Honda Twins banner

1 - 10 of 10 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
Hey folks,

Working on the CB450SC we picked up last weekend and I'd really like to get some wider rubber on the bike. I know this is going to take a lot of effort, so doing a fair bit of research first.

Front

Currently, the bike is running a 100 front tire. I would like to get this to a more "sport bike" size of 120. Doing this, I am also thinking the wheel diameter is going to get smaller, down to the typical 17 inches.

This want poses a number of issues, all of which I am looking for a bit of input:
  • Speedometer: I know this is probably the least of my issues. But, if I drop down to a smaller diameter, how do I compensate for it on the speedometer?
  • Fork width/triple trees: I have been looking around to see if there might be an easy triple tree swap to a more modern USD fork setup. But, I don't think I am lucky this time around. What would be my best course of action for getting a USD setup to work?
  • Suspension/frame geometry: Going to a USD fork setup with a smaller diameter wheel/tire combo is bound to make my trail shorter in the front end and drop the front of the bike down a bit. I am sure this is bound to cause some issues. Anyone want to give me a run down?
Rear

Out back, the bike is running a 130 rear tire. Looking at the frame and other things, I get the feeling a 180 tire in the rear isn't going to be doable without some major modification. But, I would still like to have something a little wider than the 130 shoe size it is currently sporting.

Here are the issues I can gleam from that situation:
  • No customization max tire width: Does anyone know the maximum rear tire width on these bikes without any major modifications to the suspension?
  • Chain alignment: If I did want to go with a wider wheel and tire combo, how do I compensate for the different sprocket position on the rear? I am assuming the front sprocket would have to come out a bit. Will making modifications here have major adverse effects?
  • Swing arm replacement: Are there any manufacturers of swingarms that are built to handle a wider width tire?
If anyone reading this can think of anything else I should take into consideration, please let me know. These are the major things I am looking at now but I know there is a lot I am sure I haven't looked at yet.
 

·
Sensei
Joined
·
27,023 Posts
Just my opinion, but if you want a more modern looking, handling bike buy one... Modifying this bike to those expectations will likely be more expensive than to purchase a newer one.....IF you are simply in it for the challenge, Have at it!.... :D

I'm sure an R6 front end could be fitted (several members have done similar mods), and you could probably adjust it to keep somewhat close to the stock geometry with custom trees....

A 130 is about the limit with the stock swingarm...You'll need to fabricate a "special" one if you MUST go wider, and you are correct about moving the chain outwards in that case... (special hub and sprocket adaptations).... This of course will widen the bike's profile and REDUCE the maximum lean angle before you ground out parts......

You'll need to evaluate changes to forward or rearward weight bias, center of mass, rake angle, and trail for starters, not to mention the HP losses from turning that additional unspring tire weight......

Other than "looks", What advantages do you expect the "wider rubber" will yield?...(I have nothing against building for looks, I do it regularly).....I would almost be willing to wager a 1979 Yamaha TZ 350 with a 120 rear and 80 front tire will out-lean/out corner your R6.... Each bike is a SYSTEM....Every change to that engineered system requires other compensating changes......
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
66Sprint said:
Just my opinion, but if you want a more modern looking, handling bike buy one... Modifying this bike to those expectations will likely be more expensive than to purchase a newer one.....IF you are simply in it for the challenge, Have at it!.... :D
Definitely in it for the challenge. I didn't grow up in a "mechanical family" per se and I am learning everything on my own. This is my first major project with a bike. I've done some smaller things but never anything to this scale before. The project is for looks, knowing it is something I built with my two hands, and it is different than anything everyone else has. My main project concern is I don't want to make it unsafe to ride. I know performance ties into the safety bit. But, I am not looking to let it "all hang out" on this bike.

66Sprint said:
I'm sure an R6 front end could be fitted (several members have done similar mods), and you could probably adjust it to keep somewhat close to the stock geometry with custom trees...
The custom trees were my main concern when it comes to doing a USD setup. I'd need to have the same stem and bearing sizes but have the right width on the trees in order to fit the wider tire/wheel combo. A couple questions about this...

1. Do you know which posts would have this info [re: the R6 fork setup]? I know this place has a search function but it is hard when you don't know which bikes this is being done to in order to search.
2. I am guessing I would have to replace my speedo to something more modern in order to use the new speedo gears in the front end? Or would the stock gauges (or similar style) work as well?
3. Is there anything wrong with doing a "Rake In" type setup? Something that will shorten the front end a bit? What would the pros and cons of this be? I know putting a smaller diameter wheel on the front will decrease my trail but it will be marginal. A shorter fork length would have a major affect on geometry. Just don't want to **** things up severely.

