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Discussion Starter #1
I noticed the new triple clamp designed on the cb300f and wondered whether this part will interchange easily on the CBR250 to get us a more upright position. This looks like the hot ticket to adapt to our bikes to make riding more comfortable over those long hauls. And the wider grip position will make handling easier too, although it's already easy enough w/ the clip ons. Any thoughts on this not working out?
 

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What about the wind screen?
 

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Cb250f

When I first saw the CB300F I wanted one because of the upright riding position, unfortunately I can't buy one (something to do with "The grass is always greener . . ."), so last week I ordered a top fork bridge to find out if it is compatible with our steering stem. It will be here tomorrow.
CB300F parts needed
1. bridge, top fork
2. holder (clamp for bars)
3. handlebars
4. longer throttle cables (A & B)
5. longer clutch cable
6. longer brake hose
7. Misc nut, bolts, etc.
If the 250's steering stem don't work with the CB300 fork bridge a CB300 steering stem will be needed. I will find out if they fit in a day or two. The left and right handlebar switches will probably need longer wires, so you probably need CB300 switches unless you are handy with a soldering iron and heat shrink tubing. If you want handlebar mounted mirrors like on the CB300 you also need a new master cylinder and clutch lever clamp off the CB300 that's were the mirrors mount.
 

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The CB300F Steering Stem is different from the one used on the CBR250R & 300R... not sure if that means you would need to change the steering stem or not.

As isaacm12 points out, I'm sure there would be clearance issues with the CBR's windscreen when making tighter turns.
 

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CB250F project

Well the mailman came today, (I forgot about Sunday delivery) and delivered my CB300F top fork bridge. Just setting it on top of forks everything looks to line up perfectly. I will install it tomorrow, then order the handlebars, top clamp, and brake hose. The throttle, clutch cables, and switch wires may reach when moved from the front of the forks/top bridge to the rear.
 

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Please keep this post coming and let us know when you get this done and tested. I was considering Helibars but this looks even better if it all works out and clears the windscreen....Thanks.
 

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Switching the fork bridge

I installed the top fork bridge today, everything went well, everything fits good. The only difference is the hole for the ignition switch is a couple of mm bigger. It is difficult to see in the pictures. I think I can put a rubber o-ring in the space and it will look good. I ordered the handlebars, cables, brake hose, and other misc. hardware today. Got a little delay when I got an email from my parts supplier saying that the handlebars are on back order with no ETA. Changing the ignition switch is a little involved because it is held in with one-way screws. I had to cut slots in the head of the screws for a screw driver to remove them. Honda sells replacement one-way screws, but I don't know if a special tool is needed to install them, so I made my own. Took two M8-1.25x25mm cap screws rounded off the heads on a grinder, installed them, then drilled out the head so a allen wrench no longer catches. I added washers on the cap screws because the head are smaller than the originals. The screws on the right are the original Honda one way screws. Also you need to use a triple tree stand when removing the top bridge because the weight of the bike flexes the steering stem just enough that the top bridge interferes with the steering stem threads.
Now i wait.
 

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When you remove the clip-ons and complete the job, Do you plan to slide the fork tubes down and increase front end height? Also how much will this change the hand grip positions? 1) distance up? 2) distance back? 3) how much wider?. I plan to wait for you to finish paving the way before ordering my parts. Also any Idea on total cost of this upgrade? Thanks again.
 

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Discussion Starter #10 (Edited)
The only difference is the hole for the ignition switch is a couple of mm bigger. It is difficult to see in the pictures. I think I can put a rubber o-ring in the space and it will look good.
THX for doing the legwork for us!

Do you think maybe a section of 1" PVC pipe could work to fill in the gap?



That's a bummer that the handlebar's on back order.
I suppose a dirt bike handlebar can work out as a substitue, but
that would mean locating new bar end weights and having to mod something to address the nubs sticking down under the throttle and turn signal collars. I know from sitting on that 300F, the stock 300F bar is PERFECTLY contoured for me. That is my 1st choice for a bar, so I suppose it's worth the wait just to have it.

