Cb400t project

[MADDAD]

I have been working on a 1979 cb400tii for the last couple of years. It’s finally getting to a rideable state so I thought I’d make a series of posts that kind of outline the journey. I put some before and after photos with this post in case anyone wants to skip to the end and see how it turned out. I got the bike years ago and while I’ve had several bikes during that time, for some reason I always liked the 400 and found myself riding it even with more “fun“ options. I like how it turned out.
To answer a couple of questions right away; why a cb400t? I‘ve had it a while and I like it. It‘s not fast or traditionally cool but now, for me anyway, it‘s pretty cool. I worked on it off and on over the last couple of years because my with my job I have quite a bit of extra time in the winter and almost none in the summer so I go in spurts of lots of work and then nothing for months. The project cost me enough money for sure but fortunately I have access to some cheap or free parts. I also took advantage of a lot of used parts I scrounged from here or there. I have all the receipts for what I spent but honestly I’m too afraid to put the math to it.
I’m interested to here what others have to say, hopefully not too harsh. I‘ll try to stay up the follow up posts with more details of how things came together.
Thanks for looking.
-Rich

 

[Maritime]

I like it. My first bike was an 80 CB400T and I liked it enough to put 40K KM on it in 2 years so I'll agree with you, I rode it even with other options to choose because it's fun to ride a slow bike fast. I'd do the run to work in it more often then on the GL1000 that I had to ride in 3rd gear to keep my license. I sadly did have to sell it to buy a new fridge for the house.

 

[Popeye SXM]

I like it, especially the seat unit, the bike looks so much better than stock. Looks like a fun build too

 

[Maritime]

oh and check out Murray's carb conversion for those engines. You can wake it up nicely with his Mikuni's and intakes. He dyno tests and jets them, plug and play and they run better than rejetted CV's with pods. If I had kept mine that was my next upgrade, I got it to run ok with K&N's and deleting the airbox and modding the exhaust but after seeing a demo CB400T with his carbs run it was night and day how much the mikunis did for it. Speedmotoco. on here sells his kits. Irk has used them on 2-3 of his bikes and they all run better than stock ever could. Also know 2 other members who have installed his CX500 kits and those bikes went from runs ok to wheelie mosters.

 

[MADDAD]

oh and check out Murray's carb conversion for those engines. You can wake it up nicely with his Mikuni's and intakes. He dyno tests and jets them, plug and play and they run better than rejetted CV's with pods. If I had kept mine that was my next upgrade, I got it to run ok with K&N's and deleting the airbox and modding the exhaust but after seeing a demo CB400T with his carbs run it was night and day how much the mikunis did for it. Speedmotoco. on here sells his kits. Irk has used them on 2-3 of his bikes and they all run better than stock ever could. Also know 2 other members who have installed his CX500 kits and those bikes went from runs ok to wheelie mosters.

I have been trying different combinations of velocity stack lengths and filters but still not perfect in the mid range. I may just have to bit the bullet and get a set.

 

[Maritime]

Mid range was always the worst. I could get good acceleration and if I was 3/4-WOT it was fun but it ran like poo when cruising in mid throttle settings. CXMan on here is Murray and you can PM him about his carbs. He knows his shit.

 

[trek97]

Cxman fixed the carbs on Rachels 400a. One circuit had a hidden clog that I just could not remedy. I sent em to Murray and he had them set up and ready the same afternoon he received them. Bike runs like new.

 

[Maritime]

That's stock with air box though. You want this when you've pulled the air box and crossover and installed a new exhaust:

https://www.speedmotoco.com/cm400-cm450-vm30-mikuni-carburetor-kit-cb450-cb400-p/400.30.mikuni.htm

 

[MADDAD]

I had the seat laying around and always liked the look. I thought I would be cool to make it fit somehow. Before I made any permanent changes I had to sort out a mental challenge. I had a lot of back and forth, it looks cool, I don’t want to cut it up, etc... before I finally committed to it. I’d also like to get a new emissions label if anyone knows a source.

