Tri Spark ignition

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Need to sort out a good ignition system for my Dommi 88 and leaning towards a Tri Spark. As my motor has a Distributor and just has a `sprocket` which is simply held in place with a roll pin and no auto advance /retard I`m wondering if the Tri Spark kit comes with all the bits to accommodate this ? Has anyone fitted one to a distributor motor ? Youtube only show fitting to a Commando .

Quoted from Tri Spark…

Quoted from Tri Spark blurb. "early 60s fitted with distributor and coil will need a suitable replacement magneto drive gear".
E-mail them and they will tell you what is possible for your Dominator

Easy answer CORRECT

Trispark blurb is wrong-18D2 is too small for the ignition, and is a parallel shaft so magneto drive gear is no good.
The 18D2 distributor will NOT take a Trispark. I can fit a Boyer Bransden sytem to the 18D2. And the 18D2 does have an advance retard it is under the cap/points plate. If you want to fit a Trispark you will have to purchase a 'mushroom' housing, as fitted to the early Commando even late Atlas/650SS/Mercury, as well as the appropriate drive sprocket, as the 18D2 has a parallel shaft drive and the magneto has a taper drive shaft.
All good fun.

Thanks guys , I new i would…

Thanks guys , I new i would have to discard the old Distributor but couldn`t be sure if the Tri Spark came with a parallel shaft to fit the original sprocket . I`m guessing the only thing to do is get a kit as if I`m replacing a Magneto AND then find a good advance /retard unit . Anyone got one ?

Wrong again.

The TRispark doe NOT come with any shafts. Yes you need the 'mushroom' that replaces the magneto-BUT you do NOT need an advance/retard sprocket as the Trispark has an electronic advance built in, as does Boyer, Pazon, and Lucas RITA. If you get the 'mushroom' with the tapered shaft (a la magneto) you need the magneto fixed sprocket to drive it.

Ok , so now I need to find a…

Ok , so now I need to find a `fixed` drive sprocket to fit the tapered shaft in `the Mushroom ` and the Tri spark ignition system . ( are fixed taper fit sprockets easily available ? ) Thanks for helping explain things .

Sort of

Magneto 'manual' drive sprockets are available. The 'Mushrooms' that fitted the first Commando and the Mercury and the last of Atlas are extremely rare, if any one has/buys one do make sure you have the drive sprocket that goes with it. If you buy a 'mushroom' as a magneto replacement then you would have a taper shaft (a la magneto) so you would need the taper drive sprocket.
A lot cheaper to retain the 18D2 and fit a Boyer.

All parts of the points…

All parts of the points housing used on the first Commandos are available from A.N.

Thanks everyone. I `Bit the…

Thanks everyone. I `Bit the Bullet` and have ordered all the bits required . Not cheap just to get some sparks but hey what the hell we`re only here once ! I want eventually to fit a belt drive but going to run with the standard clutch for now . Still waiting for the head to come back and frame (and parts ) are in for powder coating .

Attachments

P1050480.JPG

Are you sure?

I have just spoken to Andover Norton and I am assured that the 'mushroom' to take the electronic ignition (or points) is extremely rare and there is no stock. You could get sparks from the 18D2, but your choice. It will be interesting to see what transpires.
This bike will have to be 12V as well. And you will need 2 off 6V ignition coils (check with Trispark).

I am assured that the…

I am assured that the conversion kit comes with all the bits to convert from Magneto to Tri Spark electronic ignition system. I had to buy a new `tapered fit ` sprocket as my `straight / roll pin` distributor sprocket wouldn`t fit. Still unsure if or how you can tension the chain that drives it though ?

The magneto...

The magneto body would swivel around the bottom bolt on the rear of the engine, the magneto conversion should do similar. So you would have to set the chain tension BEFORE setting the ignition timing.

I imagined as much but…

I imagined as much but having looked at the original distributor fittings it didn`t seem to be adjustable at all . Cheers for that advice Alan.

Got the `Kit ` today but not…

Got the `Kit ` today but not sure it`s right as it fixes on 3 mounting studs which are much smaller in diameter than the actual holes in the `Mushroom` ! If the studs were bigger it might be ok but still cant see how you can possibly adjust the timing chain tension as it would be in a `fixed` position. Any idea ?

For chain adjustment

Slacken all 3 nuts, move housing forward/backwards (radially) as required and nip up nuts. That is why the studs are slim and the holes large as it allows the housing to move.
To do this properly, you will need either a cut away timing cover or the 'special tool' that holds the intermediate shaft in the correct position. Tool part number is 06.7325.
If you don't use this, your chain tensions will be wrong. Not might be wrong, but will be wrong. You should also adjust the cam chain while you have the tool fitted.
Hope this helps.
George

not looking right

Offered up the `Mushroom ` but nothing looks right . The studs are way too long and would need spacers to secure the `Mushroom. It doesn`t fit properly in the casing hole either. As for rotating the `Mushroom` to slacken/tighten the timing chain the sprocket spindle is central so as far as I can see that wont make any difference (even with the minute clearance between the mounting studs and the larger holes ). Have attached some pics of my plight !

Attachments

Whereabouts are you located?

Hi Wayne,
I must have shorter studs than you.
I also have a 'mushroom' and have never had an issue with chain tension - mine has enough slack on studs and also in the large hole to move it to get correct tension. I should add that this method of tensioning is identical for magnetos and distributors as well. Was it possible to tension the chain with the distributor fitted?
Is the chain also new? Does your new drive sprocket have the correct number of teeth?

I have to ask, but whereabouts are you located?
In the UK at least there is bound to be someone near you who might be able to assist (look up the centre lists). Might be an issue if you are further afield though.

Regards, George

I`m in Fleet , Hants

It appears that the Studs I have are long as It had a distributor fitted previously. I will have to sort some shorter ones. I have done a dry fit and was amazed to find that what seems like minute movement does actually allow you to tension the chain as you said ! My drive sprocket is correct also and the chain seems ok. The bottom stud/nut still looks impossible to get to if the engine and gearbox are in the frame especially with oil pipes connected. The Tri Spark mushroom looks like the diameter would stop the use of the special `long` bolt I know is available for Magneto`s . Its hard enough to get to even when I have the engine alone on a bench . I really appreciate you time and advice George .
Best Regards ,
Wayne .

Bottom nut

Hi Wayne,
later 650 and Atlas had the lower bolt the other way round - the awkward bolt now being tightened from inside the timing cover. Have no idea whether it is possible to modify the crankcase to do this on earlier engines.
The 'BSA' bolt won't work as it will foul the crankcases. ( Does work on 500 and 600's apparently).
Regards,
George

As mine is a 500 88 Dommi I…

As mine is a 500 88 Dommi I might try buying a `BSA ` long Bolt . I cant see it clearing the `Mushroom ` though . I came across some old Norton Owners Club forum chats from 2001 which you may have contributed to. It discussed this exact problem and did mention the bottom bolt being fitted. However , some said bolt head inside the timing chest ,another said the nut inside the timing chest . Either way you still have to get a spanner/socket or allen key on the awkward end to tighten up the bolt . I will have a look at maybe doing this too .
Cheers
Wayne

Norton Owners Club