MHR backfiring through carbs

Trevor · Post by **Trevor** » Sat May 03, 2008 5:46 am

Hi All,
I was in the process of taking my MHR to a local classic bike meeting and whilst riding there a I passed a car missed a gear and revved it a bit nothing serious and the bike starting missing and back firing through the carbs. I turned around and headed for home and when I got home I checked the plugs, the compression (1050kpa on both cylinders), the ignition pick ups were tight, swopped the plug caps over, checked the carbs where clean. Everything seems to be ok but the bike does not like to run below 3000rpm and spits flames out the carbs every now and then. The bike was running perfectly yesterday when I rode it. It has a Rita ignition, NGK BHS 7 plugs and had a carb overhaul 6 months ago when rebuilt.
Any ideas to solve.
thanks Trevor

wdietz186 · Post by **wdietz186** » Sat May 03, 2008 7:49 pm

Trevor, I had a similar problem on my 77 900SS. I assume the Rita you have is mounted on the vertical cylinder. The ignition rotor is not keyed to the shaft it bolts to, so it is possible the rotor has come loose on the shaft and the timing is retarded. Or the cam nut has loosened and has altered the timing. Both are pretty easy to check and rectify. Hope this helps,Bill

Trevor · Post by **Trevor** » Sun May 04, 2008 1:39 am

Thanks Bill, will check it out. Unfortunately I am working 600km from home so it will only be in a couple of weeks before I can get to it again.
regards
Trevor

Trevor · Post by **Trevor** » Tue Jul 01, 2008 8:05 am

Just to say that it was exactly as Bill suggested, the timing rotor has shifted, I stripped it out set the timing carefully again and it is now running better than ever before.
Thanks Bill
regards