66Sprint said:
A 130 is about the limit with the stock swingarm...You'll need to fabricate a "special" one if you MUST go wider, and you are correct about moving the chain outwards in that case... (special hub and sprocket adaptations).... This of course will widen the bike's profile and REDUCE the maximum lean angle before you ground out parts...
Not massively concerned but it is definitely good to know this ahead of time. I don't think it would be a big issue with this bike though as the alternator sticks out WAY further than the front sprocket. There'd be tons of clearance. I am more worried about putting extra stress on the driveline if I extend the sprocket outward.

66Sprint said:
You'll need to evaluate changes to forward or rearward weight bias, center of mass, rake angle, and trail for starters, not to mention the HP losses from turning that additional unspring tire weight...
This is where I wish I would have measured/weighed a bunch of things before doing the tear down this past weekend. It would be great to know the weight bias front/rear with everything bolted on. Also, I didn't measure the angle of the forks but I am sure that is something I can look up.

HP loss only concerns those who can't corner well ;)

66Sprint said:
Other than "looks", What advantages do you expect the "wider rubber" will yield?...(I have nothing against building for looks, I do it regularly).....I would almost be willing to wager a 1979 Yamaha TZ 350 with a 120 rear and 80 front tire will out-lean/out corner your R6.... Each bike is a SYSTEM....Every change to that engineered system requires other compensating changes...
Yeah, you caught me. It is mostly for looks. It would also be nice to have a little bit larger contact patch with the road. Something about it makes me feel better/more secure/safer for no logical reason what-so-ever.

The other major reason, other than the looks of a wider wheel/tire, are the wider tires themselves actually look better. The tread patterns are more aesthetically pleasing. You can't say that an 80s bike running modern suspension and rubber wouldn't turn a few heads!

Thanks for the reply!
 

·
Sensei
Joined
·
27,023 Posts
shiftanddrive said:
66Sprint said:
Just my opinion, but if you want a more modern looking, handling bike buy one... Modifying this bike to those expectations will likely be more expensive than to purchase a newer one.....IF you are simply in it for the challenge, Have at it!.... :D
Definitely in it for the challenge. I didn't grow up in a "mechanical family" per se and I am learning everything on my own. This is my first major project with a bike. I've done some smaller things but never anything to this scale before. The project is for looks, knowing it is something I built with my two hands, and it is different than anything everyone else has. My main project concern is I don't want to make it unsafe to ride. I know performance ties into the safety bit. But, I am not looking to let it "all hang out" on this bike.

66Sprint said:
I'm sure an R6 front end could be fitted (several members have done similar mods), and you could probably adjust it to keep somewhat close to the stock geometry with custom trees...
The custom trees were my main concern when it comes to doing a USD setup. I'd need to have the same stem and bearing sizes but have the right width on the trees in order to fit the wider tire/wheel combo. A couple questions about this...Custom trees were mentioned to maintain original height, offset and trail....If you want to change these anyway, others have simply put bearings that fit the R6 stem and Honda neck on.....

1. Do you know which posts would have this info [re: the R6 fork setup]? I know this place has a search function but it is hard when you don't know which bikes this is being done to in order to search.
2. I am guessing I would have to replace my speedo to something more modern in order to use the new speedo gears in the front end? Or would the stock gauges (or similar style) work as well?
3. Is there anything wrong with doing a "Rake In" type setup? Something that will shorten the front end a bit? What would the pros and cons of this be?...Bracket (trees) forward offset can be used to "pull" the front end closer to the neck. Rake won't change as this is a function of the original neck ange....Shorter forks WILL alter the effective rake angle as they tilt the original neck to a different position relative to the horizontal (ground line).... I know putting a smaller diameter wheel on the front will decrease my trail but it will be marginal. A shorter fork length would have a major affect on geometry. Just don't want to **** things up severely.

66Sprint said:
A 130 is about the limit with the stock swingarm...You'll need to fabricate a "special" one if you MUST go wider, and you are correct about moving the chain outwards in that case... (special hub and sprocket adaptations).... This of course will widen the bike's profile and REDUCE the maximum lean angle before you ground out parts...
Not massively concerned but it is definitely good to know this ahead of time. I don't think it would be a big issue with this bike though as the alternator sticks out WAY further than the front sprocket. There'd be tons of clearance. I am more worried about putting extra stress on the driveline if I extend the sprocket outward....Yes, an outboard bearing might be required (or a jackshaft assembly), to get you out past a 150 +tire.....

66Sprint said:
You'll need to evaluate changes to forward or rearward weight bias, center of mass, rake angle, and trail for starters, not to mention the HP losses from turning that additional unspring tire weight...
This is where I wish I would have measured/weighed a bunch of things before doing the tear down this past weekend. It would be great to know the weight bias front/rear with everything bolted on. Also, I didn't measure the angle of the forks but I am sure that is something I can look up.

