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Open pipe=Must ReJet?

elskipador said:
it'll run better with 140 mains and a 3mm flat washer under each of the needles.
Click to expand...

I will do this mod tomorrow.
The mains, round or hex?
By 3mm flat washers, what do you mean? Would you happen to know the ID and OD of the washer needed?

For the mains, I assume you don't need to remove carbs, but to shim the needles, do I remove carbs?

Any air screw adjusting?

Thanks man....
 
fjackie said:
I will do this mod tomorrow.
The mains, round or hex?
By 3mm flat washers, what do you mean? Would you happen to know the ID and OD of the washer needed?

For the mains, I assume you don't need to remove carbs, but to shim the needles, do I remove carbs?

Any air screw adjusting?

Thanks man....
Click to expand...
3mm in thickness, not ID/OD
 
Yeah i understand that, but im wondering the approx ID and OD of the washer which is 3mm thick. Thanks.
 
fjackie said:
Yeah i understand that, but im wondering the approx ID and OD of the washer which is 3mm thick. Thanks.
Click to expand...

The ID & OD don't have to be exact, other then fit into the slide recess for the needle, and allow the needle to slip through.

I believe on the jet kit that i last used *(EX500) it was a 3/8"od x 1/8"id
 
the main jets are keihin rounds, street jets. the washers can be had a lots of places. any decent bike shop should have them. you'll need to remove the carbs to put both the mains jets in and the wahers. i'd start with the fuel/air screws @ 1.75 turns, though with your set up you may need them @ 2.0 or 2.5 turns out from fully closed.
 
Great. Thanks for the useful info. So Cycle Gear or Road Rider should have the washers for needles? What should i ask for? I was thinking of running to OSH with the measurements you gave:)

I will try this mod tomorrow. Should be straightforward(if the carb boots dont give me hassles like every other bike ive removed carbs from!) Drilling the CA blockoff plates for air screws should be fun...

THANKSx100
 
fjackie said:
Great. Thanks for the useful info. So Cycle Gear or Road Rider should have the washers for needles? What should i ask for?
Click to expand...

"Needle washers."

Don't forget the synch the carbs once all is said and done. Spraying some WD40 down the intake boots can assist when you reinstall the carbs. ;)
 
Let's deal with a few points. There were bikes built with carbs forward and pipes facing back. They never got it working well. Velocity stacks on motorcycle engines allow the incoming air to increase velocity by channeling it into a narrow passage. Simple fluid flow dynamics. They work real well. Intake velocity on a moto engine is all important.

It has been known for decades that open pipes move power around. In the case of most bikes, the less resistance the higher the power range goes. Put an open pipe on a moto and you lose midrange and gain peak HP. Put a pipe with a silencer on and you gain midrange and some peak hp. OPEN pipes just SUCK when it comes to streetability. That's why the only place you see them is the drag races.

fjackie you are giving every motorcyclist a bad name with loud pipes, and what you are really saying is: "FUCK YOU" and " HEY OFFICER HERE I AM!!! GIVE ME A TICKET"
 
PS: anyone want washers PM me you address I have a "few" lying around.
 
fjackie said:
I will run an open pipe for however long I please no matter what anyone says.

Explain the theory of an open pipe being peaky or only making power at a certain rpm and losing power elsewhere. Last time I checked, my tri-oval was an open pipe. Granted, it absorbed sound, but still a big open tube straight down to the collector.

The bike runs fine, BTW.
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You may call it an open pipe but that doesn't mean it doesn't create backpressure. That very fact that it's a pipe means it does have backpressure.
 
Dopesick said:
The ID & OD don't have to be exact, other then fit into the slide recess for the needle, and allow the needle to slip through.

I believe on the jet kit that i last used *(EX500) it was a 3/8"od x 1/8"id
Click to expand...


Use proper aluminum alloy washers designed for use with carb needles. Don't just go down to your local hardware store and use any old washer. Any decent motorcycle shop that sells jets can get the washers for you. Probably have them in stock.
 
afm199 said:
Let's deal with a few points. There were bikes built with carbs forward and pipes facing back. They never got it working well. Velocity stacks on motorcycle engines allow the incoming air to increase velocity by channeling it into a narrow passage. Simple fluid flow dynamics. They work real well. Intake velocity on a moto engine is all important.

It has been known for decades that open pipes move power around. In the case of most bikes, the less resistance the higher the power range goes. Put an open pipe on a moto and you lose midrange and gain peak HP. Put a pipe with a silencer on and you gain midrange and some peak hp. OPEN pipes just SUCK when it comes to streetability. That's why the only place you see them is the drag races.

fjackie you are giving every motorcyclist a bad name with loud pipes, and what you are really saying is: "FUCK YOU" and " HEY OFFICER HERE I AM!!! GIVE ME A TICKET"
Click to expand...

So your streetbikes all have stock exhaust systems, right? Its not like its open header. It goes into a collector and out two tips. Its not as loud as you think. And if it was, I disregard your negativity towards me.:troy
 
fjackie said:
Bone stock 94 cbr F2. The bike ran fine with stock pipe and everything, but I installed an open pipe(stock headers). The bike revs harder but roll ons on the highway seem to suffer just a tad. I know this is lean symptoms, but I can live with it. The question is, can my bike live a little lean without holeing a piston? I am planning on jettin it eventually, just not for a couple months. This bike is not really important to me, its a beater. Never the less, I don't want to chunk a motor.
Click to expand...

You'll hole a piston and chunk your motor for sure.. Beats 1000's of other things you can do to your motor that might be harder to diagnose like a spun muffler bearing or a power band breaking tho.. So I say, give er!
 
ST Guy said:
Use proper aluminum alloy washers designed for use with carb needles. Don't just go down to your local hardware store and use any old washer. Any decent motorcycle shop that sells jets can get the washers for you. Probably have them in stock.
Click to expand...

#4 or #5 washers at the hardware store.. I forget which.. I use them for an interm solution before a needle change.
 
fjackie said:
So your streetbikes all have stock exhaust systems, right? Its not like its open header. It goes into a collector and out two tips. Its not as loud as you think. And if it was, I disregard your negativity towards me.:troy
Click to expand...

My street SV is stock, my VFR has a $1k Two Bros full system which sounds beautiful on the track but is so loud on the street I am probably going to take it off and sell it.

I am old and conservative. You are young and radical. You should have fun while you are young and then when you are my age you can be a PITA stick in the mud crotchety fuck. :twofinger
 
Its a #5 washer. Did the 145 main jet and washers mod today. Runs stronger. I found a beat up Yoshimura can i think i will morph onto the bike to quiet it down a tad.

Thanks for the help.
 
Ironbutt said:
#4 or #5 washers at the hardware store.. I forget which.. I use them for an interm solution before a needle change.
Click to expand...


Washers from hardware stores should only be considered a temporary fix. They are not made to as tight tolerances as the washers made for the needles. Sometimes they're all pretty close on thickness, sometimes they vary widely.
 
ST Guy said:
Washers from hardware stores should only be considered a temporary fix. They are not made to as tight tolerances as the washers made for the needles. Sometimes they're all pretty close on thickness, sometimes they vary widely.
Click to expand...

I agree, however if you have a caliper and measure them, you'll be fine. :thumbup
 
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