Misfire after tear-down

cantdecide

The tear down on my '02 RSV Mille I did was for two reasons; valve clearances and to remove the front head and barrel to sort out a stripped plug (which involved removing the engine). This was the most involved engine work I've done myself and although I'm always trying to educate myself, I don't purport to be any kind of expert.

After re-checking the valve clearances, reassembling, servicing and refitting the engine, the bike started without too much trouble. I tested the bike for a short time. It appeared to be running on just the front cylinder initially although the rear downpipe did become reasonably warm and the revs smoothed out somewhat but it wasn't quite right. I fitted the airbox and it didn't seem to make a huge difference. There was some backfiring and some popping through the rear cylinder intake. It got late so I left it until this morning. Today was much of a repeat- the front pipe got hot quickly while the rear took some time to get pretty warm although cooler than you'd expect. The bike appears to run pretty well at high revs but when you try to drop the revs down, it appears hesitant and the backfiring and popping from the intake returns. There appears to be plenty spark and I've performed some tests on the injectors and they appear to be working fine.

What are the possibilities? I felt very confident I got the timing back to where I found it but if I haven't, how do I proceed from here? Another possibility are the intake flanges- they're looking rough but appear to be okay- I swapped them front and back and thought there was an improvement in the way it was running but it started popping the back cylinder and backfiring at idle pretty quickly making me think that there had been no change.

Any ideas about how to proceed folks?

Wossack

does it have a power commander fitted?

cantdecide

No power commander or any electronic gizmos.

Wossack

okie

check all the rubbers, and that the body is fitted securely - could be an air leak leaning out the mixture to that cylinder

jimgoose

Those things become possessed by the devil if the throttle-bodies aren't balanced properly.

Hotblack Desiato

are you 100% sure the valve timing is correct?

Wossack

spotted your other thread over on rsvr.net - very very interesting! Hope you get it sorted

cantdecide

Wossack wrote: »

spotted your other thread over on rsvr.net - very very interesting! Hope you get it sorted

Sorted now...

ninja900 wrote: »

are you 100% sure the valve timing is correct?

Errr... made a balls of it actually.

In a nutshell, I believed wrongly that the front cylinder fired 60 deg after the back. I was suspicious that it would work that way but honestly, I believe a lot of what's in the Haynes did nothing to correct me. I had lost my way with it between the time it took to get it back together as well as having to work on both heads separately. For the benefit of other noobs the front fires 420 deg (360deg+60deg) after the rear. I quickly changed it all over and as soon as I did it fired right up and ran beautifully. I'm relieved it's sorted now and chuffed that (in the end) the purpose of the tear down appears to be sorted too.

Hotblack Desiato

Great