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Zetec On R1 Carbs Running On 3 Cylinders


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Hi all

 

Any help would be greatly appreciated on things to check befor I strip the carbs down

 

Running (or trying to) blacktop zetec, r1 carbs on megajolt. Exhaust is cold on the cylinder 1, closest to the coil pack, if I have that right.

 

Plug shows no sign of running but does spark when removed and checked.

 

What would you check next??

 

Thanks for any help

Cheers

Simon

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Cylinder 1 is the one at the cam belt end and 4 is at the flywheel end so you have number 4 not firing!

Ignition wise it could be a coil, lead or plug problem.

I would swap the plug leads from coil posts 1 and 4, not at the plugs. If 4 now fires and 1 is cold that would point to one output of the coil being duff.

If the problem is unchanged then try swapping 1 and 4 plugs. Does the problem move. If it does then its a duff plug.

Do you have any spare plug leads, even non zetec ones? If so then replace lead 4 and try. Does 4 now get hot? If so then its a duff lead 4. If you haven't a spare lead then pull lead 4 of its plug, pull lead 1 off it's plug and stick it on plug 4. It may run on two cylinders, or three cylinders or not at all. If it runs on two or not at all you have eliminated the plugs, leads and coils.

Compression test might be next best step to check engine mechanicals on number 1 cylinder.

If compressions are good then you can concentrate on the carb which is probably the culprit anyway but the above is quick and easy and might show the problem.

 

Nigel

 

Edited because I was slow to notice the backward cylinder numbering.

Edited by Longboarder
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Hi all

Cheers for the ideas, tried them and to no avail.

Nigel you 100% number 1 is cambelt end? Mine is set up on the coil pack with the shortest lead on coil pack at number one so I had it the other way round. Never checked just assumed who I got the coil pack from had it right. Would it still start if in reverse?

 

Not got a compression tester so may save that for the last check. Stripping the carbs it is then, sure I'll find a guide online but if anyone has one to hand that would be great

 

Cheers for the help

Simon

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if the plug is sparking when you remove it there isn't a problem with sparks, is there fuel getting into the cylinder ie wet plugs or smell of fuel?

Have you taken the float bowl off the carb on the dead cylinder and checked for fuel?

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As it looks like I need to take the carbs to bits is there an ideal inlet jet size for a 2l blacktop? Thinking I may as we'll change if need whilst I'm there as think these are straight off the bike.

 

Anything else I should do whilst I'm there?

Cheers

Simon

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Guest steve8274

I just had the same problem on my car and although not same engine or carbs, it is something you can check.

On mine, the idle jet(pretty sure that's what it's called) had simply unscrewed itself probably with vibration, and fell out.

My car had spark and it would drive without problems except for bit of popping.

Luckily it had fallen onto chassis rail and had got stuck in corner. Screwed back in and all well.

With mine, I also, tried spraying carb cleaner into each throat. The engine would almost die on the other 3 but engine increased when sprayed in faulty one

Hope this helps

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Evening, All sorted.

After stripping the carbs I couldn't see anything wrong, however I had forgotten to blank off the vacuum input into the inlet manifold, once this was done all was good, albeit still ropey.

 

Still a couple of issues though,

 

1. Does anyone have a Megajolt map that I could upload as a start - Standard blacktop on Standard R1 Carbs.

2. Only starts if the choke is opened, after which a blip of the throttle and it wants to die....if you do it slowly of when hot then its ok - could this be flooding,

3. Really cant get the throttle cable to have a smooth action, anyone got any pics of how they have done theirs. I'm using a bike cable as fits the R1 nicely but getting it to the pedal is a nightmare as doesn't return fully all the time. Albeit once I do get this working I have found I cant wear shoes when I want to drive it.....using a zero pedal set (another mistake) and the pedals are very close together - I'm telling myself this is a good security measure.

 

Cheers for the previous help....got a bit more motivation now its going!

 

 

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Guest davidimurray

Will it rev up at all?

 

If it is fuelling related then if it is worth bearing in mind the different circuits :-

idle

Pilot

Needle

Main

 

Pilot gives fuel all the time and the idle screw basically adds/removes fuel as a trim.

With the throttle shut, the diaphragm sits at the bottom with the needle down into the nozzle in the carb body. Fuel sits in the carb upto the float level and when there is sufficient vacuum is sucked through the main jet, and through the gap between the needle and the hole.

When you accelerate, the diaphragm rises lifts the needle (which tapers) and the hole gets bigger so more fuel comes out.

When the diapragm is fully at the top the hole the needle creates is larger than the main jet, so the main jet size now becomes the limiting factor.

 

Generally, from the troubles I had, I found that 'blocked' pilots were the most troublesome, they have tiny openings in them.. The car would run rough, die when lightly revved, but put your foot down and it would run at higher revs but with a misfire.

 

Tried cleaning the pilots by blowing through and it worked with limited success. then I soaked the pilots in carb cleaner for 24 hours, the sh*t that came out was unbelievable and cured all my problems.

 

When setting up carbs, balancing is very important and makes a massive difference to how well they run. As soon as you get it idling reasonably you should balance them. Then set the idle fuelling. Then with a wideband drive the car and setup the needles and main jet. The internet always seems to talk about main jets but they will only affect wide open throttle and setting the needles is just as important.

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Guest mcramsay

When I built my zero I found the pedals far too close together, I took the pedals out and with the aid of a bit of heat I bent a crank into the throttle and brake pedal to push them away from each other. Worked quite well

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