First start tips

i’m ready to start my Commando tomorrow after the rebuild. I did a full rebuild of the combat engine and gearbox, including CNW breather, super blends, gearbox bearings, stock compression pistons , new valves, springs, etc and tri spark ei. I’ve rebuilt the Amal’s with gaskets, new needle, jets and floats. I’ve never started or ridden a Commando, or any British twin for that matter. The only vertical twin I’ve owned was a 76 KZ 400 back in 79. so I’m nervous and excited. Also my first full engine rebuild so it’s been very rewarding and my tool box is much more complete.

Any tips on first start? Assuming it starts and runs, how long should I run it (it’s not yet registered and waiting for the tank from painter), when should I first check valves, torque head and cylinder bolts, change engine and gearbox oil? After cycling the engine I plan on checking and torquing all fasteners on the bike from bow to stern.

It’s impossible to overstate the part the forum and members played in getting this done. Thanks and credit to everyone, especially those who ran out to their garages to photo assemblies on the spot and posted diagrams and notes. Also to Grandpaul who posted the first words of encouragement three plus years ago. I’ll try to post a video and will post pictures in my build thread. Ben

Here's my break in proceedure. I know others may do it differently, I'm just stating what has worked for me in the past. I don't use any special break in oil, Castrol Go 4t 20w/50 which is rated SG. Don't use a SL or SM rated oil which have a lot of friction reducers as the SG oils seat the rings faster and avoid glazing the cylinder walls. Might as well use the cheap dino until you reach a 1000 miles and then switch to the more costly synthetics because you are changing it fairly frequently.
I kick the motor over a few times with the plugs out just to get some oil into the pump. Then I start it on the stand. I generally let it run for about 5 minutes or so checking for oil return in the tank and pressure on my temporary guage. Keep the rpms up a bit say 2-3k to get some splash on the cam. Don't let it idle. Once it gets up to operating temp I shut it off. When cold, retorque the base nuts and head bolts and check valve gap.
Next start, I have the timing light ready and check the timing and do a rough carb adjust and take it on first ride. Preferrably in a rural area, up and down the gears, varying speeds. Gradually start increasing rpm. First 100 miles, keep it under 3500, next 400 4000. At 100 miles I change the oil and filter and retorque base and head bolts and adjust valves. Repeat at 500 and 1000 miles. After that just regular maintainance.

Don't freak out if it takes a bit for the oil to start returning to the tank and then probably in spurts and not a steady stream. If you haven't seen anything in 30 seconds shut it off and find the problem. Starting proceedure. Fuel on, push each carb tickler down until fuel drips from the carb. Chokes down if you have them. Throttle closed to slightly open. Turn key on, kick through to get up on compression. Then kick it like you mean it. Be prepare to give it some throttle. On a tite new rebuild I find it easier to put the bike on the centerstand and stand along the right side of it and kick with my right leg.

Run it til' hot , then retighten the exhaust rose nuts. Check oil return and level , should settle in halfway between high and low on dipstick. Go ride , come home , pull tank and retighten rose nuts and re-torque head and barrel nuts cold. Check valve clearances.

Yep, tighten those exhaust nuts when hot.

Hope you remembered to remove the exhaust covers and squirt some oil in there onto the cam/ followers as you have done to fill up the crankshaft.

You don't mention whether you replaced the camshaft. If so it needs to be run in. The easiest thing to do is google camshaft running in. You can search on this forum as well, as I asked a question about this a while ago and there was some good information given by Jim Comstock (among others). You'll find lots of camshaft manufacturers give detailed instructions on their web sites. From memory the procedure involves running the engine at 2 -3 thousand rpm for twenty minutes or so as soon as it's running and has oil pressure - and avoiding letting it idle. It's standard practice with muscle car people but seems to be little known in bike circles.

Bernhard said:

Hope you remembered to remove the exhaust covers and squirt some oil in there onto the cam/ followers as you have done to fill up the crankshaft.

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I liberally oiled the followers during assembly. I’ll do it again this morning. Thanks

Well Ben - it seems you have passed me ! Good for you !
I know from previous conversations that you have an oil syringe and have primed the crank. You may want to use it to prime the rocker feeds . When I did my ES2 motor I removed the spark plug and oil feed at rocker box and kicked it over (fuel off ) until I had oil coming out of feed - then reassembled rocker feed before starting. I plan on doing the same for the Commando .
I don’t believe you have a new cam and followers but if you do , research break in procedure as others have mentioned . New cam or not , remove exhaust rocker covers and squirt some oil in pushrod tunnels as mentioned to lube cam . Everyone above has given good advice that I can’t add to . I am envious as I have a ways to go before I can light mine up .
Good luck and go for it - keep us posted .- RT

Just to add a cautionary tale of what happens if you don't remove the covers and liberally squirt oil all over hell and back, back in 70 I replaced the standard cam on my 750 with a cam with pretty hot lift and duration (don't remember details). It all seemed oily enough when I assembled it. I did use assembly lube. And it started in a couple of kicks and ran great. I shut it off after 20 or 30 seconds or so. And as the engine almost came to a halt there was a small, but quite audible "tink". Valve had frozen in the guide and was smacked by the piston. I had used assembly lube, but maybe I missed a valve stem. Always wondered if even with assembly lube the oil had probably better start circulating fairly soon. And with that comes a question: How quick will a gear pump pick up and push oil?

If you don't see oil returning to the tank in 30 secs there's a problem.

Jim Comstock did a really good video test of the problems that can be caused by using STP (and similar products) as an assembly lube on valves. Something to do with the molecular structure (or something equally beyond my understanding), but basically it resulted in the valves sticking (seizing?) in the guides. I watched the video on this forum so it should be searchable.

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I didn’t replace the camshaft but did oil the followers liberally. It started on the 13th kick. Here you can count them.

here is a shorter saner clip of the bike running.


I think the bike last ran in 1982. I took a short ride around the block and everything appears to work ok. The tank is not mine. My interstate tank and side covers are out at the painters. I’ll post before and after picks on my build thread to close this out.

I think a few nights out of the garage are in order.

I meant to upload this video.

Very nice, feels good! Now hop on over to the "real kicker of a question thread" and don't forget those exhaust nuts. Had one turn out on me earlier today. Burnt holes in my gloves tightening it till I got home.

Go for a ride yet?

Well Done ! Couldn't help but notice something hanging from your garage ceiling - just as I suspected , mine is longer than yours -

Richard Tool said:

Well just as I suspected , mine is longer than yours -

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That's what they all say.

My wife’s board. No sane person surfs around this part of the Cape due to the white sharks. Those who do build a sand mound on the beach and leave their bleed kit on it in full view.