HP loss only concerns those who can't corner well ;)

66Sprint said:
Other than "looks", What advantages do you expect the "wider rubber" will yield?...(I have nothing against building for looks, I do it regularly).....I would almost be willing to wager a 1979 Yamaha TZ 350 with a 120 rear and 80 front tire will out-lean/out corner your R6.... Each bike is a SYSTEM....Every change to that engineered system requires other compensating changes...
Yeah, you caught me. It is mostly for looks. It would also be nice to have a little bit larger contact patch with the road. Something about it makes me feel better/more secure/safer for no logical reason what-so-ever. ....A larger tire on that narrow rim could actually REDUCE the contact patch....Do you intend to change wheels as well?...(That alone could eliminate the additional wheel/tire weight issue)....

The other major reason, other than the looks of a wider wheel/tire, are the wider tires themselves actually look better. The tread patterns are more aesthetically pleasing. You can't say that an 80s bike running modern suspension and rubber wouldn't turn a few heads!

Thanks for the reply!
We'll discuss this more I am certain..... :D :D :D
 

·
Registered
Joined
·
7 Posts
Discussion Starter #5
Did a bit more reading this morning (dangerous affair) and have come up with a bit of a solution. Tell me if this sounds right or not.

I am playing with the idea of a CBR600RR front end swap onto the CB450SC. Bearings match up [Upper: 26ID 48.5OD 15H; Lower: 30ID 50OD 14.25H] but I am really concerned about steering stem length and the offset of the triple trees.

I think the stock offset of the triple trees for the CB450SC is 60mm (please correct me if I am wrong). From what I am reading, it looks like the CBR600RR triple tree offset is 35mm [NOTE: triple tree offset is actually 30mm]. This is a massive difference. But, with a smaller wheel diameter, I am wondering if there will be any major difference in trail?

The steering stem length is also of concern. Does anyone know where to find the steering stem lengths for the CB450SC and CBR600RR? Or can I press out the steering stem from the CB450SC and press it into the CBR600RR lower triple?
 

·
Registered
Joined
·
7 Posts
Discussion Starter #6
No love?
 

·
Registered
Joined
·
1 Posts
650 front end on sb450sc

Did a bit more reading this morning (dangerous affair) and have come up with a bit of a solution. Tell me if this sounds right or not.

I am playing with the idea of a CBR600RR front end swap onto the CB450SC. Bearings match up [Upper: 26ID 48.5OD 15H; Lower: 30ID 50OD 14.25H] but I am really concerned about steering stem length and the offset of the triple trees.

I think the stock offset of the triple trees for the CB450SC is 60mm (please correct me if I am wrong). From what I am reading, it looks like the CBR600RR triple tree offset is 35mm [NOTE: triple tree offset is actually 30mm]. This is a massive difference. But, with a smaller wheel diameter, I am wondering if there will be any major difference in trail?

The steering stem length is also of concern. Does anyone know where to find the steering stem lengths for the CB450SC and CBR600RR? Or can I press out the steering stem from the CB450SC and press it into the CBR600RR lower triple?

I have a 1985 Honda nighthawk. As I am told, during the middle of the production year the government tightened stopping distance test regulations and the nighthawk did not meet the new standard. The quick fix Honda did was to use the 650 front end parts on the 450. If you have before a certain number vin you had standard 450 parts on the front. but after a certain number vin you were given the bigger front rim, bigger brake caliper, etc...

I have ordered brake pads for the front twice now, and each time I forget that the ones listed for my bike wont fit. I always end up taking the numbers stamped into the pads and throwing it at google to get the right ones...

anyways, I have a set of gs-11 vintage style tread tires on mine that are a bit wider than the stock ones both front and back.. the bigger beefy feel of the larger 3.25 x 19 on the front is just delicious. I test rode a newer 2014 star and a 2014 rebel .. both of which had a dinky not enough grip in the front feel to them. so personally I can tell you that I would completely dislike owning something with a smaller or thinner tire.

see what your vin number is and do some googling. if yours came with a 19 rim on the front, you already have 650 front end parts on it. and if it didn't, then a 650 setup on front would be absolutely wonderful...

there is an entire array of after market trees, gauges, etc available online.

the one thing I did think about doing to mine is maybe put a lower profile tire on back next time I need a set. I cant actually touch the ground with my feet flat. I end up tippy toe on each side at the stop light. a smaller profile tire would help that plus give it more of a lean back feel.

