Bike won't start - suggestions please.

stay_upright

stay_upright

New member
A bit of history.

The bike had a crank seal go and was rebuilt over xmas. The first race this year the bike did not want to start in the garage.

Tried the usual fresh fuel, plugs cleaned the bottom of the carb out. Eventually got it to run. Went to the race and was very reluctant to start, spent 10mins kicking it in the paddock and after several new plugs it ran. For the start of the race with the bike warm it startted 1st or 2nd kick, rode great back to how I remember it - carburated nicely. Then I stall it or it stalled and I could not retart it after about 1/2 to 3/4 hour of running. After 1/2 an hour trying to restart it no luck so I DNF'd

Now back home still no luck, took the carb off to clean it there was some muck in the bottom of the bowl. Re-assembled and all I can get is an occasional misfire, backfire or burning in the exhaust or something, very strange. With the choke on I get nothing but without the choke I get these misfires or whatever they are.

I've now cleaned the carb 3x and gone through loads of plugs, tried fresh fuel again which made no difference.

Looked in the stator cover and everything looks OK - It's almost like the timing was out or something but there's nothing to move in there I don't think.

Could something have gone wrong after it's been rebuilt, maybe lasted OK for that 1/2 hour in the race then give out?

Or maybe because it's been stood for a while there's a problem?

There was a bit of green dry looking residue on some of the parts in teh float bowl of the carb I assume from the morris 2 stroke mix I'd been using which I think was green.

I changed the pilot for a richer one but that's made no difference either.

The plugs are coming out wet after many attempt at starting so at least some fuel is getting through.

Any suggestions?
 
Plug has been pulled and tested quite a few times - always a spark present when the plug is dry.

Also I'm getting the misfire or whatever occasionally so I think it's igniting something.

When installing the plug on the bike after 10 kicks or so the plug is then wet. But that's probably normal?
 
re the reeds I did a compression test and got 150psi after about 4-5 kicks, That seems about the same as I've alwats got.

If the reeds were damaged would it show up with low compression?

I've inspected them from the carb side and they look good - they were replaced just before the engine rebuild so have seen very little action, I can pull them and check the engine side if it's still worth doing?
 
Check you air filter, and the passage way to the carb. Maybe it's blocked.


Here is an odd ball suggestion but rotate your kickstarter forward to get a little more throw and rotation to start the motor.
 
Filter looks OK but for easy access to the carb the rear airbox is not connected to the carb so it can pull in fresh air easily.

I don't think any different styles of kicking it will help - something's wrong with it but it's good to check the basics.

I got a new plug cap and plug fited them and now I have no spark???

Tried the plug cap and lead off my trials bike - still no spark.

I measured the coil ground to blue/white input wire and got about 0.1ohm (seems about right)

Measured the HT output to ground - open connection should it not have some resistance there is the circuit basically 2 coils?
Measured ground to HT output on my trials bike and that was open circuit as well but the coil and ECU are different they are all integrated on the trials bike.

Will try resistances for the pick up and stator next..
 
When you were kicking it(with spark) did you hold the throttle wide open.

You also said you cleaned the carb.

Did you clean the pilot jet and stick a wire in the hole to clean out stuff. When I read back through, it seems like your carb was gunked up, you cleaned it and it was gunked up again once it ran. You also mentioned that the choke had no effect when on which leads me to believe you still have stuff in your carb.

I would go back to cleaning the carb thoroughly. Maybe head to the auto parts store and buy a can of carb cleaner that is made to dip the whole carb into the can.
 
I would alternate kicking with throttle closed and throttle open to try and get it to start and clear out the plug from wet fuel.

I cleaned the pilot with an airgun, I don't run wire through or anything for fear of wearing the hole size but you can look through it once cleaned and see it's clear.

Yeah second time I pulled the carb there was some gunk in there now the bottom of the float bowl is clean everytime I pull it the only thing that isn't perfect is the green residue on some parts of teh carb but as far as I know all the fuel passageways are clear. - also the plug's getting wet but maybe there's fuel getting through but not the right mixture to ignite?

Now i've got this wierd situation where I HAD a spark and now don't have one anymore.

