V8 Bike Riders Forums banner
1 - 18 of 18 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter · #1 ·
Hey guys, I have been reading these posts for a couple of months now and I almost feel like I know some of ya'll,. Its a great forum and everyone seems to want to be helpful. So I'm just gonna dive in here. I recently bought 2 hosses, One is an 02 with 2 speed which I love, I guess because I haven't had time to break it. I bought this one from Ron at Wildrose, Great guy from my dealings with him. Other one is a 98 single speed purchased off ebay. Does anyone know if It is possible to change the pulleys to lower the RPM. It turns 2900 at 60 mph. It would be nice if I could get that down some. If I could change this how would I do it and where would be best to get parts? Would it still get going from start alright. Thanks, I know this was a little bit long winded And maybe even a stupid question but Im a rookie. I'll get Better. Thanks for any help anyone can offer. Bob
 

·
Premium Member
Joined
·
7,038 Posts
Hey guys, I have been reading these posts for a couple of months now and I almost feel like I know some of ya'll,. Its a great forum and everyone seems to want to be helpful. So I'm just gonna dive in here. I recently bought 2 hosses, One is an 02 with 2 speed which I love, I guess because I haven't had time to break it. I bought this one from Ron at Wildrose, Great guy from my dealings with him. Other one is a 98 single speed purchased off ebay. Does anyone know if It is possible to change the pulleys to lower the RPM. It turns 2900 at 60 mph. It would be nice if I could get that down some. If I could change this how would I do it and where would be best to get parts? Would it still get going from start alright. Thanks, I know this was a little bit long winded And maybe even a stupid question but Im a rookie. I'll get Better. Thanks for any help anyone can offer. Bob
That sounds high for RPM..if that is a clutch bike then at 5500 Rpm you would would not even double your speed so less than 120 mph. From what I recall those were a 160 mph or single gear...wonder if someone geared it lower for faster acceleration off the line? As always I stand to be corrected by guys with a bike like yours.
 

·
Registered
Joined
·
1,427 Posts
Hi there Bhilldw0111

Here is a summary of posts on this forum I found when I was researching the 98 single speed auto I bought from Texas Boss Hoss 3 years ago - includes some info on what's needed to lower rpm. Hope it helps. (I did not go ahead with any mods on mine, I like it the way it is. I just cruise slower than on the 2-speed :) )

Boss Hoss Single Speed Auto Transmission

Glenn B - “I usually run around 70 mph @ approx 3400 rpm. When traveling I usually did 500-600 miles/day. Have done many 1,000 mile + days, 2 1,500 mile + days etc. For the longest time I just used the Harley throttle lock that came on it. I went with the 1/4 turn throttle lock for a while. I am currently using a Rostra cruise control (from Juliano’s here in CT - they are like a Summits and I have been happy with them). Works well.”

Bruce Butler - “RPM @ 65 is approximately 3100; I have the stock converter with a 32 front sprocket.”

LaMonster - “I went to a 34 and it dropped it down some and was a lot better on the highway. You would need a frame loop for a 36”.

Dean - “I have done that change. First problem you will find is the down tube on the frame gets in the way. You have two choices: cut the frame and do a "loop" (Mountain BH is a good resource for that) or machine the outer shoulder off the new sprocket (my choice). The end result is I do 2900-3000 rpm @ 70 w/ the Avon 230 tire.

wtrippe - “I also have a 97 clutch bike and I dropped rpm from 3000 @ 70 mph to 2800 by changing from the Avon 230 to a 235-70-15 car tire. My bike has the older Dayton drive belt and a 30 tooth front sprocket and a 74 tooth rear. The car tire is 2 inches taller than the Avon and in my opinion rides smoother.”

Dean - “I have a 98 and made the conversion to a 36T. It only lowered my rpm by 200-300. I run 2900 to 3000 @ 70mph, with my single speed auto.”

Gizmo - “Has anyone changed the front pulley in order to drop the RPM? at 70 mph I am turning 3000 rpm. I have a SB single speed with a 225/60/15 rear tire.”

