Theyre baaaack!.........starter and primary noise.

Gidday. On another thread i thought I had resolved my horrible noises in the primary on myMark 3. But Magically, overnight the noises are back with a vengeance. so, another train of thought. The starter doesnt turn the bike over sometimes, but just makes the horrible noise. Occassionally it starts it instantly. On my pevious thread I thought I had too much side play in the anti backfire device as the drive cog was brushing against the stainless plate on the hydraulic tensioner.

Could my anti backfire device be slipping? It is tensioned at 48lbs so I didn't think it was worth pulling down for 2 lbs. I have the more compact after market starter (probably more powerful ) and I've upgraded all electrics to gruntier everything as well. The reason I'm thinking this way is that it doesn't make the horrible noise when, the plugs are out, or the clutch plates are out or it is more likely to turn the engine over when its hot. should I try the backfire device tensioned at maybe 60 lbs. Currently it just doesn't turn the engine over but makes the grinding noise.

On the deep knocking noise, could my triplex primary chain be worn, causing the dampeners to bottom out? How do you know when the chain is stretched or worn too much? Are there some measurements please? I also cannot find any ball valves that was suggested. All I can see is the main body, the 2 piston tensioners, 2 springs, 2 nylon bushes that I presume go in the dampeners.

The starter doesnt turn the bike over sometimes, but just makes the horrible noise

Click to expand...

This sounds like the sprag clutch is slipping. The inner surface of the primary sprocket and the inner bushing will wear. In fact it is recommended these be replaced whenever you fit a new sprag clutch. I have had some success by glass beading these and re-using, but YMMV.

hillbone said:

Could my anti backfire device be slipping?

Click to expand...

I sugest you remove the primary cover and observe what happens when you operate the starter? As it should be fairly obvious if it is slipping, because the main gear that drives the sprag will stop rotating when the device slips, but the starter motor gears will keep turning.

hillbone said:

On the deep knocking noise, could my triplex primary chain be worn, causing the dampeners to bottom out?

Click to expand...

Unless you are operating the tensioner in its FULLY PRIMED condition with the tensioner reservoir full of oil so that pushing one tensioner piston inwards forces the other piston outwards then they will knock against the body. If the chain is excessively worn then it could be hitting the case?

hillbone said:

I also cannot find any ball valves that was suggested.

Click to expand...

See my reply on your other thread.

If you forget to put the idler spindle in the inner chaincase (part # 4 ,see picture : http://www.oldbritts.com/1975_g12.html ) you will get these symptoms. Don't ask me how I know. In my case it also broke a tooth off the idler gear (#5)
Bill G

I think LAB's advice is sage.

I would only add that you can "prime" or bleed the tensioners by working the tensioner pistons while adding the oil you intend to run in the primary. You will feel the tensioners buck-up as the oil replaces the air.

When I went to start my Mk III, after the initial and required kick starting ritual my new sprag (18 element) made horible sounds, sometimes grabing sometimes spinning free. I had cleaned up the anti-backfire clutch and set it following the Old Brits tutiorial. After 5 starts no problems ever again. I have the CNW 4 bush/ball bearing starter.

If you primary chain is out of spec you will see gouges in the primary cases.

RS

Thanks for all the advise again. Will investigate all suggestions. Cheers

Hillbone -

I've been having a similar (same?) problem with my Mark III.

Over a year ago I replaced the sprag clutch unit after the original one came apart in my hands while i had the primary apart to replace the alternator and deal with an oil leak.

Prior to this the starter was working fine (had the heavy-duty cable upgrade).

Within a few weeks, the starter would occasionally fail to turn the engine over,producing a gnashing/ spinning noise in the primary instead. This got more and more frequent, until the starter wouldn't turn the engine over at all.

I got my right leg in shape and kicked the bike for a while, but after switching to rearsets, kicking became a challenge without taking a divot out of my tibia, so i pulled things apart again.

The "new" sprag also came apart in my hands, and even with a magnifying glass and patience, I gave up trying to get it together properly so it would engage both the engine sprocket and the starter gear properly.

So i sent it to the graveyard after only about 1,000 miles and a few months of service and ordered a new one.

The new one only worked for a week, and I was back to the same problem. I took things apart again and, following Fred Eaton's technical notes, carefully measured the ID of the engine sprocket and the OD of the starter gear. The ID of the engine sprocket was a few thou out of spec, so I ordered a new one and reassembled.

this new setup only worked for a few weeks too. Now what???? The starter motor spins strongly, and engages through to the starter gear, which spins but the engine doesn't turn over. (And oh yes, the bike always starts on first kick). (And Yes, I am absolutely certain the parts were assembled correctly, and yes, the anti -backfire assembly is torqued so that it spins freely at 50 ft lb)

There are only 3 parts in the equation, and two connecting surfaces between them - it should be simple:

A (Starter Gear) connects to B (Sprag Unit)

B (Sprag Unit) connects to C (Engine Sprocket).

Simple math tells us that if A is engaging B, and B is engaging C, then if A turns, C turns (and thus the engine will turn over).

I talked to Fred about this, and pointed out that the engine gear and sprag are new (and asked him if there was any history of problems with these sprags, as I have been through 2 of them very quickly), and my measurements show the OD of the starter gear are in spec. He is mystified, but suggests the starter gear is the issue - perhaps it is out of round?

Anyway, a new starter gear is $260, and I've already thrown too much money at this already, so I'm as frustrated as you, Hillbone.

I will definitely pull the whole thing apart soon, and re-measure the OD of the starter gear, then decide what to do.

I doubt that my monologue helps you any, but hey, I feel better.

keith

I'm hearing you Brother. I will measure all the parts diameters as well. report Back. Cheers. Sleepless in wagga Wagga.

If I have this much trouble when I put mine back together, I'm just going to sell my starter, and buy a belt drive. $200 for sprag $260 for gear, $? 3rd part..... this adds up way fast!

Keith,
I'm impressed with what you went through, emotionally and financially, and with no real positive results. I also have a Mk III, I replaced the sprag and added the CNW starter. While I was assembling the primary I marveled at the un-nessary complexity of the electric starting system and wondered how long it could work. One of this forum's members suggested that the starter should only be used in emergency situations, such as stalling in traffic...
I assume that you assembled the primary with a parts book close by, certainly you have had enough "pracitce"; if either one of the two surfaces that the sprag engages are out fo round that could be a factor, but the parts are un-godly expensive (try Clubman Racing--$120 for the new 18 element sprag). And you are fitting the sprag with the "lip" facing the engine.
What oil are you using?? I put in exactly what the "book" calls for, and change it at the same time I change the tranny oil, about 2-3 time a year.

Hope your problem is very short lived,

RS

Thanks for the price tip on the sprag. My mates Sprag has just lost the plot as well so he will go thru the mob you suggested. $120 is a great price. I will replace the engine sprocket so i will try the same guys and check that price as well. I have rebuilt heaps of primarys in mk3's and never had these issues.
we will get there and I'll post the results. I use 20W40 in the case . Cheers

question?- you supposed to grease the sprag and starter gears when reassembling, or does enough oil sling off the chain??

pelican said:

question?- you supposed to grease the sprag and starter gears when reassembling, or does enough oil sling off the chain??

Click to expand...

I certainly wouldn't grease the sprag.

Primary oil appears to provide adequate lubrication.