leaking fuel into cylinders

[rickybobby]

@ Lane

You're right, the outer carbs have 105 jets. I misread the numbers before.

@ Callum

Good to know I don't have a leak from the carby gaskets


UPDATE:

IM PISSSSSEDDDD!!!

1. cleaned up the carbys, no more fuel leak.

2. Set the pilot screws to 1 3/4 turns.

I want to clarify that this means 1 whole 360 degree revolution + 3/4s of a whole revolution right?

3. brand new plugs, fully charged battery, kill switch off, in neutral.

4. NO START!!!!

5. It will start for about 2 seconds then die right away. I felt the headers and found that only cylinders 2 and 3 were warm, 1 and 4 were totally cold, this was after a few tries of 2 second idles.

6. checked for spark, and yes the new plugs gave strong, beautiful sparks from all plugs.

Am I missing something?

the problem seems to be with cylinder 1 and 4.

[clevermetal]

you might have disturbed some fine particles but didn't remove them, so now they've blocked your jets.

However I'd say it was because your carbs are very badly out of balance (would explain why someone had changed the mixture screws on 1 and 4).

the engine will run on 2 cylinders, just takes a bit of trial and error with throttle positions and choke settings (off is probably best) to keep it running. Once you've got it sort of going I'd check the flow of carb 1 (left if sitting) and 2, 2 & 3, and 3 & 4 (you'll have to take the nipple of 1 and use it on 4) with a homemade/bought manometer.

You want them all to be drawing the same amount of air, the adjustment screws are quite hard to find and if you move the throttle they move. Also don't push too hard on the screw or you'll open the throttle and everything gets harder (maybe have someone holding the throttle so you can push on the screws a bit more).

It's not as hard as it reads, just a bit fiddly, once you get it the next three adjustments are piss easy

---

just to check - the excessive fuel leak occurred while it was running, not when left for a while right?

[rickybobby]

the fuel leak occurred when I kept trying to start up the bike, after carby clean, no more fuel leak.

I think clevermetal is spot on, a carby sync is the solution here. would make sense that the 2 outer mixture screws are so differently set, resulting in bad mixture when reset to the stock settings.

Thanks a lot clevermetal! will research on how to make a home made manometer.

update in a bout a week's time!

[clevermetal]

good luck!
hope it works

[lico]

I dont think that the balance of the butterfly valves is going to stop the bike running on 4, maaaybe at idle but as soon as you open the throttle a bit it shouldd run on all four cylinders...

Confirm this?

[Aduro]

unbalanced carbs wont cause you to drop a cylinder unless youve messed with the balancing screws in a serious way and even then itd just be a very lumpy idle.

[rickybobby]

not really sure what's up with the other cylinders not firing, but I did manage to start up the bike and balance the carbs

link here:

http://cbr250.com/forum/thread-8449.html

as of recently, only cylinder 1 is not firing on start up and the other 3 are good. but when the bike gets warm enough, cylinder 1 will eventually fire.

rides sweet

[Lane]

When did the bike last go for a solid rode with a good flogging?

[lico]

Yeah check that spark plug to see if it's getting fouled, replace it for $5 while you're at it, check the voltage to it from the coil, check the idle jet again for that carb....

...Then use choke when you start it cold, should run on 4.