Major Problem and cant fix

creeprs

Ok, heres the issue
I have a 95 cbr 900, has a wasco piston kit bore 2 over, racing cam, dynojet stage one, used 124 jets with needles on slot 3, K&N , stock airbox

Ok - I can be riding along and the bike seems to want to bog down like Im out of gas, I twist and power is always there, I release the trottle and then twist it again and there is a small delay and them bam power. Also it seems to get worse when a gust of wind blows across my nose. Seems to happen less at low speed, but riding at 6k rpm and 65+ and it starts in real bad.

What I've done to fix.
1. Replaced fuel filter
2. Replaced RR
3. Replaced coils
4. Rebuilt and installed differant set of carbs.
5. Replaced plugs


Things that have not been done
1. replace plug wires
2. check carb sync
3. replace cdi unit

Someone help, my wife is about to blow it up from hte time and money I keep putting in it.

lois

Question, is this thing using a lot of fuel ?

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SORRY HONDA....I COULDN'T WAIT ANY MORE.

flipy351

Put your standard air filter in and try it. The K&N filter lets a heap more air in so that upsets the air flow of carbys venturi operating the slides. As a result when you throttle on the slides open too early and then engine leans out bogs down and no power. Back of the throttle close slides and all is well. If you want to run the K&N you need to stiffen up the slide springs so they dont open as easily. All else should be ok.

gixxer11

what kind of petcock do you have? if it has a prime position see if you put in prime position if the symtom changes.Also make sure if you have a vaccum petcock that the line is connected propperly. If you have a drop in vaccum you fuel delivery will be starved so try prime position see if it helps and then if that seems to be the culprit install a profuel petcock they make 2 versions race and street and solved my problem on my gixxer1100 with 39mm flatslides with a similar condtion.Hope this helps

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1999 REDBIRD givi screen and air visor,genmar risers,corbin gunfighter and lady seat w/osb rest,fender eliminator kit,k&n air filter,black powdercoated wheels.

creeprs

My issue is just the oppsite, although the jet kit came with new springs which I would assume that they are stronger then stock. I was going to try the filter because of the horror stories I have read about K&N

creeprs

no I get about 50 miles to the gallon, this did the same thiong with the orginal carbs and a factory pro stage one kit as well

ravi

flipy351, would something similar happen to a fuel-injected model with a k&n filter? i've had a couple of instances when i've just started riding the bike and as i'm changing gears say 1-2-3, the bike just suddenly seems to choke and then yes, releasing throttle and re-revving resolves the problem. maybe i'll just put the stock air filter back. do let me know. thanks, ravi

creeprs

Wow, you may have hit something, when I read your post, I remembered that when I first got the bike in Jan this year, it was not doing this. THen the petcock starting leaking so I replaced it. There is no prime postion and all vac lines are proper, but it may be a faulty petcock, do you have a link to the profuel petcock or a place I can buy one?

gixxer11

I got mine from diamond powersports in florida but I wanted to call pierre first with a heads up havent talked to him in a while know him from when he lived in the northeast I'll call him first keep you posted.....chris

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1999 REDBIRD givi screen and air visor,genmar risers,corbin gunfighter and lady seat w/osb rest,fender eliminator kit,k&n air filter,black powdercoated wheels.

gixxer11

update sorry he is no longer doing perf parts but check the other bike performance websites i'll take a look and let you know

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1999 REDBIRD givi screen and air visor,genmar risers,corbin gunfighter and lady seat w/osb rest,fender eliminator kit,k&n air filter,black powdercoated wheels.

creeprs

Ok, did not troubleshooting.
1. Removed the K&N and ran without a filter for about a mile, got real bad.
2. Put K&N back in and covered the airbox with a move resrtrictive cloth, opps to much cant get it to run at all.
3.Removed bad cloth and placed a different one just over the K&N, to make it more like stock. -Nope doing samething actually a litte worse.
4. Removed the rag, taped up one side Ram air inlet. Rode this morning and it seem to be a little better but only once it go warmed up, after that I only had the problem when I am decel and then try to accel again, I get sputering.

I do not think this problem is a fuel pump or petcock or fuel delvery issue as those issues would cause this to happen all the time. I also do not think it is a fix/air mixture issue.

