Foreword: The changes presented here do not claim to be in technical perfection, nor do I have a very long-term experience that proofs all modifications are perfect which I could share. The chapters are changed frequently and are workshops to be continued. All changes that make the legal use of the vehicle expire were installed on a trial basis and tried out on private properties. The technical aspect to develop solutions and prove that they work is the aim of my amateur fiddling on my bike.
So be careful: always use a road legal bike on public roads: before you start your test ride make sure that all screws are fixed, your brakes and lights work and your oil stays where it is supposed to be.
Test rides are dangerous rides: Take care that all bolts are fixed and your brakes work. Always wear full protective motorcycle equipment when you test your bike !
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Content
- IAT Sensor
- OBD2 data
- rear shock and kinematic
- Oil Temperature Sensor
- Eliminating passenger seat
- Dismantling my spare engine
- The 8 disc clutch from Hitchcocks
- My own clutch project
- Fork spring load adjuster
- Free programmable ECU
- ABS switch, self re-setting ( like BS6 models )
- Free flow airbox cover
- New paintjob project “ Pegasus „
- Crash guards … and how they should look like
- Steering head bearings – be careful
- Hydraulic clutch activation
- Disassembly of fuel pump / cleaning internal fuel filter
- Replacement for the rear hub / sprocket rubbers
- Petrol Pump, some insights
IAT …or similar
With a name that suggests performance, an adapter plug is currently being sold on eBay, which apparently consists of a thermistor, a cable, a box and 2 plugs. The way it works is likely that the temperature sensor (IAT) uses a second series-connected thermistor to send incorrect data to the ECU. The ECU is thus led to believe that the temperature is lower, which increases the injection quantity.
Without ever having this box in my hands and without knowing which components are used, this led me to an experiment. In a post in the Ducati Forum I read about IAT sensor tricking.
I transfered this interesting idea to my Himalayan and finally found the core of the improvement: an additional thermistor is needed.
A „thermistor“ – what is it ??
„A thermistor (combined word from THERMally-sensitive resISTOR) is an electrical resistor whose value changes reproducibly with temperature. Thermistors are divided into two groups in terms of their temperature behavior:
- NTC thermistors that have a negative temperature coefficient (NTC) and conduct electricity better when hot than when cold
- PTC thermistors, which have a positive temperature coefficient (PTC) and conduct electricity better when cold.“
We are dealing here with an NTC thermistor. It is necessary to increase the resistance value that is passed on to the ECU in a way that that the same delta is always achieved compared to the sensor on the airbox. Of course, this does not work with a rigid resistor because if the resistance value of the IAT sensor is low, the resistance of the rigid resistor would be too high in relation to the ratio, and the same difference value over the entire temperature range could not be achieved.
Parts used:
- 1 Thermistor NTC
- 2 AMP Superseal connectors 2 pin
- 2 Automotive connectors fitting the wiring loom
- Shrink tubing, suitable cables, etc..
How to:
- Be careful: To avoid your engine warning lamp indicating a fault better disconnect the battery. Never switch on ignition before all connectors are properly plugged in !
- Dismantle the seat, side cover and rear screws on the tank, raise the tank 5cm and support it.
- Remove the white connector at the top (white); the snap hook of the plug must be released !
Note: PU is not exactly cheap, the pot life is somewhere around 3 – 4 minutes (holla the forest fairy) and somewhere release agent was forgotten (you know construction foam – is it the same thing only without foam) Gloves, mask and good ventilation are mandatory because who likes to inhale superglue!
- Plug the adaptor between the white male and female connector
- Plug in the thermistor. Take care that the cables are nicely stored under the tank.
- Fix the thermistor in the document box
The very first experience after 3 test drives / 6h drive. at temperatures between 4 ° and 8 ° C.
Cold start problem disappeared, cold run is very stable.
Better torque at low speeds, from 2500rpm useable power output.
Don’t feel any loss in the higher speed range.
Spark Plug colour neutral, not sooty or dark.
Update 18.01.20
Today I did another two hour test drive. This time with 2 thermistors connected in parallel. This halves the temperature correction, so to speak.
Conclusion: The correction is too small and not satisfactory, the full torque from 3000rpm and the possibility to roll through the town at 2500rpm were gone, this tuning is too close to the original.
I reverted to the one thermistor on the route … and then it was the relaxed single-cylinder again. Interestingly enough, the backfire, the popping sound when you take off the gas, disappears almost completely.