EDIT:

BTW... do you think the 300F bar will clear the screen? Not that it matters, b/c the end improvement clearly justifies the means.
 

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I just couldn't wait. I just ordered the 53110-k33-305 Handlebar, 53130-mgs-d30zb top holder, 53230-k33-700 Bridge, Fork Top, and the 6 bolts from discounthondaparts.com for $122 Shipped. Did not get a ship date yet.
 

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When you remove the clip-ons and complete the job, Do you plan to slide the fork tubes down and increase front end height? Also how much will this change the hand grip positions? 1) distance up? 2) distance back? 3) how much wider?. I plan to wait for you to finish paving the way before ordering my parts. Also any Idea on total cost of this upgrade? Thanks again.
Dropping the forks down will be the first thing I do. It will alter a few specifications slightly and probably give me cb300f specs.
stock specifications
-----------CB300F -CBR250R -----difference
wheelbase 54.3" ----- 53.9----- 3/8" (10mm)
rake ------ 25.30----- 25.0 ----- .3 degrees
trail --- 98mm (3.9")-- 98.6mm (3.9")-- rch
seat height 30.7----- 30.5----- 3/16" (5mm)

My seat height is already 32 1/4" at it's lowest point so it will be almost 32 1/2"

I'm not sure how much it will change things, If I knew the handlebar rise I could guesstimate. I went by the Honda dealer today to look at the rise but they didn't have one on the floor, they had one still in the crate that will probably be on the floor tomorrow.

Cost: all prices rounded off
top fork bridge $52
holder (h/b top clamp) $23 I didn't order the four bolts for this because of the price. Got them at home depot.
handlebar $23
throttle cables A&B $23
clutch cable $ 9
brake hose $19
two cable guides $24 ($9 & $15) I don't know if these are needed but I ordered them anyway. stock ones may work.
Total $172 + s&h

My Helibars that are on my bike now cost me $170
 

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THX for doing the legwork for us!

Do you think maybe a section of 1" PVC pipe could work to fill in the gap?



That's a bummer that the handlebar's on back order.
I suppose a dirt bike handlebar can work out as a substitue, but
that would mean locating new bar end weights and having to mod something to address the nubs sticking down under the throttle and turn signal collars. I know from sitting on that 300F, the stock 300F bar is PERFECTLY contoured for me. That is my 1st choice for a bar, so I suppose it's worth the wait just to have it.

EDIT:

BTW... do you think the 300F bar will clear the screen? Not that it matters, b/c the end improvement clearly justifies the means.
The hole for the ignition sw. is 34.71 mm (1 1/2") The diameter of the sw is 31.25 mm (1 1/4) and is tapered and gets larger toward the bottom. I tried a 1" pvc pipe, to small, it fits in the cbr250r hole good and tight.
I doubt if the bars will clear the screen. You do have a lot more adjustability with handlebars. Will have to wait and see. I've got my saw ready just in case.
 

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Discussion Starter #16 (Edited)
Dropping the forks down will be the first thing I do. It will alter a few specifications slightly and probably give me cb300f specs.
stock specifications
-----------CB300F -CBR250R -----difference
wheelbase 54.3" ----- 53.9----- 3/8" (10mm)
rake ------ 25.30----- 25.0 ----- .3 degrees
trail --- 98mm (3.9")-- 98.6mm (3.9")-- rch
seat height 30.7----- 30.5----- 3/16" (5mm)
With the 300F's forks being positioned down lower from the top bridge, the resulting 0.6mm shorter trail dimension (98mm vs. 98.6) will add to a sharper turning radius, but straight line stability will be slightly less stable as that of the CBR.

If you do alot of hwy, I think keeping the stock CBR fork protrusion might work better w/ the full fairing.
 

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CB300F Higher handlebars

What about the wind screen?
I tried a handlebar with a 1 1/2" rise similar to the 300f bar and it does hit the screen, a bar with a higher rise (3" or 4") might be pulled back far enough to clear. Right now I am planning to trim the windscreen. If I don't like it I can buy a new windscreen for $35.00. I have helibars installed right now and I do like them so if the 300f bars don't work out the helibars will go back on.
 

