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markparrish

C15 not running well - help please!!

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Hi - I have just put my C15 engine back together after fixing a number of oil leaks (I hope!). It never ran very well before - it seemed to never idle properly. I've only owned it for a short while and managed to nurse it through for its first job which was just to deliver my daughter to her outdoor wedding (about 100 yards up a drive!) without getting oil on her dress!

Now I have it all back together, it starts easily and I seem to be able to get a lovely, smooth, medium speed idle but as soon as I open the throttle it bogs and dies.

I am out of my depth and need some help - maybe a sequence of things to eliminate/try?

It is a fairly standard looking engine but has Electrex world ignition. I think I have put this back correctly as I made a couple of punch marks before removing it to fit a primary chain tensioner.  I tried it with a newish Amal MK1 first which it was running with (but quite badly) before the rebuild (although I notice there was a fair amount of sticky residue in this when I removed it). It started well after a good tickle but no chance of ever pulling away because the throttle caused it to stall.

I then swapped it for a newish Mikuni lookalike and with choke it starts first kick and runs with choke out. As soon as choke is pushed in it does the bogging/dying behaviour so I can't even rev it to keep it running. I've tried fiddling with the mixture screw and it makes a bit of difference when choke is out but still won't run with choke in. I think the valve clearance is ok, but maybe it's not - I used the Rupert Ratio trick of listening for the click when moving the rocker to get a nice quiet engine. I did back this off a bit on the inlet side as I thought perhaps it was too tight and this might be contributing, but it doesn't seem to have helped much.

I'm happy to try anything but don't really know where to begin.

Thanks in advance, Mark

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Has it got an air leak between the carb and the head?Get it ticking over then go round the inlet between the carb and head with an oil can.If its leaking it'll suck oil in and start smoking 

Edited by huski
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41 minutes ago, huski said:

Has it got an air leak between the carb and the head?Get it ticking over then go round the inlet between the carb and head with an oil can.If its leaking it'll suck oil in and start smoking 

Thanks Huski - that's a good idea - I will try that tomorrow.

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I would make absolutely sure the pilot jet isn’t blocked. Even if it means sticking a small piece of wire through it. 

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If you put the amal back on, make sure the float level is correct before doing anything else.  I take it your use a slow throttle ?

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1 hour ago, b40rt said:

If you put the amal back on, make sure the float level is correct before doing anything else.  I take it your use a slow throttle ?

I might do that - after giving it a thorough clean. I'm not sure what the throttle is - it doesn't seem particularly fast.

 

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17 hours ago, markparrish said:

 

 

I've completely stripped the Amal carb and cleaned all the parts in ultrasonic tank. I've cleaned the jets which had a bit of gunge on them and made sure everything is clean and reassembled correctly. I can't see any way of adjusting the float height in the carb - it is a rigid unit which bears directly on the needle. I'll just have to hope it is right. Fingers crossed for re fitting it tomorrow! 

Edited by markparrish
quoting myself!

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17 minutes ago, archie01 said:

That is the coolest wedding pic I have ever seen :)

 

Thanks Archie - it was a very special day and done in my daughter's unique way! I was a very proud daddy!

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Thanks for everyone's help with this. I have got it running quite well this morning - I carefully reassembled the cleaned carb and did my best to tighten it to eliminate any leaks (without over tightening it!). It idles quite well and picks up well from idle ok. I notice it won't idle on the side stand - seems to slow down and stall - I guess that's something to do with the height of fuel in the chamber (its a bent stand and it lays fairly low on its side).

only a couple of tiny oil leaks too! Much better than before! I guess its hard to eliminate them all and new ones appear every time I try! by the way I was wrong - it's a monoblock carb not a Mk1, sorry.

Edited by markparrish
added note on carb
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