C90Club.co.uk

After running around on the bike for the past few days I suddenly remembered that I hadn’t taxed the bike....ooops.

Still I’ve done it now and it’s charged me for the whole of Jan anyway.

Minor Update.

About 200 miles on the clock so far and it hasn't self destructed yet, no MPG figures as I've been using up all the leftover diesel I had in old containers/jars and the parts washer tub. The clutch/primary oiling system seems to work fine and in archetypal brit bike tradition - it leaves a nice little stain on the floor wherever it's parked. I think I have finally bled all the air out of the cooling system, mostly relying on the expansion bottle and numerous heat cycles to expel the air and suck back coolant.

Good bits:

Acceleration is very good, a tad better than Sluggy the first.
Doesn't overheat either around town or flat out on a dual carriageway (but it's not exactly hot out there).
Having a 55/60w headlamp is very useful, as is the disk brake.
It's nice to have cruise control, holding the throttle steady means the motor will try to maintain that particular speed and it works within 2mph so 30 or 40mph zones are dead easy.
The 14AH battery appears to be up to the job of powering the glow plugs and cranking the motor. It only takes 20 seconds running to put back the juice used for starting (45amp alternator). How long the battery will stand up to this kind of abuse only time will tell.
Although I haven't tried it yet; it will be a much better towing vehicle for the trailer as first is low enough for easy pull aways.


Need Improvement
Regulator bolts dig into my right thigh (easy fix).
Idle is too low.
Twist grip needs a new rubber (it's too narrow to grip easily).
There's a weird slow weave when rocking off the throttle from around 60 - feels like too tight head bearings or low tyre pressure, but may also need stronger fork springs.
I should have swapped out the gearbox change plate to reverse the shift pattern (it's the opposite to Sluggy I).


I'm having a blast running around on it; especially starting it after being parked up and folks look around expecting to see a taxi.

This machine was already creating interest last August!

About 300 miles on testing so far and yes there is a problem.

It overheats; but only on full bore running down a dual carriageway - it seems that my particular motor might be a tad more than the advertised 12HP as it runs past 65 mph in favourable conditions. The seals are (were) still on the regulator settings so it’s not been ‘tweaked’, I had to remove the seals to increase the idle speed after lightening the flywheel.

Several things may be at fault:

1) the radiator is too small
2) the system is airlocking preventing flow through the rad.
3) the thermostat is not opening fully
4) insuffecient airflow through the rad.

So, reasoning that 125 petrol bikes radiators can handle the less efficient heat byproduct than the more efficient but equal power 500cc diesel motor, then it’s down to airflow through the rad. Solution would be to relocate the rad to the front of the bike but there’s not enough room. In the short term I have wired the fan to be on whenever the ignition is on.

Thermostat has been removed so fulll flow of coolant should be ensured.

As for the airlock problem, removing the thermostat should help when filling the system with coolant, but I have also changed the plumbing (yes it’s copper piping and soldered fittings). It’s a tricky routing to the water pump as it needs to clear the fan belt and the throttle operating arm.

So all completed today and will be testing tomorrow if the weather holds dry,

On another front, the 5 speed gearbox has been proving problematic, downshifts are fine but upshifts are more hit and miss than I like so I’ve modified the change plate stop to allow more movement on the operating shaft - not a simple change but hopefully worthwhile..

Nothing is ever easy when building experimental stuff

sometimes removing the thermostat is not good it flowes through the bypass hose does not get full flow so may overheat ive had it in the past on cars

JOHNBOY wrote: ↑

Sat Jan 26, 2019 11:26 pm

sometimes removing the thermostat is not good it flowes through the bypass hose does not get full flow so may overheat ive had it in the past on cars

+1

And you must have positive pressure to the pump's inlet, otherwise it will cavitate.

Take a good look at the article linked below.

https://www.valin.com/resources/blog/ru ... p-problems

Thanks for the input chaps - much appreciated.

I did manage a flat out run today, even hitting 65 at one point, without boiling over; but thats with the fan wired on with the ignition.

I do have an SV650 radiator on order as they are cheap enough from China; that way there will be enough reserve cooling capacity for the south of France in the summer.

Onwards and upwards