bultaco_modifications

Modifications

The Bultaco Brinco was unlike any other bike on the market when it was launched, however most of the technology used dates from the early 2010s and is now unmaintainable or obsolete.

Some of the issues owners will encounter are related to age, or flaws in the technology selected.

Today its possible to update the Brinco to be a very capable bike with current components and more modern technology.

Looking After Your Bike

Day to day, there are few key points you can follow to keep your bike in good shape :

DO NOT JET WASH YOUR BIKE! : This is clearly stated in the Brinco owners manual on page 57, section '4.6 washing'. Jet washing your bike will increase the possiblity of electrical component failure, and also increase the likelihood of problems with the suspension, swing arm, wheel bearings and driveline.

DISCONNECT YOUR BATTERY WHEN NOT IN USE : This is good pratice as many owners have had problems where the bike have been left and will not switch on. In section 3.2, and specifically p32, where is states "If you will not use the vehicle for long periods of time you must disconnect the battery from the moto-bike". This is generally good practice to avoid drain of the battery over time.

CHARGE YOUR BATTERY REGULARLY : Care of the battery is detailed in the manual in section 3.2. It states "we recommend to keep the Brinco battery connected to the charger if it is not going to be used for more than 30 days. In case you decide not to keep the battery connected to the charger, make sure you remember to perform a charge of at least two hours every 30 days."

Rear Wheel & Motor

The Bultaco Brinco used a HRS3538 hub motor manufactured by Crystalyte. This is fairly heavy (just over 7kg) and experienced a number of problems in operation with the bike. The motor itself is now discontinued, but it is fairly repairable by specialist around the UK.

Cooling : The Brinco used a square wave motor controller. This not only generates noise but heat. When ridden hard for extended periods some riders experience overheating, with the bike derating perfromance. One solution people have used is the fit 'Hubsink' fins to the motor to radiate the heat.
Loose spokes : These bikes are heavy and the rear wheel takes a beating if used hard off road. Spokes loosen over time and if they are left untighted the rear rim can fail, eventially cracking at the seam in the rim. Several ebay shops still have Bultaco OEM rims available.
High power cable chafing : There are 3 power cables from the controller to the motor. These pass through the centre of the rear wheel axle. At the point they enter they can rub, damaging the cable insulation. Repair needs specialist dissassembly of the motor.
Hall sensor failure : The controller needs to know where the wheel is in its rotation, and to determine this it uses hall sensors. Some motors have had these sensors fail. Again, ebay has vendors offering motor repairs.
Hall sensor connector : This connector is very fragile and can be easily damaged (on the motor side and on the bike look side) when removing the rear wheel. Repair (especially on the bike side) is not easy, and some owners have resorted to fitting other connectors.
External damage : On some bikes damage can be seen on the surface of the motor. This is usually caused by a loose brake caliper rubbing on the left, or the derailleur rubbing on the right due to poor adjustment or being bent.

Controller & Wiring Loom

The controller used on the Brinco is probably the single most failure prone element of the design. The location on the bike was always a compromise, and this contributed to the demise of many bikes. The controller design is now fairly outdated, and doesnt perform well compared to more modern alternatives. Many owners have chosen to replace the entire electrical system on bike due to repair costs and limited availability of parts.

Controller Water Ingress : Despite using a waterproof connector, many controllers have drawn water in over time. It is possible to (carefully) open the case to repair the electronics if the controller fails. Several specialists advertise repair services on ebay.
Overheating : Due to the choppy power delivery to the motor, the original controller can get hot. Over time this can cause damage and degrade its performance.
Bike Manager Failure : On all the models except the RB, the bike is activated via a RFID card or bracelet. This is held against the screen, but the activation takes place within the 'bike manager'. If the battery is charged and the bike will not turn on, this module is often the source of the problem. This module is mounted inside of the frame, behind the headstock, an area that catches a lot of mud and water. Despite being full sealed and hacing waterproof connectors, they can fail. Some stocks of spares are still available from several ebay sources.
Broken Throttle : The Bultaco throttle is robust, but breakages do happen. Replacements can be found, but they are expensive and hard to come by. If you take the path of a controller upgrade, I would consider switching to an aftermarket throttle like a Domino, they are stronger, waterproof, and your old throttle can be recycled to another owner in need!
Loom Connectors : The white connectors fitted the bike loom can be very fragile and are extremely difficult to replace if broken.

Controller Replacement

If like many owners you find yourself with failed controller, options are limited. There is no easy way to get the controller repaired, so replacement is the only real option. Changing has some positives and negatives.