HAWK88 - “I have a single speed 97 clutch Boss with a 38 tooth front and 80 rear. It seriously drops the rpm @ cruise, but being a clutch, gives up a lot in how much I have to slip it to get it going from standstill. Mountain Boss Hoss applied a "Frame Loop Mod" to change the left aft down tube to accommodate the larger front pulley. Don't know if the single speed auto has the exact same ratio as the Curtis, but @ 70 I'm almost exactly 3000 RPM.”

Dean - “I am in the process of that mod right now. I have a 98 SB 350 w/ a SS automatic trans. I purchased the larger pulley from Mountain BH and was told they could do the "frame loop" or I could machine the outer flange of the pulley. I opted to have the pulley machined, and everything seems to fit. The other problem you will need to address is the old Gates belt will be too small. You will need to go to the new Kevlar belt, which is larger. You will need to make some modifications to the rear wheel adjusters.”

Bud C - “Gizmo, count the cogs on your existing pulley to see if it is worth the change. I have a 1996 Boss Hoss that had the 1998 auto single speed transmission installed when I bought it. With the 29T cog and an Avon 250 tire (I think much shorter than your car tire) I was only getting about 13 mpg. (I don't remember the rpm). I made my own frame loop mod and tried a 38T cog. That seemed to kill too much of the bottom end. I went back to a 36T cog and I have been very pleased. The mileage jumped up to around 19 to 20 mpg. But with the shorter tire, I am still running around 3000 rpm at 70 mph. I rode it 2600 miles in 5 days last year to Daytona and it was very smooth at that rpm. I was worried about slowing the rpm down too much for fear of slipping the convertor (building heat) at slower cruising speeds around town. I have done a lot of mods to my bike and this was by far the best. If you are only running 3000 rpm at 70 and you slow it down much, you may find like I did that it really kills the low end punch. I did not have to change the rear pulley on mine. I found my old calculations from when I was changing things up. With my 34T / 74T pulleys and Avon tire, my calculated rpm at 70 mph was 2950 rpm. The tach registers 3050-3150 rpm. For every 2 teeth I went up on my front pulley, rpm only dropped about 250. A larger circumference car tire made the rpm drop.”

Glenn B - “Mountain Boss Hoss had told me that if I converted to the new belt on my 98 and changed the front pulley than the back would be fine and didn't need to be changed. I am still running the old gates belt. Changed my rear pulley this fall but that is due to the teeth having worn down by approx. 1/3 from high mileage.”
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #10 ·
Hi there Bhilldw0111

Here is a summary of posts on this forum I found when I was researching the 98 single speed auto I bought from Texas Boss Hoss 3 years ago - includes some info on what's needed to lower rpm. Hope it helps. (I did not go ahead with any mods on mine, I like it the way it is. I just cruise slower than on the 2-speed :) )

Boss Hoss Single Speed Auto Transmission

Glenn B - “I usually run around 70 mph @ approx 3400 rpm. When traveling I usually did 500-600 miles/day. Have done many 1,000 mile + days, 2 1,500 mile + days etc. For the longest time I just used the Harley throttle lock that came on it. I went with the 1/4 turn throttle lock for a while. I am currently using a Rostra cruise control (from Juliano’s here in CT - they are like a Summits and I have been happy with them). Works well.”

Bruce Butler - “RPM @ 65 is approximately 3100; I have the stock converter with a 32 front sprocket.”

LaMonster - “I went to a 34 and it dropped it down some and was a lot better on the highway. You would need a frame loop for a 36”.

Dean - “I have done that change. First problem you will find is the down tube on the frame gets in the way. You have two choices: cut the frame and do a "loop" (Mountain BH is a good resource for that) or machine the outer shoulder off the new sprocket (my choice). The end result is I do 2900-3000 rpm @ 70 w/ the Avon 230 tire.

wtrippe - “I also have a 97 clutch bike and I dropped rpm from 3000 @ 70 mph to 2800 by changing from the Avon 230 to a 235-70-15 car tire. My bike has the older Dayton drive belt and a 30 tooth front sprocket and a 74 tooth rear. The car tire is 2 inches taller than the Avon and in my opinion rides smoother.”

