Something wrong with bike. Advice please [Archive]

blossomsowner

2nd May 2008, 20:53

recently bought a 98 rf900r and am very happy with it. However am now having problems with it not running properly. Symptoms are lumpy idle, missing at low revs, almost feels like its running out of gas with a surging feeling. Still surges at highway speeds.....just enough to be annoying especially around corners as i can't tell when the power will come on properly. Once revs get up top end its all go as per normal.

The bike recently got covered with very fine ceramic dust being parked in wrong place. Problem started first time out afterwards.
My first stop was to find and blow out air filter element....put back and problem seemed fine,.........for about five minutes then back again.

so i have replaced filter element and sponge and mesh filter bits as well as they were all knackered anyway. Thought this would fix it but still the same.....
what do you think????????? carburettor jet/s partially blocked maybe, or some other unrelated thing like sparkplugs or something. Just thought i would get some ideas before i start taking the bike to bits again..

98tls

2nd May 2008, 21:01

If mine i would drain gas tank remove carbs and clean put back together.If not a fuel problem then next stop is electrics starting at plugs/leads and go from there.Easier to start the other way round i guess but methinks its a fuel issue,good luck and let us know what it was.

riffer

2nd May 2008, 21:13

I reckon it's blocked jets.

Are you any good at cleaning out carbies? Probably best to spray with a carb cleaner rather than try to blow them out with an air compressor as jets don't really like that.

A tip when getting the carbs back on - they're a right bitch how tightly they go back on to the rubbers - I use a block of wood covered in a towel - lay it flat across the back of the carbs and give it a bit of a whack with a rubber mallet and they pop back on. The airbox is a bitch to get right too.

YellowDog

2nd May 2008, 21:21

Did it run well before the ceramic dust incident?

riffer

2nd May 2008, 21:26

Did it run well before the ceramic dust incident?

The bike recently got covered with very fine ceramic dust being parked in wrong place. Problem started first time out afterwards.

I would say it's likely.

blossomsowner

2nd May 2008, 21:45

ran sweet as before the dust incident........hence my suspicion that its related to that rather than some other problem arising at same time by sheer coincindence. But still can't rule out other problems.......

YellowDog

2nd May 2008, 22:25

You probably need to go deeper than changing the air filter. Ceramic dust is very heavy and it's momentum will take the fine grains into places that are not so obvious to find. The likely hood is that as soon as you started the bike for the first time after the incident, the engine air inlet sucked the crap straight in and there is no way out.

There is never any harm in cleaning out the carb jets. There are some pretty good fuel additives you can get to force out debris from the system.

Will be interested to hear how you get on afterwards.

blossomsowner

3rd May 2008, 09:36

There is never any harm in cleaning out the carb jets. There are some pretty good fuel additives you can get to force out debris from the system.

Will be interested to hear how you get on afterwards.

thanks for that...........have you used these said additives and do they actually work........or am i better off saving the cash and pulling bike apart again now? Asking this because I have never tried them....

Katman

3rd May 2008, 14:43

YellowDog

5th May 2008, 07:59

thanks for that...........have you used these said additives and do they actually work........or am i better off saving the cash and pulling bike apart again now? Asking this because I have never tried them....
I have seen amazing results from additives. I don't know if it is comparable, but a mate of mine had a bike parked under cover for 2 months at a cement factory. Even though it was under cover, it got caked and took forever to start (2 battery charges and a jump). I don't even know what he bought however the guy at Infinity in Farnborough offered him a $400 strip down or a $40 additive. Not a difficult choice. He had to empy the fuel tank and then add 3 litres of fuel to said additive. The smoke and smell was quite something, but after 10km of riding, he said the bike just started to pull and pull at all rev levels. I have emailed him to ask what the stuff was called, but have not received a reply. He said that one of the other engineers told him not to use the stuff, as the cleaning process would add 10k to the engine wear. He was very happy with the result. Will get back to you when I get an answer.

YellowDog

5th May 2008, 08:02

scumdog

5th May 2008, 11:22

If the problem is indeed dust that has got past the air filter and sucked into the carbs it could only be the air jets that would be blocked. No amount of additives in the fuel are going to clean air jets. Compressed air blown back against the normal direction of air flow is the only remedy.

I'm with him.
If the dust is not soluble no amount of additive is going to dissolve it.

Additives go into your fuel, through your fuel system and through the fuel related parts of your carbs, the dust most likely is in the 'air-only' parts of your carb which the additive would most likely not be in contact with.

