I just got this bike and have been getting it going...

it has...
stock carbs...MJ 128
tyga pipes

with the top of the airbox removed...
in 1st gear it accerates almost perfect with power
with but slight hesitation through 9-10k...
the exhaust sound changes...

I am trying to make the bike as much as stock as possible...

I want to run it with the airbox and filter in...to extend its life.

but when I install the airbox lid...with or without
a filter that I made from foam approximately the same width and
sensity as the stock one that came on the bike (it crumbled in my
hand as I removed it...

the bike will not accelerate in first gear....at about 7-8k the sound
changes like the mixture is not correct...

if I add the tyga pipes...do I have to do all that
pluggin the power jet and changing the mj up to 180....

or can I rig it so that it just works normally with a full airbox?

the bike came with the pipes already on it...so I don't have the
stock pipes....have to make it work with the tyga pipes...

I think that they are tuned for a higher frequency than the stock
pipes...

and they also suck more fuel and air....

can I adjust the needles to let less fuel out?

I better e-mail tyga....

I'm sure Mr. Ben (aka StephenRC45) will appear by magic in a moment and give you some clues!!
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Andy.
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Until he does, I'll have a stab!

Fitting the airbox lid restricts the airflow, so the bike will run richer. If it runs properly without, and badly with, then I'd suggest that it has large jets in there to match the extra air flow.

Have you removed the carbs and checked the jet sizes?

If you simply fit tyga pipes to a stock bike with stock air filter, you will probably get away with stock jetting, especially on an unrestricted MC18. Obviously you need to know what's fitted now, and adjust them accordingly once you have the intake setup to your requirements.

The TYGA pipes generally make peak power just below 12000 in my experience - a good thing for engine life!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Ta daaa,

The '18 works very well with the stock filter and lid in place. Like Dave said though the lid does hold it back. Best results have been 4 x 1" holes in the roof of the lid.

Couple this with the wire splice and teh thing will sing along.

The tyga pipes are alittle tricky on the r5k. They give good power and good over rev but are hard to jet the midrange. Normaly with Tyga pipes you will get away with stock jetting (128's) or one size up (130's). The bike should then pull nice and clean from 3k up to 12k making peak about 11,250-11,500. But the bike stumbles at around 7,000 on full throttle then they tend to be a little weak, you can sort that by going up one size again on main jet.
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If I have to take the carbs off once more...

I didn't see you say that you have done the wire splice,you need to find out if it has been done.

thanks for all the posts....

this is what is on the bike...

airbox lid....
my own filter that I made from foam...(any idea where I can buy one)
stock carbs
main jet 128
plus stock power jets
the oil injector is set to be just about 1mm still open when the throttle is closed
tyga pipes



in this configuration...
it doesn't accelerate in 1st gear...
it will accelerate up to about 7000 rpm then crack and sputter...
miss firing and with no power.

if I remove the airfilter, it seems to work a lot better...

I don't understand how the wiresplice can help....
I thought that the wiresplice was just speed restriction in 4,5,6th gears...
how can it have anything to do with accelerating in 1st gear...

I have not done the wire splice yet.

The wire splice has nothing to do with speed on the MC18. It alters the opening time of the RC valve and the ignition curve.
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If I have to take the carbs off once more...

.If it goes better without your foam filter then I would say bin it as it sounds like its restricting airflow.

does it rev Ok in the other gears as I dont understand why it would be bad in 1st but OK the rest of the time

I don't want to trash the airfilter because sucking dirty air will significantly shorten the engine life...

as for the wire splice...

remember I have the R5k which is similar to the mc21....

does the first part of the wire splice control ignition advance and
the second part control speed restriction in 4,5, and 6th gears...?

i was not sure...

following the given guidlines they show that the wire splice for the
88 MC18 is different that the later '89 MC18's

mine is and R5k and I am supossed to follow the MC21 guidelines...

but the PGM-II under the rear left of the seat cowl is different than
that of the PGM-III of the MC21's it doesn't has differently shaped
white and black connectors....

i don't want to destroy my stock airbox cover...

does anyone know where I can get an extra one to cut the holes
in....?

thanks..

tonight running regular 87 octane fuel...
with the top off but my foam pad installed...
it seemed to run just fine...

I would like to get an airbox cover that I can cut the top
completely off of and use the frame to hold in my
home built filter.

also,


I hope it isn't a problem with the PGM
and the throttle position sensor...

dooh!


I will be praying....

mister_robato wrote:
tonight running regular 87 octane fuel...

87?

Don't even like to run mine as low as 97!!
_________________
Andy.
NSR-WORLD.COM

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well...

a lot of people don't even really know what octane rating means...

now if under a load,

if the NSR produces a higher compression than 8 to 1
even up to about 10 to 1

than 93 octane is ok...you won't get pre-ignition...

and since the engine is water cooled...
I am not worried that much about detonation
running the mixture rich as well...

this is a completely stock NSR250r....except for tyga pipes.
and this bike is not for racing, just riding around town
to work and stuff...

the NSR is the street version of the RS250...
which I had before... and ran AV GAS in
100 Low Lead...pre-mix

but of course that engine and carbs are set up totally different than
this one...

I think that the NSR is made to run on standard gasoline in Japan
which might have a rating of 89 or 92 can't remember...

it is slightly higher than the 87 octane rate gasoline in the U.S.