So last time I got the carbs back on the SRAD 600 and was almost ready to fire it up but I ran out of day light and energy so I came in and raided the fridge instead.
Next day I needed an answer to every bike mechanic’s question – did I waste my time yesterday? I stuffed some fuel in the carbs, all I had was some old stuff that I had taken out of a tank from I bike I scrapped. It wasn’t ideal but the nearest petrol station is 5 miles away so I used what I had.
I was glad to see the carbs didn’t leak, that’s always a worry when you separate ancient gaskets – it’s not uncommon for the float bowls to leak – if they look really manky a smear of RTV sealant is a wise precaution, be frugal with it though, you don’t want it creating havoc in the float bowl.
The SRAD has an electric fuel pump within the tank and a vacuum operated tap, I wanted to take both items out of the equation for this test, I just wanted to know if it ran or not. I knew the ignition side of life was ok as it had previously started on easy start.
I gave it a quick snort of easy start now to help it on it’s way, the choke was put on full and the starter button prodded. It fired straight up but only ran for a second or two – basically until the easy start had been burnt off. Undeterred I tried again and it ran for a few seconds more then died again. Oh shit – no more easy start! Ho hum, just used neat petrol dribbled carefully in to the intakes. Next time she fired and kept running albeit not very well – it sounded very lean. I let it warm up for a bit and felt confident enough to put the airbox and associated pipes on – the theory being with all that in place it should richen up and run properly.
It did run a whole lot better to the point where I think it would be ridable but it has a nasty flat spot around 6-7000 RPM, which is the point at which the main jets take over from the needles. I am now more convinced than ever that the mains are too small for the bike with the free flow exhaust and K+N filter. I think I shall order a set of 130’s to replace the 122.5’s and 127.5’s currently in there and see what they perform like. It’s ok for now though as my next job is to investigate the fuel pump problem.
I took the plate off the bottom of the fuel tank, the pump, inlet filter and level sender unit are all part of the one assembly. It smelt really nasty in there so I thought maybe the motor was gummed up. I suppose really I should have checked it was getting 12 volts to it first but as I was pretty sure it had gone bad I went this route. A blue wire and a black wire come out of the motor, the blue is live, the black goes straight down to earth. I removed the retainer, took the motor out and connected it to a battery, my suspicion was confirmed, the pump was dead. While it is probably possible to open it up and maybe do something with it a brand new replacement can be had for £25 so that’s the way I went, I will have to wait for it to arrive but it should be a simple job to fit the new motor and get it working. There may be another problem as well but I doubt it, I will cross that bridge if and when I come to it.
While I had the engine running I checked the electrics – all good but it has no rear light and no indicators in it’s current track day configuration. I haven’t decided yet whether to sell it as a track bike or do it up as a road bike. I’m not in any hurry to make a decision as it’s now just before Christmas 2020 and not the time to be selling bikes really – I will decide later and have it ready for March or April sort of time. These bikes are fantastic for the track – 13,500 red line, absolute monsters that respond well to having their arses thrashed off.
Another job I need to do is to balance the carbs but sadly my carb balancers have the wrong adapters on them – mine are 5mm and the holes in the inlets provided for the job are 6mm. I might make a set on the lathe if I get bored or maybe just order a set. I will most likely change the jets first as it’s best to leave balancing as the last job on the list.
Next time I get to it I will do the jetting put fresh fuel in, finish sorting the pump and have a look at the fork seals which don’t seem to be doing their job any more. Bastards.
Article provided by David Powell of Boston Bike Bits.