After driving about 1000km with this modification, as final result:
The identified thermistor seems to be optimal.
Be careful with a cold start / the first few turns: do not accelerate. Here the ECU already regulates to very rich; if you accelerate, the mixture may become so rich that the engine dies. If the engine is already a bit warmer, this effect does not occur.
At constant speeds, the ECU regulates to lean again via the lambda sond, so consumption remains rather unchanged on long journeys with some constant speed.
The fuel consumption has not increased; the increased injection quantity is compensated again if necessary by a lower engine speed level.
„backfire“ / the popping of the exhaust almost completely disappears.
Usable performance from 2500 min-1.
All previous test drives have taken place both at temperatures below 10 ° C and at higher ambient temperatures in recent weeks and show the same results. The test phase is thus completed after about 800km.
any comments or questions just leave me a message.
update September 2021
Now, after a total of more than 8000km I have the experience of almost 2 years with the IAT tricking cable and I can confirm that this little modification is a huge enhancement for the engine. Several friends received a copy of my cable in the last 2 years. All could replicate my findings. It is now time to handover this project to a professional, which I did. www.royalbikeparts.com took over, you can order it here for worldwide shipping:
Petrol Pump – some „insights“
Petrol Pump, some experience
OBD2 data
In a post on YOUTUBE, a Portuguese-speaking Himalayan fan showed how he reads data from the ECU with the help of an OBD2 bluetooth dongle. He connects the 16-pin connector of the dongle with individual cables with the 6-pin diagnostic connector of the Himalayan. Now there are adapters that fit directly „plug and play“ and establish a connection with the Himalayan ECU. As example KTM actually has the same plug here and the whole thing also works with the Himalayan. (6 pin square connector)
Installation of the cable and the bluetooth adapter:
OBD data recovery:
Block 1: The temperature of the IAT sensor (modified with a thermistor). Instead of 25 ° C, -8 ° C is displayed and forwarded to the ECU.
It is interesting that you can read out both the current and the average consumption from the ECU. The average speed is also displayed. While driving you can see how the ignition point is changed back towards retard at high engine speed. This limits the speed upwards.
If I switch off the headlight, I have about 0.5V more available.
I found that several apps work with this dongle. Don’t ever ask me about Apple Products, Android works fine and I even found an app with which I could delete Error Codes like the MIL lamp which goes on error when you forgot to re-plug the petrol pump plug after tank removal.
Suspension Kinematic
Since I changed the rear tire today and there are some stories circulating about the lack of lubrication of the linkage, I thought „take a look!“
Oil Temperature Sensor
In the cockpit of the Himalayan we find a gauge for the ambient temperature, similar what one finds int cockpit of a car. Well in a car, when the heater makes a comfy 22°C one might forget how cold it is outside. As I am sitting outside already on my Himalayan I always struggled why one needs to know why he feels freezing cold. What I really miss is an oil temperature gauge. The idea: use the ambient temperature display as an oil temperature gauge.
Also for the ambient temperature sensor a NTC is used, but it is a different one as the one I used for my IAT correction. This one is not too easy to be found. I have chosen the water tight and temperature resistant version with the silicone cable and a stainless stell cap of 6mm outer diameter… which also is a rare item it seems.
I took 22mm hexagonal rod and turned on my lathe a modified oil plug in which I can push the sensor in. Blind hole drilled into the head and a longer shaft so that the oil can directly drip on the brass which surrounds the sensor. Make sure to drill a not too loose hole, and apply some thermal conductive paste.
The display in the cockpit can indicate a range between the values -10°C and +85°C. I first thought that this insufficient but soon recognized that this exactly is the range I needed:
In wintertime or cold climate I would like to check if the engine oil has already sufficiently warmed up. Above 85°C and especially in summertime this display would make me nervous and I would probably stare on it, maybe even try to drive with less load to get the engine a little less hot?
So I went on and now know when the slower warm-up phase is over.
At +6°C ambient temperature when departing for a test ride it took me around 20km mixed town and country ride to have an oil temp. around 70°C . This value was not exceeded on the whole rest of the 1h testride.
Update 07.03.21 with 5 – 7°C ambient temperature: Testing how warm the engine oil gets. I removed the tape from the oil cooler which I used to cover and went on a 2hrs mixed small street, town, highway ride. In average the oil did not exceed 65°C, highest loss in temperature was when cruising with 90km/h on straight roads. Even in town no chance to reach 80°C.
