Fit & tune – BGM 177 kit: verdict & video | WORKSHOP
Venlo or bust?
A last minute replacement kit was fitted the day before Venlo, not ideal, especially with temperatures set to scorchio and a long motorway journey planned. Nevertheless Boris got the scooter built in the nick of time and set off to run the new engine in the scooter boy way… Fast and hard.
If you missed the earlier parts of this BGM 177 kit and tune feature you can follow these links:
Running in – on the Autobahn
I had arranged to meet my two travel companions, Melli and Marc from the Cochinos SC, on Friday morning in Würzburg. That meant I had 200kms to do on my own to get there and opted for some minor country roads in order to break the kit in properly. After a while, I felt confident enough to test the kits potential under acceleration and was happy to find out it really torquey, pulling up hills in fourth gear without any problems. Also top speed seemed adequate – I stuck to 90kmph but from the way the engine wanted to accelerate on at that kind of speed, you could sense that top speed was way beyond this mark. Increasingly I started to enjoy myself as I hummed along into this summer’s eve. The real trial for the kit however was yet to come the next day. A massive heatwave was forecast for that day, with temperatures well beyond 30 degrees. Plus we would change over to the motorway now, with Autobahn A3 being one of the most crowded and dangerous motorways in Germany.
Melli and Marc arrived on two BGM 225-kitted Lambrettas, so my Vespa would clearly be the weakest scooter of the trio – times of pottering along were definitely over. We kicked off into the blazing heat at about 11 a.m. and soon travel speed was established at 100 – 110 kmph. I was relieved to find my BGM 177 was quite happy with that sort of speed, even if it seemed to be running a bit lean at half-throttle. Unfortunately there was nothing I could do about this as I had not expected a richer atomizer than BE3 would be necessary and had left the BE2 at home. Still the kit coped very well while I tried to avoid running at a fixed throttle opening for too long. At one stage I left the throttle fully open when overtaking and saw the speedo read slightly more than 125 kmph – of course the EFL speedo is exaggerating quite a bit, but still this was a very pleasing result.
VIDEO | BGM kit road test
In the afternoon the heat became almost unbearable, with the tarmac and the surrounding cars adding to the oven-like temperatures, plus we now got stuck in some traffic jams – typical for Friday afternoon. When we had a brief stop, I wanted to take the engine side panel off and found I could barely touch it because it was sizzling hot. Marc’s Lambretta started to show signs of fuel starvation at higher speeds, probably due to the petrol frothing in his carb. So we finally left the motorway to find some shadow on the country roads, crossed the Rhine and after another stretch of motorway finally arrived at Venlo, ready toasted but safe and sound. This day had certainly been a real tester for any scooter engine, eight hours of constant riding at any speed from walking pace to full throttle in the blazing heat. I kept thinking that a cast iron barreled tuning kit would have probably seized ten times before we arrived. Thumps up to the BGM. It always kept its distinct rattle under load, and emitted all sorts of other noises depending on revs and temperature, but performed perfectly all the time. With a bit more time spent setting the carb, you would have been able to cruise at 110 kmph day-in-day-out.
On Saturday morning the dyno was up at Venlo so I queued up to have it tested. The dyno made obvious that some additional time spent to set up the engine would have certainly been helpful because when revved, it started to splutter slightly from 5.500rpm, thus reaching a bit less than 14hp. BGM’s own demonstrator produces two horsepower more, so to what extend this difference is due to the lack of fine tuning, to the different exhaust I’m using or to the LML-reed being restrictive is something only further testing can reveal. The torque figure however is very promising – my engine delivered more than 18NM at the real wheel, thus nearly equaling the figure of BGM’s own demonstrator. For comparison – a GTS 300 usually produces something around 17NM on the dyno. As torque equals pulling power, this figure illustrates why the BGM is so much fun to ride. The task of building a good touring bike has definitely been accomplished.
The journey home was rather uneventful, especially as Marc and Melli had rented a van for the journey back, so I joined them for a good proportion of the trip. The last 200kms I was on my own again and the engine didn’t miss a beat.
So after all this, what can I say about the BGM? The problems I encountered with the first kit wearing so quickly are hopefully just a singular situation. SCK say that they didn’t have any other complaints like this, so I put this down to individual bad luck.
After my return from Venlo, I dismantled the second kit I’d been using to see what condition it is in. The barrel looked basically as new. The piston showed some normal wear and again you could see it has been tilting slightly, which is just in line with the slight rattle you could hear. Given the fact that the kit has now done more than 1200kms under all sorts of conditions and it hasn’t got noticeably worse, I’m quite certain that this will not cause problems for several thousands of miles. Still you can see the piston is under stress, and while the BGM seems to be a high quality piece of kit in terms of cylinder layout and materials used, if there is one thing that I think could be improved on, it is the piston design. The short piston with its unnecessarily narrow skirt on the inlet-side quite obviously would benefit from some more skirt surface to prevent the piston slap phenomenon. However as long as all tolerances are according to spec, this is rather a matter of personal sensitivity than a real reason for concern. So I guess for the time being, I’ll simply live with the noise and see how things develop.
These minor niggles set aside, the overall performance of the BGM – in terms of power delivery, torque and overall touring capability – is superb. I think it is perfectly suited to build a powerful engine that provides just what you need for long distance motorway work. Bottom-end power is plentiful which is great for touring as you usually struggle with the additional weight of luggage and touring gear. With the BGM you can simply whack the throttle open when overtaking and it will pull from whatever speed in fourth gear without hesitation. Equally comforting is that heat seizures do not appear to be an issue. Considering the trip’s extreme conditions and the fact that the engine was far from being set up perfectly, it’s obvious that there is a good safety margin against overheating. When I took the cylinder cowl off, the cooling fins had partially molten through it, which shows that the cylinder is quite good at dissipating heat – and I certainly rather have the cylinder cowl melting away than the piston. Fuel consumption was constantly around 4 litres per 100km, which is similar to a standard P200 – only that at this sort of speed, you would be riding the P200 at full throttle all the time rather than cruise along without any hassle. Finally, the BGM is versatile in that it can easily be upgraded to a real race engine by using a 60mil crank, larger carb and exhaust and has lots of potential for further tuning as port timings are rather low as standard.
To sum it up, the BGM is a well thought out kit – at least if you put down the rattling as a feature and not as a bug. So if you have an old PX lurking in your shed you want to turn into a fast but reliable touring bike, the BGM is definitely worth looking at. For my own part, I’ve put it back on just as it came off, as I will have a few more horsepower to find…
Words and main photos: Boris Goldberg
Additional pics: Melli