Author Topic: 18" rear wheel mod for AVL - possibilities?  (Read 5252 times)

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Machismo

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on: March 29, 2014, 09:38:46 am
Hello Gentlemen.

Been quiet for a long time here and recently bought a KTM 390, life has been all about revving now  8) Awesome ride.
So I finally get to work on the AVL peacefully, without the worry of being stranded for the commute to work.
Some things in line are a paint job for the fenders, headlamp nacelle(started chipping paint), new luggage rack, checking the valves and cams and the title of this post, tires.

The options with 19" wheels are really pathetic here in Bangalore and hence pondering on the thought of switching over to 18" ones.
What kind of a change would this usher in?
Would it be good to go for a different sprocket and chain?
I am not the type who would wants to pop wheelies or do drag races. I need good throttle response throughout the mid range and perhaps a cruising top end of about 65mph - a touring machine.
Suggestions would be very helpful..


Adrian

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Reply #1 on: March 29, 2014, 02:54:49 pm
Hi,

should work OK, but be aware when the UCE/EFI Classic was introduced over in the UK with the 18 inch front wheel they found it could be a bit unstable at higher speeds, some owners have reverted to 19" front wheels, or have fitted fork braces. Also watch out for the effects of reduced ground clearance on the center stand when cornering, and reduced tire circumference will affect your speedometer accuracy. If you CAN get the Avon AM26 tyres, 90/90 (3.25") section for the front and 100/90 for the rear wheel I'd stay with 19". I'm guessing the 18" wheels are off the shelf items for the current RE India models

A.


ace.cafe

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Reply #2 on: March 29, 2014, 02:57:54 pm
I agree with Adrian that there could be an issue with ground clearance when cornering.
The people that I have known who tried 18" wheels on their Iron Barrel models have reverted back to 19".
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Machismo

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Reply #3 on: March 29, 2014, 08:02:17 pm
Hi,

should work OK, but be aware when the UCE/EFI Classic was introduced over in the UK with the 18 inch front wheel they found it could be a bit unstable at higher speeds, some owners have reverted to 19" front wheels, or have fitted fork braces. Also watch out for the effects of reduced ground clearance on the center stand when cornering, and reduced tire circumference will affect your speedometer accuracy. If you CAN get the Avon AM26 tyres, 90/90 (3.25") section for the front and 100/90 for the rear wheel I'd stay with 19". I'm guessing the 18" wheels are off the shelf items for the current RE India models

A.
I agree with Adrian that there could be an issue with ground clearance when cornering.
The people that I have known who tried 18" wheels on their Iron Barrel models have reverted back to 19".

Sorry Tom/Adrain, I should have been more clear - I would want to retain the 19" front wheel but only the rear would go in for a change. Hence the question on sprocket change.
If only the rear wheel is changed, how much of a change can be felt with the new one?
The GC wouldnt greatly be effected, would it?

Most tire dealers dont even know the Avon brand! So that's out of the equation. I can only see Pirelli with an option of 110 an 100 section 19" wheel.

Been to the market today and kinda felt sad - AVL parts are drying up badly, even the common stuff like levers, breather catch can, decomp. mechanism window cover. Might as well stock up few ones that remain. Pretty outraged at why RE should kill a good bike as this.


Vince

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Reply #4 on: March 29, 2014, 09:23:09 pm
      If you install a 4.00-18 tire the rolling diameter and ride height is the same as a 3.50-19. 18+4+4=26
19+3.50+3.50=26 inches. The problem you will have is with width. The extra 1/4 inch on each side of the tire may cause interference issues. Of particular concern is the tail light wiring. You will probably have to re-route it outside the fender or the tire will tear it up. If you go to a 3.50-18, the one inch difference in rolling diameter (18+3.50+3.50=25) will not change the gearing enough to worry about. The 1/2 inch difference in ride height would not cause clearance problems for someone riding in a safe and sane manner.
     The bigger question is: Why bother?  The stock 19" tire is perfectly adequate and gives good mileage. The cost of a spoke set, rim , and labor doesn't seem worth the trouble.


Adrian

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Reply #5 on: March 31, 2014, 12:56:24 am
Hi, if it's only the rear wheel, then yes, you'll be fine, the project has an 18" x 90/100 rear and 21" x 90/90 front (road, not off-road tyres),  no problems.

Sorry to hear you're having problems with AVL parts availability,  is this just a local problem or more widespread across India? I heard that some of the 500 Machismo parts were getting scarce, shame if the 350 stuff is going the same way.  :(  Still, for every one of us mourning the end of the AVL models, there are five more grieving for the loss of the traditional "cast iron" models. And we hoped they would go on for another 50 years...


Machismo

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Reply #6 on: April 05, 2014, 11:05:50 am
Hi, if it's only the rear wheel, then yes, you'll be fine, the project has an 18" x 90/100 rear and 21" x 90/90 front (road, not off-road tyres),  no problems.

Sorry to hear you're having problems with AVL parts availability,  is this just a local problem or more widespread across India? I heard that some of the 500 Machismo parts were getting scarce, shame if the 350 stuff is going the same way.  :(  Still, for every one of us mourning the end of the AVL models, there are five more grieving for the loss of the traditional "cast iron" models. And we hoped they would go on for another 50 years...
Yeah, its only the rear one. But would this upset the torque or acceleration curve? I dont mind if the top end suffers but would not want the low end to suffer.
About the parts - I stay in Bangalore, about 300kms from Chennai, the city where RE manufactures the bikes and the AVL parts are really hard to find these days. RE has either stopped manufacturing these or is in real low quantities. Bore kits and cams have to be waited upon after the order. There are certain non OE vendors for the less complicated parts but the quality is shit. Well, you might be surprised to know that the cast iron scene is pretty upbeat. Owing to the huge number of bikes here, the company still produces the spares, in good quantity.

      If you install a 4.00-18 tire the rolling diameter and ride height is the same as a 3.50-19. 18+4+4=26
19+3.50+3.50=26 inches. The problem you will have is with width. The extra 1/4 inch on each side of the tire may cause interference issues. Of particular concern is the tail light wiring. You will probably have to re-route it outside the fender or the tire will tear it up. If you go to a 3.50-18, the one inch difference in rolling diameter (18+3.50+3.50=25) will not change the gearing enough to worry about. The 1/2 inch difference in ride height would not cause clearance problems for someone riding in a safe and sane manner.
     The bigger question is: Why bother?  The stock 19" tire is perfectly adequate and gives good mileage. The cost of a spoke set, rim , and labor doesn't seem worth the trouble.
The whole idea of switching to a 18 tire is that I have better options with some decent tires. 19 has hardly anything to offer, other than the wet-road-nightmare MRF and Dunlop.
How about a 90 spec tire since the 100 would probably interfere with the swingarm?


ace.cafe

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Reply #7 on: April 05, 2014, 10:19:02 pm
Yeah, its only the rear one. But would this upset the torque or acceleration curve? I dont mind if the top end suffers but would not want the low end to suffer.
About the parts - I stay in Bangalore, about 300kms from Chennai, the city where RE manufactures the bikes and the AVL parts are really hard to find these days. RE has either stopped manufacturing these or is in real low quantities. Bore kits and cams have to be waited upon after the order. There are certain non OE vendors for the less complicated parts but the quality is shit. Well, you might be surprised to know that the cast iron scene is pretty upbeat. Owing to the huge number of bikes here, the company still produces the spares, in good quantity.
The whole idea of switching to a 18 tire is that I have better options with some decent tires. 19 has hardly anything to offer, other than the wet-road-nightmare MRF and Dunlop.
How about a 90 spec tire since the 100 would probably interfere with the swingarm?
It will not upset the torque or acceleration
It will either remain the same, or it will get slightly better if the tire has a lower profile and is smaller diameter than the 19" tire.
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Machismo

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Reply #8 on: April 06, 2014, 12:37:36 am
It will not upset the torque or acceleration
It will either remain the same, or it will get slightly better if the tire has a lower profile and is smaller diameter than the 19" tire.
That's comforting to hear Tom.
Thank you everyone, I will post an update once the changes are complete..


suitcasejefferson

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Reply #9 on: April 06, 2014, 07:39:14 pm
      If you install a 4.00-18 tire the rolling diameter and ride height is the same as a 3.50-19. 18+4+4=26
19+3.50+3.50=26 inches. The problem you will have is with width. The extra 1/4 inch on each side of the tire may cause interference issues. Of particular concern is the tail light wiring. You will probably have to re-route it outside the fender or the tire will tear it up. If you go to a 3.50-18, the one inch difference in rolling diameter (18+3.50+3.50=25) will not change the gearing enough to worry about. The 1/2 inch difference in ride height would not cause clearance problems for someone riding in a safe and sane manner.
     The bigger question is: Why bother?  The stock 19" tire is perfectly adequate and gives good mileage. The cost of a spoke set, rim , and labor doesn't seem worth the trouble.