Dean - “I have a 98 and made the conversion to a 36T. It only lowered my rpm by 200-300. I run 2900 to 3000 @ 70mph, with my single speed auto.”

Gizmo - “Has anyone changed the front pulley in order to drop the RPM? at 70 mph I am turning 3000 rpm. I have a SB single speed with a 225/60/15 rear tire.”

HAWK88 - “I have a single speed 97 clutch Boss with a 38 tooth front and 80 rear. It seriously drops the rpm @ cruise, but being a clutch, gives up a lot in how much I have to slip it to get it going from standstill. Mountain Boss Hoss applied a "Frame Loop Mod" to change the left aft down tube to accommodate the larger front pulley. Don't know if the single speed auto has the exact same ratio as the Curtis, but @ 70 I'm almost exactly 3000 RPM.”

Dean - “I am in the process of that mod right now. I have a 98 SB 350 w/ a SS automatic trans. I purchased the larger pulley from Mountain BH and was told they could do the "frame loop" or I could machine the outer flange of the pulley. I opted to have the pulley machined, and everything seems to fit. The other problem you will need to address is the old Gates belt will be too small. You will need to go to the new Kevlar belt, which is larger. You will need to make some modifications to the rear wheel adjusters.”

Bud C - “Gizmo, count the cogs on your existing pulley to see if it is worth the change. I have a 1996 Boss Hoss that had the 1998 auto single speed transmission installed when I bought it. With the 29T cog and an Avon 250 tire (I think much shorter than your car tire) I was only getting about 13 mpg. (I don't remember the rpm). I made my own frame loop mod and tried a 38T cog. That seemed to kill too much of the bottom end. I went back to a 36T cog and I have been very pleased. The mileage jumped up to around 19 to 20 mpg. But with the shorter tire, I am still running around 3000 rpm at 70 mph. I rode it 2600 miles in 5 days last year to Daytona and it was very smooth at that rpm. I was worried about slowing the rpm down too much for fear of slipping the convertor (building heat) at slower cruising speeds around town. I have done a lot of mods to my bike and this was by far the best. If you are only running 3000 rpm at 70 and you slow it down much, you may find like I did that it really kills the low end punch. I did not have to change the rear pulley on mine. I found my old calculations from when I was changing things up. With my 34T / 74T pulleys and Avon tire, my calculated rpm at 70 mph was 2950 rpm. The tach registers 3050-3150 rpm. For every 2 teeth I went up on my front pulley, rpm only dropped about 250. A larger circumference car tire made the rpm drop.”

Glenn B - “Mountain Boss Hoss had told me that if I converted to the new belt on my 98 and changed the front pulley than the back would be fine and didn't need to be changed. I am still running the old gates belt. Changed my rear pulley this fall but that is due to the teeth having worn down by approx. 1/3 from high mileage.”
Thanks for taking the time to post all these, It almost looks like a different tire might be the easiest thing to start with. Doc, Do you know what you are running on your bike, or what is the tallest one I can fit under the fender? Bob
 

·
Registered
Joined
·
281 Posts
A few years ago, I had a question similar to yours. Tom, at Mountain Boss Hoss told me the following. Perhaps it will apply to a 1998 as well.


"In 1999, a Gates belt was used. Stock gears are 32 tooth front and 75 tooth rear, which equates to about 3000 rpm at 63 mph with an Avon motorcycle tire on the rear. If the 32 tooth front is changed to a 36 tooth, 500 rpm will be lost at 60 mph."
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #14 ·
A few years ago, I had a question similar to yours. Tom, at Mountain Boss Hoss told me the following. Perhaps it will apply to a 1998 as well.


