Topic: SOHC Honda

[Bodain]

Over the years I've had many 70's CB 750's. I no longer work and now retired. I haven't had a CB750 in a few years. In my retirement I think the Honda Grom is my favorite ride.  Anyway time marches on and yesterday something came up on CL in the Dallas Fort Worth area. A 1974 Honda CB750 with orginal pipes...I see the ad has been on CL for only an hr... I call the guy. He's about 40 minutes from where I live. He wan'ts 300 bucks for it with no title. I load the trailer and I'm on my way... Saw it. Bought it. Looks to be 12k on odmeter.So the engine wasn't siezed... thats a plus... Gas tank is totally rotten with holes. Suprisingly the original factory pipes are in reasonably good shape with no holes.This afternoon I did a compression test... 1-4 are fantastic with 150 psi... Needs #$%*load of cleanup and work, but it's gonna be great..... I've encountered something I've never had to deal with before and thus far I don't have an answer.... I wanted to remove exhaust to clean them up properly.  The two outside exhaust come off farily easy, because your able to to rotate up under the foot pegs, and that action break them loose to be removed, however that rotation is not possible with two center cyclinders. I just can't break them loose to remove... Tried heat. No luck. Tried pribar between pipe and frame. No luck.     Anyone done this battle?

[BenelliSEI]

I’ve had this problem too. One I got out with a 1” ratchet strap wrapped around the pipe a few times, twisted, then around the frame. I use a luggage type strap, it has no hooks, just one long strap that comes of the buckle and then slides into the rotating drum..... lots of tension, then tapping away at the joint with heat and a soft mallet.

Another one that just wouldn’t move, I backed the clamp away, pulled the two screws, and removed it with the “spigot”. Then set the end in a brew of diesel and oil for a few days. Locked the pipe in a large vice, sandwiched in scraps of plywood, and twisted the spigot loose with a 24” pipe wrench...

Good Luck.

[HondaMan]

I have removed the 2 crosspoint screws (with a right-angle screwdriver) instead of trying to get the pipe off the spigot sometimes. Heat works: use MAPP gas, propane is not hot enough.

[PeWe]

Head spigot angle make the pipe impossible to move on or off if the rear part is not leaning down from its rear mount.

The pipe has a self locking design. Very important to not bang pipe in place making dents when the entire pipe must have right angle to move into the spigot, off the same.

I have only seen problems to mount them the first time, finding the correct position where rear bolt could find its way thru both pipes and hole in frame. Saw that pipe could glide out at front while working with rear.
Only thing to do is to remove bolt, lean pipe downwards so front could glide in deeper on head spigot. Using a strap around the 2 pipes and cylinder block helped to keep them in place.

I have seen that it can differ a little between 2 bikes. My K6 had to get all 4 to bottom the head spigot to match rear mount in frame.
My K2 had a few pipes that should not sit that tight.
This with same set of pipes, Yamiya no numbers, HM300 replicas.
I do not recall if it changed with later head on my K2 that first had a K1 head, now K6 that better match EU K2 year 1975.

Have this in mind when heating the front "froozen" on the head spigot before loosen it.