Topic: Just Put a 400f motor in my 350f today :)

[schwebel]

 So today my brother and I did a heart transplant on my 73 cb350f. Took us about 4 hours. Luckily I had some slow jets from my cb500-4 project. Those were really the only things I needed to make her run. I do need to figure out what to do with the rear brake pedal, as the clutch housing on the 400f sticks out much further and I can barely touch the pedal. I think the cases in general are wider, even though I didn't measure them. What a difference this engine makes. The bike seems to just really scoot, and the 6th gear is awesome. I'm going on a ride in a couple days with my friend and his CB500-4, and my other friends XS650. I'm anxious to see how well the 400 will do. I'd really like to do some suspension modding next. Any suggestions?

[kghost]

Ya could use the 400F pegs....

Instant resets.....plus the 400F brake lever clears the cases...

[CafeRacin350]

How much did the 400f engine cost you? What else did you need for the switch? I have a '74 350f.

[bender01]

I would do that too if the stars and moon align  right.

[Hush]

Oh sixth gear......drool....
One of our Kiwi forum members put a 400f bottom end into his 350f but used the heads and barrels from his 350, instant 350f with 6th gear.

[schwebel]

How much did the 400f engine cost you? What else did you need for the switch? I have a '74 350f.

 I paid $200 for the motor. The guy I bought i from guaranteed it ran and shifted, and it does. However the clutch is slipping a bit and the kickstarter doesn't work. But the motor runs like a top. You use all the same mounts, and I used my 350f exhaust/carbs. All you really need is larger slow jets. The 350f's are 35's, the 400's are 40's. Also the air screws need to come out 2 turns instead of 7/8's. But it is litteraly a plug and play swap, the wiring is exactly the same. There is one more clearance issue though, the rear brake light switch actuater doesn't line up quite right, but I'll figure something out today.

[kghost]

Were the sprockets the same?

Or did you use the 350F ones?

I'm interested in your findings on the RPM VS MPH if you used the stock 350F sprockets....vis a vis the 6th gear.

Let us know would ya?

[schwebel]

I have the front sproket from the 400f, and the rear from the 350f. At 40mph, in 6th it tacs around 3000-3200 (my tach needle has a little jump here and there), at 60-65mph it is around 5000-5200. I am unsure what the 350f front would do on there, would it give me quicker acceleration?

[many408]

I have the front sproket from the 400f, and the rear from the 350f. At 40mph, in 6th it tacs around 3000-3200 (my tach needle has a little jump here and there), at 60-65mph it is around 5000-5200. I am unsure what the 350f front would do on there, would it give me quicker acceleration?

If I recall correctly, 5th is the same, and both the 350 and the 400 would do 10mph/1000rpm in that gear.

[Owned]

Sweet news indeed.  I have a 400F motor just waiting to go in my 350F.  Picked up for a whopping $37 bucks.  It's complete, less carbs and has 4700 reported miles.  Turns over freely with compression.

Glad to hear you had such positive results.

Probably won't do the swap until the fall.  I'm having fun with the little 350 as it is!

[fmctm1sw]

One of our Kiwi forum members put a 400f bottom end into his 350f but used the heads and barrels from his 350, instant 350f with 6th gear.

This thread has my brain in high gear.  Sixth gear to be exact    I have a 400 engine that I got in a parts lot from a guy moving here.  Upon closer inspection has broken fins in addition to being locked up.  Really beat up and no guarantee the bottom end is OK either I guess but....  I have numerous spare 350F top end parts.  So I can bolt a 350F top end right onto that 400F?  Do you have a link to that thread?