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Discussion Starter #1
hi, i have a problem with my cbr 1100 xx 98model with a rough running,spluttering in just highway speeds when im crusing,it starts easy warm or cold and runs fine on idle and runs nice up to 60 kmh and runs fine after 6or7000 rpm and up to rev limiter but difficoult crusing 60 up to relative high speeds in high gears. runs fine in low gears in town.
the fuelconsumtion seams to be some high at crusing speed that indicates that is rich mixture but it runs better at crusing speed if i pull the chocke a little that indicates lean mixture, i know this sound stupid but this is true so i was thinking the fuel is not properly mix with the air, more like drops than mix with air maybe?
sparkplugs looks nice light brown. carbs and petcock have be cleaned many times, new sparkplugs, the ht leads looks good.
it changes the speed it splutter at to higher speed if i shim the needles higher but if they too high i can almost not take off bcoz too much fuel at small trottleopening and black smoke from the exaust, my bike dnt have needles with groves for a clip thats why i shim them instead.

a bikemechanic friend he told he have some simelar problem on a yamaha tdm 850 before and first when he change the nozzle in the carb that the needle goes in to it was cured, the nozzles was oval worn he told and its a problem on downdraft carbs he thinks, but on the xx carbs the nozzle is not specified as sparepart and its pressed in to the carbbody, my nozzle looks a little bit oval on atleast 2 of the carbs if looking closely or maybe only imagination in my eyes, im not sure.

do someone had problem with the nozzles in the carbs before?

i have cleaned the carbs and petcock many times, the airfilter is some dirthy but its worse without filter so its for sure not bcoz of the filter, the bike have a twobros 4in1 exaust and i have try 140,145 and 150 mainjets,but the problem is not with mainjet circut i think for sure.

i had be very happy if someone could have a solution for this bcoz the bike is only irritating to use now and have be more or less the same all the time since i bought it.
hope someone can help get my bird flying as it should do!
thanks in advance!
 

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Since you say the "nozzle" (needle jet) looks oval, I'd try inserting the round end of a drill bit in as a reference and see if it still looks oval.
This should make it appear more obvious.
Lets start there.
Hank
 

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Discussion Starter #3 (Edited)
Im sorry for not be online for a long period but i was on a road trip for a while and after that i get sick with pheumonia for a longer period.

Thanks Hank for your reply!

I have try with drillbits into the nozzles and i think that they pretty much round maybe only a litlebit out of shape at the edge,but this it not so easy to see as my eyesight seams to to going down with the age for see the smallest details...

Another friend have suggested that maybe it can fuelstarvation because very small difference the height of the carbs and tank,it seams to be better with full tank.he suggest try with a fuelpump designed for carb bikes,he have be in the buissness buying and selling cars and bikes all his life so he have alot of experience but not a real mechanik..

Real mechaniks are extremly difficoult to find in this country or atleast in this part of it:crap:

Then I realise that my tank is rusted inside but it seams like the rust and shit collect in the bottom of pockets on each side of the tank as they 3to4inches lower than the outlet, have some of you any idea to fix this?

I have before cleaned and epoxyed tanks with rust inside but all of them had normal shape in the bottom,this one is difficoult to get shit out of because of the pockets...:thumbd:

Thanks again,hope the bike can be good again...
 

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NEED WORK!
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What ari filter are you running man?
I use a K&N and have found it works well for my country with 155 jets (akra 4-1 here..)
 

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I have a 98 and at sea level here in Florida. I am using 165 mains. The needles are one the 3rd clip without the washer. The pilot screws are 3 turns out. Using a hi flow paper filter. My bird is running great and getting around 38 mpg's. Hope that helps.
 

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Hi, I have a 98 and when I had this issue it was a torn diaphragm in the petcock...you said you cleaned it but did you check the diaphragm itself??...a small tear will leak vacuum and not allow enough fuel down to the carbs...I fit a whole new assembly and problem solved...you can get a rebuild kit too...good luck...hope you get it sorted...cheers.
 
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Discussion Starter #8
I have checked the diaphram properly 2 times and it is in good shape without any tears. The vacumdiaphrams in the carbs also without any tears.