Key learning from this project: Apply 2 strips of duct tape on the front side of the oil cooler in winter time. This will gain around 10°C oil temperature and the cold run phase will be significant shorter. Apply this trick at temperatures below 10°C when mainly driving outside town. This bike is made for tropical climate as it seems.
As already several people asked for this sensor I might make a small batch of them. The part itself is made from brass and turned on a lathe, there is hexagon with 22mm etc. so some work on the bench. And also the internals are a rarer breed.
I meanwhile developed an aluminium version which incorporates a magnet and therefore has the dual purpose of temperature sensor plus oil magnet. Tests still pending.
Eliminating passenger seat
As seen on prevoius pictures I removed the passenger seat and replaced it by a metal sheet so that I could load my luggage between the boxes a little lower. I did this a second time because I found it very practical to use my small magnetic bag which then easily could be attached. The aluminium profile is a cargo profile in which hooks with rings can be fixed. Final pictures of the platform painted and in use will follow.
Dismantling my spare engine
By chance I found an online advertisement for used Himalayan parts. I ordered some spares and some months later again got in contact with the seller who offered me a complete engine. 14000km old and running without any technical issues.
After draining the last drop of oil I decided to dismantle the clutch side
My first impression was dominated by the loose chain and chainwheel of oil pump drive. But when I disassembled the oilpump from the block and inspected it there was no doubt that it was meant to be like this. No worries, there is not a lot of power to be transmitted to the oil pump. Engines with ball ball bearing cranks do not require a lot of oil pressure.
The 8 disc clutch from Hitchcocks
Inspired by my recent experience that the clutch slightly slips in 5th flat out when one finger is touching the lever. This observation again underlines the importance to use a motoroil which is compliant to JASO MA or JASO MA2 ( wer clutch ). So I ordered the Hitchcock 8 disc set. Cost is around 120.-€ including shipment, TAX etc. You may find it here
First observations:
- Surface of each friction disc is estimated 2x bigger.
- 2 additional friction discs / 2 additional steel discs
- A set of heavier springs is supplied with the set.
- Hitchcock are worldclass quick in shipping but shipping cost is really on the high side ( 4 days / 20€ )
The springs are the same in wire diameter, windings but are harder. Length is a little shorter.
Old clutch out:
Be careful, the springs are longer than expected, to expand you will need bolts with a length of min 60mm:
Further observations: The 8 disc clutch is in total higher. As shown here it adds up to 1.8mm in difference.
It is an illusion that just with the adjustment of the cable you can compensate 1.8mm which you are missing on the clutch side. Actually the gap between the clutch bearing and the activating pin will be 1.8mm wider. This means that the clutch lever on the engine will hav a totally changed angle thus not providing sufficient angle to activate. The cable adjuster screws are anyhow on the very end.
To overcome this issue 2 options came in my mind:
- Bearing 6003 to be replaced by 6202 ( 1mm higher ) plus a shim of 0.8mm below the bearing
- Adapter on the activation pin which makes it 1.8mm longer
Unfortunately the clutch set was not working …and the set was finally returned. The total height was not as the total height of the OEM clutch, all sleeving of the pin did not bring a proper solution. Finally I returned the clutch set as it could not be made operational on my bike.
My own clutch project
After finding that the improvement of the clutch is not just solved by just buying some parts… I had meanwhile been busy to develop a complete new clutch set from scratch which is a 6 friction plates setup. Back to zero now.
Why just six: The advantage is that the clearance / free travel between the discs is – due to limited movement of the engage mechanism – constructed for 6 plates, not 8.
An 8 plate clutch will, if not opened wider, have significant drag due to oil adhesion, an effect known from automatic transmissions. Add up the max. clearance between 6 discs and divide by 8, then you see that clearance will not be sufficient to have a gearbox with an easy to find neutral ( permanent low drag ).
The new 6 disc set consists from friction plates with approx. 60% more friction surface, 20% higher compression rate of the springs.
I had the opportunity to find a company who designed springs to my requirements. They measured the OEM springs: length, number of windings as well as wire diameter and force. Design of the new spring was then done by a specialist who is very experienced, a datasheet of measurements specifies now the OEM springs and this had been used to design the new springs. The suitable steel quality plus the hardening is key. Crucial that no relaxation will take place.
The clutch set now runs for about 9 months in my bike: hand force needed is a little higher but really acceptable, Himalayan clutch actuation force is anyhow on the very soft side. The clutch is more responsive, you feel a quicker clutch in, and no matter how abusive you use it, I never got it slipping.
