
http://www.ninjette.org/forums/showthread.php?t=131399

if TL-DR here is summary
On a stock engine, with pod filter, block off plate, full race exhaust, and BRT tis programmable advanced timing I started at 40 pilot, 3 washers under needles, and 115 main. WOT was rich, mid throttle felt ok, idle and 1/8th was good. I had 118 main, threw it in for fun. Bike still ran, WOT was very rich, mid throttle felt good, 1/8 throttle felt fine. Ordered and went to 112 main and my mid throttle was lean WOT was improved, Shimmed with 5 washers ~0.125" raised height with 5 washers and i also put in 110 main jets. 1/2 throttle feels great, WOT still feels slightly rich but much improved up to 12k rpms but leans out after that. But now my 1/8th throttle is rich. Going down to #38 pilot and probably 108 mains next weekend

Sounds like your main is rich but hard to tell with out me riding it and with a rich main your mid throttle and revs can feel decent as the rich main has some overlap with the mid throttle and mid rev response. Perhaps why removing the washer felt better, because the rich main has the mid throttle slightly rich as well.
So once you start going more lean with the main jet you will notice your mid throttle will start to suffer and lean out and you will have to go back in and most likely add washers to get it back to where it needs to be. Once you add washers you will also notice that your 1/8 throttle is suffering because it is to rich because of new needle height. You will then have to go down a pilot jet.
See how it all feels again and with any luck good. Set idle mixture screws and you should be gold!

[tubarney]

Originally Posted by bruce71198

42 pilot is too big/rich. remember your port work and large bores have little to do with pistons moving at a slow speed. The amount of air the throttle blade allows in, at idle, is the same as on your stock engine while cranking to start.

Thats what I'm thinking. Also the longer duration cams are going to pull less air through the engine at low revs than the standard cams due to lack to intake pressure.

I am going to go back to the settings for a stock engine/no airbox. 110 main, 2 washers and turn the pilot screws back 1 turn to about 1 1/2 turns out. I think this will help a lot.

If I can get it just about right I can take it to get tuned. Will save me some cash.

[bruce71198]

[QUOTE=tubarney;688295]Thats what I'm thinking. Also the longer duration cams are going to pull less air through the engine at low revs than the standard cams due to lack to intake pressure.


Brad, I love talking engines, so take this lightly, I'm not challenging your opinion.
More cam duration will allow more valve open time, increasing the amount of air that the atmospheric pressure can push into the cylinder. This is especially true at lower engine speeds. Its the cam timing and overlap that will effect the actual cylinder filling. As far as intake pressure, it is always whatever atmospheric pressure is on a given day and regulated into the engine by the throttle valve.

[mgentz]

[QUOTE=bruce71198;688306]

Originally Posted by tubarney

Thats what I'm thinking. Also the longer duration cams are going to pull less air through the engine at low revs than the standard cams due to lack to intake pressure.


Brad, I love talking engines, so take this lightly, I'm not challenging your opinion.
More cam duration will allow more valve open time, increasing the amount of air that the atmospheric pressure can push into the cylinder. This is especially true at lower engine speeds. Its the cam timing and overlap that will effect the actual cylinder filling. As far as intake pressure, it is always whatever atmospheric pressure is on a given day and regulated into the engine by the throttle valve.

agreed. that's why with the bigger cylinder (265 i.e. larger pump) and the longer duration cams I thought too that it might need more. I can go back to the 40's and down to 110/112 mains and drop the needle to lean it all out, but I still thought it would start!

I have been way off on jetting before and things still started!

[bruce71198]

[QUOTE=mgentz;688323]

Originally Posted by bruce71198

agreed. that's why with the bigger cylinder (265 i.e. larger pump) and the longer duration cams I thought too that it might need more. I can go back to the 40's and down to 110/112 mains and drop the needle to lean it all out, but I still thought it would start!

I have been way off on jetting before and things still started!

These carburetors are by far the pickiest I have ever worked on ! I highly recomend CR's.

[Racer x]

I love the CR carb. But if it won't start with starting fluid there is something wrong outside the carb tune.

[bruce71198]

Originally Posted by Racer x

I love the CR carb. But if it won't start with starting fluid there is something wrong outside the carb tune.

In my experience if you have an over rich condition, adding fuel (starting fluid) wont help. I love being an "arm chair" mechanic. LOL

[mgentz]

Update. Upon one of their attempts at starting the bike it backfired hard enough to break teeth off the bronze starting gear. The tech had told me that they already tried to "loosen" the gear because they thought it was hanging up and that this confirms it. I think he's partially right because it is supposed to free spin in that direction...but....

It would be weird if this is what is causing the failure to start. The thought is that if this is hanging up, it could be putting too much resistance on the motor.

Still investigating everything. ..

[Racer x]

Originally Posted by bruce71198

In my experience if you have an over rich condition, adding fuel (starting fluid) wont help. I love being an "arm chair" mechanic. LOL

then the plugs would be dripping wet.
the arm chair thing is fun when its not your head banging on the floor. LOL Mike I feel your pain.

In 2010 I was running in the top ten in the points championship at Maxton. I blew a hole in my piston really good. I had three weeks to turn the bike around and race again.

I replaced the top end of the motor and it would not start, I tried everything. Took the motor apart five times.I was up till four AM. I figured I bent the crank and the pick up was shifted, I have a motor 150 miles away. I figured I would get a couple hours sleep and drive 300 mile and go get it.

When I came to bed I took a shower. But fifteen hours of fooling around with gasoline will not just wash off. I said to my wife I was sorry about the smell, She said what smell?


Gas that has no smell will not burn. I ran to the garage. Sure enough I was using six month old race gas. The new fuel was in a cooler. The fuel I was using was in a matching can from under the work bench.

