Rockpool - you really have done this before haven't you....I've wriggled and rotated a bit but that rotating thing you described is something I haven't tried (yet) but it's certainly the case that the bottom of the carbs seem to be more securely "welded" to the boots than the upper portion. I've been trying to prise from the top 'cos there's nowhere at the bottom to lever off. Now you've given me this tip I'll have another go first thing in the morning. Hope I get a decent night's shuteye - I suspect I'm going to need all the strength I can muster in the morning.

 

every.few.weeks.

It seems whenever I want to ride the bike I need to clear the idle jets - so I do, then I think "I'll take a ride tomorrow.."

then something comes up, and three or so weeks later I try to start the bike and....

 

Rockpool, your tip was so good I just had to test it straight away rather than wait until the morning. 5 minutes and ....miracle! What a great relief. And what a toptip. If you're ever in the South of France, I'll be the first to buy you a beer. Now I can sleep more easily and get up ready to attack the cleaning. Cheers.

 

Just read you very last post. Surely, if you find yourself doing this so often there has to be something else you could to do avoid it - unless that is, you love doing it so much! I had my bike stood for over a year with un-stabilised petrol in before it started to show clogging symptoms.

 

Took me a couple of tries to work this out - I struggled and had skinned knuckles the first two times - don't forget to grease the inside of the tubes before you try to reinstall, otherwise you'll find it really hard to seat the carbs back in ;-)

 

I have no fricking idea why my bike is so subject to this - I even switched to ethonol-free gas to try to solve it. As you say, in the UK my bike would go months and never missed a beat in 15 years.

I just changed my tank gas line - maybe it was degrading, and I'll put a paper filter in as I am beyond tired of pulling those carbs.

 

So I've got the carbs off and undone all the float chambers (thank God for molegrips as a couple of the screws were impossible to budge with a screwdriver). In fact, the chambers are not as bad as I was prepared for. Yes, there was some green "varnish" but it was pretty superficial and came off relatively easily. I found that i.) some of the idle jets were clogged (now cleaned) ii) some of the main jets were grotty (now cleaned) iii) there was some greenish deposit around the throats of the choke plates (not yet cleaned) iv) the plungers are a little sluggish but not too bad (see questions below) iv) one of the floats was stuck (now free'd) v) the floats seem to ride at different heights with a maximum variation of 2.5mm (which seems rather a lot) (also see questions below). QUESTIONS.....Q1. Do I need to open up the top of the carbs to access the diaphragms/springs/plungers/needles etc in order to throughly clean all that, or will a quick spray through the throat of the carb suffice? Q2. Are the float height differences acceptable? Measuring from the "lip" of the opened float chamber to the highest point on the round float the heights are between 6.5mm (cyls 1 & 2) and 8mm (cyls 3 & 4). I've looked at the owner's and service manual but they give no indication of what the heights should be, the tolerances, or precisely where to measure them Q3. Am I right in thinking that to adjust the float height it's a question of gently bending up/down the metal tab that sits on the sprung needle until the height is correct? A lot of questions but now that I'm stuck into it I'd like to get it done, but done correctly hoping to avoid having to do the whole process again. Yikes!

 

Update - I decided to go with an across-the-board 7mm float height as it seemed like a reasonable average and I couldn't find anything saying what the correct height is. Took 2 of the plungers out and cleaned them. Couldn't the the other 2 off without chewing up the screw heads - I'll save that for another day if necessary. I've put it all back together now and YES, it does run without choke when warmed up, and YES it does even accept the throttle being opened!! This represents great steps forward as it means I can actually get it out of the garage. There is one remaining ****ly thing which is - there remains an intermittent and occasional popping/backfire. I seem to recall this being the case when I last rode the bike on the road 5 years ago. The bike has a Remus 4:1 exhaust fitted and looking on this forum and elsewhere on the www I've seen people talk about a lean mixture creating such a symptom. I haven't touched the pilot screws (ever) and so am considering doing that but saw in the Honda service manual "if the pilot screw position is altered a new screw needs to be fitted"! Firstly, should I be looking at it as a lean mixture problem? Second, is it true I'd need new pilot screws if I fiddle with them, or is that just Honda's way of discouraging people like me from playing around with them?

 

Backfire on deceleration is common with aftermarket pipes, especially after you've wrung it out a bit towards redline.

Removing the carbs sucks. I got it done by getting a buddy on one side of the carbs and me on the other. Lock hands under the carbs & pull. Works like a charm.

The vacuum piston & diaphragm is NLA, so when I pull mine apart, I smear Dow Corning High Vacuum Grease on the rubber diaphragm. Will help them last damn near forever. Useful on all the carb gaskets and o-rings and such.

 

I got the carbs off (on my own) by carefully prising with a piece of wood one side then the other in an upwards and backwards motion as suggested by rockpool. That worked a treat. I'll remember the vacuum grease thing for next time. Does anyone know about the correct float heights for the CBR1000FM (1991) and where to measure them from? I can't find anything anywhere?