New Moto Guzzi Door Mats Available Now
You can use your GPS to check both speedometer and odometer. Assuming nothing is broken the odometer and trip meter are fixed ratios that are counting driveshaft revolutions. Either it is correct or it isn't. It can be adjusted by changing the cable drive worm at the rear of the transmission. Changing drive tire diameters will change odometer readings. Final drive gearing change will also change odometer readings. Speedometer (assuming all is mechanically correct and needle shaft is not binding) is an eddy drive that pits the eddy drive applied torque against a hairspring (think old alarm clock). Two type of errors here. If the error is a simple number of miles high or low at any speed the fix is to pull the indicator needle and relocate it by the error. If the error is progressive (like +10% of any reading) then the solution lies in freeing the outward end of the hairspring and re-anchoring it in a way to increase its tension by the equivalent percentage.......or you could just get an electronic unit and eliminate the whole cable drive and all the related problems.
Shouldn't be in 5th gear at 60 MPH. Save 5th for the other side of 75. Don't be afraid to spin that engine. Cruise 3,500 to 4,500 RPM and you'll be in the sweet spot.Phone have a GPS app with a suitable odometer?
As an update, I got the trip reset knob from MG Cycle and it fit nicely so I can now zero it when I fill up. I just refilled the tank today after 106 miles and it took 2.6 gallons US for around 41 MPG US. I also have a tomtom GPS mounted and 80 MPH on the speedometer is 60 MPH on the GPS so the speedometer is reading 1.33 X too high so perhaps the Odometer is reading 1.33 to high also? That would make the MPG more like 54 MPG.
10% off is normal for a speedo. Yours is outside that range. I would look at rear tire size, speedo gear on the transmission, and possibly rear gear ratio. One, two, or three of those items could be non-stock on a bike nearly 20 years old, causing the speedo error.Of course, the speedo could be off just because it's broken.If you have a GPS, you can measure distance against your odometer. You can also measure distance with the mile markers on I-49. Take it for another ride and compare what the GPS and the mile markers say vs. the odometer. If the odometer is off, then you can bet that rear tire size, speedo transmission gear, or rear gearing have been changed at some point.
The fellow who sold me the bike said the final drive gear ratio had been changed by a PO to get better gas mileage, but he had it backwards when he said the speedometer would read low. He gave me what he said was the original drive gear which has 8 teeth and 10 splines and is scribed with 71E and -0.20 on the end of the gear. He also said he had the “flange” replaced when he had new tires put on, which I took to mean the driven gear in the rear hub. Since stock gearing reportedly was 7/33 and the removed gear has 8 teeth I wonder if this bike was converted to Convert 9/34 gearing. That would be about 1.25 times higher gearing than stock 7/33 and 60 MPH X 1.25 would be 75 MPH and if there is a built-in 10% error in a stock speedometer, adding 10% would make it 82 MPH on the speedo which is about what I am seeing.Anyone know if a Convert speedo drive gear would fit my 96 Cali?To MMRanch, I hope that the low gas mileage I calculated at the last fill up was an error because if my trip odometer is reading too high it would be even worse.
Ask your wife if she has an old cell phone that she doesn't care about that has GPS. You don't need cell service for the GPS to work.My EVT, the low fuel comes on anywhere from about 115-130 miles and takes about 3-3.25 US gallons. 70mph is about 3500rpm.Tom
DigiHUD works fairly well for Android and it's free for the basic version.Tom
philwarner , I didn't know we could change the gear ratio on a Guzzi . I'd like to have a taller gear on my V-7II , it don't have so much extra power but that stuff of being done with 1st gear in the middle of most intersections seems kinda silly. A little more relaxed RPM at Super Slab Speed would be good too ! I did find the speedometer error went away when I went from an 130/80 to a 130/90 rear tire. Yea its right with the Garmin with-in .5 mph now.
I think you're onto it, now!
On the road today the Guzzi's trip Odometer was averaging 1.174 miles higher than my old Galaxy S4 cell phone running DigiHUD speed/mileage app which showed 25.60 miles traveled when the Guzzi trip odo turned over to 30. So my gearing is 1.172 higher than whatever the odometer gear is designed for and that falls half way between what I'd expect to see if it had 9/34 gearing VS 7/33 (1.248) or 9/34 VS 8/33 (1.092). Rather confusing if I did the math right.
No such thing as 9/34 as far as I know.Stock is 8/33. Typically installed is 7/33. A difference of 1.143 (probably your 1.174).I have put an oddball 8/35 in mine. I did not care for the lower fuel economy of the 7/33. And the 8/33 wasn't real good for towing a trailer like I did.
I didn't know there was an 8/35. I got an 8 tooth drive gear with the bike that the PO said was replaced with different gearing by his PO. He also said the "flange" was replaced when he had new tires put on. The manuals say the drive and driven gears are always sold in match pairs so I am not sure what mischief may have been done. I have the names of two local shops the PO said worked on the bike so I need to see if anyone can tell me what gearing is in it. Being new to Guzzis I don't know if all the whines and noises are normal Guzzi sounds or something to be concerned about.
Do you mean a large pinion gear, or a tiny speedo gear. I know the tiny speedo drive gear comes in a 9, 10 or 11 tooth.The ring and pinion are a matched set. Often with a number on it that is matched to the other.Yes, the gears are normally 8/33, often people install 7/33. There are a few odd ones like the 8/35. http://www.mgcycle.com/index.php?main_page=advanced_search_result&search_in_descripti on=1&zenid=5031ea1d035f1ea1bd748dddb3e0beca&keyword=8%2F35I wonder it the flange was the 'cush drive' flange in the rear wheel. Those can wear out.
So with a 7/33 gear set, 60 MPH should be 3444 RPM ? And I was seeing 3600 ? Got to recheck, but I may have a 7/33 then which would make more sense (ignoring the PO's statement that the gearing had been changed to get better gas mileage).
Yes, if the gearing was changed, it is 99% likely to be 7/33 from the stock 8/33. Easy to pull the rear drive pinion and look.Yes, people oddly claim the 7/33 gears gets better fuel economy. Well, if that were true, just stay in fourth gear, DUH!The 7/33 does of course give better torque for launching from a stop, and may give a bit better gear ratios in some situations. But I clearly noticed a slight drop in fuel economy. Yes, I emptied out the 4.7 gallon tank in under 100 actual miles once.
Wow! 21 MPG? That make my calculated 41 sound not quite so bad, but it was probably more like 35 MPG now that I know the odometer is reading 1.172 high. My Triumph gets 45 to 50 over the same roads that Guzzi traversed. Good thing I put a new low fuel switch on the Guzzi. I see a new 5/11 speedo gear set on eBay for around $40. I am guessing you can't just swap the speedo pinion without changing the ring gear; is changing the ring gear a big deal? I did read about having to be careful to not drop the bottom washer on the pinion into the trans.
The speedo gear is a worm drive, if that matters.I have changed the output gear as you are doing, and not changed the internal worm gear. I'm not sure they are matched.