Im surprised that some of you use 155 or even 165 jets because at factorypro they send you up to 148 in the jetkit, 148 up to 165 is a very big difference in my opinion.

Have some of you checked the air/fuel ratio when you tuning your bike or you only looking at the sparkplug color or use your seat of the pants dyno to check how it runs after the different mods?

I hope that Im feeling so well next week from my pneumonia that i can check out a couple of things again on the bike.
 

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Every climate is different around the world man.
Every petrol is diferent too!
Mix it with various leves of tune on these bikes and thats your answer!
My bike on 155 (solex jets) with the bits I've added on, runs better than most stock birds I've riden so far!
:)
 

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Flyin' Lo and Free
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I have a FP stage 1 kit and the jets went from 140/142 to 145/148...stock air filter with slip ons...runs like a champ...
 

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Try putting the stock airfilter back in it the carbies are very finicky about air flow.
 

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Yes the CV's in the carbies are very, very sensitive. There are deflectors installed up in the fairing area to diffuse air flow from the factory. The engineers found that the air moving over the box intakes would destabilize the carbs. So I am betting the K&N has leaned it out I am betting.
 

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OK I have an update !!!!!!! One of the jets had come lose in the bowl and came off completely also I had the 140 yet on the wrong carb 140 on the out side carbs and 142 on the inside, Now when you gun it it sits your but and takes of like a bat out of hell. I had my kids with me and had to take it easy but got it up to 85 like nothing, I can still feel it could run better but I am missing some screws on the air box and the deflector are missing but what a difference I had a big smile on my face . I am going to take the K&N of and use stock filter see what happens. will let you know
 

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OK I have an update !!!!!!! One of the jets had come lose in the bowl and came off completely also I had the 140 yet on the wrong carb 140 on the out side carbs and 142 on the inside, Now when you gun it it sits your but and takes of like a bat out of hell. I had my kids with me and had to take it easy but got it up to 85 like nothing, I can still feel it could run better but I am missing some screws on the air box and the deflector are missing but what a difference I had a big smile on my face . I am going to take the K&N of and use stock filter see what happens. will let you know
Get everything back to stock then put the K&N back in and see if it changes. The deflectors come into play at speed you'll feel a surging at a steady state cruise. You can always do a plug check with the stock then a check with the K&N to see if it changes it much or pushes it too lean.
 

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Just to add my 2 cents for those experiencing similar problems, as Beestoys said and many others, these deflectors known as Air guide A and B in the microfische are pretty critical to the birds running and manifests itself to feel like a missfire, vacuum leak etc.
check you have both deflectors each side both vertical and horizontal on the carbies before you do anything otherwise you will not get anywhere.
Just bought my 2nd 98 bird with 49000kms and was hesitating cruising steady throttle trying to open her up then goes like the clappers, found left Vertical air guide missing, replaced and all sorted.
Hope this helps anyone,
Mark.
 

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Get everything back to stock then put the K&N back in and see if it changes. The deflectors come into play at speed you'll feel a surging at a steady state cruise. You can always do a plug check with the stock then a check with the K&N to see if it changes it much or pushes it too lean.

Related info:

http://www.cbrxx.com/introductions/32617-greetings-all-carb-help-needed.html#post440177

http://www.cbrxx.com/engine-airbox-...kn-air-filter-weird-behaviour.html#post434226

http://www.cbrxx.com/engine-airbox-...98-cbr-1100xx-air-guide-plate.html#post398931




T.
 

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ill throw in my 2 cents for good measure, im just after buying a carb model blackbird that was previously crashed. the previous owner changed carbs, got the carbs balanced and set but the bike was still dying off and spluttering around 60 mph almost unrideable . anyway i bought it cheap cause he couldn't get it running right, i bought the air deflectors for it and now its flying !!. it still doesn't have the vertical air deflectors on it tho but to be honest its still flying without them, massive improvement just by fitting the bottom air deflectors. its that good now im not going to even bother fitting the vertical ones. the lesson is if you dont have the air guides on the bike it will run like crap, simple as that !!.
 
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