I sprayed some new fuel in the engine and it fired right up.

[lgk]

Originally Posted by mgentz

Update. Upon one of their attempts at starting the bike it backfired hard enough to break teeth off the bronze starting gear. The tech had told me that they already tried to "loosen" the gear because they thought it was hanging up and that this confirms it. I think he's partially right because it is supposed to free spin in that direction...but....

It would be weird if this is what is causing the failure to start. The thought is that if this is hanging up, it could be putting too much resistance on the motor.

Still investigating everything. ..

if it kind of started and then died i could see this being the culprit.

[mgentz]

It starts and instantly dies

[Racer x]

Then what? Can you repeat that over and over ? Is it like it just runs till you let go of the starter button ? It will it sputter any after you let go of the starter button?

[mgentz]

my best description is that it will run with the starter button. it will also run with the starter button and spin up to 3000 rpm and then die. I can do this again and again.

[cuong-nutz]

When I started my bike that was the issue I was having and then I kept giving it some throttle to keep it running until it could stay running without throttle. My exhaust ports are all gummed up with carbon/oil right now.

[tubarney]

[QUOTE=bruce71198;688306]

Originally Posted by tubarney

Thats what I'm thinking. Also the longer duration cams are going to pull less air through the engine at low revs than the standard cams due to lack to intake pressure.


Brad, I love talking engines, so take this lightly, I'm not challenging your opinion.
More cam duration will allow more valve open time, increasing the amount of air that the atmospheric pressure can push into the cylinder. This is especially true at lower engine speeds. Its the cam timing and overlap that will effect the actual cylinder filling. As far as intake pressure, it is always whatever atmospheric pressure is on a given day and regulated into the engine by the throttle valve.

Yes your increasing the total amount of flow enter the chamber, but not the rate of flow, or how much flow per second. Which is what larger jets are for.

With the longer duration cams. Your intake and exhaust valve is kept open for a longer period of time which in turn drops cylinder pressure and hence intake pressure at all revs. At high revs the late intake closing helps because there is enough intake pressure to generate enough momentum on the intake air/fuel to fill the cylinder even though the piston is rising in the cylinder. At low revs there is not enough pressure, hence the intake air/fuel does not have enough momentum so therefore gets pushed back out the intake.

It is not the amount of the air/fuel that passes through the carb that is important; this does not change much at. It is the amont of air/fuel that gets trapped in the combustion chamber.

It has to do with the way air reacts in a cylinder head. its one of the reason a longer duration cam will hurt your idle. A longer duration cam does not give you more power a low revs than a shorter duration if they have the same lift.

Basically you make more a high rpm, but less at low rpm.

If this was a car engine, try getting a 280 degree cam to run well below 4k. Its not gonna happen. Only difference between the ninja and a car engine is the rev limit which is why I can run one. the 14k rpm limit helps to generate enough cylinder pressure.

You don't need bigger jets because of a longer duration camshaft. If anything you need to lean the idle out while keeping the mains rich. Only to help with idle and low rev performance

[tubarney]

Originally Posted by mgentz

It starts and instantly dies

Better than nothing

What valve clearances are you running. I'm using .15mm-.19mm intake and .20mm-.24mm exhaust.

[tubarney]

Also, checking your sparks plugs works on 4 strokes the same as it does on 2 strokes. The only difference between the 2 is the way air enters and leaves the combustion chamber. Other than the fact 2 strokes fires 2 times for every 4 stroke spark.

[tubarney]

I changed to 110 main. My pilot screws were not even so I fixed them. They are 1 1/2 turns out.

It goes a lot better now. At least I can ride it to the dyno now.

I can tell if has a lot more power than before. It pulls hard with very little throttle.

I will try to get to the dyno tomorrow for a tune, might have to wait till Monday.

[mgentz]

New update: dealer believes the motion pro switch was installed wrong. I have asked jason for his help.

Also when it runs he says there is a lot of top end noise. @tubarney did yours make a lot of noise on startup?

I cannot imagine why but by now it might need oil!!

[rojoracing53]

I'll trace the motion pro wires but only if you still need me to. There's no point in tearing my bike apart if you don't still need me to.

[tubarney]

Originally Posted by mgentz

New update: dealer believes the motion pro switch was installed wrong. I have asked jason for his help.

Also when it runs he says there is a lot of top end noise. @tubarney did yours make a lot of noise on startup?

I cannot imagine why but by now it might need oil!!

Mine is making some noise too. I think its just the camshafts breaking in. Makes sort of a tapping noise. The noise it is making doesn't seem bad. Pretty much the same noise that occurs with an engine with noisy lifters. I am going to flush the oil after I ride it once more tomorrow.

I took it for a good half hour ride today to break it in. It was still smoking a little as of yesterday but it has completely stopped now. No leaks, no lights, same amount of oil as before.

Dyno Monday 27th May.

[tubarney]

I took it for another ride today. Absolutely thrashed it and it was fine.

The noise from the head is still there. Hopefully it will goes away when I change the oil tomorrow. I'm thinking it will because it sounds exactly the same as noisy lifters and if you have seen the oil inside it, it is all black and weird from the the assembly paste, so some clean oil should fix the problem.

You want to change your oil after a couple of rides. Basically all the metal particles that are going to break off are going to do so in the first hour or 2 of operation.

Also, the brand new camshafts are coated in nitride to help oil stick to them. This has to break off and wear away so your oil is going to be full of it.

Here's what it sounds like. The engine is sort of cold so I didn't want to give it much throttle. I still have the stock gauges, I'll get around the koso install after I'm done stuffing around with the engine.
http://www.youtube.com/watch?v=XDbO7eESBJ8