Secuirty : Moving away from the bultaco controller will mean repacing all the bikes electronics. As a result you will no longer have the bike manager to fail, but you will lose the protection of the RFID card activation.
Performance : The temptation is to upgrade the bike to produce more power. This can result in the motor running hotter, and more current load being put on battery.
Response : One clear benefit is improved throttle response. The standard Bultaco setup can feel laggy, with a slight delay between the throttle twist and power being applied. This will be improved with a newer design of controller.
Noise and vibration : Switching to a new controller will significantly reduce noise and vibration from the motor.
Torque vs speed : Some controllers will prioritise torque over speed. This is a consideration when selecting a replacement.

The MQCON (sabvoton) SVMC7245 is a good match to the bike, without overstressing the battery and motor.

Battery

The original battery is 1315Wh, 50.4v 26.1Ah. Internally it is made of Panasonic NCR18650PF MH12210 18650 type cells, arranged in 14s 13p configuration. The battery is protected by a BMS. As the bikes have been out of production since 2018, many bikes are now developing battery issues due to cell aging and poor maintenance.

The sticker on the battery and the information in the manual stated to charge every 30 days :

'If you will not use the vehicle for long periods of time you must disconnect the battery from the moto-bike, but we recommend to keep the Brinco battery connected to the charger if it is not going to be used for more than 30 days. In case you decide not to keep the battery connected to the charger, make sure you remember to perform a charge of at least two hours every 30 days.'

Battery problems you may experience :

Water ingress : The battery case is injection moulded plastic, screwed together with a 'tongue and groove' seal. The front wheel sprays a lot of mud and water on to the seam, but also on to the connector and the battery lock. Over time, some batteries have absorbed water, corrding cells and causing internal short circuits.
Connector wear : The battery uses a Sourai UTS 18X2M3 connector. (Datasheet in the documents section) this has 3 small 'ears' that the mating half from the bike loom screws on to. This is quite easily to misalign, especially when dirty and can be easily damaged if forced. Also over time, due to the softness of the plastic, dirt can wear the connector. Replacement is possible, and specialists advertise this service on ebay.
Battery Management System (BMS) : The BMS used from the factory seems to struggle to balance the battery as it ages. One fix for this is to fit an more up to date BMS, preferably something with Bluetooth so the internal health of the battery can be monitored, like the screenshot on this page.
Cell degradation : There are now a number of eBike battery repair companies in the UK that have experience of the bikes and will repair Bultaco batteries. If you are at the point the battery needs to be rebuilt, there are now 18650 cells with higher capacity that can push the battery to around 30Ah, or with more complex repackaging and 21700 cells 40Ah (around 2kWh) is possible in a custom build.

Suspension

From the factory, the Brinco came with DNM USD-8 forks and a DNM Burner RCP-2 rear shock. This brand is not well liked by the mountain bike community, but they actually perform extremely well on the bike in most scenarios. Over time, things do wear out, and this presents some challenges for the Brinco.

Fork Guards : The Bultaco bikes were supplied with a specific design of fork guard. This is no longer available. As the fork is an off the shelf design, DNM guards are available from many sources.
Servicing : The DNM suspension components have gained a reputation of being unservicable. If they develop a fault often there is no choice but to replace like for like with a complete new unit, or upgrade.
Upgrade - Front : The obvious upgrade path for the front suspension is the Fox 40 fork. These are a direct fit, but only if the steerer tube is uncut. The headstock on the Brinco is very deep and the full length of the steerer tube is needed.
Upgrade - Rear : Due to the 240mm length of the rear shock, options are limited. Several of the Fox range will fit, including the VAN and the DHX RC4.

Everything else ...

There are a few other things worth mentioning.

Tyres : The Bultacos came with 24" wheels. This is relatively uncommon. For the dirt, there is the DURO razorback in limited supply, but also the Halo Contra. For the street there seems to be more choice, as some BMX bikes use 24" also, but the Schwalbe Crazy Bob chosen by Bultaco is still a great option.
Brakes levers : Brake leavers are redily available, but seem to not actaully break that often. Instead the master cylinder / housing breaks instead. Housings can be found in a few places but are very expensive, in fact for a little more you can often find a complete replacement system, so its more cost effective to upgrade.
Brake calipers : Its fairly straight forward to upgrade the RB, or the rear of the R to 4 pot calipers. If you find yourself with a broken lever housing, its worth considering.
Lighting : It is of couse possible to put lights on a Brinco. From the factory a kit was available to fit the Supernova M99 light to the handlebars, powered from a loom adapter that took 12v from the feed to the display. In practice this does not work on some bikes. The extra current draw seems to block the start sequence and the (!) warning remains.
Chain : The chain is a SRAM PC991. Its fairly easy to come by once you know the SRAM description.