Yoshimura Mikuni TMR-MJN32 Carburetor for the Ninja250R

[lgk]

Originally Posted by fordendk

You are probably right. The 4hp was just what one of the guys selling it here told me so he would probably tell me anything to get a sale. I will probably go for it anyway and also go for the 282cc sleeves, JE pistons and cam once I get a week to do it. Anything for a laugh I guess. The only worry then will be heat so may also need to install a larger radiator, sub-radiator or different coolant... any ideas? Pretty hot here year-round.

BTW nice Zappa photo Jiggles. Ever listened to Zappa at all ?

a thermobob might help the efficiency of the cooling system.

once you get everything else sorted.

[Jiggles]

Here's my dyno with an area p race pipe and k&n intake. As you can see its far from being appropriately tuned. Since this dyno I've smoothed out the **** spot in the lower rpms but I'm still way too rich EVERYWHERE. I'm waiting for my relay to come in so I can wire up my O2 sensor and dial in my jetting.

The ideal AFR ratio for max power is about 12.8 so that's what I'm shooting for. I'd imagine once I'm able to attain that I can get at least 31hp at peak

[fordendk]

Originally Posted by Jiggles

1 foot pounds = 1.35581795 newtons meter

Thanks for the physics lesson... maybe I should consistently use the term "torque curve" to keep you happy but we did get some nice artwork on this thread so I guess that's a win-win.

The point is that using these carbs the bike is a lot more responsive, accelerates harder, is quicker and pulls away from my buddies bike easily even though the maximum HP of his bike dyno'd slightly higher on the same day on the same machine with the same idiot dyno'ing it. We were a little confused at first. Perhaps you can explain why.

[Jiggles]

Final drive ratio perhaps? Maybe he has different gearing? Though changing gears will not alter your torque or HP it will change your rate of acceleration

Also max hp isn't the end all be all, if your bike is producing a consistant and flat torque curve and your buddies bike has a very peaky torque curve then he may have higher hp at that top rpm but you may have more hp throughout the lower rpms

[lgk]

Originally Posted by jiggles

here's my dyno with an area p race pipe and k&n intake. As you can see its far from being appropriately tuned. Since this dyno i've smoothed out the **** spot in the lower rpms but i'm still way too rich everywhere. I'm waiting for my relay to come in so i can wire up my o2 sensor and dial in my jetting.

The ideal afr ratio for max power is about 12.8 so that's what i'm shooting for. I'd imagine once i'm able to attain that i can get at least 31hp at peak

what jets did you end up using?

[Jiggles]

I haven't changed anything yet, I'm still at 118 keihns, gna do 115s since 112s are too small

[fordendk]

Originally Posted by Jiggles

Final drive ratio perhaps? Maybe he has different gearing? Though changing gears will not alter your torque or HP it will change your rate of acceleration

Also max hp isn't the end all be all, if your bike is producing a consistant and flat torque curve and your buddies bike has a very peaky torque curve then he may have higher hp at that top rpm but you may have more hp throughout the lower rpms

Both bikes have standard gearing and are also using the same tires. After we did the dyno job he also went ahead and put the TMR carbs on his bike a couple of weeks back. We tested subsequently (with a few straight line drags). Both bikes now seem to have very similar pull/acceleration. It surprised me that we were so close to each other during these drags as I thought that one bike or another would be at least slightly different. I am quite a bit heavier than he is too (about 20kg... he is Indonesian and I am a westerner). The only differences between these two bikes is that mine is 2012, his is 2011, he has a locally made R9 exhaust and I have an Arrow titanium exhaust. We didn't dyno his bike again yet.

Therefore the difference probably is the torque curve due to the carbs. We could not test to top speed due to the roads around here. What you said just above "max hp isn't the be all and end all" is exactly what I meant to say.

[Jiggles]

Originally Posted by fordendk

Therefore the difference probably is the torque curve due to the carbs. We could not test to top speed due to the roads around here. What you said just above "max hp isn't the be all and end all" is exactly what I meant to say.