Having said that I am surprised that an ingestion of dust has actually caused the problem - maybe it is of a type that cakes solid when it comes into contact with moisture??
Just my 2-cents wirth.

MSTRS

5th May 2008, 12:14

If the dust was fine enough to get through the airfilter, then why would it block anything downstream? It's not as though the air carrying it goes anywhere except straight through the open throats of the carbys, through the inlet manifold/valves and then burnt in the combustion chamber...
OK - it's possible that the carby slides have a coating of the stuff, but that should only make them a bit sticky when opening/closing. If it's on the needles, then it's above the mainjets anyway, so shouldn't be a problem there.
My guess is that if the dust is the problem, then it's causing it at the coils.
Otherwise, the timing of the problem is coincidence and you have the old RF problem of worn needles/emulsion tubes.

Katman

5th May 2008, 19:47

It's not as though the air carrying it goes anywhere except straight through the open throats of the carbys, through the inlet manifold/valves and then burnt in the combustion chamber...

Ever heard of air jets?

homer

5th May 2008, 19:56

stupid thought ,
get the carbs balanced

new set plugs

MSTRS

6th May 2008, 08:52

Ever heard of air jets?

Idle jet. Main jet. Both feed petrol. By means of air vacuum created by air passing through the carby throat. The air only passes through when the inlet valve is open and the piston is descending. Why would there be an air jet in a (relatively) simple carby-fed internal combustion engine?

Katman

6th May 2008, 10:28

Idle jet. Main jet. Both feed petrol. By means of air vacuum created by air passing through the carby throat. The air only passes through when the inlet valve is open and the piston is descending. Why would there be an air jet in a (relatively) simple carby-fed internal combustion engine?

Stick to signwriting.

MSTRS

6th May 2008, 10:36

Stick to signwriting.

Very informative. Too difficult to actually post where/how an air jet is utilised? Perhaps with pictures?
Since you obviously know so much about them...

Katman

6th May 2008, 10:52

Air jets introduce a flow of air into the fueling circuits of carbs to help atomise the fuel before it's feed into the venturi.

Like I said, stick to something you have a few clues about.

MSTRS

6th May 2008, 11:11

Like I said, stick to something you have a few clues about.

Good advice that applies to you as well. Not knowing about air jets does not mean I know nothing about engines.
Oddly enough, problems like the OP's are usually very simple, but damnably difficult to diagnose. Sometimes the wildest guess is the right solution. All suggestions so far could give symptoms as described.

ManDownUnder

6th May 2008, 11:22

Cheap and dirty test

Remove air filter
Ride it

If it goes ok then look no further

If not - see riffers post

Katman

6th May 2008, 14:23

All suggestions so far could give symptoms as described.

Except perhaps for "dust on the coils".

I mean - WTF????? :rofl:

MSTRS

6th May 2008, 14:31

Except for "dust on the coils".

I mean - WTF????? :rofl:

Sad little man with nothing better to do than pick holes in people. Fuck off and check your tyre pressures.

blossomsowner

6th May 2008, 17:16

thanks for all the advice so far.....i've been really busy and have not done anything since i posted the question but hopefully tonight i can strip it down and start cleaning and checking all these bits mentioned. I will check back in with any results and progress. thanks heaps

FruitLooPs

6th May 2008, 17:30

I'm not sure what carbs it's got, but i'd wager they're Mikuni BST or simlar like the gsxr's had.

http://www.gixxer.com/forums/showthread.php?t=159718 fully illustrated guide on dismantling and reassembling carbs. :2thumbsup Might need to sign up, not sure.

Another note, carb cleaner like CRC stuff will stuff rubber gaskets - so watch it, they swell to twice their size (eventually come back ok, but bad idea).

blossomsowner

9th May 2008, 21:47

some progress.......sort of.
finally had some time and managed to get carbs off ok, had service manual and the stuff from fruitloops link. So commandeered the lounge coffee table and started to take things to bits properly. Sadly for me I decided that it was all very fiddly and didn't want to wreck anything so before i made a mess of it put the bike back together again. And managed to do so correctly...thanks riffer for the whacking with a mallet and block of wood tip.
i did inspect sparkplugs and while they are not by any means new all seemed ok and in a uniform sort of condition.
so bike in one piece but i got it running again although no improvement is there yet.

for my next trick I will try some fuel additive carby cleaner stuff and see if it makes a difference.

i would be happy to pull carbs apart further but only with the supervision or help from someone who knows how to not wreck it and to put them back together again.