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I currently have helibars and I do like them over the stock bars, but they do leave me wanting a even more upright position. I am reading this thread hoping you all come up with a more up right riding position.

In the end, I hope someone can list everything that has to be purchased and installed to get the setup like you all have.

Thanks

Bent
 

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I will try to post a list of all parts needed. My handle bars should be here by this time next week. If after market bars are needed to clear the windscreen that might take another few days, they are the same price as honda bars. The cb300f bar end weights might be heavier, It has a different part # than thecbr250. The part of the weight inside the handlebars is the same except for some rubber bushings (4 @$6 ea.) and two small metal rings ($6 ea.) Whether any of this is actually needed I don't know yet. Also,I forgot to mention before, a 1 3/16"- (30 MM) 1/2" drive socket is needed to install the steering stem nut on the new fork bridge, its setting down in a hole between the two bar risers and a wrench won't work. I got one from autozone for $7.50, it's their duracrap brand, oops I mean duralast. Torque to 76 ft-lbs.
 

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Honda cb300f handlebars installed on cbr250r

I installed the new handlebars yesterday. The handlebar switches (turn signals, horn, starter, lights, and kill switch) use location pins that fit in holes in the bars. The location holes for the pins in the handlebar switch assemblies are not in the correct place. The pins need to be removed, or the bars can be drilled to locate the switches in the correct place if you know exactly were you want them. The left side switches have a plastic pin, the right side has a steel pin to keep them from moving as you rotate the throttle. I ground this pin down with a 3" high speed air cut-off tool. You should leave enough of the pin sticking up to still make contact with the bar, its the only clamping contact you have to prevent rotation of switches when you move the throttle. The wires from the switches must be moved from in front of the top fork bridge to the rear side. They can be clamped to the rear side of the fork tubes using the reusable plastic ties originally holding the wires on the front of the forks. This cable tie can be easily released, there is a small tab sticking out were the end exits the clamp that you lift with your finger to release, no screwdriver needed.
All of the control cables and the front brake hose are longer. The clutch cable is 1" longer, and the end at the handlebar is straight compared the original cbr250 cable which has a sharp bend at the clutch lever. One throttle cable is 2 1/4" longer, the other one is 2 1/2" longer. The front brake hose is 1 3/4" longer.
When the handlebars are rotated in their clamp, it changes the height of the handlebars, when the bars are pushed forward, the ends of the bars rise up. When the bars are pulled back towards the rider the bar ends drop down, in this position they don't hit the windscreen. I already have two different sets of handlebars ordered, one with a 2' higher rise, and one with a 1' higher rise and 3' more pullback.

LIST OF 2015 HONDA CB300F PARTS USED

1. 53230-K33-700 BRIDGE, FORK TOP
2. 53110-K33-305 HANDLEBAR
3. 53130-MGS-D30ZB HOLDER (top clamp for h/bars)
4. 90111-362-000 BOLT, FLANGE (M8 1.25x36) Four are needed. These are bolts
for the holder, I think they are chrome plated and cost about $3.25 to $4.50
each depending on where you buy them. I used regular bolts from home
depot.
I expect them to rust soon.
5. 45125-K33-701 HOSE, FR. BRAKE
6. 17910-K33-700 CABLE A, THROTTLE
7. 17920-K33-700 CABLE B, THROTTLE
8. 22870-K33-700 CABLE CLUTCH
9. 45158-K33-700 GUIDE, FR BRAKE HOSE
10. 45159-K33-700 GUIDE, CLUTCH CABLE
If I forgot any thing I will add it later

I also should mention the throttle cables exit the cb300 switch housing on the front, the cbr250 on the bottom, no problem though.

the pictures show the bars adjusted high and low, high is probably normal cb300f position, the windscreen would need to be trimmed in this position. Low is where they clear the windscreen. I have the controls pushed in as far as they will go in these pictures, they still clear when slid out to the ends of the bars. I would cut off the ends if I use these bars.
 

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