I always tell people my bike has 3 modes. with the Honda-line highway bars and universal foot pegs up front.. I put my feet forward and lean back a little, that's Harley mode. I sit upright with my feet on the stock pegs and that's regular Honda mode. or I put my feet back on the passenger pegs then lean forward, that's crotch rocket mode...

IMG_20140522_133943.jpg
 

·
Registered
Joined
·
3 Posts
Hey folks,

Working on the CB450SC we picked up last weekend and I'd really like to get some wider rubber on the bike. I know this is going to take a lot of effort, so doing a fair bit of research first.

Front

Currently, the bike is running a 100 front tire. I would like to get this to a more "sport bike" size of 120. Doing this, I am also thinking the wheel diameter is going to get smaller, down to the typical 17 inches.

This want poses a number of issues, all of which I am looking for a bit of input:
  • Speedometer: I know this is probably the least of my issues. But, if I drop down to a smaller diameter, how do I compensate for it on the speedometer?
  • Fork width/triple trees: I have been looking around to see if there might be an easy triple tree swap to a more modern USD fork setup. But, I don't think I am lucky this time around. What would be my best course of action for getting a USD setup to work?
  • Suspension/frame geometry: Going to a USD fork setup with a smaller diameter wheel/tire combo is bound to make my trail shorter in the front end and drop the front of the bike down a bit. I am sure this is bound to cause some issues. Anyone want to give me a run down?
Rear

Out back, the bike is running a 130 rear tire. Looking at the frame and other things, I get the feeling a 180 tire in the rear isn't going to be doable without some major modification. But, I would still like to have something a little wider than the 130 shoe size it is currently sporting.

Here are the issues I can gleam from that situation:
  • No customization max tire width: Does anyone know the maximum rear tire width on these bikes without any major modifications to the suspension?
  • Chain alignment: If I did want to go with a wider wheel and tire combo, how do I compensate for the different sprocket position on the rear? I am assuming the front sprocket would have to come out a bit. Will making modifications here have major adverse effects?
  • Swing arm replacement: Are there any manufacturers of swingarms that are built to handle a wider width tire?
If anyone reading this can think of anything else I should take into consideration, please let me know. These are the major things I am looking at now but I know there is a lot I am sure I haven't looked at yet.
650 front end on sb450sc




I have a 1985 Honda nighthawk. As I am told, during the middle of the production year the government tightened stopping distance test regulations and the nighthawk did not meet the new standard. The quick fix Honda did was to use the 650 front end parts on the 450. If you have before a certain number vin you had standard 450 parts on the front. but after a certain number vin you were given the bigger front rim, bigger brake caliper, etc...

I have ordered brake pads for the front twice now, and each time I forget that the ones listed for my bike wont fit. I always end up taking the numbers stamped into the pads and throwing it at google to get the right ones...

anyways, I have a set of gs-11 vintage style tread tires on mine that are a bit wider than the stock ones both front and back.. the bigger beefy feel of the larger 3.25 x 19 on the front is just delicious. I test rode a newer 2014 star and a 2014 rebel .. both of which had a dinky not enough grip in the front feel to them. so personally I can tell you that I would completely dislike owning something with a smaller or thinner tire.

see what your vin number is and do some googling. if yours came with a 19 rim on the front, you already have 650 front end parts on it. and if it didn't, then a 650 setup on front would be absolutely wonderful...

there is an entire array of after market trees, gauges, etc available online.

the one thing I did think about doing to mine is maybe put a lower profile tire on back next time I need a set. I cant actually touch the ground with my feet flat. I end up tippy toe on each side at the stop light. a smaller profile tire would help that plus give it more of a lean back feel.

I always tell people my bike has 3 modes. with the Honda-line highway bars and universal foot pegs up front.. I put my feet forward and lean back a little, that's Harley mode. I sit upright with my feet on the stock pegs and that's regular Honda mode. or I put my feet back on the passenger pegs then lean forward, that's crotch rocket mode...

View attachment 39821
Hey bro..I literally just brought home an85 nighthawk 450 this afternoon.. this is my first Honda..my experience is building Harley and Yamaha...so this bike has Bent forks so they need to be replaced..I plan on completely customizing this bike. Cutting grinding and welding my way to complete.. immediately I wanted to swap to USD I seen you post and I wanted to know if you figured everything out with the forks..can you let me know?
 

·
Premium Member
Joined
·
24,208 Posts
The original poster hasn't been heard from for 6 years so unlikely there'll be an answer.
You can start a new thread in the SOHC Suspension section.
I would start with the All Balls Racing conversion chart to see what front ends they supply bearings for, there's a couple hundred options to choose from.
 

·
Registered
Joined
·
3 Posts
Yeah I read about all balls other sites ..thank you.i can't believe I never owned on of these before.im really enjoying these hondas
 
1 - 10 of 10 Posts
Top