CBR250 Forums banner
1 - 20 of 46 Posts

· Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
Hi guy,

I have change the new spark plug last week, and everything run well, start ok. But after yesterday sit in the traffic jamfor half hour, and the bike is overheat, the revs drop and it just dies, I need to keep thorttling to prevent the revs drop until I got home.
Next morning, I try to start it, just having cranking sound, but cannot start, then I give the battary a full charge, and take out the plug, it was full of oil, because the plug are new, so I just clean and sand it, then put it back in. Try to start again, still no luck, take the plug out again, and it is full of oil again....??? What 's happening, did I flood the engine? how can I fix it? thanks.
 

· Registered
Joined
·
888 Posts
sounds like when you overheated you might have blown (possibly melted?) a gasket.

Is oil on all of the plugs or have you just checked one?
Are the plugs sparking? When covered in oil? After you've cleaned them?

If not, check your coils by putting an allen key into your spark plug lead and holding it a fraction of a millimeter from the frame/ground and seeing if it sparks.

I know the coils idea seems to be ignoring the oil symptom, but I had almost exactly the same problem and I think the oil/petrol was just getting there after trying to start it too much and thus fouling the plugs.
 

· Registered
Joined
·
14 Posts
Discussion Starter · #3 ·
clevermetal said:
sounds like when you overheated you might have blown (possibly melted?) a gasket.

Is oil on all of the plugs or have you just checked one?
Are the plugs sparking? When covered in oil? After you've cleaned them?

If not, check your coils by putting an allen key into your spark plug lead and holding it a fraction of a millimeter from the frame/ground and seeing if it sparks.

I know the coils idea seems to be ignoring the oil symptom, but I had almost exactly the same problem and I think the oil/petrol was just getting there after trying to start it too much and thus fouling the plugs.
I have check 4 of plug were all cover with oil, I have check the plug lead and its fine with spark. I have use lot of choke when starting it, so I think I have fouling the plugs and lot of petrol inside. What should I do now, should I leave it for 2 day ( holpfully the petrol will dry up) and try to start it again, or is there any way to clean it.
 

· Registered
Joined
·
6,256 Posts
teddy_ace said:
the bike is overheat, the revs drop and it just dies, I need to keep thorttling to prevent the revs drop until I got home.
Sounds to me like you've killed it mate. Bad idea to force an overheated engine to keep running!

Justin.
 

· Registered
Joined
·
14 Posts
Discussion Starter · #6 ·
sir.b said:
teddy_ace said:
the bike is overheat, the revs drop and it just dies, I need to keep thorttling to prevent the revs drop until I got home.
Sounds to me like you've killed it mate. Bad idea to force an overheated engine to keep running!

Justin.
Im not sure if it is overheat, the temp gaug is arround 3/4, then the rexs drop and die.
 

· Registered
Joined
·
6,256 Posts
teddy_ace said:
Im not sure if it is overheat, the temp gaug is arround 3/4, then the rexs drop and die.
Ahhh ok, when you said overheat I thought you meant it went into the red. That's not so bad then :)

Justin.
 

· Registered
Joined
·
5,378 Posts
Plug 1


Plug 2


Plug 3


Too much oil on plug one..?? (this is the one I am worried about)

Plugs got progressively cleaner until no oil at all on plug number four. Plugs are about 6 months old. I'm hoping this doesn't mean rooted rings on cylinder one.. Though having never taken the head off I don't know if the bit that is covered with oil is exposed to the inside of the chamber. Bahumbug : (

Just worried about the bit between the thread and the silver housing/bolt.
 

· Registered
Joined
·
6,786 Posts
bahumbug you have summoned.

looks to me like you have just fouled your plugs. Here you have two solutions; replace your plugs or bead blast/soda blast them.

Just so you know, the plugs are fouling on the ceramic insulator around the electrode... not on the electrode its self.

Though your rings are prob fucked as a little oil is normal, but alot is not. It shouldn't be fouling your plugs like that.

If you have flooded it, just leave choke off and crank a few times with no throttle. taking off the air filter helps a little fresh air get in... you can even blow out the air/petrol mist from the carby throats and that will instantly unflood your engine.
 

· Registered
Joined
·
5,378 Posts
I cleaned them up with a brass brush and plopped them back in. If it doesn't start tomorrow I'll change the plugs straight away.

So fouling the plugs up that high is combustion chamber cause. As in that's the way the oil is getting in... Ok thanks.

Is it viable to do the rings at the same time as the valve clearances? I guess you will have to take off the entire head :S jeez. Getting a little over my head now.

