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View Full Version : What have I done? Bike not starting after cleaning carbs



vindy500
29th April 2009, 18:05
so my bandits having issues with bogging down at past 50% throttle so the guy at the shop told me to clean the jets with a wire from a wire brush and set the pilot screws, done. 1.5 turns out for a 1992 bandit 250 and scraped out the 2 holes in the jets in all the carbs, put it back together and it wont start, push start electric start and electric start with "start ya bastard" all not working. any ideas?

autobatch
2nd May 2009, 15:50
There is a simple test to see if you have done something bad to the carb so you are not getting any fuel. Take out the plug(s) and put a tiny amount of fuel in the cylinder. Put the plug(s) back in and try to start it. If it starts and runs for a couple of seconds, you know for certain that it isn't getting any fuel. That being the case, you have done something wrong when you reassembled the carbs.

Let's assume that it does start and run for a few moments. Make sure fuel is getting into the carb. Take off the float bowl and check to see if it is full of fuel. Don't worry too much about the idle adjustment as improper setting will not prevent starting. You might have dislodged a bit of dit that has found itw way into the carb. jets. You might have to remove the carb again and blow it out with compressed air.

If the bike does not start, when you put a little fuel into the cylinder, you most likely have some kind of ignition problem. Make sure your spark plug is clean. After cleaning the plug, with the plug removed, connect the wire and hold the plug against the metal of the engine while cranking the engine over. You should see a nice fat spark in the plug.

That's a couple of things to try.
regards,
Johnny

vindy500
2nd May 2009, 15:57
ive been trying to start playing with the pilot screws, (its an inline 4) and very occasionally it will start for a couple of seconds and then die again, and sometime you can hear it trying to fire and it just kinda burbles but doesnt catch. SHould i be trying

xwhatsit
2nd May 2009, 16:01
Like the guy in the VT250 thread, have you set the fuel tap to `Prime' to fill the carbs first? Just leave it on prime until it starts. Vacuum fuel taps are a pain in the arse.

I got told off for scraping out jets with wire. Brass is very soft and if you scratch the inside of the jet, you're making it bigger. It might not seem like a lot but jets are very small so a gouge or scratch can make a difference.

The Pastor
2nd May 2009, 17:10
yeah use carb cleaner not wire, way better idea.

i would go as far as to replace the jets now that youve stuffed em!

i find after taking the carbs off a bike, it is often hard to start them, so i just roll start it down a big hill and 9 times out of 10 it'll start up and be good.

vindy500
2nd May 2009, 18:30
where would you get new jets from

vindy500
13th May 2009, 17:30
took the jets into a couple of bike shops today and they both said they were fine... any other reasons a bike wouldnt start? any troubleshooting ideas i could do?

Ragingrob
13th May 2009, 18:47
Spray in a load of engine start into the air box and see what happens!

vindy500
13th May 2009, 19:50
tried that too :/

cs363
13th May 2009, 21:14
Unfortunately this is a bit like performing surgery over the phone! :lol:

I would stop, take a deep breath and then go back and recheck everything you have touched - like are all the hoses connected to the carbs
(and correctly?) no kinked hoses, have you disconnected or knocked any wires off?
Did you do as xwhatsit suggested and prime the carbs? Is there fuel getting to the carbs? (try turning the tap to prime and undoing one of the float bowl drains, better still both of them)
Do you have spark?

One other thing - the two holes in the jets? Which jets were you cleaning - not being smart but do you know which bits are which in the carbs?

Did you have the slides out of the carbs and are they back in properly?

It really could be a lot of things, but if you are confident you've put the carbs back together exactly as they came apart without damaging anything then I would think it's probably just a hose or two somewhere on the wrong way or kinked etc.

98tls
13th May 2009, 21:18
Unfortunately this is a bit like performing surgery over the phone! :lol:

I would stop, take a deep breath and then go back and recheck everything you have touched - like are all the hoses connected to the carbs
(and correctly?) no kinked hoses, have you disconnected or knocked any wires off?
Did you do as xwhatsit suggested and prime the carbs? Is there fuel getting to the carbs? (try turning the tap to prime and undoing one of the float bowl drains, better still both of them)
Do you have spark?

