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It is a well known fact that all GL1000s smoke at startup, but this has always annoyed me and it has been embarrassing at times. I even had a brand new 1975 GL1000, and it smoked badly from the day I drove it home. I decided to give it my best shot at solving this issue and bought some .50 oversized pistons and new valve guides. Next, I took the engine apart and took the parts to the Ridge Reamer machine shop in Denver. I gave them the minimum piston clearance specs out of the manual and they did a beautiful job with the boring/honing process. I also had them resurface the heads and cylinder mating surfaces. It took them a few weeks to complete the work, but I am very impressed. Hondaman (Mark Paris) recommended this machine shop to me. Today, I started putting the engine back together. After I finish, I will put the engine on my test stand and see how it does.

Cliff- Sorry, I didn't take "before" pictures. I should have done that.

Thanks

Cedric, ya got any “adult” beverages for when you fire that baby up ? I will be more surprised if it doesn’t smoke than if it does,, sorry.. My 76 has smoked at start up off & on from the very first day when I bought’ it new. The cranking compression was always 135-145psi from new as well, not the advertised 171psi.

It is generally caused from parking them on the side stand where the crankcase oil can run into the cylinders and through any open ring gaps that are oriented to the bottom. On later models (I think 78) Honda started clocking the ring grooves away from the bottom & I believe at some point actually put pins or something like that in the grooves to keep the ring open ends oriented away from the bottom,,, but they still smoke on start-up.

Even my 76 LTD does it occaisionally and the motors in those were hand assembled with great care so that things are as perfect as possible (maybe ?) And even the new 1800’s smoke on start-up occaisionally , it’s a common complaint with a flat motor.

So I hope you have success and I believe that if anyone can do it you can, good luck ! I have found that the best way to minimize the start-up smoke is to keep it on the center stand and not the side stand, but even that is not a garuntee. Keep us in the loop.

How much did you take off of the head and block surfaces ? I “clayed” and measured everything on my 76 and ended up taking .040in off of my heads to bump the compression up which noticeably helped with the power & torque and still runs fine on regular fuel. And personally I wouldn’t recommend more than .050-.055in max on regular gas and valve clearances, but if you have things apart I would recommend .040in.

On the head gasket failure problems these are my thoughts,,,, I believe that the problem there is that the top of the cylinder is unsupported and probably moves around and damages the gasket. I believe that retorquing the head bolts after a couple of heat cycles will help this , even the no retorque head gaskets….

My .02

Steve- I am not optimistic either, but maybe it will help. My thinking is the piston/ring design are probably the major reason they smoke. These .50 oversized pistons look like the originals, but maybe there are some minor improvements, or not, I don't know. I also thought by matching the exact piston to the cylinder might help. The machinist did this for me and set each one to the minimum clearance, .001" (.03mm). I am not sure how much material he took off when he resurfaced the heads/cylinders. They look beautiful. Seems like someone mentioned they found newer automotive rings that helped a lot, but I can't remember who that was, maybe Cyborg. I used the rings that came with these cheap pistons. Stay tuned...

Certainly a lot of us are watching your efforts.

Cedric, I’ve often thought that if I was to get into this I’d use Total Seal Gapless (?) rings if they are available, they basically use a multi piece (gapless) second ring where the gaps are offset and should (in theory) not allow oil to pass through. They are supposed to improve leakdown & efficiency as well but quite frankly the couple of “hotrod” engines I’ve built using them didn’t really show me any real leakdown improvement. There are some that swear by them but I haven’t seen any real improvement over a properly fitted set of normal rings.

A couple of things that I have found piston wise that do what they say though is thermal barrier coatings on the piston crown that keeps the heat in the chambers and also coat the combustion chamber as well, noticeable improvement ! Also I like to use is a dry film lube onthe skirts. Now none of this would really help with the start up smoke problem they just seem to help with overall efficiency.

Those gapless rings would probably help a lot, but finding the correct size might be a challenge. Maybe another person can try those in an engine and report the results.

I have the engine back together, but I have to finish a different project first. I also need to rebuild a set of carbs for this engine. It will be a few days before I can get back to this project.

I had the smoking problem on my '76 GL 1000 LTD when I first got it. What I found helps is to limit parking using the side stand and I keep the oil level in the lower 1/2 of the view window.

-P.

Oil level works for me as well. And a lot cheaper fix.

As a addition to cyborg & pj’s comments,,,,, I tend to keep the oil level at the high mark and maybe slightly above,,, park it on the side stand and kill every mosquito in the area but it’s an OCD thing that can’t be helped….. but if I keep it on the center stand it is minimized.

In full disclosure I have a modified side stand that lets the bike stand up more when parked

A strategy a fellow had offered up that works for him re: left side smoking was to shut off the engine and lean the bike towards its Right side for a moment to influence whatever engine oil was accumulated underside the left side pistons to drain back into the base of the engine.