Also whilst you are here. At a standstill my gearbox has been very stiff. Ie. It won't shift through the gears like it used too when I had the bike still and not switched on or warm. I cleaned under the front sprocket, so I figure I might as well take a look. So I took off the selector bar thingy. Anyway popped it back on to see if tightening up the selector bar-bolt thing would do anything. Now not sure if I am
Putting it in the right place. Ie. Is it too far back. It's not going into second gear and not sitting in neutral either. I change it around bit it's not making much difference. Manual is not helping. Can anyone tell me if it's connected in the correct position for first gear? It's currently pointing towards 6 o'clock.

Thanks :/

[hr]
It's the ball joint connector between the spline??? (correct term) or gear drive? And the selector bar?? (again I don't know the name)..

Thanks
 

· Registered
Joined
·
6,786 Posts
first time I used a brass brush, it left a residue of brass on the insulator... and as you know, brass is conductive, so technically the plug was still fouled. I'd use a steel wire brush in the future.

i'll get back to you on the gearbox... I can see what is wrong from the pic... just abit busy atm.
 

· Registered
Joined
·
6,786 Posts
ok, your problem is just a mechanical leverage problem... and the fact that you dont know where 1st and 6th is because you've put the pivot arm upside down lol. now if you had cleaned your bike, you would have noticed that there is a dot punched on the pivot arm and on the spline. line these up and you will be rotating the correct direction and with the appropriate angle to apply force to.

this is how its supposed to look (sorry its the only photo I can find on my laptop atm)



[edit] I suppose you could call it a push rod with ball in socket joints... the star shaped pattern on the shaft is called a spline
 

· Registered
Joined
·
5,378 Posts
Ok I have fixed it. I line up the little divot on the ball pivot holder, with the large indent on the engine case on top of the spline.

That's the one right? You can see them both on my dodgy picture.

[hr]
The large indent has a little bit of impossible to remove concrete grime (must be as old as the bike and baked in the sun).

I also thought it could be mounted both ways? One for a reverse style shifting (1 up 5 down)?

I was in a hurry when I pulled it off, then had to go and source a deep 10mm socket to get the bottom sprocket cover bolt off (damn it!). Then had to go to the city to buy some shit.. So I didn't take enough notice of how it was before. Hence I am asking now.
 

· Registered
Joined
·
6,786 Posts
it could be that you are due for an oil change... if the ratcheting cover has been removed or fiddled with, it might not of been assembled correctly.

if its none of the above, then its not going to get much better. You could try stripping it down and rebuilding the ratcheting mechanism and look for wear/damage and that its together properly with all of the washers.

If its still sticking and slipping, its something further down the system.

You can have these reverse 1 up 5 down so long as you get the right angle and you adjust the pushrod to the correct length. but i dont think honda ever designed it to do that.

To answer your question about the plugs, oil can get in a couple of different ways. It can get in through the valve stem seals and past the piston rings. Doing valve clearances is really quick and easy (in terms of labour and what you have to remove to get the job done) but doing the rings is a big job. I'd remove the entire engine to do this. Not only would you have to take the head off, but you also have to split the case... Once you get the pistons out, you should also give the cylinders a hone... and hell, if you've gone that far, you may as well replace the pistons, bearings, give the engine a paint and clean everything in and around the engine...
 

· Registered
Joined
·
5,378 Posts
Perhaps it's worn a selector within the gearbox. I haven't ridden it since noticing, so I'll give it a whirl tomorrow evening.[hr]
Fook I don't have the time in the day to do that, not until June next year. Then it's a very high possibility. I could do valve clearances, in fact I have been planning too, just need to get a torque wrench, and new tyres still. Uni/living costs have taken preference for the last two months and I don't think that will change for another month or so.

Hopefully BigAl down here can give me a hand with the valve clearances.

[hr]
Oh yes, oil was changed today, along with a whole load of other general maintenance things. After a balance and if I can get the valve clearances done, I reckon it will be running better.

Piston rings can wait, as I'm not 100% on the need for it anyway, as of yet.
 

· Registered
Joined
·
1,609 Posts
Humbug said:
ok, your problem is just a mechanical leverage problem... and the fact that you dont know where 1st and 6th is because you've put the pivot arm upside down lol. now if you had cleaned your bike, you would have noticed that there is a dot punched on the pivot arm and on the spline. line these up and you will be rotating the correct direction and with the appropriate angle to apply force to.

this is how its supposed to look (sorry its the only photo I can find on my laptop atm)



[edit] I suppose you could call it a push rod with ball in socket joints... the star shaped pattern on the shaft is called a spline
May be an old photo, But the chain looks a bit tight Sir Humbug, Disreguard if so (Old photo, That is):D

Sir jlyall, Can you get any gears at all? Just asking is all.
 
1 - 20 of 46 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top