How do I tell if mine is twin or single rotor idle

[Haggler]

HI, I am a little confused how to tell if my interpol is sinle or twin rotor idle. There is no retard box or anything that would suggest where it might plug in, but also I cannot see any micro switch. On the right hand inltet tract between carb and throttle there are t pipes that have been blanked off. Also when I removed the alternator cover I noticed the ignition trigger was spaced out off the engine case with 4 washers, is this usual? There is also a blue wire that runs with the horn wiring and I am guessing this goes to the thermal switch, am I right?. Getting very excited as getting near to trying for a start.
Thanks for looking

[Haggler]

Thinking it is a twin rotor idle as the blue wire apparently should run to the retard unit. Just need to work out where that splices in. Also can you tell me where the temp guage sender is fitted on the engine? can identify wiring in binacle but not sure where it runs to.
Thanks
Pete N

[Richard Negus]

Hi Pete,
Yours is almost certainly twin rotor idle as most of the singles were factory-converted to twin. That you have a temperature switch on the r/h housing is confirmation as that wasn't fitted to singles.

The blanked-off pipes are main bearing oil scavenge connections that were discarded on later IP2's.

The ignition trigger should sit on a tufnol spacer, about 8 mm thick, between it and the engine plate. Are you saying that you have the heat insulator and washers?

The blue wire runs from the temperature switch to the retard box, telling the ignition system whether the engine is 'hot' or 'cold' and modifies the amount of ignition retard for best slow idling. Without that retard box, the engine will run at full advance all the time and will idle reliably much below 1000 rpm. With the retard box functioning correctly, you should be able to adjust the idle down to around 600 rpm.

Original retard boxes were not weather-proof and notoriously unreliable which is why many were removed.

Have you identified what ignition system is fitted? Original Sparkrite CDI, replacement Boyer system as used on Classics and Commander, or a more modern digital system?

The temperature sender is a thermocouple just above either spark plug. Both rotor housings are tapped M6; the thermocouple is usually in the l/h housing. If it's in the r/h, it usually means that the brass fitting into the l/h has broken off.
Apart from a feed for the bulb, the gauge has no connection into the 12 volt bike system.
R.

[Haggler]

Thanks for that Richard, I was leaning that way. I notice that AN have retarder boxes so take it it would be a plug and play. The ignition is still original Sparkrite, but I do not know if it is still functioning as have not got that far. The pickup was on the tufnal block but with 2 washers behind it on both bolts lifting it away from the casing. Have removed these. Noticed some type of fitting by one of the plugs so that explains the temp sender. Are these still available or can you use any PRT or K type sensor?
Thanks again for your assistance

[Richard Negus]

Pete,
Before paying out for a new retard box, I suggest you first see if it runs on the Sparkrite.
If not, then the MiniMagneto system is the one to go for. It uses the same trigger, but needs conventional Lucas-type ignition coils in place of the original CDI ones.

I don't think AN have any thermocouples now and, unfortunately it isn't one of the common types. Brain fade means I don't recall the actual wire type but, when I investigated a few years ago, it was available as a 50 metre roll at some enormous price. The VDO gauge will only work correctly with that particular wire.
R.

[Haggler]

Thanks for that insight Richard. Does it not need the retard unit to run at low speeds? I had a look on the mini magneto site but to be honest didn't know what I was looking for. It also still runs the original reg/rec unit, are these ok or would you recommend changing it ? Do you know of a cable supplier as always like to have spares. Didn't know if venhills would have patterns for these.

[Richard Negus]

Pete,
Without the retard box, it will run perfectly OK at engine speeds over about 1200 rpm, but will not idle smoothly below that. For general road riding, that's not a problem, but if you spend much of your time creeping along in traffic, you may find the engine temperature starts to rise. You may also find neutral is more difficult to find with a high idle speed.

On Julian's site there is a section on his ignition for rotary engines. His black box, well aluminium actually, is very good and ultra reliable.
R.

[johnbirchjar]

Hi guys,reading Richards info on the blue wired retard/advance coupling,I thought "Perhaps this is why my Commander engined Classic is such a pig at low revs" .Further investigation revealed that there"'aint no 'oles" to screw coupling into.Is it located somewhere else?Please advise,J.B.

[Richard Negus]

Yer 'tis, alongside the fan switch and above the sender for the temperature gauge.

4032-48.jpg

[johnbirchjar]

Thanks Richard,(Engine all nice and clean,not a bit like mine, )ride safe,J.B.

[Zed]

Richard,

Which air filters are those in the image?

Thanks

Zed

[Richard Negus]

Hi Zed,
They were made by S&B, direct copies of K&N at half the price.
I have no record of the part numbers though.
R.

[johnbirchjar]

I have fitted the same ones on my Commander/Classic,I will have a look at my records tomorrow and report back,J.B.

[Zed]

Thanks Gents.

[johnbirchjar]

There you go Zed,nothing special about mine,"Universal Motorcycle Air Filters" £26-00 the pair,not too shabby ,
Oh,and the "Thermo Coupling" only made the bike run worse ,so its back to "Sans T/C" ,ride safe,J.B.