Forum

[jefrs]

Sorry - I misunderstood as if it won't start rather than running badly. However I still think you should look at the work you did on the barrel as a starting point regarding the valves, and the ignition timing can also be done static on the cam which as it is electronic just needs to point at the right place (and in all probability you didn't touch it). It's as if you're not getting fuel in, inlet shut or not opening at the right point.

[mike139]

Hi Jefrs thanks for your reply, it is getting fuel ok as it will fire up and you can smell fuel at the exhaust but is very lumpy once it starts and will only keep going when on a very high tick over. I have checked the clearance on the valves and the inlet was a touch loose but nothing i would say would effect the engine. One thing i havent tried is a new spark plug so that will be next on the list of things to try.
I reverted back to the old air filter and rejetted the carb back to how it was and it did attempt to start first turn over but i couldnt keep it going i will try again tonight as i dont think the pilot jet was set correctly but it was starting easier than it was with the standard air filter and jets.

[Boxerman]

I'd check the starter motor brushes if it isn't spinning the engine over properly. Solenoid contacts can get burned so shorting it out was a good idea, just be careful of sparks. You can get starter motor brush kits on ebay, I'm surprised that Hitchcocks don't seem to sell them.
Frank

[jefrs]

I would try another plug because some will 'track' under pressure if they're cracked or have oil or crud burnt into the outer ceramic insulator but give a good fat spark in the open air. The plug can look clean so it's not an easy one to see but it is easy to swap a plug out. What jumps that spark gap at 1atm may not want to jump the gap at 7atm and find an easier route. Also make sure the HT cap is fully on and fully connected to the HT lead.



Lumpy running is usually fuel. That assumes you don't have sparks missing but the ignition spark timing can be well out and still idle quite smoothly.



Clean out all filters including the one in the tank. Clean sediment out of float bowls and everywhere, clean jets etc.



The K&N is a good thing. It won't alter the mix much on a carb but will let air in more easily.



Throttle stop gap?

[mike139]

Thanks for the replies, the starter will be coming out at the weekend so that i can check it.
I have ordered a couple of spark plugs which should be here by the weekend so i will try a new one in it.
Everything else appears to be ok i have cleaned all filters and cleaned out the carb twice.
I should also be able to get hold of a timing light at the weekend so that i can check out the timing.
One thing i noticed which i thought was a bit strange was that there was a plastic restricted in with the K&N air filter, it reduced the bore down to about an inch and just didnt look like it was engineered in any way to be there. I am going to remove that and see if it makes any difference, is this a usual addition when fitting a k&N type filter?

[mike139]

I didnt get much further forward over the weekend, i fitted and gaped a new plug and no difference, i really struggled to get it started after fitting the new plug and this time i got it started on the choke, but once off the choke it cut out and would not start again. It is now back firing through the carb worse than before with some load pops coming after i have attempted to start and the ignition is turned off which are concerning.
I didnt get the starter out but a second opinion on the starter issue was that the sprag clutch is sticking hence the reason the starter spins up but does not turn the engine over which was what i thought. So next is to get the sprag out for inspection and then try to start it again, i am thinking of buying a new carb to see if that makes any difference.

[PeteF]

Have you checked the ignition timing?

[PeteF]

"i am thinking of buying a new carb to see if that makes any difference"
That would just add to the confusion.

[Mark M]

Pete is right, I'd check and eliminate ignition timing before doing anything else. (It is often said 99% of electrical problems are in the carb and 99% of carb problems are in the electrics but dismantling the sprag clutch to fix a carburation/ignition problem is taking this to a whole new level!)

REgards, Mark

[papasmurf]

Loud pops with the ignition switched off? I would have thought that means the ignition may be switched of at the key but is still live.