Let me try and explain my trouble
5k RPM and hold at the speed no decel or accel, after a few moments the bike will act like it is out of fuel, you can watch the RPM's drop, then few moments later or if I accel if clears up. This happens throughout the from rpm range I just choose 5k because I hate doing 10mph. It not as bad at low rpm's and does not happen under 4k rpm's also does not happen while I am under accel, it is only if I am at a static speed/rpm.

flipy351

Ravi The wonders of electrickety. No, the EFI system should automaticaly readjust for more air and different air flow characteristics. The exhaust sensor would read lean and richen it up where necessary. Also most computer management systems (or all these days) have a memory and run from previous use data stored and continually updates. If all power is lost for some time ( 5min to 1 hour) computer will run in factory default settings until it relearns your requirements. Clever stuff the efi. The only way to remove any doubt is give it a run with standard air filter and see if problem goes away. Then you will know if theres something else more sinister happening.

flipy351

Definately sounds like fuel starvation. Check fuel lines from tank, on other motors as fuel line ages it reacts and swells up eventually blocking. Tank the tank of the bike and fuel line from carby and watch the fuel flow from tank out of fuel line and drain into container. Doing this you will know for sure whether it is getting the fuel required to the carbs.

creeprs

I agree with you flipy it does sound like fuel delivery, however it that was true it would happen all the time, exspecially under acceleration. I get true clean power as long as I am always accelerating, I guess there is nothing wrong with that at least until your reach 120-130 and a ton of traffic(lol).

Anyway this sounds to me like maybe if it is truely fuel related, the only thing I can think of is the floats. These are one thing I did not check while I was rebuilding the carbs. Sounds like the bowl is getting fuel and then floods the engine, when I accelerate it clears the bowl until if fills again( sound right?). The carbs I put on were just as old as the stock ones. So I guess the floats could be bad
or
Carb sync, not sure what carbs out of sync does.

The next bit on money I put into this, I want it to fix the problem,

Growler67

Check the fuel filter. If there is debris in there, it may only restrict flow under load temporarily until enough fuel pushes through.

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creeprs

Forgot to put in orginal post, I replaced fuel filter like 3000 miles ago, after the problem started.

creeprs

more info
today I tested more
here is what I found
1st and 2nd gear all the way through the rpm range no problems
3rd and up once between 4500 and 5800 rpm things started happening
in 6th gear at 6200 rpm no problems

I do think it has to do with throttle position now, 0- 1/4 no problems, 1/4 to 3/4 problems and 3/4 to wot no problems, this sounds like it is my needle jets causing the issue, but what to do to fix it?

the slow jets are fine and the mains are fine hence the 0-1/4, 3/4-wot no problems, anyone?

flipy351

What you say the part throttle cruise is where the problem is?
You mentoined you had the needles on clip 3. Try needles at standard position or on leanest postion no1. It could be fueling up due to needle setting too rich. Yes the float settings may be out but the birds floats are plastic and un settable dont know about the carbs youve got. Also check needls and seats are ok clean and not gummy they could stick causing irregular fuel level. Have a look and check but if flat out is ok idle is ok the only other is the needles setting. If all else fails put the carb back to standard and stat again changing one thing at a time.

creeprs

well i was part right, I used a trick I found on here, the throttle position I mentioned before was wrong, I was using hte rpm to determine postion, so Iwent out and marked the grip with a sharpee

once I did this I was able to see what is going on, my problem is at 0 -1/4 throttle, so this would be the slow jets. As far as being gummed up, cant be I jhust tore the carbs apart and rebuilt them a week ago.

I have now just started hearing lifter chatter, so I am going to tear it down and check valves again.

creeprs

Well after much money and working on the bike, I may have finally found the problem, As I was searching I found a lot of post like this one but no final solution was ever given, I am testing the bike now and will know for sure from the ride home, the ride to work was great no problems, here is what I did after all the stuff above.

There is a vacuum line that runs along top of the carbs, the line connects to each bi-set of carbs, I just remove the vacuum line and left the two t- connectors bare.

I think what was happening, was when the engine got hot it in turn heated up the vacuum line which made it softer, so when a big wind blew across is created a negative pressure closing the already partly closed vacuum line. This in turn starved the bike of fuel since this is the line that allows air behind the fuel for the carbs. That takes care of the wind, the other weird part about it dying at certain throttle position was just a coincidence, the heat softened the line and the vacuum closed the line about 80%, so after a short while the bike was running out of gas, giving it more throttle just allowed it to suck harder to get the air needed.

The bike now has a ton more power. I just hope the ride home is at good.

I will post pics when I tear it back down to readjust the carbs, if this does solve the problem.

flipy351

Good to hear you fixed it.

051100xx

those hoses you are describing are the float bowl vent pipes and on the european dynojet kit instruction sheet it says that these must be removed

as you have just found out
i have had a 1992 rrn blade and a 1996 rrp blade and the 92 was fitted by the local dyno shop with a kit and they had it on the dyno about 5 times until they gave me the instruction sheet and i took it apart at home and found the hoses still attached

i removed the hose and the bike ran like never before ,power wheelies in second and viscious ones at that

and i got all my money back for the botched dyno time

and he was a dynojet agent
i fitted the kit to the 96 myself after that fiasco

just make sure you rotate those plastic "T" pieces to face down or you may get water in the float bowls in heavy rain