Topic: Piston Ring Compressor for Inline Fours?

[Dr. Frankenstein]

Anybody know of a good piston ring compressor to use on inline four motorcycle engines? Once I get the head back on my 500/4 it might be kind of tricky getting all those pistons back in their holes.

[M 750K6]

Clean and everything well lubricated, I was able to lower the barrels on my 750, just using my fingers to guide the pistons and rings in. They didn't just drop in, but it wasn't too fiddly.

[bryanj]

Care and a small screwdriver, there is aig lead in on the sleeves of the fours unless they have been very overbored

[HondaMan]

I have a set of hose clamps (virgin) of which I sanded off the little ridges and sharp edges of the screwdriver slots to protect the rings. I use them for all the SOHC4 engines.

Avoid the hose clamps that have a thin metal band in between the threaded-slot band and the hose it would contain, as those thin bands will simply slide out of position when the cylinders are pushing down on the hose clamps. This prevents the rings from going in and also scratches the bore! (Don't ask how I know this, I won't tell you...).

[seanbarney41]

Anybody know of a good piston ring compressor to use on inline four motorcycle engines? Once I get the head back on my 500/4 it might be kind of tricky getting all those pistons back in their holes.

uhhh, you are gonna need those ring compressors BEFORE you put the head on...and Hondaman's method worked for me and also just do 2 pistons at a time, center 2 first

[Deltarider]

You can make the "compressors" yourself. All you need is a strip of that thin metal used on shipped goods, often found in the streets. Cut it to the right size and then bend it into an open ended circle.

[newday777]

You can make the "compressors" yourself. All you need is a strip of that thin metal used on shipped goods, often found in the streets. Cut it to the right size and then bend it into an open ended circle.

As in banding straps found on lumber bunks and steel shipments? Are they wide enough?

[Deltarider]

You can make the "compressors" yourself. All you need is a strip of that thin metal used on shipped goods, often found in the streets. Cut it to the right size and then bend it into an open ended circle.

As in banding straps found on lumber bunks and steel shipments? Are they wide enough?

Yes, I have seen them being used. Should have taken a pic. Long time ago, long before cell phones with inbuilt camera's. They looked like this.

[MauiK3]

+1 hose clamps method
I also have a pair, carefully cleaned up and smoothed. I keep them in a bag in a tool drawer

[Bodi]

All the fours I've done this on the barrels have a chamfer on the bottom that makes it pretty easy to get rings in with my fingers. Haven't done a 750 though. And on the 400 with a 466 kit overbore there's not much chamfer left so I used brass shim stock and cable ties to tighten it to where they would just slide.

[HondaMan]

All the fours I've done this on the barrels have a chamfer on the bottom that makes it pretty easy to get rings in with my fingers. Haven't done a 750 though. And on the 400 with a 466 kit overbore there's not much chamfer left so I used brass shim stock and cable ties to tighten it to where they would just slide.

I've done the brass shim stock, too, on the big-bore 750 engines, but inside of the hose clamps I usually use. Without the bevel on the bottoms of the cylinders, it's testy to get them started!

Funny thing is: I have both the standard-to-1.00mm overbore Honda ring clamps and the ones for the 836 big-bores. The hose clamps work better, by far.

[Tracksnblades1]

Blue point has manufactured these for as long as I’ve known..
They work very well.. or you can make your own as Delta mentioned..
I’m not sure how big of bores they make bands for..
I have a homemade band for 6.500 + 0.125 inch..
If you need to borrow it for your build 🤫

https://b2b.snapon.com/productDetails/635923/2/885254

[dave500]

if you look close at those tapered lead in ramps they are pretty rough,ive sanded down and almost polished them smooth and it all goes real easy!

[RAFster122s]

Small engine plastic ring compressor bands work on the smaller SOHC4 s. Recall a few years back folks using a set molded in red plastic....

[Dr. Frankenstein]

Never having used one before, esp on an inline four, how does it work? Do you do one piston at a time, or put one ring on all four and work them in at once, or...? I've done plenty of two-cylinders, working each one in by hand, but that of course takes a while so I'm trying to step up my game here...particularly with the hose clamps - I assume you just remove the screw and then bend up the stem to allow you to manipulate it, yes...? 

[RAFster122s]

Two cylinders at once... Generally 2&3 first then 1&4

[HondaMan]

Like Rafster said...I'll tighten the clamp on the 2-3 first, then release the screw about 1/4-1/2 turn as I tap the cylinders down onto those 2. Then I put the clamps on the other ones and repeat.

I also made some flat [mine are brass] pieces to help hold the pistons squarely to the face of the engine itself so the tops of the pistons are held square to the cylinders. I can make pix of them tonight if you care: I slide them underneath the pistons opposite the camchain-hole sides of #2-#3 and the outer sides of #1-#4, and remove them after the rings are in all 4. This brass is 0.040" thick, not flexible (from the local Ace Hardware).

[Dr. Frankenstein]

Yeah, pics would be great! I'm sure I'm not the only one who'd like to see that...and the brass is available at Ace Hardware?

[Dime]

Would definitely like to see that as well HondaMan.

[seanbarney41]

I made mine out of some nice hardwood

[HondaMan]

Here's the ring tools, CB750 size.
The notches clear the cylinder studs and hold the piston stabilizers (that's all I can think of to call them?) in position while you fiddle things around.
The bars sit under the pistons to hold them square to the bores and cases.
They are about 3/4" wide, 0.040" thick brass strip from Ace Hardware (K&N Brass).

They are shown as they would be installed: #4 on the left and #1 on the right, as you will be facing the engine.
The 2 outside ones (#4 and #1) are flat because it's easy to get your fingers in to remove them (last), while the 2 inner ones (#3 and #2) have little bent tabs to help your fingertips or needle-nose pliers to nab them for removal after the rings are in the bores.

[newday777]

Here's the ring tools, CB750 size.
The notches clear the cylinder studs and hold the piston stabilizers (that's all I can think of to call them?) in position while you fiddle things around.
The bars sit under the pistons to hold them square to the bores and cases.
They are about 3/4" wide, 0.040" thick brass strip from Ace Hardware (K&N Brass).

The 2 outside ones (#4 and #1) are flat because it's easy to get your fingers in to remove them (last), while the 2 inner ones (#3 and #2) have little bent tabs to help your fingertips or needle-nose pliers to nab them for removal after the rings are in the bores.

👍

[Oddjob]

Weren't the genuine Honda tool for holding the pistons upright much thicker Mark, I seem to recall them holding 2-3 right at the top of their stroke and just sliding under the skirt, seem to recall they were around 3/4" or thereabouts thick and just a slotted U shape.

[Medyo Bastos]

I’ve always used my finger tips. For some reason closing my eyes helps me see things better when sliding the barrels over


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[bryanj]

Yes the original piston holders went round the rods