"In 1999, a Gates belt was used. Stock gears are 32 tooth front and 75 tooth rear, which equates to about 3000 rpm at 63 mph with an Avon motorcycle tire on the rear. If the 32 tooth front is changed to a 36 tooth, 500 rpm will be lost at 60 mph."
Thanks for the post, Mine turned to be 30t front and 74t rear , I ordered from mountain a 34t front pully and new swing arm kit, I am also changing rear tire from a 225 70 to a 225 75. I hope these changes drops the rpm at 60 mph from 2900 to about 2450. Any one know if I have to split the frame to get the 34 on? The 30 was pretty tight coming off. Thanks Bob
 

·
Registered
Joined
·
2,679 Posts
Thanks for the post, Mine turned to be 30t front and 74t rear , I ordered from mountain a 34t front pully and new swing arm kit, I am also changing rear tire from a 225 70 to a 225 75. I hope these changes drops the rpm at 60 mph from 2900 to about 2450. Any one know if I have to split the frame to get the 34 on? The 30 was pretty tight coming off. Thanks Bob
Bill, I have a 2004 bike......I am able to swap from a 32 to a 34 without splitting because of a trick I learned here from Adrian. There is a thread here somewhere about it. All you do is grind off a section of the outer flange of the 34 tooth pulley and you can get it on or off. I went one step further and took it to a machine shop and had them take the entire flange off. This works great as long as your belt is aligned and you still have both flanges on the rear pulley.

I could not say for sure if it will work on your bike as the frames are a little different.

Bryan.
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #16 ·
Bill, I have a 2004 bike......I am able to swap from a 32 to a 34 without splitting because of a trick I learned here from Adrian. There is a thread here somewhere about it. All you do is grind off a section of the outer flange of the 34 tooth pulley and you can get it on or off. I went one step further and took it to a machine shop and had them take the entire flange off. This works great as long as your belt is aligned and you still have both flanges on the rear pulley.

I could not say for sure if it will work on your bike as the frames are a little different.

Bryan.
Thanks Bryan. When I receive the pulley from Mountain I can tell more about it. I like the idea of machining the whole flange off, do you do both sides or just the inner one. I wondered if you just grind out a chunk would it have balance problems or is this not enough weight or spinning speed to matter. I will post results here when finished and let all who are interested what final outcome of this protect is. Thanks to all and have a good one.


Bob
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #17 ·
Thanks Bryan. When I receive the pulley from Mountain I can tell more about it. I like the idea of machining the whole flange off, do you do both sides or just the inner one. I wondered if you just grind out a chunk would it have balance problems or is this not enough weight or spinning speed to matter. I will post results here when finished and let all who are interested what final outcome of this protect is. Thanks to all and have a good one.


Well, the 1998 Frame must be a little tighter fit. I received the 34 tooth pulley with the flanges already machined off on both sides all the way around and it still would not go in. I ground on it on a few select places an got it so it would go in and out of the frame, I only got into the teeth about a quarter inch in one place and an eighth inch at another place but it seems to be alright. With the change from 30 to 34 tooth front I had to go to the longer belt and this put my rear tire a little to the rear of centered on the fender and it looks a little funny(IMO) but it is what it is. I had to cut off the axle adjuster bolts about 1 inch. I also had to do some work to extend the rod that holds the rear caliper as it would not extend far enough to reach. I changed the swing arm bushings while I was in there but they weren't really worn bad. I changed from a 225-70-15 Goodyear to a 225-75-15 Khumo
to gain a little more MPH per RPM and also the Khumo has a more rounded profile, It corners a lot better, almost like a MC tire. I gained ,with all changes, about 10 MPH at 2900 RPM. Was 60 now 70. All in all was worth the effort. That's about it, Thanks for reading, Bob
 

·
Registered
Joined
·
1 Posts
Sorry, I should have said it is a single speed automatic (no clutch)
Hi there
I have a 1997 boss hoss with a 1 speed nesco automatic.
Guys at mountain boss hosss geared it so that I would get highway speeds with lower rpms
I'm getting 16 miles to the gallon. Couldn't tell how many rpms I'm pulling because I have no tachometer.
However, the transmission tends to slip during launch due to the high gear.
I would appreciate any ideas to change my transmission to a better one.
Been told winters 2-speed won't fit my frame.
My bike is one of the last kit-bike boss hoss used to make.
 
1 - 18 of 18 Posts
Top