Slow jets

[basketcase]

Been for a run on the K3 today....first time that it`s run for ages. Didn`t go too well The revs were all over the place, stop, adjust to about 1200, pull away and they were back up to 4000 when I pulled in the clutch. Uphill was a struggle, having to change down a couple of cogs. Also there was fuel peeing out of one of the overflow tubes when I came back. The carbs were stripped, cleaned and balanced last year. I didn`t touch the jets, just left the whole lot soaking in carb cleaner and redex for a couple of weeks. Could it be that the slow running jets are still blocked? If so am I better off installing new ones or do I attempt to clean out the old ones? Has anyone bought from sisusconinc on ebay?
Sorry for the ammount of questions but carbs are not my favourite things to play with, I sold the last one because I couldn`t get it to run right . Also all of my manuals and literature are still in storage so I`d` be doing this `blind`.
Cheers in advance basketcase.

[Bryanj]

You can clean the originals but you have to get them out as they are a press fit, grip with mole grips but not too tight or they will deform then twist and pull at the same time. Re-Fit with a tap from a copper hammer.

Sirius i have bought from and they are goos but get yours out first and  try cleaning them

[mickwinf]

I had similar problems with my k3,the slow jets were blocked solid and defied all attempts to clear, so i ordered some new ones from Sirius and found them very good to deal with.Also check the float needles as i had problems with fuel flow, turned out to be a faulty needle.Regards Mick

[K2-K6]

If you need to leave it for anything more than about 4 weeks it seems that the carbs need to be dry to avoid the jets getting blocked.

Petrol didn't do this in the past, but it does now so if you are going to lay it up for a while then run it with the fuel swicthed off until it's dry.

It appears to affect the smallest jets quite quickly now and is a real pain.

[basketcase]

Four weeks!!!!! Ooops! More like 4-5 months since it last had a good run, what with the house move and work. Funny that the old Matchless has stood for the same time and that kicked in on the second kick and ran as sweet as anything:) (apart from spitting it`s chain off after a mile or so) but that was probably `operator error`.

So it looks like more split knuckles, trapped fingers, swearing and all of that....just to get the carbs off!!

Thanks guys, always there when needed. basketcase.

[matthewmosse]

The 500 carbs use more petrol but clog less easily, I'm therefore thinkingh that I'll be pulling my 550 k3 carbs off my outfit and putting on 500 carbs having had the same issues. long term I'll be sticking on an SU car carb as that's apparently the gateway to massive economy savings.

[mickwinf]

when taking off the carbs i remove the carb to airbox rubbers then unbolt the inlet manifolds from the head complete with carbs, they wiggle out easily and no chance of damaging the inlet rubber mounts,and less chance of damaging your knuckles!! I got good at it after doing it for weeks (see my old posts for details!)

[basketcase]

Hhmmm, think that I did it that way when I took the engine out of the frame. But there was a lot more bits off as well. Can you access the slow jets without stripping the carbs right down? From `underneath` ie with the floats removed.
Like I said, all of my manuals are still in storage so I`ll be working blind.

[mickwinf]

possibly but fiddly, best to remove will be quicker in the long run

[Bryanj]

Personaly, even tho' the carbs are a sod to remove, i would still say its quicker (and a lot less swear words) to remove rather than try and do in situ.

Not to put you off but when i built a chop---Just 'cos the frame came in a load of bits i bought---I ahd to take the carbs off every time it sat foe more than 3 months

[basketcase]

Misunderstanding on all sides!! I understand that the carbs have to come off the engine, do I have to strip the carbs right down after they are off or is it possible to access the slow running jets via the underside of the carbs by removing the float bowls, floats etc, or do I have to strip them completely? `cos last time I did that it took an absolute age to put them back together....and that was with notes and photo`s!!
Sorry for the misunderstanding!

[Bryanj]

Yes jets come out with floatbowls(and maybe floats) removed---In fact thats the only way!

[K2-K6]

Just a comment about running it dry. I've got an old lawn mower with a very small main jet and left with petrol in the float chamber it always ends up blocked, but letting it run dry it will always start next time without dismantling it to clean the jet. Jet size is only just bigger than a steel wire from a wire brush, similar to pilots on these bikes.

On the same tack, my 750 K6 would just about run to 5 miles with fuel off and gentle throttle to get the carbs dry so it's something you need to do as more of a routine on the way home from a run if you feel it would avoid the need to strip it down.

The 550 K3 appears to be one of the most sesitive to blocked jets judging by the other experience on the forum.

[matthewmosse]

The 500 carbs are far less sensitive to the problem, I even had a project bike with full on furry alloy inside and out on the carbs - quite shocking to behold but a very cursory brush with a toothbrush and  the engine started right up on the bench. The 500 airbox and carbs are also a tiny bit shorterr than k3 ones which is a massive boon for fitting and removing

[florence]

I have to say I haven't ever had any trouble with my cb500/4 carbs either.

Points, however are always a problem, don't seem to be able to get hold of decent sets anymore.