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

[HondaMan]

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.

The ones we got from Honda (back then) were like big, curved Vise-Grips with a spring holding them closed. The aftermarket ones I have (somewhere around here) look much like them. They are awkward to use unless the engine is raised up quite a bit higher than frame-level, and I have mis-installed one of the thin oil ringlets (as pictured in my book) and bent it when using them: that was when I got tired of struggling with them and built the ones shown above. They work far better.

[Don R]

  I made two ring compressors out of an old sleeve sliced into 1" rings and split into two pieces, held with a hose clamp they worked good until one got away from me and fell into the engine. Magnet fishing time.
  Well, that was enough of that silliness.

[Oddjob]

No I meant the piston holders for holding them upright, not the ring compressors which were like wrist exercisers, Charles Atlas designed those I think. The piston holders were slabs of metal in an elongated U shape with a slot of the rod to slide through.

[Dime]

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.

This is great. Thank you

[HondaMan]

No I meant the piston holders for holding them upright, not the ring compressors which were like wrist exercises, Charles Atlas designed those I think. The piston holders were slabs of metal in an elongated U shape with a slot of the rod to slide through.

I think you're right about Charles Atlas, Designer! The old ones I still have are real hard to remove from the 1-4 cylinders after the 2-3 are in place because you must fully open them against their hefty springs, which is almost impossible with my bad right hand.

I first made the U-shaped piston supports from brass but found them hard to use because they would slide down against the rod and then the top end could get caught down inside the crankcase, making them real hard to remove. Making the top end of the "U" longer could fix that, except the materials needed for that were not readily available, nor cheap (the latter being important to me...). So, I made the 1-sided ones pictured above, instead. With their little notches that slide around the cylinder studs: they don't move out of place while fiddling around with the rings. They sort of lock onto the studs once positioned, which made the bent end of the 2-3 parts necessary because needle-nosed pliers are needed to reach in under the lowered cylinders to unlock them after ring assembly. Then they are simple to slide out without falling into the crankcases.

[Medyo Bastos]

Yeah i have a set under my bed, i only used 2 because 4 didn’t make since once 2/3 were in the sleeves





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[HondaMan]

Yeah i have a set under my bed, i only used 2 because 4 didn’t make since once 2/3 were in the sleeves





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Those look just like mine!

[Oddjob]

Now you know who robbed you Mark 

[HondaMan]

They LOOK like a good idea, but they are too 'deep' in actual use underneath the cylinders. While I thought about trying to cut down their height somewhat, it would take at least a mill to accomplish it (which I don't have). That's when I spent a few hours rethinking it. In the "old days" we had some real nice band-clamps that were sorta like hose clamps with liners in them, and those liners were flexible stainless steel that reminded me of feeler gages, about 0.005" thick or so, They were the inspiration for me to make the hoseclamp version, although the first time I made them from those "lined" hoseclamps (because the old tools had that liner layer in them) but there is no way to make the 'liners' stay inside the clamp when the rings start sliding toward the bore. Then that liner snags the ends of the lower oil ring, much like my previous mistake.