Anyone fitted a fuel filter to a 1991 CBR1000FM?
 

Hi folks,

having just got my 1991 CBR1000FM back on the road after a second round of pilot jet cleaning within 3 weeks, I'm now wanting to take Tentacleslap's advice and fit a fuel filter to prevent further contamination of the carbs. My 1991 model is gravity fed (no fuel pump) and built without a fuel filter - just strainers in the tank. Has anyone fitted a fuel filter in what seems to be a pretty limited space on the fuel line and if so which one? Would a filter from an earlier model of CBR1000F fit in the space? Thanks for any thoughts.

Pics might help. Glad you got it running in the meantime

I was kind of hoping I was not the only 1991 CBR1000FM owner who had had this problem and that a "standard mod" had been identified. Otherwise, it begs the question why am I the lucky chosen one? In any case, I'll get a photo and post it for those who are more familiar with other models of CBR1000F.

Here

http://i457.photobucket.com/albums/q...lFilter002.jpg

http://i457.photobucket.com/albums/q...lFilter004.jpg

http://i457.photobucket.com/albums/q...lFilter001.jpg

An in-line filter is a bit of a squeeze, but there's just enough space.

Hawkwind, do you know what inline filter that is ? Is it one from an earlier model of CBR1000F with the fuel pump? Also , if so, was there no problem with the filter slowing the fuel for a 1991 gravity fed system?

The filter was just a standard one I bought off E-Bay and fitted it to the existing fuel line.

My bike was also a '91 gravity fed and at 140mph she was still begging for more, but sanity and fear for my licence won out. So I would say there was no problem with fuel starvation.

It was only the MK1 bikes that had a fuel pump, many of which have now been converted to gravity feed, with no ill effects.

Hawkwind - thanks for confirming no subsequent problems with fuel starvation. I'll look around for a filter meant for the earlier models. Thanks.

This was probably the same as the one I fitted:-

https://www.ebay.co.uk/itm/PETROL-FU...IAAOxy2FZSRftX

Thanks for the link. I'll get one ordered.

Just be sure to check the fuel pipe measurements first.

Will do.

A 10mm connection should be just fine.

Something sticking now???
 

The fuel filter is fitted and seems to be working well (at least for the 5 miles I've driven so far). Getting the bike (temporarily) back on the road has made me discover what appears to be a "new" problem - sighs. If I open up the throttle and release it again and then immediately pull the clutch, the revs increase as if the throttle is still held open. This can last a few seconds. The same happens when changing gear. It's as if something holds the throttle open for a few seconds before it then re-closes itself. And it seems to get worse as the engine warms up. I haven't yet checked the lie of the throttle cable runs for any snags (it's too early for that but will do later this morning) but I'm pretty sure that's not the problem. I did notice when cleaning the carbs (again) that one of the sliders was a bit "sticky" when both rising and falling and now wonder whether that could be the problem. I did try gently cleaning the slider and carb body where the slider runs up/down but didn't want to go at it too hard in case of damaging something. Could it be a sticky slider causing the problem or something else causing the symptoms? If I'm forced to remove the carbs a third time to tackle it, does anyone have a suggestion how best to remove the stickiness from the slider without wrecking the plastic of the slider or damaging the bore of the carb in the process? Starting to drive me crazy but I suppose all this shows it's best to do things properly once........

That looks good. I have a tiny little guy I bought at a Honda dealership that hasn't been installed yet, not sure you would have to worry about fuel starvation anyway. It is barely larger than the fuel line diameter. If you have issues still, I'll tell you how mine worked when I get it put in. My bike is rideable so I don't want to take my tank and carbs off yet as I need to figure out my idle problem as well.

I have the same issue as you, only it's much less severe. A quick snap of the throttle at vehicle stop or while steadily holding the throttle at the same position does it for me. But under any weight load the problem disappears. I did not clean my pilot screw orifices when cleaning the carbs last, that may be an issue but I agree with others here that it could be a vacuum leak. The isolator boots may have not been seated properly. I know the airbox boots are good and the previously cracked and separated points on that side were repaired properly. Will keep you informed!

[QUOTE=KMCBR1000FM;1315935I haven't yet checked the lie of the throttle cable runs for any snags (it's too early for that but will do later this morning) but I'm pretty sure that's not the problem.


I did notice when cleaning the carbs (again) that one of the sliders was a bit "sticky" when both rising and falling and now wonder whether that could be the problem.[/QUOTE]

The throttle cables would be my first port of call, might also be an idea to turn the handle bars from lock to lock and listen for any change in the idle speed.

Mine were old and sticky and a bit pinched, so I didn't bother with lubing them, I just changed them out for new ones.

The sliders can be checked with the carbs still on the bike, just pull the air-box and you can lift each one up with a finger. They should snap back down fairly quickly, any dragging will affect your throttle response.

If they are slow, it's worth giving them a squirt of carb cleaner and moving them through their range of motion, to see if they improve. It can work as a quick fix.

Hawkwind2016, thanks for your response. The cables are fine , and it is "as if" the throttle is sticking open causing the revs to race, but the throttle and handgrip snaps back normally so it's not them or the cable that are the problem. I've tried to remove the airbox to access the slides without actually dismounting the carbs but on the CBR1000F that seems impossible (unfortunately). But I get the impression you too think it could be a problem of sticking slider(s). Yes? If so, do you have a preferred way to clean the sliders and carb bore. I've given both a good dose of carb cleaner twice to no avail. Is a gentle wet'n'dry safe for the plastic slider?

I wouldn't advise any abrasives near the carbs at all.

I only suspect the sliders because you said you noticed one of them sticking.

It might also be a vacuum leak, so check all the pipes and connections are tight and not leaking.

I sold my bike a couple of years ago and cleaned the carbs years before that so memories are a bit vague I'm afraid, maybe this vid will help


Also have you balanced the carbs since you worked on them?

Hi (again) hawkwind2016. P-L-E-A-S-E take a look at my "Can I sand my carbs..." thread as things have moved on (well, backwards actually). I haven't sanded the carbs (you'll be pleased to learn). I won't repeat what I've written in that other thread as it would just be filling up the forum but I'm back to just 3-out-of-4 cyldrs and that's with a fuel filter fitted. I will take a look at that video you linked for me. Thanks again (please do take a look at that other thread) as I need all the morale boosting that's around!

Forgot to mention I bench balanced the carbs with feeler gauges and they were fine untouched - but not dynamically as I don't at the moment have a set of vacuum gauges.