Lol yes, but, a flat torque curve with the highest max hp is

Like say, if you tuned for just max hp, highest torque at the highest rpm, didn't care about the torque curve at lower rpms then it would be feasible for another bike with a flat torque curve to be faster at the lower but slower at the higher. It would have to be 2 very different setup bikes for it to be very prominent, like say a bike set up for the highest top speed possible versus a bike set up for the track

[Nemesis]

Originally Posted by fordendk

Ninja Chris asked me to update this thread with Dyno results etc. Here is the Dyno after the carbs were fitted and re-jetted by the guys at the dyno shop:



I was not impressed with the guy doing the Dyno work as he was not rolling the throttle on smoothly but pinging it every time. This results in drowning the engine in lower rev range (see the dip from 6XXX -> 7XXX). Obviously he had no idea. Anyway the HP is now around 30 as expected. The main improvement same as the feel of the bike now is improved acceleration due to improved torque.

As you can see the torque is a much improved (19.88Nm pulling from 7XXX through to around 11XXX before dropping off vs the supposed standard of Max 18.4Nm at 10,000).

Next step for me is to get a port and polish job done on the heads. Here it costs about $150 and is low risk. The mechanics here told me that it will add around 4-5Hp to the bike as it is.

Hahaha...This product fails.

And the main reason why I said this product was a waste (considering the price and all) is because I knew in advance the 300 was coming out.

[lgk]

they are good carbs,
its just the fact that they are wayyy overpriced.

if they were 3-$400 they would be worthwhile, but not $900...

[Nemesis]

It produced 29HP and they're still good? You can get that using a jetkit @ $80

[lgk]

Originally Posted by Nemesis

It produced 29HP and they're still good? You can get that using a jetkit @ $80

yeah they are good, its just he didn't do enough tuning and from what i heard he also still had the stock airbox.

if you don't do enough to make it work, then i agree that its not worth it.

[Nemesis]

Originally Posted by lgk

yeah they are good, its just he didn't do enough tuning and from what i heard he also still had the stock airbox.

if you don't do enough to make it work, then i agree that its not worth it.

How do you know they're good? Do you own one? If so, put up some numbers.

But I agree at that cost you might as well sell your bike and buy a 300.

[lgk]

Originally Posted by Nemesis

How do you know they're good? Do you own one? If so, put up some numbers.

But I agree at that cost you might as well sell your bike and buy a 300.

i do not own one, but RacerX uses similar FCR carbs with good success.
was going to upgrade to FCRs as well, but fuel injection was actually more cost effective for me, so i went with that option.

like i said they are priced way out of proportion, and are not a magical performance booster.

[tubarney]

Originally Posted by lgk

i do not own one, but RacerX uses similar FCR carbs with good success.
was going to upgrade to FCRs as well, but fuel injection was actually more cost effective for me, so i went with that option.

like i said they are priced way out of proportion, and are not a magical performance booster.

fi a cheaper option? The keihin CR carbs can be found for 450 online and sh*t all over fi. The carbs racerx uses are CR specials, not FCR.

[lgk]

Originally Posted by tubarney

fi a cheaper option? The keihin CR carbs can be found for 450 online and sh*t all over fi. The carbs racerx uses are CR specials, not FCR.

i got the carbs mixed up but the cr specials, IMO, are better than the Yoshi carbs... in price and performance. i wanted to try the yoshi carbs but the cost put me off.

in the end, EFI was more cost effective since i didnt have to buy custom inlets/fittings, my EFI auto tune so i save on dyno time.
they deliver a perfect air fuel ratio with two maps at the flip of a switch, and give both fuel economy and power. have instantaneous response, and ignition advance is tunable. i save fuel costs as well. overall it was a win win.

to have similar performance you must buy the
carbs $450
custom fittings $100
jet kit $50
BRT-TIS $200
dyno $100

the difference is not as great as you think, but with the yoshi carbs it would have added another $500

i love carbs, but paying $500 or even $1000 on carbs alone when they are not the bottleneck is wasteful. like nemesis said he can rejet his bike and get the same HP for $10.

[Racer x]

I would have to second all of that. The stock carbs are really good. New pilot and main jets jets cost 25 bucks and a couple washers and you are good to 35 hp!

The CR are great because you can change jets and needles at the track. And they are a little bigger. But there is no real power increase with just carbs. Power comes from compression and porting.
EFI is the way to go. I had these carbs before FI came around Ina. Affordable package so I am sticking with them for now.

The Yoshi carbs are more money but are better carbs come with aluminum velocity stacks and an a throttle tube. But cost 500 bucks more.