Re-checked teh coil seems like the secondary winding resistance is supposed to be 6-16kohm and mine measured 13kohm so OK.

Also checked all the suggestions in the manual - pickup, exitor (whatever that is) and stator windings - all OK. - still no spark though.
 
I had a 05 250 and did some top end work, put it together and no spark, just the funny back fire thing. Thought maybe the kill switch was stuck, coil, stator,etc. Pull the plug and it was wet but didn't seem to get spark. Messed with it for hours and finally decided to buy a brand new plug and bam started right up.

Go back to the plug that worked when it ran the race. Plugs usually don't just die so you know that one works.


I would stick with looking at your carb and then use a new plug. I get the feeling that it's in your carb. Air screw backed out too much, choke blocked, blocked hoses on the outside, you could also have a sand pebble in the pilot and it looks clear but isn't(I have had this before).
 
I bought a new plug with the plug cap - but no spark now...

Also tried the plug I was using in the race - that would spark OK but the bike wouldn't fire.

My symptoms sound like yours einstein except i've tried the new plug and no good.
 
Could you try the trials carb?

as far as the spark. I had problems with the yellow wire and the yellow with green stripe. Also the connection with the white plug in the upper right.

async
 
OK thanks I'll have a closer look at those wires, I've gave them the once over and they looked OK but I'll check in a bit more detail.
 
wont start

try acouple shot of starting fluid if it trys to start its probably a fuel problem if not its a good chance its a stator, take flywheel off [need puller] look at stator for burn marks! u could try and bump start also , if it starts or trys to start its the stator! good luck
 
Got the spark back - was some of the connectors under the seat were just a bit dirty it looks like.

Still no luck starting it.

Could a crankseal have failed since the rebuild - could one side let air into the cylinder?

Is there any way to test this?

I've got spark, fuel and compression but it won't go :mad:

Will try to find some easy start today despite a friend warning me it blew the engine on one of their works trucks (though I'm wondering if it was diesel now)
 
Hold that baby wide open and kick it like mad.


Also, do you tip your bike on it's side prior to starting until fuel comes out the bottom of the carb hose? Usually results into a one kick start.

I am dying to find out what the problem is.
 
Already tried kicking at WOT can try again kicking more aggressively...

I've never tipped the bike over but I'm willing to give anything a try.

I was going to go and get some easy start next plus some carb cleaner to submerge the carb in overnight in case blowing it out with a air line is not clearing something.

Also what is the brass cylinder near the front of the carb - long thing the bottom must sit near the bottom of the float bowl. That's the only think I've been able to check I get airflow through 'cos I don't know where it goes.

I've also asked a mate to borrow his 300 to try swapping parts, hopefully he will say yes. I've got 10 days off and really want to ride the stupid thing!

I may also cut the centre electrode off a plug to see if the spark can jump right across in case maybe the spark's too weak to jump when there's compression in the cylinder.
 
wow found the problem, no wonder it wasn't easy.

I tried the easy start and that just made it more likely to go bang without turning the engine round, felt the exhaust it got warm so I'm thinking maybe the timing's out.

I push the engine to before TDC with the kickstart where the compression starts to make it hard to push around and the raised section for the ignition timing is about 120degrees away from the pickup. It should be very close at TDC.

So I remove the generator cover and find the culprit - a sheared woodruff key.

So the timing was miles out hence why most of the time it wouldn't fire and when it did it was burning in the exhaust.

I've got a 12oz FWW fitted also I guess that adds to the stress on the key quite a lot so probably more prone to failure.

Anyway I'm really happy, if I can get a key tomorrow I could be riding tomorrow night.
 
You must log in or register to reply here.

Similar threads

M
Engine surge/runaway?
Replies
4
Views
168
Mustyeddie
M
H
2009 450 won't start.
Replies
0
Views
34
Homer
H
Anders
Bad smell from gear oil
Replies
4
Views
63
Anders
Anders
Wbdisco
24v for starter
Replies
3
Views
79
Wbdisco
Wbdisco
T
Top end rebuild question
Replies
15
Views
5K
(F5)
(F5)
Back
Top