New Member, 1974 Commando with several issues

Previously ronald_wellman wrote:

I'm Ron Wellman, Midland, Michigan, USA. Just reassembled a beautiful '74 commando and have the following list of problems below listed in descending order of concern. This Commando was stored for 13 years before I bought it.

There is good news however, my Commando runs very strongly and is a joy to feel its huge torque -- the sound is sweet music. This is my first Brit Twin since I sold my BSA Lightening in ~ 1970.

My other current bike is a V45 1983 Honda Sabre where absolutely everything works, nothing leaks and it starts every time. That said It's not close to as much FUN as the Commando

Issues:

1. Left carb (Amal 932) tickler leaks prolifically when engine is at idle with typical vibration. Have inspected float/float needle. Float is pale yellow polymer Amal and float needle is polymer tipped. Have confirmed that needle tip DOES effectively shut off gas flow so it's not a float seating issue. Floats are sound without holes or other things that would keep them from floating. There appears to be no mechanism to adjust the float level, at least I don't see one. Have even checked and rechecked for evidence of the float bowl gasket overhanging and interfeering with the float lifting fully. See http://www.jockeyjournal.com/forum/showthread.php?t=89790 for a discussion of a similar problem of the issue of an Amal 930 on a Triumph Bonneville.I'm ready to simply plug up the left carb tickler and just use the right carb's tickler to start the bike. Better than having bike incinerated.

2. Excessive oil leak appeares to be from pushrod galleys between head and cylinder. Will try retorqueing the head and hope this fixes the leak, will replace head gasket if retorque doesn't stop the leak. Recommendations for best head gasket to buy please.

3. Have original Lucas horm but it won't make a peep, measured resistance across connectors and strangely the resistance seems to drift downward starting at ~ 20 MOhms and drifts down to ~ 10 MOhms or least. Also interestingly when I check for continuity across these contacts I get none. The resistance reading may just be an artifact of my multimeter ? Is this horn worth saving with as a last resort drilling out its rivits and seeing what I find inside -- suspect a corroded something.

4. Turn signal flasher is slow and sometimes doesn't flash on and off at all. Are there aftermarket flashers that are more reliable ?

5. Gear box leaks as does the primary chain case, not horribly. Is this just the price of a Brit Twin or do better after market seals and gaskets exist to remedy these leaks ?

I had the same problem on my carbs. The problem is that the Commando engine shakes in the rubber mounts. I cured mine by fitting new stay up floats with Brass Viton tipped needle valves. I also replaced my float bows as they were in a bad condition. With the lighter Aluminium needle valves I could get the valves to seal with the engine not running, but with the vibration of the engine running the carbs flooded with petrol coming out the ticklers. The stay up floats have metal tangs whick can be bent to set the fuel hight, The only way to adjust the float hight with the old plastic floats is to move the float chamber valve seat.

Look up Bushmans Amal site for tips.

Previously ronald_wellman wrote:

I'm Ron Wellman, Midland, Michigan, USA. Just reassembled a beautiful '74 commando and have the following list of problems below listed in descending order of concern. This Commando was stored for 13 years before I bought it.

There is good news however, my Commando runs very strongly and is a joy to feel its huge torque -- the sound is sweet music. This is my first Brit Twin since I sold my BSA Lightening in ~ 1970.

My other current bike is a V45 1983 Honda Sabre where absolutely everything works, nothing leaks and it starts every time. That said It's not close to as much FUN as the Commando

Issues:

1. Left carb (Amal 932) tickler leaks prolifically when engine is at idle with typical vibration. Have inspected float/float needle. Float is pale yellow polymer Amal and float needle is polymer tipped. Have confirmed that needle tip DOES effectively shut off gas flow so it's not a float seating issue. Floats are sound without holes or other things that would keep them from floating. There appears to be no mechanism to adjust the float level, at least I don't see one. Have even checked and rechecked for evidence of the float bowl gasket overhanging and interfeering with the float lifting fully. See http://www.jockeyjournal.com/forum/showthread.php?t=89790 for a discussion of a similar problem of the issue of an Amal 930 on a Triumph Bonneville.I'm ready to simply plug up the left carb tickler and just use the right carb's tickler to start the bike. Better than having bike incinerated.

2. Excessive oil leak appeares to be from pushrod galleys between head and cylinder. Will try retorqueing the head and hope this fixes the leak, will replace head gasket if retorque doesn't stop the leak. Recommendations for best head gasket to buy please.

3. Have original Lucas horm but it won't make a peep, measured resistance across connectors and strangely the resistance seems to drift downward starting at ~ 20 MOhms and drifts down to ~ 10 MOhms or least. Also interestingly when I check for continuity across these contacts I get none. The resistance reading may just be an artifact of my multimeter ? Is this horn worth saving with as a last resort drilling out its rivits and seeing what I find inside -- suspect a corroded something.

4. Turn signal flasher is slow and sometimes doesn't flash on and off at all. Are there aftermarket flashers that are more reliable ?

5. Gear box leaks as does the primary chain case, not horribly. Is this just the price of a Brit Twin or do better after market seals and gaskets exist to remedy these leaks ?

Best Head gasket:- Eyelet Gasket, paint Wellseal sealant around pushrod tubes.

Gearbox:- look up Old Brits Norton, good technical articals.

Better x seals advaliable for Kickstart and gearchange, or can be modified to take MK3 type seals. Mk3 breather can be fitted to gearbox cover. New gaskets with Wellseal sealant..

Dear Ron,

I agree with comments about oil leaks, I too would reccomend Wellseal painted onto both surfaces - but clean them with a solvent first - I use petrol from the Tank!

I have had 2 commandos with oil leaks from Pushrod tunnel and tried new gaskets ans sealer before finding true cause. There are 3 studs on the underside of the head, if either of the front ones has been overtightened it will pull the threads slightly and produce a ridge around the stud; this will prevent head pulling down in pushrod tunnel area. To check for this while you have head off remove studs and use a steel rule as straight edge to check for raised metal. If it is this, answer is 3/8 BSF Helicoil - kits easyily available on well known auction site. Do them both as removing / fitting head is rather time consuming.

regards martin

Hi Ron

You are asking straightforward and common questions, but you have not had a pile of replies so far, so I am happy to chip in with a few comments.

1.If fuel is coming out of that tickler then the float needle is most likely not sealing, and you will be wasting fuel. The black tipped (viton) on brass body type are the best; when you say 'polymer' I wonder if you mean the older, all white bodied plastic ones? They are a problem and more inclined to leak at tickover because of vibration. You seem clued in about checking the float, etc. but I would suggest looking at the needle seat with a good magnifying glass/microscope in case it has been damaged by someone poking a screwdriver in there. The latest ethanol resistant floats are black.

2. It could be a head gasket leak but when you take the head off check the following. A known reason for oil appearing 'somewhere at the front of the head and barrel joint' is porosity in the head casting. Even if the head is absolutely clean as soon as you run it the oil seems to be everywhere. You need to test with a crack finder kit but you are only looking for a pinhole.

3. The horn resistance should be very low at just a few ohms (V=IR and it takes a few amps). The contacts are probably corroded. You can take it all apart, but I forget whether you need to drill out some rivets and replace those with screws and nuts.

4. You can get small replacement solid state flasher units. I would gess any bike shop will have them.

5. Gear boxes do not leak when they are rebuilt with new seals, etc. so it is all fixable.

Best wishes and have fun!