Otherwise might even take to local bike shop if nothing else works.

FROSTY

9th May 2008, 22:52

i would be happy to pull carbs apart further but only with the supervision or help from someone who knows how to not wreck it and to put them back together again.

Otherwise might even take to local bike shop if nothing else works.
Dude--rip the fuckers back out--hop in yer cage and come out to my yard--We'll have dem carbs clean in a whissle.
Lis secret--One at a time so ya have the others fora reference

blossomsowner

10th May 2008, 21:35

Dude--rip the fuckers back out--hop in yer cage and come out to my yard--We'll have dem carbs clean in a whissle.
Lis secret--One at a time so ya have the others fora reference

thanks frosty.........will pm you if i can clear some time from work and family to arrange and come up..........fantastic offer.

Blossom

10th May 2008, 22:00

FROSTY

11th May 2008, 10:33

Darling just go see Frosty... You are not I repeat NOT riding my bike whilst yours is not running properly so get the girl fixed would ya...:calm: (Yes i am afraid its catching and my girl will get it next) lol.
Thanks for the offer Frosty
Blosom--ya don't get it --Bikes are afraid of me. If he brings it here it will sit -NOt daring to run badly
-except ZXR400 racebikes but thats a whole other story

blossomsowner

25th May 2008, 16:43

seemed to be running quite lot better with the fuel additive/crby cleaner stuff in it,....still missing a bit at low revs but not all the time and running pretty well at open road speeds.

however i refuelled without any additives and performance appears to have dropped off again. consistently missing at low revs and sometimes surging again at highway speeds.

so i think more work is needed

FROSTY

25th May 2008, 17:00

Mate the carbs in the rf's do seem to wear internally quite badly. -could be ya problem

FilthyLuka

25th May 2008, 17:21

slide wear perhaps?

FROSTY

25th May 2008, 17:25

nahh needle/jet from memory --bitta slide too prolly

riffer

25th May 2008, 17:42

Oh yeah, those slides sure can wear. (http://www.kiwibiker.co.nz/forums/showthread.php?t=44711&highlight=stupid+mikuni+carbs) Remember they're made of some cheap and shitty plastic.

However, that seems to manifest itself with fluttering jet needles which can get stuck on full throttle leaving you either with one carb wide open or a snapped jet needle making the bike ONLY run on full throttle.

I'm still picking some kind of blockage in the pilot air jet, or even some crap stuck in the needle jets themselves, particularly as it's manifesting itself with rough off-idle running.

Just a thought though - didn't Lou Girardin have something similar happen to his Bandit which was eventually tracked down to some kind of damage to the diaphragms caused by muppetish carb rebuilding?

Could some shit have caused some holes in the carb diaphragms?

wickle

25th May 2008, 17:58

thanks for that...........have you used these said additives and do they actually work........or am i better off saving the cash and pulling bike apart again now? Asking this because I have never tried them....
If you use a additive in your fuel, change your oil pretty soon afterward some additives can muck up the viscosity of oil which is most probably what 'Yellowdog" menitioned about extra 10k to engine

blossomsowner

29th May 2008, 06:25

have completely stripped and checked/cleaned carbs (big thanks to frosty for his help on this) but didn't seem to be too much wrong. However can now say for sure that there are no blockages in any jets and no obvious wear problems anywhere. will replace sparkplugs before carbs go back on ..........hopefully after work tonight........and keep you all posted.

blossomsowner

29th May 2008, 22:50

well............its all better now...........just got back from a quick test run and it pulls like a schoolboy in a brothel.........as it should.

so it now has new air filter, clean shiny carbs without worn bits, and new sparkplugs.

funny thing was sparkplug no1 had a stone on top of it. this stone prevented the plug spanner from going on until said stone was removed. might also have prevented the lead from connecting properly...........could explain a lot.

don't know how it got in there though............

thanks again to frosty for help and advice and to the rest of you lot for useful suggestions
cheers

Blossom

30th May 2008, 10:02

Yes a BIG THANKYOUto Frosty for the hands on help with the bike. :niceone:The man is on cloud nine thismorning.:love: He even left the company cage at home and took the bike to work today despite the fact it was kinda raining thismorning. (he HATES riding in the wet the big girl):crybaby:
Anyway its a huge sigh of relief to have the girl going properly again. You guys have all been so great with all the advice and help.
Your all awesome. :rockon: