Kawasaki Vulcan Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hello all...
NICE FORUM!

I'm here for a friend that just got a mint 2004 Vulcan 800 (I'm pretty sure it's the "800a", with the 21-inch front wheel). We went out for a small group ride and he was having problems with the 80/90-21 Dunlop front tire loosing traction in the twistys. I noticed the rubber on the front tire is hard as an oak plank. I couldn't even sink a thumbnail into it. I suggested to let out some air for the remainder of the ride.

Anyway, I'm going to help get him set up with a Shinko set like I did for my wife's bike and mine. I swear by those tires - they're sticky! But, before I recommend anything, I want to know EXACTLY what I'm talkin' about so that he and his wife will be safe!

I have the front figured for the 90/90-21 Shinko 777 but have questions about the rear. I've searched here and Google ...but...

1) What is the rear rim WIDTH?
2) To anyone that's done it, what is the max width rear tire that will fit without swingarm mods?
3) How many teeth are on the stock sprocket?
3a) Has anyone changed to lower tooth count sprockets?


To try to answer any questions about my questions...

Why a wider tire?
The answer is self-evident to some: More rubber on the road. Why wouldn't anyone want a larger contact patch in the curves? I went from 200 to 240 on my Fury and I WILL NOT go back. :)

Why change the sprocket?
I'm not sure he'll need to but if the chosen tire profile is smaller, then the RPMs will go up to achieve the same speed. On my wife's Spirit 750 I went from the stock 42T to a 37T and it was an enormous improvement for hitting highway speeds with extra throttle left over.

It was kinda scary watching my friends creep through the turns because of crap tires.
I hope you folks can help me help him & his wife!

Thank You
 

·
Registered
Joined
·
42 Posts
@sprokets:
  • usual setup is 17/42.
  • a very popular exchange is 18/40.
  • the lenght of the chain remains the same.
  • rpm drop at 65 mph with about 400 rpms
 

·
Super Moderator
Joined
·
3,306 Posts
Here is a few threads about the rear tire. Apparently have to be careful of the rim width in relation to the wider tires.



 

·
Registered
Joined
·
2 Posts
Discussion Starter #4
@sprokets:
  • usual setup is 17/42.
  • a very popular exchange is 18/40.
  • the lenght of the chain remains the same.
  • rpm drop at 65 mph with about 400 rpms
That's exactly what I wanted to know about the sprockets. Thanks, Ciprian!


Here is a few threads about the rear tire. Apparently have to be careful of the rim width in relation to the wider tires.



Thanks for those links! I had read 2 of the 3 threads. The last one you listed I hadn't seen - and it confuses me a bit... they're discussing 15-inch rear wheels, but according to this spec sheet his rear wheel is a 16-inch.

And I still can't seem to find anything about what the rim widths are, front or back. I'm assuming 3.5 inches for the front?

...
 

·
Super Moderator
Joined
·
3,306 Posts
Yeah that third link was for a classic. Wheel width is not measured at the edge of the wheel. It is measured from the outer edge of the tire where the tire sits in the rim. I think front wheel width of an VN800a is 1.90 inches and the rear is 3.5 inches. Here is a video that explains how to measure.

 

·
Registered
'05 800B
Joined
·
1,704 Posts
on the front sprocket, every increase of 1 equals the same as decreasing the rear sprocket by 3, for example, let's take the stock sprockets 17/42, and you go to an 18/42, that would be equally the same if you were to go 17/39, so it might be better to leave the front at 17 stock because if you go 18 front that limits your rear choice sizes, and i think going to a 18 front you lose low speeds off 1st gear but you gain more mpg and less rpm's at highway speeds, for example, going 18/39 you're bike will jump ahead 15 feet when you let out the clutch in 1st gear but you'll go much faster on the highway with less rpm's, so sprocket choice is always going to be a compromise
 
  • Like
Reactions: Tourer

·
Registered
Joined
·
255 Posts
not sure about the rear wheel width, but 3.5 sounds right. I wanted the largest i could get.
Ended up with a 150/80 B16 Dunlop 404. Some say 160 will fit. after that and rim width becomes an issue.
The 150/80 has good clearance. I've got the 17/42 gear, but 18/40 or 16/46 or any other ratio wouldn't change the spaceing between the chain and the wheel/tire. After 7 beers and dim light Imeasure it at less than 3/4" clearance.
I went with what will stay on the back and work well. I ride Florida. can be wet. can be super hot (and super hot asphalt).
The 404 works well. never an issue about my azz sliding out. I do have and "altered" classic so have the big fat front tire.
just my two cents.
 
1 - 8 of 8 Posts
Top