[tubarney]

450 include fittings, they aint custom. But I see your point about the gains vs money spent. Have you had it put on the dyno to see how much hp or torque you got from your FI conversion?

Stock carbs should only be upgraded to support other mods. I think it is a waste if you are not going to do any porting, compression changes. Theres plenty of other ways to get Hp/torque without changing carbs. Cams for example.

[lgk]

Originally Posted by tubarney

450 include fittings, they aint custom. But I see your point about the gains vs money spent. Have you had it put on the dyno to see how much hp or torque you got from your FI conversion?

Stock carbs should only be upgraded to support other mods. I think it is a waste if you are not going to do any porting, compression changes. Theres plenty of other ways to get Hp/torque without changing carbs. Cams for example.

i have not had the time to do a dyno test yet, i plan to soon.
currently, i'm trying to make different intake pipes to test the intake harmonics on the bike.

due to me not really having any motor upgrades, i'm expecting power levels to be real similar to a well jetted carb with the rich map. the only advantage being faster response and flatter power band. and about 1-2hp less on the self tune map.

the injectors and pump i have will support from idle to 45hp easily, so it'll provide enough fuel if i over bore or decide to transplant a bare 300 engine into my bike.

don't get me wrong, my reasons for installing EFI on my bike was purely for fun and convenience, not power really.

i'll look for power after i install cams, pistons, and my new intake.

[choneofakind]

Originally Posted by lgk

currently, i'm trying to make different intake pipes to test the intake harmonics on the bike

Let me know how that goes, and I'll copy your intake runner length if it is significant enough to feel on the butt dyno. I'm still sorting out my fuel/ignition timing/warm-up maps.

[lgk]

Originally Posted by choneofakind

Let me know how that goes, and I'll copy your intake runner length if it is significant enough to feel on the butt dyno. I'm still sorting out my fuel/ignition timing/warm-up maps.

i got aluminum pipes from 2-4-6 inches in length, silicone couplers, both new and old gen boots, filter support bracket, zip ties, and a four piece velocity stack.

just need some free time to see what works best, should be fun.

[tubarney]

Originally Posted by lgk

i have not had the time to do a dyno test yet, i plan to soon.
currently, i'm trying to make different intake pipes to test the intake harmonics on the bike.

due to me not really having any motor upgrades, i'm expecting power levels to be real similar to a well jetted carb with the rich map. the only advantage being faster response and flatter power band. and about 1-2hp less on the self tune map.

the injectors and pump i have will support from idle to 45hp easily, so it'll provide enough fuel if i over bore or decide to transplant a bare 300 engine into my bike.

don't get me wrong, my reasons for installing EFI on my bike was purely for fun and convenience, not power really.

i'll look for power after i install cams, pistons, and my new intake.

I have a tuned stock carb with a full stainless steel exhaust. It makes peak torque slightly above 9000 rpm for comparison. I have a dyno graph that I can post when to get around to dyno-ing it.

The only reason I would go EFI is for the convenience. Also if the temperature outside regularly drops below freezing.

My 2 cents on making more power. Don't buy pistons unless you bore it out to 282cc. Go for a porting job (they don't polish anymore) by someone who knows what there doing. 5hp gain over 2hp gain (265cc bore kit). Not to mention pistons end up being more expensive after boring, re-sleeving and balancing.

And if you do bore it out. I talked to sudco and they have even had people order the Keihin FCR 35 mm for Ninja's. Not sure how much they bored it out but, he didn't say.

[lgk]

Originally Posted by tubarney

I have a tuned stock carb with a full stainless steel exhaust. It makes peak torque slightly above 9000 rpm for comparison. I have a dyno graph that I can post when to get around to dyno-ing it.

The only reason I would go EFI is for the convenience. Also if the temperature outside regularly drops below freezing.

My 2 cents on making more power. Don't buy pistons unless you bore it out to 282cc. Go for a porting job (they don't polish anymore) by someone who knows what there doing. 5hp gain over 2hp gain (265cc bore kit). Not to mention pistons end up being more expensive after boring, re-sleeving and balancing.

And if you do bore it out. I talked to sudco and they have even had people order the Keihin FCR 35 mm for Ninja's. Not sure how much they bored it out but, he didn't say.

the EFI does start great in the cold, i had an easy start and rode off immediately as low as 17f(-9C).
coupled with the thermobob, i still get 70mpg in cold weather, about 10mpg better than my carbs.

i realize the pistons are a large investment, thats why fitting 300 motor is appealing to me. if the price gets within $300 of the total cost of piston installation, i'll most likely experiment with the new motor.

