MPG's Does this sound right??

I am only getting about 33 mpg and it just seems a little low for my bike. The bike runs great but at 100 mile my tank is empty. Spark plugs look good light tan color.

STATS:
1980 KZ 550 A1
4-1 Kerker
Pods
Jets 32/95
Sprockets 16/40
Rear tire 130/80/18
Front tire 100/90/19

Type
6 speed, constant mesh, return shift
Clutch multi-disc, wet

Gear ratio

1st --2.57

2nd --1.78

3rd --1.38

4th --1.13

5th --0.96

6th --0.85

Primary reduction ratio--2.94

Final reduction ratio--2.50

Overall drive ratio--6.25 @ top gear


The gearing calculators are just a little different than what I'm getting.
6th gear/ 67 mph/ 6000 rpm (if I remember right)

I'm wanting to bring my rpms down while on the Highway. Was thinking about changing front sprocket to a 17T.

I don't know much about the little bikes but I think you should be getting better fuel mileage than that. I think I would try a larger front sprocket. I always go for the cheapest fix first. Roy

Pods and kerker and a happy right hand could mean 33mpg. :whistle:

I have a huge range depending on whether I'm commuting around town or on the highway most of the time.

I'm kinda wondering if its me being 6'5" 250 with sometimes a heavy right hand every once in a while. but most of the time its just highway riding 60-65. Almost every tank is the same. I hope changing the sprocket will help.

Weight and size definitely matter, but it seems you are running fairly low gearing - stock they turn around 5000 rpm @ 60 mph IIRC. That may have a small impact. So you're big, gearing is short, chain may be a bït stiff, tyres a bit low on pressure, brakes dragging slightly and jetting not ideal for frugality = 33 mpg easily. Stock, with tiny journalist testers and a frisky throttle hand they delivered mpg in the low 40s.

what size chain does it run a 630?? or 530???

Just to put things into perspective here, before I crashed my KZ650 I was getting about 40 mpg @ 80 mph. My specs were 720cc big bore kit, pod filters 4 into 1 pipe, 17 tooth front sprocket and 42 tooth rear. 130/80x18 rear tire, 100/90x19 front. My carbs were stock 24mm mikuni's with #15 piolt jets, 115 mains and the needle in themiddle slot. The bike got great gas milage, I'm 6-01 and 185.
I would think you should be getting better that that.

It a 530 chain.

I think it should be doing better too, I've seen all these other bikes getting 40-50. Maybe it's just under powered for hauling my big butt.

Or running rich. It's hard to use the plugs as an indicator with the fuels we have nowadays.

I dealt with a float height issue that was causing poor MPG performance too - caused me to run rich and also dump some fuel from time to time out the overflows.

I had a new GPZ550 back in 1981 and got 60mpg and I'm 200+ lbs. So you are not doing great on MPG for sure.

Yeah, definitley not right. Your jetting is not even a whole lot different from stock. If anything, I would have expected you to be slightly lean.

The 40 rear will reduce your mileage a tiny bit, but not much. Stock should be a 38. Your RPMs at 65 mph will be about 300 RPM higher than stock.

I would check to make sure both of your wheels spin freely. If they drag, it may be time to rebuild the front caliper or inspect the rear brake.

I'm not sure if the GPZ 550 gets better or worse mileage than the standard A1, but I have a Kerker and pods and get between 60 and 70 mpg if I stay light on the throttle on the highway.

The KZ550 A standard has a slightly larger tank than the KZ550 D Gpz, and the gpz can get 200 miles before reserve (as tested in 1981).

My bike gets about 35mpg so I would be really dissappointed by getting less than that on a little old 550.