Next Imaginary Problem!

[Wingnut]

My 82 850G is considerably slower than my 80 (TSCC) 750L. OK 50 lbs heavier, shaft and all, but there is a significant difference. The bike runs PERFECT! Just doesn't pull all that hard. I would like to check the timing but do not have a book. The 750 book I have says no timing needed due to electronic ignition. That ain't right! You can advance or retard the plate with the crank pickup on it. I tried to use a timing light on the 750. I lined up the T mark at idle and the bike did not run right. I knew something was wrong because the timing plate was almost all the way retarded. Not much power. So I just put it back to where the screw marks were from before. Seems to run fine. Question:

What is the proper procedure for timing these bikes?

My Motto: "Just because it ain't broke doesn't mean it don't need fixing."

[NICK!]

There is an F mark, thats the one you should be lining up with the timing light. T is for top dead center, the spark plug needs to fire before top dead center. If for some reason your advance unit doesn't have an F mark you can do it with an advance timing light but you would need the specification for how many degrees BTDC the spark plug should fire. As far as your 850 being slow, if of course everthing is working and carbs and ignition are all what they should be I would check the valve clearance, these older 8 valve shim motors run pretty tight clearance, 1 to 3 thousanths on the intake if I remember correctly, you could have tight valves. Check your compression first, nothing worse than buying umpteen million dollars worth of valve cover gasket and cam end plugs and making 3 trips back and forth to the dealer for shims to just find out you have a dead cylinder.

[Wingnut]

Thanks Nick,

You are correct, I meant to say the F mark. Do you time to the F mark at idle or at speed.

The timing light is hooked up and I am going to see where its at first. I'll be right back.

I do not think I have valve issues because the idle is very good and I did do the farmers compression test. ie. Pull the plug wires off and crank with the starter. If a cylinder is low you can hear the difference in cranking speed as it passes the bad one. Not to scientific but a good quick check. The only thing it won't tell you is if they are all bad! LOL

[Wingnut]

The F mark is right on the money. Timed off #4 then tried #3 and they both were right on. They lined up at idle and advanced fully by about 2500. Must just be my imagination, like most things.

Oh well, nothing left to do but go for a ride!

Thanks for the input though.

[NICK!]

My pleasure Bob. As I'm sure you now know the F mark is for idle and if you keep the timing light in there and rev the motor up there is also an advance mark, if the advance mark doesn't line up (this is assuming that the F mark does line up at idle) it means your weight stops need tweaking.

[bwringer]

Doesn't your 750 have a 16 valve engine that makes more power? I think I remember it had the stock exhaust and intake, so that's not a factor.

Even though chain drive is ugly, greasy, and uncivilized, I have to admit it does transmit power with very little loss compared to shaft drive. The 750 could also be geared lower than the 850.

Are you getting the 850 into its powerband? You have to get an 850 above 6,000 rpm to get serious poke.

Another point to remember is that you are closer to the ground and the riding position is different on the 750, so your perceptions of speed could be off by quite a bit. You'll feel like you're going faster if you're closer to the ground. If you've done some sort of timed run or scientific testing, then never mind.

Too bad you didn't have these questions in Asheville -- we could have had an 850 drag race! :twisted: :twisted: :twisted:

As long as the guys on 1150s would have given us a good head start...

:roll:

[Wingnut]

Doesn't your 750 have a 16 valve engine that makes more power? I think I remember it had the stock exhaust and intake, so that's not a factor.

Are you getting the 850 into its powerband? You have to get an 850 above 6,000 rpm to get serious poke.

Another point to remember is that you are closer to the ground and the riding position is different on the 750, so your perceptions of speed could be off by quite a bit. You'll feel like you're going faster if you're closer to the ground. If you've done some sort of timed run or scientific testing, then never mind.

Too bad you didn't have these questions in Asheville -- we could have had an 850 drag race! :twisted: :twisted: :twisted:

As long as the guys on 1150s would have given us a good head start...

:roll:

I think you are right. Your speed sensations are quite different like you stated and also the windshield on the 850 may add to that. And like you said the 750 is a TSCC so it probaby has about the same power with less weight and drag from the shaft.

Above 6 grand? Hmmmm. Don't go there often. I have to set up something more scientific. Maybe I'll time them on a stretch of road with identical conditions. This will be interesting. I hate to abuse the clutch so I'll do a rolling 10MPH start and run like 8 grand through the gears to a given point and record MPH. That should show their true colors!