carb jetting

[bcguide]

Hi all I have 91 fj1200 with 24000 km on it.
I have a jettting question when i am running at highway cruise speed the bike feels like it is pulsing, is this caused by being to lean or rich?
I did advance the timing on the bike. 

[fj1289]

Is this a new symptom?  Has the bike been sitting for a while?  Or is this just after the timing adjustment?  Maybe take out half of the timing change to see if it is better?  I think we had someone in the past with similar results and they had inadvertently retarded the timing?

If you are sure it is jetting - always try richer first!  If worse, then try leaner.

[Pat Conlon]

Happened to me...Check the 2 float bowl vent hoses. Make sure they are open.

Next time this happens, open your gas cap, see if the pulsing goes away. Perhaps you need a flappectomy.

[Waiex191]

Next time this happens, open your gas cap, see if the pulsing goes away. Perhaps you need a flappectomy.

Yep, my new favorite symptom/problem.

[bcguide]

Thanks guys. This  bike is new to me, I will check the vent hoses and tank vent.
I am planning on shimming the needles up or trying the ones from my old fj1100

[RPM - Robert]

If the 1100 has flat bottom slides, the needles are not the same and won't work. They will go in there but the tune will be all kinds of screwed up. Unless someone did some serious engine work or changed the needles to something else already. I would venture to say it's not a needle problem. We only have to shim a stock bike with pod filters usually one shim. More than that and it gets too fat.

[Old Rider]

Hi all I have 91 fj1200 with 24000 km on it.
I have a jettting question when i am running at highway cruise speed the bike feels like it is pulsing, is this caused by being to lean or rich?
I did advance the timing on the bike. 

Im not sure what you mean by pulsing since im not so good in english ,but if you run at highway and have steady throttle and the bike surges/or feels like
engine is enginebreaking  it can be that it is too lean.I dont know how fast you are going or what the engine rpm is when this happens.if it is under 3000 rpm
try to pull the choke out a little if it runs better it is too lean
it can help to screw the mixture screws out a little try with a quarter turn first.You should take a look at the sparkplugs first if some of them is white its a sign
it is running lean on that cylinder.Any backfiring?

[bcguide]

Thanks gents
I did get a quick ride today and found  the bike runs  better with the choke on. I am thinking i should pull the carbs and check the emulsion jets.
When I say it pulses it sound like a twin engine boat when the motors are running in sync.

[racerrad8]

The choke indicates a lean condition. The emulsion tubes wear and cause a rich condition.

You need to look at things that restrict fuel flow and have already been recommended.

Randy - RPM

[bcguide]

Thanks Randy
The bike has sat for 10 years ,I was thinking that they could be plugged up. the bike only has 25000 km on it

[fj1289]

 

Thanks Randy
The bike has sat for 10 years ,I was thinking that they could be plugged up. the bike only has 25000 km on it

This is NOT a jetting issue, it is a cleaning issue!

The carbs need to be THOROUGHLY cleaned!  It takes on average three tries for people to be successful with this!  Ultrasonic tanks with carb cleaner in them help a lot!  Get a FULL rebuild kit for the carbs - you are probably going to have to split the carb bodies to get them as clean as you need (unless you have a large ultrasonic tank).  The first try is usually a simple disassembly and spray carb cleaner, the second try is usually a more thorough disassembly with maybe soaking and spray carb cleaner.   The third try is then the resignation to a full strip, ultrasonic cleaning, replacing all o-rings, etc.  This isn't like cleaning carbs 20 or 30 years ago - the additives in fuels these days really do a number on carbs - especially sitting for 10 years!

[mike g]

had trouble with mine, but as it was running, stuck some Motul carb / injector cleaner in it and ran for 100 miles, cleared it out ok.

just reviving my old R1, which has been stood for 12 years, needed tank flushing, new fuel guage sender and fuel tap, carb kit as a couple of float needles were shot, slides stuck, chokes seized- urgh it's running now but horrible. not sure if it's just one cylinder playing up or all the pilot jets as running a lot better above 3k, any way needs MOT before I can ride it and investigate further

[Pat Conlon]

Find a shop with a ultrasound bath to clean your carbs. To save money you can disassemble and rebuild them yourself, however best results on cleaning come from a bubble bath. So...completely disassemble the carbs and take the carb bodies in and say, "clean them" . That's the best way those internal passages will come clean.....in the old days before ultrasound we had to soak the carb bodies (for days) and blow them out with compressed air. (Wear goggles) Although in the old days we didn't have to deal with ethanol laced pisswater.
The ultrasound baths do a much better job with those internal passageways.

[gdfj12]

I've used the Harbor Freight 2.5L ultrasonic tank to clean most of the carbs & other parts I've serviced/refurbished/rebuilt and it has paid for itself a few times over now.

Search Google for "ultrasonic cleaner tank". Find one at least 2Liter capacity, the bigger ones can do all of the carb bodies and parts in one shot. Then search Google for "simple green aircraft cleaner", this stuff is great for aluminum parts. Goo-Gone will also work for heavily greasy parts too. There are also other cleaning solutions. Dawn dish soap and water isn't bad either, just dry off iron alloy parts and protect them from oxidation.

[Pat Conlon]

There is 6 liter unit that looks like it could fit the entire 4 carb rack:

https://www.harborfreight.com/6-liter-ultrasonic-parts-cleaner-59430.html