One other thing - the two holes in the jets? Which jets were you cleaning - not being smart but do you know which bits are which in the carbs?

Did you have the slides out of the carbs and are they back in properly?

It really could be a lot of things, but if you are confident you've put the carbs back together exactly as they came apart without damaging anything then I would think it's probably just a hose or two somewhere on the wrong way or kinked etc. Xactly what he said(good post mate) Start with making sure there getting fuel..both.

vindy500
13th May 2009, 23:45
its a inline 4... but yeah. i know at least one of them is getting fuel cause i drained it, didnt check the other 3 tho... the carbs i cleaned were the pilot jet and the main jet im pretty sure, they unscrew with a normal flat head.

vindy500
17th May 2009, 14:22
one of the carbs carb 4 from left to right isnt getting any fuel, dry bowl. what could cause this?

Crasherfromwayback
17th May 2009, 14:31
one of the carbs carb 4 from left to right isnt getting any fuel, dry bowl. what could cause this?

Float hight or a needle valve problem

vindy500
17th May 2009, 15:38
Float hight or a needle valve problem

hmm the needle valve "looks" the same as the other 3, i dont really know what to look for though

MSTRS
17th May 2009, 15:47
one of the carbs carb 4 from left to right isnt getting any fuel, dry bowl. what could cause this?


Float hight or a needle valve problem

It could also be a blockage in the feed line before the needle valve. There should be 2 hoses from the fuel tap...1 feeds carbs 1+2, the other feeds 3+4. Obviously 3 is getting fuel so check the link pipe from there to 4.
Or it's got a blockage in the valve itself.
I think you'll have to remove the carbs to enable strip/clean

vindy500
17th May 2009, 15:53
It could also be a blockage in the feed line before the needle valve. There should be 2 hoses from the fuel tap...1 feeds carbs 1+2, the other feeds 3+4. Obviously 3 is getting fuel so check the link pipe from there to 4.
Or it's got a blockage in the valve itself.
I think you'll have to remove the carbs to enable strip/clean

its a vacuum fuel tap, one hose for fuel connects between carb 2 and 3, one hose for vacuum.

vindy500
17th May 2009, 16:05
with engine start being sprayed in it starts, but is obviously only running off the engine start because it quickly dies unless you put more in

MSTRS
17th May 2009, 16:15
its a vacuum fuel tap, one hose for fuel connects between carb 2 and 3, one hose for vacuum.

Whatever...what I mean is the hose from the tank is getting fuel to the carb/s...so the issue is downstream of the initial 'contact' point. Still means removing the carbs to dismantle. Not a job that can be done in place, generally.
In saying that, if you can get the bowl off #4 with the carbs still in place, just maybe you can drop the float, needle and valve. Then put the tap on prime and see if you are getting flow through the hole that the inlet valve screws into. If so, that may have cleared the blockage (dirt in the valve) so clean the valve before replacing. Otherwise, it would indicate a problem the feed pipe from carb 3, or with the float not dropping, or needle stuck in the valve.
There is nothing else it could be.

vindy500
17th May 2009, 16:31
sweet as ill give it a go :)

vindy500
17th May 2009, 16:40
as an aside i dont think my prime is working right, it should just pour out right? so the fuel filter should fill up with fuel?

vindy500
17th May 2009, 16:49
well cant make any fuel come out, i might just take it into the shop

MSTRS
17th May 2009, 17:45
well cant make any fuel come out, i might just take it into the shop

Under what circumstances? Bowl etc off?

vindy500
17th May 2009, 19:09
Under what circumstances? Bowl etc off?

bowl off, float off with its little needle valve attached, do i need to take more off?

MSTRS
18th May 2009, 08:36
bowl off, float off with its little needle valve attached, do i need to take more off?

Ok. You are zeroing in on the source of the problem. It is either a blockage in the link pipe to carb 4, or a blockage in the jet that the needle valve seats against.
I think you will need to remove the bank of carbs to get at either issue.