[tubarney]

A Ninja 250r with a ported head and camshaft will out perform a stock 300 motor with stock exhaust or slip on. So keep that in mind, unless you can fit your aftermarket full exhaust to it so you don't have to spend another 700+ on one then converting to a 300 motor would be an interesting avenue to go down.

I'm interested to hear how you go with experimenting with different intake pipes. Something I think the EFI kit could benefit from because there is a reason why EFI bike's aren't putting out more power than carby ones like they should.

[lgk]

Originally Posted by tubarney

A Ninja 250r with a ported head and camshaft will out perform a stock 300 motor with stock exhaust or slip on. So keep that in mind, unless you can fit your aftermarket full exhaust to it so you don't have to spend another 700+ on one then converting to a 300 motor would be an interesting avenue to go down.

I'm interested to hear how you go with experimenting with different intake pipes. Something I think the EFI kit could benefit from because there is a reason why EFI bike's aren't putting out more power than carby ones like they should.

i think the factory EFI 250s put out less power because of a few things.
-the ecu controlling the secondary butterflies helps idle, but disrupts airflow at the top end.
-tuning is meant for emissions and not performance
-sensor placement is not optimal for response.
-no closed loop or wideband o2 usage
-the cooling system doesn't let the bike warmup, so the fuel map is distorted
-the throttle opens too slow.

there's probably more issues, but they are all problems i corrected on my bike.
the hardware for the most part seems good, its mostly a tuning issue.

i have some ideas on the exhaust, and most likely i'll be able to recoup the some of the cost by selling my existing exhaust. once i go the path of 300 i wont be looking back.

[tubarney]

have you looked into how much a 300 motor will cost?

[lgk]

Originally Posted by tubarney

have you looked into how much a 300 motor will cost?

been scouring the auctions for wrecked ones.

haven't seen one yet...

[Somchai]

Originally Posted by lgk

-no closed loop or wideband o2 usage

False, this is NOT for power - this is for emissions.
For real power tuning the o2-sensor and catalytic converter must be taken away.

[choneofakind]

Originally Posted by Somchai

For real power tuning the o2-sensor... /snip/ ...must be taken away.

Uh what? Real power? Real? Compared to what, fake power?

You do know that a wideband sensor used in close-loop mode is really the best way to go if you're tuning a fuel injection system to a fuel ratio other than 14.7 right?

If you're claiming that the O2 sensor restricts flow, then you're wrong. A properly installed O2 sensor does not significantly impact flow. If it does, it's not installed right.

[Jiggles]

Originally Posted by choneofakind

If you're claiming that the O2 sensor restricts flow, then you're wrong. A properly installed O2 sensor does not significantly impact flow. If it does, it's not installed right.

Or your stock pipes are too tiny

[choneofakind]

...or you're using a Thai O2 sensor. Apparently those things make fake power and are HUGE!!

[Somchai]

Originally Posted by choneofakind

...or you're using a Thai O2 sensor. Apparently those things make fake power and are HUGE!!

Ok Prof., in a real tuning you have to consider HC, CO, CO2, O2 and AFR all together. Everything else is hobby only.

[choneofakind]

Yes, but an O2 sensor is still the most important, seeing as hydrocarbons react with Oxygen in a combustion reaction. The other gasses are just present because air is not completely oxygen.

What do they stick in your exhaust pipe at the dyno? An O2 sensor. Sure there's a 4 gas sniffer that reads all 4 gasses, but that one isn't in your exhaust.

[Jiggles]

I'm going to have to side with chode on this one, he used the word 'hydrocarbons' compelling and scientific.

[Racer x]

I think it's time to start a new thread. The Yoshi carbs are to expensive. That's for sure. I am also looking for a 300 engine. It will be a couple years for the price to drop below 2000 dollars. I payed 1500 dollars for an 08 engine in 08 my wife is still pissed. But that is the engine I am having built.

I have played with intake length and exhaust length some . From the little bit I have done I found . The carbs hit the frame with first gen intakes so length is restricted to what I wanted. But I found the length of the exhaust is also important. It would appear the longer you make both the higher the power is on the power band. Not much gain in power. It just moved it up a couple hundred rpm.