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Cough and spluttering under load
https://www.ausmini.com/forums/viewtopic.php?f=2&t=61910		 Page 1 of 2
Author:  Turns01 [ Sun Mar 21, 2010 9:33 am ]
Post subject:  Cough and spluttering under load
Was driving my mum to the airport this morning, no problems. On the way home, the mini started coughing and spluttering under load.
I pulled over and checked to see if there was anything obvious. No leaks that I could see.
I pulled the spark plugs out and found that the condition of cylinder 1 and 2 were vastly different from 3 and 4. I have just put in new plugs last week, and took the mini for a solid drive yesterday down the royal national park without any issues.

Image


The cleanest plugs are 1 and 2. usually they are quite black.

Can anyone point me in the right direction?

I am running a 45 dcoe weber on what I believe to be a 1380 (that was what it was registered as whe I bought it) elecvtric fuel pump, duel tanks...



Things I am thinking it could be at the moment is fuel starvation or head gasket...... Please any help would be appreciated.Image
Author:  drmini in aust [ Sun Mar 21, 2010 10:46 am ]
Post subject: 
Check the idle jets, emulsion tubes, main jets and air correctors are the same in both barrels.
I did a 1293 motor up for my wife's S replica that had used a 45 Weber, #1 & #2 pistons were pock marked like the moon from running lean. #3 & #4 were OK. :lol:
Carby had been sold but I bet the jetting was crook as stated.
Author:  Turns01 [ Sun Mar 21, 2010 10:56 am ]
Post subject: 
Doc, Thanks for the response... how do I check the idle jets, emulsion tubes, main jets and air correctors.

I haven't worked with webers before. If I start pulling things off, how do I get it back to running condition?

It was running fine for a few weeks. The plugs were all identical in terms of colour before this morning... It was running a little rich (ie dark and black) then while driving this morning something changed.
Author:  Leighton [ Sun Mar 21, 2010 11:00 am ]
Post subject: 
im also having this problem, it starts after a while of pumping accelorator and choke out and sounds alright when idleing but as soon as you let the clutch out it loses all power and backfires.

its an 998 bored .080", 266 cam, and 1-1/2" su. can somebody give me any indication to what the problem would be.

thanks,

Leighton
Author:  drmini in aust [ Sun Mar 21, 2010 11:07 am ]
Post subject: 
Turns01 wrote:
Doc, Thanks for the response... how do I check the idle jets, emulsion tubes, main jets and air correctors.

I haven't worked with webers before. If I start pulling things off, how do I get it back to running condition?

It was running fine for a few weeks. The plugs were all identical in terms of colour before this morning... It was running a little rich (ie dark and black) then while driving this morning something changed.


Take the round jet cover off the top. Inside there are 2 emulsion tube assys (at front) with 2 idle jet assys (behind).
Make sure L and R of each pair have the same numbers.
Air jets are on top of emulsion tubes, main jets at bottom.
Author:  Turns01 [ Sun Mar 21, 2010 11:20 am ]
Post subject: 
Doc the numbers are the same:

F2 - 180

and

45 F9

were the numbers on the tube/screw things.
Author:  Turns01 [ Sun Mar 21, 2010 12:00 pm ]
Post subject: 
I have had a look a the distributor and leads to make sure spark is getting through.

While the engine was running i pulled the lead off plug 1. There was little change to idle and spark was getting through. When I pulled lead off number 2 plug, idle reduced dramatically almost to the point of stall. cylinder 3 was similar to 2 and cylinder 4 was similar to cylinder 1.

So to test the theory, I pulled 1 and 4 off together and there was little change. I pulled 2 and 3 off and the engine stalled.

Is this normal?
Author:  drmini in aust [ Sun Mar 21, 2010 12:05 pm ]
Post subject: 
Turns01 wrote:
Doc the numbers are the same:

F2 - 180

and

45 F9

were the numbers on the tube/screw things.

180 is the air correctors. Did you check the numbers on the main jets at bottom of the emulsion tubes??
Author:  Turns01 [ Sun Mar 21, 2010 12:23 pm ]
Post subject: 
Doc,

Image

From top to bottom the markings are 170 - F2 - 180. the bottom number is on the hexagonal screw in part.

Thanks for your help.

Simon
Author:  drmini in aust [ Sun Mar 21, 2010 12:46 pm ]
Post subject: 
OK so the mains are 170.
Sounds somewhere near the money (if it has 36 choke tubes in it).
Author:  Turns01 [ Sun Mar 21, 2010 2:13 pm ]
Post subject: 
Thanks Doc.

Well that eliminates the fuel issues I thought might be causing the missing. Now I am led to believe it could be a head gasket. Might look at pulling the head off tomorrow. Unless it could be something else....

What are the best type of head gaskets and where do I get 'em? Karcraft?

Cheers,
Simon
Author:  TheMiniMan [ Sun Mar 21, 2010 2:50 pm ]
Post subject: 
I`d be checking that the manifold hasn`t come loose from the cyl head , or the weber hasn`t come loose from the manifold etc first

& the jets may be blocked so blow some compressed air through them (Maje sure you hang onto them tight tho,,, don`t want them shooting off into the garden or across the road etc) or even try some fues wire (or similar) through them to make sure they`re clear

do a compression test & check your rocker clearances too

^ Leighton,,, maybe you have stuffed condensor &/or points
Author:  drmini in aust [ Sun Mar 21, 2010 3:12 pm ]
Post subject: 
Turns01 wrote:
Thanks Doc.

Well that eliminates the fuel issues I thought might be causing the missing. Now I am led to believe it could be a head gasket. Might look at pulling the head off tomorrow. Unless it could be something else....

What are the best type of head gaskets and where do I get 'em? Karcraft?

Cheers,
Simon

IMO the best 1275 gasket available at the moment (GT m will shoot me down though) is the BK450, from Karcraft.
It's my (and TheMiniMan's) favourite, no correspondence will be entered into.:mrgreen:
Author:  TheMiniMan [ Sun Mar 21, 2010 3:20 pm ]
Post subject: 
here here

or there there

whatever the case (of beer) be
:lol:
:lol:
:lol:

best check the gear-shift mechanisim, just in case that`s what`s caused the problem

ok,,, i`ll stop now

hey at least the 3 of us (GTWoggsy, The Doc & Moi) know we`re all joking & friendly about it too hey??? Me thinks the 3 of us are showing our age & maturity don`t you think?

(stoopid remote shifts & copper head gaskets)

:-)

am not,,, are too,,, am not ,,, are too

:-)
Author:  simon k [ Sun Mar 21, 2010 4:32 pm ]
Post subject: 
check the compression before you take the head off....
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