 

[MADDAD]

I wanted to put cartridge forks on. I think they look cool and I wanted adjustability. I kicked around the idea of using emulators in the stock forks but for better or worse I like the look of inverted forks. I used Cbr600rr forks, brakes, and front wheel.

 

[MADDAD]

After I got the front squared away I wanted to find a rear wheel that looked reasonably close to the front. I spent a little time thinking about how to make it work with the stock swingarm but abandoned that idea pretty fast. I spent a lot of time measuring, comparing stock photos, and swingarm listings on eBay trying to find a swingarm that I could work with. I pulled the trigger on one from a cb600f and lucked out that it would be usable. The red rear wheel is from a Cbr600 hurricane from the 80’s. I figured I would powder coat the front and rear the same at some point but I kind of like them different. I had to machine the Cush drive from the wheel to get the chain to line up but the hurricane rear disk works with the 600f caliper.

 

[ex119x]

Just so you know, the cush drive from the vf500f interceptor works with the cbr600f wheel and is narrower, so you can get the wheel centered more easily. Also, the widest rear tire that works well on the stock Hurricane rear wheel is a 150-17. A 160 would probably fit in the swingarm, but the rim is too narrow and the profile is bad. If you want to gain some clearance by going to a 520 chain, the rear sprocket for a Suzuki GS500 fits the Honda cush drive. I think the front sprocket from an XL250s has the same splines as the CB400T, but you would need to double check.

 

[MADDAD]

Just so you know, the cush drive from the vf500f interceptor works with the cbr600f wheel and is narrower, so you can get the wheel centered more easily. Also, the widest rear tire that works well on the stock Hurricane rear wheel is a 150-17. A 160 would probably fit in the swingarm, but the rim is too narrow and the profile is bad. If you want to gain some clearance by going to a 520 chain, the rear sprocket for a Suzuki GS500 fits the Honda cush drive. I think the front sprocket from an XL250s has the same splines as the CB400T, but you would need to double check.

Wow, that's great information, thank you! I was able to machine the cush from the hurricane wheel to make it work this time. Stock 04 cb600f had a 180 rear so you're definitely right with fitting in the swingarm. I am using a 140 on the hurricane wheel which is a good plenty more tire than the little 400 needs anyway. I didn't know that about the xl250 sprocket, the cb750 has the same splines too. Thanks again for your reply and for sharing your knowledge!

 

[MADDAD]

I moved on to getting the framework for the seat. Took me a minute to get the seat angle/position to go along with the tank profile.

 

[MADDAD]

Blue frame!

 

[MADDAD]

Also, ordering some mikuni carbs. Thanks Maritime for getting my tiny brain thinking about it!

That's stock with air box though. You want this when you've pulled the air box and crossover and installed a new exhaust:

https://www.speedmotoco.com/cm400-cm450-vm30-mikuni-carburetor-kit-cb450-cb400-p/400.30.mikuni.htm

 

[Jimbonaut]

My favourite bikes are always the ones that have the most unfiltered creativity, and this one looks like an absolute riot. Love it. Is that a V Max seat? That alone has to add 15hp?

 

[MADDAD]

My favourite bikes are always the ones that have the most unfiltered creativity, and this one looks like an absolute riot. Love it. Is that a V Max seat? That alone has to add 15hp?

Thanks! I love your comment! It's a seat from a Harley Sportster roadster. Definitely adds some hp though. Probably pushing 45hp with it on there

 

[Jimbonaut]

It looks great on there, and I really like the front end too with that headlight set-up. Stickerbombs, FTW. If this current armageddon turns into a manga then you'll be camouflaged perfectly

 

[Maritime]

Also, ordering some mikuni carbs. Thanks Maritime for getting my tiny brain thinking about it!

Nice. Dont just order any though cxman jets his kits to work everytime and will make sure you are happy. Look at Irks build he has 3-4 kits and all his bikes run like a dream. You may need uprated clutch springs too with the murrays carbs