carb cleaning

[rwh]

OK I'm not terribly mechanically minded but I'll have a try at most things. The very last thing I would have done is start pulling the carbs to pieces without first checking that the dead cylinder was getting a spark or fuel, it pays to try the easy things first and by the process of elmination find out whats causing the problem. If you've already done that my apologies but you dont mention anything else but the carbs in your post.

You're right, I haven't been following a very ... structured fault diagnosis plan I'm a bit lazy, not thinking straight, and somewhat annoyed that I'm not up north riding, which all mix up together to produce bad results. I just felt I needed to do something.

Actually I had tried the #4 plug lead; with the help of a nail stuck in the cap, I was able to produce a spark against the cam cover. I'm not sure, however, how to detect whether fuel is getting there, which certainly seems to be a good next step. I guess I can undo the drain screw to see if there's any in the float bowl - there was when this all started; draining it to remove any sludge was one of the very first tips I followed. Unfortunately I also haven't been able to reproduce the '#4 header is cold while the rest are hot' test result, so I'm not sure that it's still the one giving me grief, or what sort of grief it's giving me.

Richard

[Paul in NZ]

Since you have gone this far I'd suggest a compression test (leak down is better but...) is essential - maybe you have a valve clearance issue?? Have they ever been checked?

[rwh]

Since you have gone this far I'd suggest a compression test (leak down is better but...) is essential - maybe you have a valve clearance issue?? Have they ever been checked?

Hmm. I'd need special tools for a compression test, wouldn't I? I guess I could dive in and check valve clearances - are shims easy to get/fit? I've only done valve clearances on a pushrod car engine, with screws on the rockers.

Richard

[Max Preload]

Try to find some O rings - you would be amazed what turns up at supercheap or repco...

The trouble being that the muppets at Ripco won't know you shouldn't use nitrile o-rings for a petrol contact application especially in something as critical as a carburettor. See here.

[Max Preload]

When does the bike run on 3 - constantly, even at idle or under light medium or heavy load (throttle opening dependant)? Or does it seem to 'clear' if you thrash it?

Did you fill up shortly before it happened? I filled up at Turangi on the way to the 'Cold Kiwi' this year and my bike started running on 3 under light load throught the first series of tight corners on the Desert Road. I thought the plug hole seals on the rocker cover were leaking again (I'd replaced them after it developed exactly the same problem when the oil went down the spark plug supressor caps - the seals were rock hard instead of being supple) but it cleared shortly after and I put it down to watery fuel at Turangi - it didn't do it again on the rest of the trip.

[rwh]

When does the bike run on 3 - constantly, even at idle or under light medium or heavy load (throttle opening dependant)? Or does it seem to 'clear' if you thrash it?

My mind is starting to play tricks on me, and I'm starting to doubt whether I can tell if it's running on 3 or 4. However, the rough sound is most noticeable under load, and at lower revs - either leaving an intersection or through the twisties. Oddly, while it seems to be down a little on power when taking off, it seems to have plenty through the twisties. Though again that's hard to tell as it varied through my test ride the other day.

Did you fill up shortly before it happened? I filled up at Turangi on the way to the 'Cold Kiwi' this year and my bike started running on 3 under light load throught the first series of tight corners on teh Desert Road. I thought the plug hole seals on the rocker cover were leaking again (I'd replaced them after it developed exactly the same problem when the oil went down the spark plug supressor caps - the seals were rock hard instead of being supple) but it cleared shortly after and I put it down to watery fuel at Turangi - it didn't do it again on the rest of the trip.

I guess I did - filled up just before heading over the Rimutakas - but I've also topped up again since then, when I thought part of the problem might just be lack of fuel. I guess it could be water in there ... maybe I'll do a drain and refill.

My other plan is to stick the tank back on and ride down to see if Boyle's are open and have time to take it on ...

Richard

[Paul in NZ]

Or you could just synch your carbs...

[rwh]

Or you could just synch your carbs...

Isn't that what you posted pics of you doing with all sorts of fancy equipment?

It's in the shop now; hopefully I'll get a little bit of my holiday.

Thanks for all the help.

Richard

[Pixie]

If I pulled those 4 plugs out of any bike i owned I'd be concerned regarding the differences between them. Somethings not working at all.. In the unleaded era and given the carbs on your bike I'd expect em to be a bit dark so the super clean one would worry me most.

