Topic: '78 CB750k conversion to cafe racer (yes, more issues)

[Stev-o]

What would you guys suggest?

Buy two new tires!  Doubt your front rim is an 18, check date of manufacture on the front tire, if over 6 years, time for new.

[deafcaferacer]

I was already going to get a Pirelli Demon for the front tire.. Rear tire is 4.25/85 H 18  which is bad news right? Tires aren't made in this dimension anymore if I read right.

I've read somewhere that Honda Man suggests a symmetrical blocked pattern for the rear tire for optimal performance.

[deafcaferacer]

120/90 x 18H = 4.25 x 18 correct?

Thinking of the Pirelli MT66 for the rear tire.. they have 120/90 x 18 and I've read good stuff about them. I'm already going with Pirelli MT66 for the front tire. Feedback would be appreciated

[Stev-o]

120/90 x 18H = 4.25 x 18 correct?

No, 120mm = 4.72", that is the width of a 120/90-18 tire.  OEM was 4" wide, but I run the 120.  Some guys will tell you that it will wear in abnormal way and cause handling woes.
My K4 is not a daily rider and will only see a couple thousand miles annually so not a concern to me.  Pirelli has a very good reputation but I've only had them on my Honda sports car not one of my bikes.

[deafcaferacer]

Would 110/90 or 110/80 be a better fit?

[Stev-o]

Would 110/90  be a better fit?

Yes, at least it would be closer to stock. 110 = 4.33"

[deafcaferacer]

Thanks.. I finally figured out that it's a straight up conversion rate.. e.g., 110 is 110mm, literally 4.33 inches. 

I know that a lot of the questions I ask here are fairly basic, and if there were a beginner's section in this forum, I would ask my questions there to avoid cluttering up this project thread, so thanks for your patience.

That being said, is the aspect ratio important? I.e., 110/90 vs. 110/80?

[Stev-o]

You can always search the forum to basic questions but we are happy to help.

The /90 is the aspect ratio, the height of the tire from rim to top of tread will in this case be 90% of the width (110mm). On sports cars, we call it low profile when they have 50 or 60 series tires, very good for handling but can bring a harsh ride on bumps.

Personally, I always stick to /90 aspect ratio tires on my bikes. I did order a /80 once, did not like the look of it at all, diddnt mount it and returned it for a /90.  Do you have a local bike shop locally that you can go look at tires?

Here is more info to educate yourself, you probably didn't know that there was so much to buying a set of tires!


http://www.totalmotorcycle.com/photos/tire-tyre-guide/Tire-TyreTech.ht

[deafcaferacer]

Started reading through it. Looking through the tires types. I'll be mastering this stuff in about 5 years. 

Question.. would 4.00 be okay? The tire I currently have is a 4.25, and the rim is 3 1/4"

[deafcaferacer]

Bike is in the shop today to have the hoop welded on. It was mocked and ended up being a little too long so we moved it up 3-4" barely enough for me (big frame) and a passenger.

I now have a 750k rear fender/brake light for sale if anyone wants it. Will be posting in the sales forum.

[deafcaferacer]

Well, it's one week later and the vinegar bath is ready to come out of the gas tank and boy did it vomit plenty of chunks of rust. I then hit it with a neutralizing bath of baking soda and 1 gallon of warm water, then sprayed with WD40 and sloshed it around for a bit, and voila!

I saw the perfect chain to use at Ace hardware, pointed edges and coated in zinc- it worked wonders. 3 feet for a total of $4.. the entire project, vinegar, baking soda, and WD40 set me back a whopping $25.

[Elan]

phosphoric acid from lowes works great too

[Bankerdanny]

I'm sure they aid slightly in cooling but most of us have put them on purely because of looks

+1.   If you ride in MA, doubt you will have an issue with overheating.

Don't be too sure. Boston traffic can suck as bad as Chicago traffic I'm sure, and an 80+ degree summer day combined with gridlock does not equal a happy air cooled motor.

[deafcaferacer]

Seat pan fabbing is done! Going to send it out to be padded soon. It looks and is long (27") but fits me because I have a tall frame (6'4) and leaves just enough room for one petite and cute passenger 

[Elan]

Seat pan fabbing is done! Going to send it out to be padded soon. It looks and is long (27") but fits me because I have a tall frame (6'4) and leaves just enough room for one petite and cute passenger 

Have you found a local place to upholster it? Im working on a cb450 for a buddy who wants to reupholster his seat...

[deafcaferacer]

Elan, there's a guy up in New Hampshire who's supposed to be good, but he hasn't answered my email yet. Will let you know who I go with.

[deafcaferacer]

Scored a nice set of used turn signals off ebay and ordered new lens because I anticipated old lens was cracked, but when I removed old lens, I found the turn signal gaskets to be thoroughly rotten. Back to ebay to order new gaskets. 

[knowsnothing]

Hey guys, I have a buddy down on the south shore that does upholstery.  Its his side business and he usually does hot rods, but i already talked to him and his is down with motorcycle seats.  If you are interested pm and I will send you his information. 

[deafcaferacer]

Hey guys, I have a buddy down on the south shore that does upholstery.  Its his side business and he usually does hot rods, but i already talked to him and his is down with motorcycle seats.  If you are interested pm and I will send you his information.

PM sent, thanks.

[deafcaferacer]

Brake light mounted. Things are really coming together. Only thing left is to get the wire harness, and get the seat pan upholstered.

[deafcaferacer]

Just got my bike back from the mechanic after some wiring issues, fired it up and took it for a ride and had a religious experience. Really love the bike even if there's much more to be done. Will try to post pics as soon as  some more kinks are worked out.

[Stev-o]

Just got my bike back from the mechanic after some wiring issues, fired it up and took it for a ride and had a religious experience.

Ha! been there. Glad to hear it's running.   Have you given it a full tuneup and carb rebuild?

[FrankenFrankenstuff]

Elan, there's a guy up in New Hampshire who's supposed to be good, but he hasn't answered my email yet. Will let you know who I go with.

You fello Mass dudes. I have seen work by a guy in Foxboro that is really nice. Mikes Uphostery ? I think it is. On rt140 .

[deafcaferacer]

Elan, there's a guy up in New Hampshire who's supposed to be good, but he hasn't answered my email yet. Will let you know who I go with.

You fello Mass dudes. I have seen work by a guy in Foxboro that is really nice. Mikes Uphostery ? I think it is. On rt140 .

Don't know of him. I sent you a PM about AM side covers.

[deafcaferacer]

Here is where the bike is at this point. Still have yet to get the seat back, and the left side mirror isn't holding- the flare up ring isn't big enough to grab on so I am looking for another one with bigger flange, and failing that, will have a nut welded inside the handlebar.