bike died aa on route carbs ,maybe

[dsr91]

hi guys , so my bike has a problem i cant figure out ,it rides perfect 5-6 rpm and above but if revs drop down to 4.5 and lower it stumbles and bogs ,if you dip clucth and throttle hard it pulls back again but yesderday i was following a slow moving pickup truck throught lanes that were narrow and revs dropped then bogged and died ,it would only start on full throttle at 1500 rpm (idle speed)after 20mins of tinkering and starting it agaian again i gave up and rang aa ,whilst waiting for them roughly 30 mins later i decided to start bike again and it fired up fine and revved clean so canceled aa jumped on and headed home at 6k above , when i stop at lights it idles but when you pull away again its bogging down again so i have to pull away hard or it will die ,what is up with my bike does anyone have any ideas? many thanks sean

[sa 71]

sounds like carbs, replace o rings etc...

[dsr91]

O rings are fine they have been replaced fairly recently , and float heights set , plus new plugs and oil etc , if the carbs were out of sync would it cause any of the above issues ? It's the only thing I can think of that may be wrong with carbs

[Awynn]

No I would not say carb balancing would cause this, if it started all of a sudden then maybe a jet has come loose or a sticking float or something like that?

[dsr91]

hi sorry for late reply , iv also had this problem since iv owned the bike but it had never died before until now even after carb rebuild it still does but doesnt spray fuel out the exhaust any more since ,orings and float hieghts done but still stumbles and bogs down at under 5k , at moment bike is in local garage having carb sync and balance as my gauges are cheap ebay ones that seem to be rather useless, and this is my first 4 cyclinder bike so not to good at setting them up ,

[dsr91]

No I would not say carb balancing would cause this, if it started all of a sudden then maybe a jet has come loose or a sticking float or something like that?

Hi , um no this was not sudden , always happens but never died until then , but a update after bike was at garage having carb sync and balance , it's worse . Still stumbles and bogs and mess up at under 5k and now the idle is all over place ,when you ride bike and pull up to a stop bike sits at 3k for awhile but doesn't also come down to idle whilst waiting for traffic lights etc , so yet again I'm stuck and still can use my bike to get work as traffic etc can be slow and bike will die , how do you tell if bike is dieing because of lean or rich ? Any help please

[4hundread]

Hi sean, this really sounds like air leaks and carb balance. The 3k then slow drop to the correct idle speed and poor running low down are exactly the same issues I had.

Have a good check for air leaks around the inlet rubbers by spraying brake cleaner or similar around them with the bike running, if it's drawing air/brake cleaner the revs will rise. The 3k then slow drop down to correct(ish) idle speed are signs of an air leak or a lean mixture.

The carb balance on these is a pain in the arse, but needs more in the way of patience and perseverance than special tools or skills. Tiny adjustments make a big difference. I don't want to knock anyones work, but when you say garage are we talking car or proper bike shop? It really shouldn't be worse after being done, if it is you should be given a good explanation why. Also should be said that all other servicing issues have to be done beforehand, i.e clean air filter ect.

Have a watch of a few carb balancing videos on you tube to get an idea of the procedure, they can be made to run nicely, just takes a while!

Hope this is of some use to you.

[dsr91]

[quote="4hundread"]Hi sean, this really sounds like air leaks and carb balance. The 3k then slow drop to the correct idle speed and poor running low down are exactly the same issues I had.

Have a good check for air leaks around the inlet rubbers by spraying brake cleaner or similar around them with the bike running, if it's drawing air/brake cleaner the revs will rise. The 3k then slow drop down to correct(ish) idle speed are signs of an air leak or a lean mixture.

The carb balance on these is a pain in the arse, but needs more in the way of patience and perseverance than special tools or skills. Tiny adjustments make a big difference. I don't want to knock anyones work, but when you say garage are we talking car or proper bike shop? It really shouldn't be worse after being done, if it is you should be given a good explanation why. Also should be said that all other servicing issues have to be done beforehand, i.e clean air filter ect.

Have a watch of a few carb balancing videos on you tube to get an idea of the procedure, they can be made to run nicely, just takes a while!
Thank you I will have a look for air leak soon , tryed using bike today but its very difficult to use at slower commuting speed , perfect in high revs I fact caught me out alittle as I throttle on in second the front lifted that never used to happen , just weird low revs are hopeless

[4hundread]

Q

[dsr91]

Aye, mine was horrible to ride round town too, either constantly blipping the throttle to stop it cutting out or sat like a twat at the traffic lights at 3000 rpm, not handy with a race can on!

I am pretty certain you are just needing the carbs set up properly. One thing I did notice with the last set of O rings I got was that the small ones that go under the carb tops were not thick enough to seal properly.

Hi , I've looked for air leaks but none found and yes you are right about cap top o rings but I've but bigger ones in already ,I've just got in from shed had a go at changing floats hieghts from 20mm to 18mm to see what happens but I've only had it running for 30 seconds it would only start on full throttle and wouldn't rev above 1500 rpm which is same as when it broke down but I'm going to try and run it tommorow to make sure there's no air stuck in lines etc 10.30 at night with a stubby can I don't think neighbours would like it