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Advice on engine problem

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RGP750:
Here you go.
Hope it's all yours is .
Good luck
http://www.sohc.co.uk/index.php/topic,13165.0.html

mike the bike:
Try swapping 2 and 3 plug leads.  As they fire the same time it won't make any difference to the running.  If the problem migrates to no. 3, then it's a HT problem.

K2-K6:
Thanks Rich,  I was in too much of a rush to look for it properly.

Something with these fours generally is that if they're built well then there's not much that really goes wrong with them, they are very reliable usually.

Sprinta,  it may take a little sorting through to properly debug each example but each little bit of attention should gradually move it forward to running really well.

Also if it's been bored,  honed, glaze busted it that rebuild with new rings,  then you'd expect the compression readings to be improving still at this point and up until closer to a thousand miles. You may be getting a discrepancy with the unburnt petrol washing oil off the bores prior to testing at the moment so any correction of running and firing reliably should give you a better look at the compressions after a decent runout.

sprinta:

--- Quote from: RGP750 on July 06, 2017, 07:07:05 PM ---Here you go.
Hope it's all yours is .
Good luck
http://www.sohc.co.uk/index.php/topic,13165.0.html

--- End quote ---

Thanks. Interesting read with several points for me to check.

sprinta:
Thanks for all the replies and suggestions.

All new NGK plug caps which all give a reading of around 5K ohms

Secondary coil resistances both around 15K ohms. Have not tested primary resistances yet.

My initial worry was that it was a guide seal or piston/ring problem when I first looked at the No 2 plug, 2nd photo. But at this stage that plug had done around 300 miles and around 30/40 miles not firing. Following the plug change it did smoke but cleared up after 10/20 miles before fouling again at around 30 miles.

The photo of the No 2 plug this time shows a less oily deposits and more black carbon as it was firing intermittently so at this stage I am still at  a bit of a loss as to the likely cause?

Will check the primary resistance of the coils and then swap the N0 2 and 3 ht plugs/leads over and see if the transfers the problem?

Also need to check the valve clearances as they may be a bit tight on No 2 and 3 resulting the slightly lower compression? 

As previously advised all the main and pilot jets are clear. Yes I did have the throttles fully open and the tests were done with the engine up to full operating temp, still got the bl**dy burns trying to screw the hoses into the plug holes!

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