I can't help with the HT lead as I can't see how it connects - ie on my old bikes they are easy to replace from repco or shite I have laying about the shed... Many jap ones are not designed to come to bits and you need to replace it as a unit. I doubt the usual bandits will have one in stock either - not a good thing to break.

This does not necessarily indicate an electrical problem.If the fueling to that cylinder is wrong (starved for instance ) you'll see it reflected in the plug colour.

On fours it is often difficult to tell when one cylinder dies intermittently.
The symptoms you described are exactly the ones my brother had on his RF 900.
I strongly suggest you check those strainers before you do anything else.

[Paul in NZ]

This does not necessarily indicate an electrical problem.If the fueling to that cylinder is wrong (starved for instance ) you'll see it reflected in the plug colour.

On fours it is often difficult to tell when one cylinder dies intermittently.
The symptoms you described are exactly the ones my brother had on his RF 900.
I strongly suggest you check those strainers before you do anything else.

Two different problems refered to -

Those carbs are the same as used on RF900s and FZR's - they all slog out their needle / needle jets making the mixture richer with time and combind that with unleaded gas not depositing the nice biscuit coloured lead on the electrode when correct (like the old days) so you expect to see a darker plug. I'd be assured something is dreadfully wrong if I pulled those 4 plugs out of any engine I owned!

I doubt it had a problem with the leads before it got pulled apart - lessons are only learnt by doing things - no biggie - done worse myself.

I'll file that diagnostic tip for 4's away as yet another reason I like twins

[Pixie]

Two different problems refered to -

Those carbs are the same as used on RF900s and FZR's - they all slog out their needle / needle jets making the mixture richer with time and combind that with unleaded gas not depositing the nice biscuit coloured lead on the electrode when correct (like the old days) so you expect to see a darker plug. I'd be assured something is dreadfully wrong if I pulled those 4 plugs out of any engine I owned!

I doubt it had a problem with the leads before it got pulled apart - lessons are only learnt by doing things - no biggie - done worse myself.

I'll file that diagnostic tip for 4's away as yet another reason I like twins

He doesn't have a problem with the leads - he said he had spark.



Fuel starvation in one cylinder will give a lean mixture indicated by the white insulator deposit on the plug
if the mixture is lean enough it won't fire.

If you loose one cylinder on a twin you're rooted at least a four has 3 left to carry on with

[Pixie]

This is a useful thread:

http://www.gixxer.com/forums/showthread.php?p=2374074

[rwh]

My carb looked rather different from that - I don't think there were any plugs left that a strainer could have been hiding under. The pivot and float valve were all part of the orange plastic assembly on mine, there is no mid jet, and neither of the two brass plugs down the bottom were there either.

Richard

[F5 Dave]

oh dear, this is all looking depressingly familiar.

Have a search on RF900 on this site. I suspect your emulsion tubes have worn on the LHS cylinders. Don't ask why they do more than the RH ones but they do. Take out the plastic blocks & emulsion jet & swap into the RH side ie: 1 & 2 to 3 & 4.

Clean the plugs & reinstall & run the bike. If the problem follows then I'm right & you need some new tubes. You can also look at the tubes & see if they are ovalised, need a good light & compare them. A little oval is stuffed. Factorypro should do replacements.

[rwh]

oh dear, this is all looking depressingly familiar.

Have a search on RF900 on this site. I suspect your emulsion tubes have worn on the LHS cylinders. Don't ask why they do more than the RH ones but they do. Take out the plastic blocks & emulsion jet & swap into the RH side ie: 1 & 2 to 3 & 4.

Clean the plugs & reinstall & run the bike. If the problem follows then I'm right & you need some new tubes. You can also look at the tubes & see if they are ovalised, need a good light & compare them. A little oval is stuffed. Factorypro should do replacements.

Interesting, thanks.

However, things have progressed somewhat. I took it in to Boyles, and they declared excessive blowby - loads of smoke coming through the crankcase breather. I'm not sure whether that and the varied plugs and the missing when hot are related or not, but I'll leave it to them for the time being - they say it needs head and barrels off to have a look, and I'm not prepared to embark on that at home (gargre isn't tidy enough for me to keep track of that many removed bits, among other things).

Thanks,

Richard