7. Get yourself a torque wrench and check the tightness on all critical fastenings. Some bolts have a dab of red paint to show they have been torqued to the specified value – but don’t trust them. I found very few fastenings that matched the torque specs in the manual. Almost none of the non-critical fasteners have been tightened past hand tight – so again, check everything with a spanner. On critical fastenings I applied some Lock-Tight – just to be sure.
8. Be careful when running the engine in. Run the bike for fairly short periods and don't go past 3/4 throttle for the first 500kms. These bikes run hot at first - but will run progressively cooler as the running-in period gets toward the end. The good thing was that after assembly and checking, the bike started without hesitation on the first go – always a good sign in my book!
9. Change the oil at 300, 600 & 1000kms - at which point the bike should be pretty much run-in. The oil drain filter and oil screen filter are both located internally. You will be surprised at how much metal accumulates in these whilst you are running in the bike - but this is perfectly normal. Just make sure they are cleaned out during the oil changes - and at subsequent service intervals. Running in the bike this way is a little tedious – and harks back to the days of the old British bikes, which were not run in on a test bed. Trust me though, the extra care taken running the bike in will pay dividends in both engine life and performance.
10. The manual doesn’t tell you how to set up the suspension, in spite of the fact that both the rear shock and front forks are pretty good units and fully adjustable.
Setting up the suspension to match the rider and conditions is essential to any bike and will considerably improve handling and performance if done correctly.
Essentially with the Hummer, you should set the free sag to about 30 – 35mm and race sag (with rider) to between 95 – 110mm. If you don’t know how to do this, there are many articles on the web that will show you how to tune your suspension properly – just Google it. The rear shock is also adjustable for compression and rebound and the front forks are adjustable for rebound only. You can however vary the compression characteristics on your front forks by using different viscosity fork oils. Again, there are many articles on the web which tell you how to do this and how to optimize the compression and rebound settings to suit your riding conditions. The spring in the rear shock is good for a person up to about 85kg’s in weight. Any heavier and the spring is struggling to perform at its best and you should really be looking at a replacement unit with a higher spring rate. Unfortunately Dreamrider doesn’t carry heavier springs as an after-market item, but if you’re willing to pay full Australian prices, they are available from the custom suspension boys – but please be prepared for a price shock!
11. The stock tires that come with the bike are fairly budget quality hard terrain units, which are not really suitable for the soft riding prevalent here in Perth. None-the-less I used the stock tires to run the bike in – and then changed over to a set of Motoz Tractionator X Circuits – really great tires!
12. Because Zongshen’s new OHC engine produces a few extra horses over the pushrod model, they have opted to provide a smaller rear sprocket (41 tooth) with this new model Hummer. I suspect this was so they could claim a high top speed of 140kph + in the brochure. The reality friends and neighbors, is that this bike will take a long time to reach that speed! I therefore opted to change the sprockets over to a 16 tooth drive and 56 tooth driven (rear) sprocket. This gives you a drive ratio of 3.5 - which is pretty torquey and provides heaps of acceleration and hill climbing ability. The theoretical top speed will of course suffer – but there aren’t many tracks around here where I can use 140 kph!
I’m also waiting on a 47 tooth sprocket from Dreamrider, which I will run with a 15 tooth drive sprocket, giving a drive ratio of 3.1. I’ll then have two drive options, which should cope with most places I ride. To allow for the larger sprocket, I ditched the original chain and opted for a DID 428 NZ black & gold. Note that this chain has a higher stress rating than the DID O-ring chain and in fact you’d have to spend big bucks and go to the DID premium X-ring chain, to get a higher stress rating. Rest assured, the DID 428 black & gold is a competitively priced chain and is just about ideal for Hummers!
13 In riding the bike, I found that it handles pretty well and with the 56 tooth sprocket and accelerates quickly on a short technical track. The suspension tends to bottom out on jumps and in the whoops – but that’s probably more to do with my 96kg weight than the bike. Inevitably I’m going to have to bite the bullet and look at a custom spring on the rear shock. None-the-less, for general work around the track, the bike behaves well and provides good cornering and agility. Note that much of this performance has to do with the choice of tyres and the suspension set up – so pay attention to these elements when setting your bike up!
14. One thing I don’t care for are the bike’s foot-pegs, which I think were designed for dainty sized Chinese feet. Personally, having size 13’s and MX boots, it feels like your standing on a pair of nails and some after-market oversize pegs would definitely be the go. Unfortunately most of the after-market boys don’t make oversize pegs for Chinas – mainly because three sets of their pegs would buy you a new bike! The only oversize peg made in Australia to fit this bike costs nearly $300, so I think I’ll wait for an enterprising Chinese company to catch onto the oversize foot-peg market, or maybe have a go at making some myself!
All in all the G4 Hummer from Dreamrider is a great bike for the money and provides an incremental step forward in the quality and manufacture of Chinese bikes.
I’ve been thinking that down the track I might look at some power improvement options – and there are a couple of books on the market which can tell you how this is achieved. Recently though, I discovered a Philippines based company on e-bay, which produces monster trick versions of the Zongshen 250cc engine for just U.S.$499. Power outputs are claimed to be up with the top Jap and European bikes – and a heavy duty custom clutch is included with the package. The only question I’d have is whether some custom sprockets would be necessary, so as to enable an upgrade to a 520 or 530 chain!
Anyway, for those who may be interested, The G4 Hummer is available from the following site:
eBay Shop - Dreamrider Store: Hummer 250: NEW 250CC TOMAHAWK G4 HUMMER pit dirt trail motor bike
The Tricked up SOHC Engine and other accessories are available from this site:
eBay Store - Zongshen performance: Performance parts, Appearance and beauty, Hausmotors
Enjoy the ride!!
Rodbox5
