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-   -   Larger rear tire. (http://www.gz250bike.com/forum/showthread.php?t=3150)

blaine 05-05-2010 07:28 PM

Re: Larger rear tire.
 
Quote:

Originally Posted by mr lmd1
The whole tire is 10mm larger width, 40% of an inch, that's less than 7/16" wider, that's about 3/16" wider on each side of mid-line measured at the widest point on the tire, so how much extra rubber is in contact with the road surface as the tire is rounded, not flat like an automobile tire? 1/8", 1/4" ? I don't know if that would make any difference but I'm not the expert. IMO I don't think there's much advantage in it but it's your bike. Where are you talking about adding the flat washer to gain clearance for the tire?



The washer goes next to the brake hub under the bar that keeps the hub from rotating.The clearance is very close even with factory tire.

DAN 03-18-2011 03:11 PM

Re: Larger rear tire.
 
I just put a Dunlop D-404 140/90-15 on the rear and a D404 130/90-16 on the front.

Results:

This raises the GZ nearly 3/4 of an inch in height for better ground clearance. You will have to put an extension foot on the kick stand by 0.7 inch. This extension worked out well for me as I was having to place a 6"x6" pad on the soft sandy ground we have in Florida to prevent the stand from sinking into the ground. The foot extinsion I made from an aluminium extrusion (piece of a telescope dovetail bar) that I bolted through the kickstand foot front and back - 4"x1.5"x0.7"

The large front tire looks impressive, but required a 3/4 inch raise in the fender. I will have to GPS the speedometer to check on the difference in registered speed, but the standard tire diameter made the speedo read higher than the actual speed so we will see how this works out after a GPS run.

The larger rear tire is a tight fit. It has a larger diameter so it works out to about 1.033 extra gear ratio as compared to the 15 tooth to 16 tooth ratio of 1.067 or about the same as going from a 15 tooth to a 15-1/2 tooth gear (not possible as a 1/2 tooth sprocket) This has a very nice feel for gear spacing and I am not looking for 6th gear anymore.

The seat height is 3/4" higher; The bike feels and looks bigger. The overall ride is about the same, but it is slightly "taller". If your inseam is over 30 inches it makes the bike feel full size instead of 90% scale.

More after I ride the GZ "Fatboy" around for a month. --Dan--
http://s2.postimage.org/1q5hppp7o/P1010806.jpg

http://s2.postimage.org/1q637p7ms/P1010807.jpg

http://s2.postimage.org/1q6esgn38/P1010809.jpg

http://s2.postimage.org/1q6opoq1w/P1010811.jpg

http://s2.postimage.org/1q6ymwt0k/P1010813.jpg

jonathan180iq 03-18-2011 03:30 PM

Re: Larger rear tire.
 
IIRC, the steering on the GZ was already a little slow thanks to the wide factory front.

Have you noticed any lag in steering since going to the fat front?

DAN 03-18-2011 03:49 PM

Re: Larger rear tire.
 
No real change in steering feel. The 110/90 seemed to pull into the turn a little more than the 130/90, the 130/90 is very balanced and does not pull either into or out of a turn. I think the brand/style shape of the tire, and face radius are bigger factors in handling differences. I will be able to answer this question better in about a month. I will be at the Sun-N-Fun airshow starting in a week from now. Will be putting 250 miles on the GZ in first and second gear on ground safety plane escort. Most of my GZ driving is below 40 mph. Slow speed steering is more important to me and I see no real difference. --Dan--

Water Warrior 2 03-18-2011 07:26 PM

Re: Larger rear tire.
 
Oh my that front tire sure fills up the fender. The larger tire will just make the Speedo a little more accurate. The half tooth rear tire is an added bonus. The GZ will happily live with that.

alantf 03-19-2011 06:22 AM

Re: Larger rear tire.
 
Quote:

Originally Posted by DAN
Will be putting 250 miles on the GZ in first and second gear on ground safety plane escort.

Where does the flashing orange light attach on the geezer? :roll: photos?

Water Warrior 2 03-19-2011 09:39 AM

Re: Larger rear tire.
 
Amber will have to do. The GZ has 2 on each end, left side and right side. :lol:

alantf 03-19-2011 10:06 AM

Re: Larger rear tire.
 
Quote:

Originally Posted by Water Warrior
Amber will have to do. The GZ has 2 on each end, left side and right side. :lol:

Ah yes, another of those quaint American customs. :whistle:

But where does the "FOLLOW ME" board fit?

Water Warrior 2 03-19-2011 01:05 PM

Re: Larger rear tire.
 
I can well imagine a bright FOLLOW ME on the back of a vest. Or just a bulls eye for a target. :2tup:

DAN 03-19-2011 04:10 PM

Re: Larger rear tire.
 
Off topic, but the portion of airside ground safety the MC escorts perform is primarily keeping a clear path ahead of the planes as they taxi from or to the primary runways through the crowds to any of a dozen plane type specific areas where the local area chairman/staff assign a specific place for each plane. There are about 80 plus bike riders. We usually position the bike just outside and 10 feet forward of the left wing. This is particularly important for the big round engine biplanes and tailwheel planes. Some of the larger planes or those with forward visibility restriction get a bike on both sides. There are some high pedestrian traffic areas which may even require a 3rd bike ahead to clear the taxi way. Sun-N-Fun is the second largest airshow in the US behind Oshkosh. This is a unique airshow as it has a flying portion (show) on each day plus thousands of arrivals and departures daily. Much of the ground aircraft movements are up close and personal so to speak with running propellers and many hundreds of people walking about, golf carts, and cars all mixed together. If it ever flew it is on display; thousands of planes are on display. The volunteer ground safety group wear red safety vests or red shirts, have our warning whistles and horns, plus individual radios for coordinating aircraft moves. The bikes are flagged with a 5 foot fiberglass pole and small orange flag from the rear rear fender. The right mirror is positioned to show eye contact with the pilot. All kinds of additional ground safety jobs will be done in addition to the aircraft movement. Show plane escort from the back hanger to the front line show staging, sorting out odd predicaments that come up, clearing an area in preparation for the warbird flybys (100 or more movements, departures and arrivals for the airshow warbird mass flyover), just about anything safety wise relating to the aircraft ground movement. The daily meeting starts at 7 am and we close movement at sunset. This goes on from 28 March through 3 April this year (2011). Plus many of us arrive The 25th to set up camp and preposition equipment, check radios etc. If you have a bike and like airplanes this might be something you would like to volunteer for. Check Sun-N-Fun.org for contacts. --Dan--

PS: I am starting a new carb question about a specific carb part, in a few minuts if anyone can help with an answer.


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