Paul Chance finishes the finicky stroker. At last!
Chancey’s RGV is finally finished, all we need to do is road-test it in the New Year; if he’ll let us…
At last! I’ve finished my lovely Suzuki RGV250M (I think)! Those of you with good memories will recall how, back in the April issue, I introduced myself and my quest to get a good two-stroke screamer.
Well, succumbing to nostalgia, I found this very tidy RGV for £2700 which was sadly not running when I came to buy it. A haggle on price and a plug clean saw her start third kick… I knew I’d had a result. Since then I’ve cleaned the thing, fitted new rings, pistons and some JL (Jim Lomas) exhaust pipes. Last time out I was screaming with rage at how the carbs just wouldn’t work and I was getting bored of stripping the things down. So, the RGV was sat in the naughty corner for a few weeks as it wasn’t behaving nicely after its rebuild with the motor seeming to die at high speeds. I was advised to try down-jetting a size as it could be over-rich. I went back to standard 270/280 jets with the leaner emulsion tubes: I also decided to renew all of the pipes on the air circuit, and clean the small solenoids that bleed air in at pre-programmed revs via the SAPC (Suzuki Advanced Power Control) controller – the gizmo which operates the power-valves, basically. This didn’t take long and it was time to blast it up the road. Oh at last! Instantly it was keener to power-wheelie in first and it really revved cleaner and harder to the redline, it seemed like were in business! And finally! I only had time to do three or four miles on the test ride but I was happy. I boxed it up completely using the brand-new top fairing bolts I’d bought and new plastic washers to protect the paintwork. I also installed new grips and bar-end weights as the aftermarket anodised knurled ones were gash, (we all fitted ’em in the 1990s though eh?). I stood back and admired it, it was the first time I’d seen the RGV250M in one piece since I pulled it apart and I was very pleased, it looked like a nice clean period example – just the look I was after. The guy from the unit next door appeared and proclaimed: “That’s the b **** cks!” And with that fine tribute ringing in my ears, it was time for the obligatory cup of tea and a call to the local dyno centre.
Time to see what she was punting out! It was a 15 mile ride from my unit to the dyno, so a few more miles on the clock to make sure the new pistons were nicely run in. I stopped to fill the tank with super unleaded as we don’t want to run out on the dyno do we? I arrived and was asked what I wanted to achieve. So I said we wanted a power run to overlay over the before and after and an all-gear run to see if the jetting was near as dammit and maybe lift the lid on the air-box to see if it liked a leaner setting. That should cover all bases, I thought. I was secretly hoping to crack 60bhp at the rear wheel as this would mean it was a “good ’un”. It was duly strapped on and blasted to the red line in fourth gear and it recorded a peak of just under 58bhp, so I was a little disappointed, but the way it now revved all the way to redline was a dramatic improvement. The RGV was now 24bhp up at the new peak; the powervalves were clearly doing their job correctly. I asked for an all gear run; usually if there is a big difference in peak between the single power run and the all-gear run as it means the jetting can be improved. It recorded a peak of nearly 61bhp – this raised fresh hopes for that 60bhp I was after! Next we opened the air-box lid and raised it the width of a bit of fuel pipe (that’s what was easily to hand) and did another fourth gear power run which resulted in 63.17bhp! I was very happy with that. So the next plan of action was a free flowing race air-filter and maybe another drop in jet size, but one step at a time, it also wanted to be richer from idle to where the main jet takes over. This would be achieved by dropping a jet size on the pilot air feed circuit.
Time to get off the dyno and head home. It was a spirited ride home as I knew the jetting was on the safe side of safe now but then the blasted thing seemed to drop onto one cylinder after consistent high speed running. I now thought we were dealing with an electrical issue… A few days passed and it was time to investigate the sparky bits. I stripped the tank and fairings off and inspected the plugs, leads and caps: it had one aftermarket plug cap and one that appeared to be original. The standard resistance for these resistor caps should be 5k; I dropped a meter across them and the aftermarket item read 4.7K, so that appeared to be okay. I then measured the original cap and it read 18K!
This obviously was way too much, I dissected it out of curiosity and found a resistor and spring that were very crusty, I was hoping I had found culprit! I bought some new HT lead by the metre from a local motor factor, also a pair of new plugs and caps to be sure. The coil and lead arrangement on these is re-buildable, it’s an old school set up with a self-tapper style affair on the coil that screws into the HT lead, as does the plug cap, but you have to get the coils off to do this. One is located by the side of the engine (easy to get to) and the other directly behind the headstock, this one is slightly trickier and requires disconnecting the loom from the ignition switch to get a T-bar on the retaining bolts. The coil set-up was rebuilt and reinstalled; balancing the spacer washers underneath the coils with gravity doing its thing was a little challenging, but I got there in the end. I then reconnected the ignition switch loom. While I was at it I carried out the jetting mods: so we were now running 250/260 main jets, and on the pilot air jets it was dropped from 1.1 to 1.0. Doesn’t sound a lot but it’s 10%! I dropped the tank on and went to fire it up. I turned the ignition switch on and…. nothing, no neutral light, no oil light, just darkness. Damn! ‘It’s got to be the ignition switch,’ I thought as I unplugged it to get to one of the coils, so it was a case of ‘tank back off and investigate!’ I cleaned, prised and plugged and unplugged a dozen times, but still it was dead. I decided to try from the other end. The battery was fully charged but then I spotted the main fuse holder. I popped the cap off and the 20 amp fuse was blown! Doh! I replaced it and she lit back up. It must have been some kind of surge or short, who knows? The RGV started first prod, so it was time to put her back together. On went the air-box with a new race filter, and I fully clothed the bike in anticipation that the misfire had been cured! Straight away pulling out of the workshop it required less clutching to get under way. I let the RGV warm up and gave it the berries all the way through to top gear – not a trace of a misfire. Job done! It’s been a bit of a trek, has this RGV250. It’s shown me that – even getting a bargain – more work and money is required to get it spot-on. I’ve spent plenty of time and money getting everything how I like it. Has it been worth it? You betcha! I’ve promised Bertie that CMM can ride it in the New Year when the weather is nicer!