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Discussion Starter · #1 ·
Hey guys,
For all the Suzuki RF900R owners out there, I would like to ask you all a question about it.
I just bought a 1994 RF900R a few weeks ago ( Check it out HERE ). And it is 98% perfect. However the choke cable sticks and I either need to take it off and lube it up real good, or replace it. Because it loads up the plugs and I puff a little bit of black smoke just after starting her up for the day. Not much at all.
Anyway, I also noticed that she "SURGES" at 4,000 RPM, which of course is the RPM your always at while in traffic..lol
Its really not bad at all, but for someone who is a perfectionist, I notice it.

So I guess my question is....
Is the 4,000 RPM surging common to the RF900R??
I read a post in these forums where someone stated something along those lines that the RF900R is known for a issue along those lines.

I'm just wondering if its a known issue...or if the surge is a result of the aftermarket Yoshi pipes on it and the carbs not being tuned properly to match them. Or if it is a result of my sticky choke cable for instance.

I appreciate the feedback people.
 

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My bike is a '94 as well but I've never had any surging problems.....as far as the choke cable, remove it and spray PB Blaster on both ends while moving the cable in and out.

Frank
 

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Discussion Starter · #3 ·
Yea, I founnd a crimp/damaged area on the choke cable and can see the strands of cable showing through the casing in that spot.

So I dont think any amounbt of lube will help it...lol..looks like its time for a new cable..

Thanls for the info anyway brother.
 

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my rf and my dads rf are both jetted and will load up really easy if i get stuck in trafic for a good mount of time it terrible the bitch will stall out and i will have to rev the shit out of it and blow black smoke all over the car behind me to clean it out. as long as i'm keeping it wound out like a dirtbike it runs great though. i have recently heard that the mikuni carbs that are on the rf have a tendancy to wear the jets making it run richer but i havent looked into it yet
 

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GnBanditoCI5 said:
Yea, I founnd a crimp/damaged area on the choke cable and can see the strands of cable showing through the casing in that spot.

So I dont think any amounbt of lube will help it...lol..looks like its time for a new cable..

Thanls for the info anyway brother.

haha I was going to say, when it doubt, Apply lube.


Guess it doesn't work for anything.
 

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94rf900r said:
my rf and my dads rf are both jetted and will load up really easy if i get stuck in trafic for a good mount of time it terrible the bitch will stall out and i will have to rev the shit out of it and blow black smoke all over the car behind me to clean it out. as long as i'm keeping it wound out like a dirtbike it runs great though. i have recently heard that the mikuni carbs that are on the rf have a tendancy to wear the jets making it run richer but i havent looked into it yet
My understanding is the carb thing is true. The wear area is the needle jet on the emulsion tube. Factory Pro illustrates this on their website.

How soon it happens depends on how the bike is driven according to FP.
 

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Discussion Starter · #11 ·
Whoaru99 said:
My understanding is the carb thing is true. The wear area is the needle jet on the emulsion tube. Factory Pro illustrates this on their website.

How soon it happens depends on how the bike is driven according to FP.
I assume this is what Whoaru99 is refering to....



Top Left side - This is a picture of the needle jet area of an emulsion tube from a stock 38mm CV Mikuni carb as installed on Ducati, Yamaha TDM/TRX 850, YZF750, FZR1000, etc..
It has approximately ~5000 miles or 8000k usage on a Ducati or TDM 850 - WITH A STOCK Aluminum NEEDLE.
Notice that the center hole is noticeably worn at the "V", the 12 o'clock position, which would be towards the engine, as installed in the carburetor.
This causes 2 conditions. First, it allows more fuel to enter the carburetor, as in using a needle with a small base diameter AND the fuel that enters the carb - it enters in larger droplets, resulting in poor combustion.
We carefully check needle jet condition on the vehicles when we create and install carb recalibration kits.
If you install a kit and it is much too rich at low rpm, and lowering the fuel level 1mm doesn't fix it, check the needle jets for any wear - it's not uncommon.

Additional: Eventually, in the 36mm horizontal mount and 38mm downdraft Mik's, the carb body plastic insert, where it holds and guides the slide from rattling back and forth, will wear out - allowing the slide to rattle and bang the needle fore and aft in the needle jet orifice - causing accelerated NJ wear. This wear is biased towards the lowered slide position - as in idle and low rpm areas - as in "in-town", "stop and go" driving.
The gist of that is that you may only get 5,000 miles out of your needle jets in your VL / VS bike that you use for cruising 4th Street and hanging out at McDonalds - but your long distance , highway cruising buddy might get 25,000 miles before mileage deteriorates to 25mpg or worse.
I haven't heard of anybody who has got the "60,000 miles" that some Tech Bulletin claims is normal with a stock needle...... I WILL change this if I ever find that person who made it to 60,000 miles on his/her VS / VL and has the original needle jets/emulsion tubes. In fact - I'll GIVE any carb needle jet rebuild to any VL 1500 owner who makes it to 60,000 miles on the original needle jets! Marc

Slide Guide Wear:
Example: The original needle jet lasted 5,000 miles in your usage. After replacing the worn emulsion tube / needle jet, they only lasted 3,000 miles or less. That's because the slide guide slot in the carb body is worn - not because of the emulsion tube or needle is bad.
Even Suzuki knows that - even though their highly optimistic estimate of 60,000 mile life with a stock needle is based on perhaps a VL1500 or VS1400 run at high speed on a highway.
A "step" inside of the needle seat in the carb slide?
It's there in virtually every Mikuni CV carb. It's supposed to be there.
It's to try to keep the needle bearing onto only one side of the needle jet - otherwise, the needle bangs back and forth onto both sides of the needle jet at idle and low rpm, instead on only one side.
Of course, if one "notches" the plastic needle shim, they are lowering the needle about 2 clip positions and that will lean out the mixture, but that doesn't really permanently fix anything.
.

It sounds about right, atleast my symptoms anyway, time for a carb rebuild I guess....lol

Thanks Whoaru99
 

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Yup. That's it.

To me, it sounds like the emulsion tubes are pressed in. Not sure if that's an easy fix or if one is just better off to send them in and pay the man.
 

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causticbelt said:
rf 900 ?? hickory pa.....i grew up in sharon pa on buhl blvd. my grandfather had an office on state street. lol small world
thought you grew up in neavitt, md
 

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Think " Ivans jet kit " specially designed for the RF900R.
ADDS ABOUT 10HP, eliminates the stumble at 4k-RPMS
Do a search for Ivans jet kit.
Call Ivan and speak with him.
 

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i bought a factory pro +4* ignition advancer and it seems to make mine run better. ignites the fuel sooner and it helped alot with the 4krpm shit spot
 

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just a question ive had my rf900 for a bit she is great ride but id like to ask watt wheels and if any swing arm can i update them with i see all these polished rims around for the sv gsxr but none for the rf900 will the gsxr or sv fit the rf900r and is there anywhere out thee that still got fairings ? lol i know im pushing it up hill on that she still looks good but the stone chips are building up .and where is there somewhere i can buy chrome or polished motor bits for her
 
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