82 650G skipping/losing power over 5500 rpm in 5th gear

[radbrad]

My 82 650G has power loss issues over 5500 rpms. I don't know how to describe it exactly, when I'm throttling it at around 5 or 6k rpms, in 5th gear, usually around 70mph or so, I hit a point where it's just like the engine is skipping out and not really connecting.

I can throttle past it and get to 6k rpms, but the engine sounds different, it rrrrrrrrrrrrrrrrs at a noticeably lower pitch. I can't get it to go more than a hair over 6k rpms even with the throttle fully open, and the bike will only very slowly accelerate over 75mph.

I don't have a lot of experience with bikes so I hope I'm describing this well enough. I just don't know how the engine could sound different after passing that funny spot at around 5500 rpm in 5th gear, and would like some ideas about what could be causing this power loss.

History on my bike:
- bought it spring of 08, the PO had it running the summer of 07, the bike was in good shape.

- new plugs last year, a few oil and filter changes, drive oil change.

- Over the last summer and this summer I fixed a few things like the charging system, speedo, clutch cable, and cleaned electrical connections.

- my air filter element is in good shape, clean with no tears and mounted on its plastic cone shaped frame which goes in the air box.

- I found the main clamp from the air box into the carbs loose and tightened that.

- I never took apart the carbs on this bike, but since I got it I've put like 6,000 miles on it, it has always ran fine except for the power loss at the top end.

** Also - every time I start this bike, I get some white smoke out of the left exhaust, it is usually gone by the time I ride for a mile or 2 - could be related?
So it does use more oil than it should, but I seem to be getting good miles per gallon of fuel.

Thank you for your thoughts on this.

- Brad

[duaneage]

General carb issues. Sounds like the slides are not rising, or one carb is clogged up and leaning the bike out. You can try to clean around this problem but the best thing to do is rebuild the set, get a set of four kits and a o ring kit from Robert Barr and do it right. It will run better for years. Otherwise you are going to be having issues for a while.

[Dave8338]

Plugged primary(s), petcock screen, float settings.

Do as Duane suggested and be done with it.

[tlepac]

Valve clearances? Could they also have a contributing effect?

[radbrad]

forgot to mention

I forgot to mention that the bike also does a lot of popping if I let completely off the throttle while traveling in any gear.

- Brad

[Steve]

... the best thing to do is rebuild the set, get a set of four kits and a o ring kit from Robert Barr and do it right.

Do as Duane suggested and be done with it.

I will agree, but with one exception ... forget the "set of four kits".

Too many of those kits have sub-standard brass pieces. The only (mostly) reliable parts are the float bowl gaskets, and they are available for just a few bucks. I said (mostly) reliable because some problems have also been noted with them, too. For just a little more than the price of ONE kit, you can get a can of Berryman's Carb Dip and clean your current parts. For about the price of TWO carb kits, you can include a complete set of o-rings from cycleorings.com, a set of intake o-rings and replacement stainless hardware to hold the boots in place. (Duane suggested an o-ring kit from Robert Barr, he is the owner of cycleorings.com.)

.

[mpls-ugly]

Im having a similar problem on my 650. Ill let you know what i find. My bike is a different story but its acting similar now. I was thinking that it may be rich because i have some smoke but not a lot and not too dark. Im going to change clips and give them a quick spray.