Interesting you mentioned the tail light wiring. I have a 2013 B5, with an 18" rear wheel, and the first problem I had was the rear tire chewed up the wires to the tail light. I repaired the wires and rerouted them under the seat. My bike is 100% stock
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St1g9203

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Reply #10 on: April 09, 2014, 06:15:59 pm
That's comforting to hear Tom.
Thank you everyone, I will post an update once the changes are complete..

Buddy let me know which parts you want. I just rebuilt a LB 500 in Hyderabad, and got all my parts (Cylinder/Cam/Crank bearings) and all the consumables within 2 days.

Regarding tyres - we are stuck with Pirelli MT 60 for front and MRF Mogrip Meteor 110/90x19 for rear
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barenekd

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Reply #11 on: April 09, 2014, 10:32:34 pm
To keep everything as far as gearing etc. goes, the rear sprocket/brake is the same on all of them. The front sprocket should be changed from a 17T to an 18T to maintain very nearly the same gearing. If you run that 350/18 tire, you would essentially end up with the same specs as a new C5. I doubt that the bike will drag any sooner than the C5. If you want more punch just leave the 17T in there, but the top end will suffer.
The advantage you will get is being able to use an Oring chain with the bigger countershaft sprocket. To do the swap out, the easiest/cheapest way to go would be to get a set of spokes for an 18" wheel and a WM2 rim and lace the new rim on the old hub. as for tires, you can find a lot of 3.50/18 tires. The stock Avon tires for the C5 would be fine.
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Ice

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Reply #12 on: April 12, 2014, 06:54:52 am
Hello Gentlemen.

Been quiet for a long time here and recently bought a KTM 390, life has been all about revving now  8) Awesome ride.
So I finally get to work on the AVL peacefully, without the worry of being stranded for the commute to work.
Some things in line are a paint job for the fenders, headlamp nacelle(started chipping paint), new luggage rack, checking the valves and cams and the title of this post, tires.

The options with 19" wheels are really pathetic here in Bangalore and hence pondering on the thought of switching over to 18" ones.
What kind of a change would this usher in?
Would it be good to go for a different sprocket and chain?
I am not the type who would wants to pop wheelies or do drag races. I need good throttle response throughout the mid range and perhaps a cruising top end of about 65mph - a touring machine.
Suggestions would be very helpful..

 I got it now. Tire market is different where you are.
 
 The trials Bullet with an 18" rear and a 21" front gives up some steering quickness but gains much stability when compared to a standard Bullet with 19" rear and 19" front. 
No matter where you go, there, you are.


Machismo

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Reply #13 on: April 18, 2014, 07:12:12 pm
The trials Bullet with an 18" rear and a 21" front gives up some steering quickness but gains much stability when compared to a standard Bullet with 19" rear and 19" front. 
Ah I see. Would the road manners be decent on the freeways with such a set up?

Buddy let me know which parts you want. I just rebuilt a LB 500 in Hyderabad, and got all my parts (Cylinder/Cam/Crank bearings) and all the consumables within 2 days.

Regarding tyres - we are stuck with Pirelli MT 60 for front and MRF Mogrip Meteor 110/90x19 for rear
Thanks for that mate! Will surely contact you when I start the rebuild. Appreciate it.
Is the Mogrip any good in the wet roads?


Ice

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Reply #14 on: April 20, 2014, 01:28:03 am
Ah I see. Would the road manners be decent on the freeways with such a set up? ~

 How do I put this?  The stability is increased but it is not the heavy handling long wheel base HD type of stability. 
 You still have good handling just flavored a little differently and can still flick a turn when you want.

 Brother Bill Harris has the 18 rear/21 front combo on his AVL based Harris Scrambler and I can't keep up with him on any curve.

 The main reason I have 19/19 on my Bullet is that it simplifies logistics for me with regards to tires,tubes, spokes etc.

No matter where you go, there, you are.