R65 Only running on one cylinder. Any suggestions?

[Blindpew]

Hi Folks,

Sorry I'm a Triumph owner myself but have a friend whos not 'internetted' up, and I'm trying to help him sort a problem with his bike, a 1979 BMW R65.

Compression test showed 40 and 90, so he stripped down, put back together, now getting 90 in each cylinder.
Spark plug sparking okay, but bike just will not fire in  one cylinder.

He has a Haynes and BMW manual but hes scratching his head over this one.

I'll have a look through the old posts and maybe turn something up, but if the problem sounds familiar to anyone, I would appreciate to hear from you.

Many thanks for your time all,

Pew, [smiley=1drink.gif]

[tagordon]

I'd check the carb on that side. These engines have few requirements to run:
Air, fuel & fire. If carb was off could have jogged some crud loose that is plugging up the flow.

[Jon_P]

i had this same problem just a little bit ago when i was getting mine going. it turned out to be a carb issue. the valves where also a little tight but if i sprayed a little fuel in through the carb it would fire.

yep you need the three basics air, fuel and spark. you have spark? i would check for fuel to the carb, then check for fuel in and through the carb. check where the idle adjustment screw is at.

[Ed Miller]

Has the bike been running before?

[BooG]

The guy who MOT'd me last week said that he had a similar problem....tried all the usual suspects with no luck. It turned out to be the metal cap on one of the hi tension leads into the plug was shorting out and this caused the problem. He said not to use metal caps but stick to the original NGK ones which are plastic. I hope that helps.

[Blindpew]

Hi,
Thankyou all for your replies.

While I had been posting up the question he actually managed to get it running on both. - Reckons it was the timing out a bit although I forgot to ask if it was the points plate or flywheel.
He did say the metal plug cap sounded interesting as the side that wasn't firing was the side with a metal cap! - He will change this.
Although firing on two now, he says its pretty rough/spluttery then dies down but hes admitted to not having the float bowls off yet to check the carbs. - The bikes been sitting for several years and I'm amazed its even running.I'm sure he'll have crud in there, I thought he had done that already!

Thankyou once more all for your help on this its very much appreciated.  

[Justin B.]

Just wanting to point out that the metal plug boots are most likely original and the plastic NGK are pure aftermarket...