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Fireblade 893 running rich of lean on two cylinders
tompat3463 - 9/11/14 at 01:35 PM

Hi guys.

I'm nearing completion of my fireblade mini project and I'm having some issues with the engine.

Even when it's just idling the left two headers (looking at the headers ) are heating up very quickly while the right two take a few minutes to warm up to running temp. I'm not sure which ones are right although I oressune the left 2 shouldn't be heating up as quick as they are.

The problem seems to be resulting in rough running and a nasty sounding idle

Could this be carbs 1-2 being out of sync with 3-4 or is this a mixture issue ?

Any help greatly appreciated


CosKev3 - 9/11/14 at 02:05 PM

Have you stripped carbs and cleaned all the jets/air correctors etc?

Also check all your mixture screws are unscrewed the same amount


tompat3463 - 9/11/14 at 02:15 PM

The carbs were cleaned not so long ago when I out the engine together.

Which are the mixture screws ?


CosKev3 - 9/11/14 at 05:38 PM

http://www.locostbuilders.co.uk/viewthread.php?tid=108172&page=2

Got a R1 eng myself, so don't know offhand.

But a quick search reveals the thread above.

Pic of mixture screws and how many turns out they should be as a base setting


tompat3463 - 9/11/14 at 08:18 PM

Just checked the mixture screws and they all seem in the same ballpark so I'm eliminating them now

I have a set of balancing gauges just need some of those little spigots tgat screw into the head then I'll ballance the carbs and see if this helps


mackei23b - 10/11/14 at 10:41 AM

Yes I would definitely get the carbs balanced and go through all the basics first.... the bleed screws will only have in impact at low throttle and should not affect the mixture at WOT.

Have you pulled out the plugs to look at the colours?

A Gunsons color tune will also let you see what is happening in the cylinders, but the colour of the plugs should also give an indication.

Cheers

Ian


Jenko - 10/11/14 at 12:29 PM

Look at the things that are common to the two cylinders - Not sure on coil packs, but usually, the carbs are individual, so balancing should be high on the list. The central balance screw may need adjusting, balancing is important for smooth running.

Things being in the 'same ballpark' may not cut it, it need to be spot on really to iliminate issues.


tompat3463 - 12/11/14 at 08:41 PM

Hi guys. Just an update and a bump as I still haven't getten this sorted. I've narrowed this problem down to a misfire on cylinder 2. Pulled the ht lead while the engine is running and there is no chance in engine when idling when I pull out the lead on #2.

I've checked for a spark on this cylinder and its sparking well with the plug out and against an earthed part of the engine so it's not a spark or plug problem.

My question is now. Could a blockage in #2 carb be so severe as to cause a misfire ? I'm guessing yes as I've had the carbs apart before and they are so delicate.

Where should I be looking for blockages ? And what things that could be adjusted inside the carb fix this ?


Also to reply to please helpers on this thread. The carbs are now balanced and mixture screws are set at 2 and 3/4 out from closed (I'm presuming closed is fully screwed in ?)

Thanks peeps


BaileyPerformance - 12/11/14 at 08:58 PM

Was the plug from number 2 wet?


CosKev3 - 12/11/14 at 09:02 PM

Is the spark plug dry when you remove it after its been running,or soaking wet in fuel?

Total blockage somewhere would cause it to misfire,likewise if its flooding with fuel it would misfire.

If the plugs totally dry I would try putting a small amount of fuel in through the intake(butterfly)when the engines running and see if the misfire goes while the eng uses this fuel.

As for cleaning you need to look through every jet in the carb and check its clear,air line is best,but thin welding wire can be good too.


tompat3463 - 12/11/14 at 09:10 PM

Thanks for the reply mate. I've pulled the carbs off and had a look and all seems fine however what your saying is right. The spark plug is bone dry. So I'm thinking total blockage.

I have however just broke one of the mixture screws and it's totally closed ! Gutted ! Don't know how I'm going to get that out !

I'll have s better look tomorrow with the air line as you say and hope fully find something


davidimurray - 12/11/14 at 10:40 PM

Air line won't necessarily get everything clean.i learnt the hard way!take all the jets out and soak in carb cleaner overnight.


tompat3463 - 13/11/14 at 08:41 AM

After taking off the carbs and inspecting all seems fine although the I couldn't find my carb cleaner. Anyways, took off the float and again everything looks good. I'm getting some carb cleaner tonight and will thoughry clean that carb.

Like mentioned before the cool and spark seems fine so I'm 90% sure this is a fueling issue.

I also noticed last night whist the engine got up to running temperature that there is oily fluid and what looks like either vapor or smoke (hard to tell) coming from the rocker cover breather pipe. Is this normal ? I know I should have a little filter on it but I thought it was just a little odd. The smokey stuff coming out is very smelly. Almost like exhaust gas.

Can anyone else shed light on this ?

Thanks Alan


BaileyPerformance - 13/11/14 at 10:04 AM

quote:
Originally posted by tompat3463
After taking off the carbs and inspecting all seems fine although the I couldn't find my carb cleaner. Anyways, took off the float and again everything looks good. I'm getting some carb cleaner tonight and will thoughry clean that carb.

Like mentioned before the cool and spark seems fine so I'm 90% sure this is a fueling issue.

I also noticed last night whist the engine got up to running temperature that there is oily fluid and what looks like either vapor or smoke (hard to tell) coming from the rocker cover breather pipe. Is this normal ? I know I should have a little filter on it but I thought it was just a little odd. The smokey stuff coming out is very smelly. Almost like exhaust gas.

Can anyone else shed light on this ?

Thanks Alan


If i was you i would compression test the engine before you go any further.
Do the test at full thottle


tompat3463 - 13/11/14 at 12:09 PM

I've just put the carbs back on and sealed the plugs around and tgat seams to have done it. Engine running well and revving up and down very smooth.

Most probably a small block somewhere in the carb.

Still got the vapor coming from the rocker breather which is worrying