Tests of 5000km through France / Jura n road / offroad were successful and I am now confident that the product is ready to be shared. It will soon be found on www.royalbikeparts.com , it is the phase of final preparation for production.
*for update on the set sign in to the newsletter / header „newsletter sign – in “ to sales@royalbikeparts.com
update: Royalbikeparts.com now start to sell the clutch spring set ( or a complete clutch with friction plates ) – worldwide shipping of these unique springs is possible!
Fork Spring load adjuster
Conversion of what can be found on the market to make it fit and functional for the Himalayan.
Testride had already been successful: I like a little more compression on the front so that the fork dives less when braking with front brake.
Free programmable ECU
I am very excited it is like Easter, Christmas plus several birthdays alltogether: I just received a freely programmable ECU – not especially developed for the Himalayan but fits the Keihin ECU connector. It seems to be made for a different Honda model – and is re programmed with the ( not realized ) aim to suit the Himalayan.
I already did a testride but I did not yet find a proper fitting dataset on this ECU which would work for the whole range. Still areas where the engine does not pick-up smoothly but as friends help me I am supplied with enhanced files of data sets but also these are more improvisations than smooth optimizrd data.
This free programmable ECU is now in regular sales, you can order it directly here, this is a reliable source, you will get your ECU, no worries: https://himalayan-tools.com/reprogrammable-replacement-ecu-for-the-bs5-euro4-himalayan/
My final findings: I did not have a proper dataset from which I could start. I would have needed a test bench for the bike – which I do not have access to. So I sold / forwarded this project to a friend. This project is closed and without any result even though it looked soo promising.
Can I recommend it: No, not without a proven mirror dataset of the original ECU. Composition of a trail and error map on the road is not recommended – you always risk to damage your engine.
above: USB adaptor, below: 4 maps switch
Self resetting ABS switch
One of the big achievements in vehicle maneuvrability in critical situations is the ABS – the anti lock brake which keeps wheels rotating while the maximum of the braking power is applied.
On gravel roads, loose surfaces this is an unwanted effect, especially on the rear wheel. Braking on loose ground immediately activates the ABS and will avoid that you can brake with a skidding rear wheel. Therefore the ABS switch was added on the BS6 bikes. The circuit to the ABS electronic is cut by a momentary switch in the instrument block. This switch can switch the ABS on / off the system but with every new start of the bike it will return in „ABS on“.
I found a nicely done switch module at AMAZON which is a flip flop relay and which can be installed on the „plus“ side of fuse 9 ( 5 A ) . With a momentary switch the ABS can be switched on/off but will be re-setted to „on“ after the next engine shut off.
One of the projects I did not finally realize, no real need to have this modification on the bike, but I might again pick it up when more offroad riding is done.
Free flow Airbox Cover
This is a prototype of an airflow cover we designed to improve airflow into the airbox. It is combined with a K&N airfilter . First prototype, but it already works perfectly.
Findings after 12 Months testing: PLA is too soft – the flange on which the air filter is clamped moves, clamping gets loose.
My conclusion after all: Yes, a K&N is a good idea, especially because of durability, it is a lifetime filter which can be cleaned. And no: you do not need an open airbox cover. I honestly found out that it will just make the bike a little more noisy but there is no improvement in power or smoothness of the engine.
New Paintjob, project „Pegasus“
I always liked the special model Pegasus from the Classic 500 range and always found it a pity that they never did a „Himalayan Pegasus“ at Royal Enfield.
My experience I gained with Polyurethane 2K convinced me to use this sort of paint. PU paint is very scratch resistant as well as resistant to all sorts of chemicals and once was developed for military equipment which could be decontaminated with acid after in contact with biological weapons. So remarkable tough coating.
Important as always with paintjobs is the pre work, so I sanded and fillered. But my 1st try was not succesful, polyurethane is very agressive on the wrong primer, without polyurethane primer this can become „mission ugly“.
I finally succeded after another sanding down and the correct layer of primer. When finished I decided to give it the last touch: I gave it another clear coat semi matte also PU 2K paint. The result now is satisfying.
Longterm experience: Extremely durable paint, no scratches, chips etc. Still looks like first day after paintjob. I even used a magnetic tankbag which is usually the quickest option to get your tank scratched: nothing, not the slightest scratch !
Crash guards … and how they should look like
After my unsatisfying experience with the SW Motech crash guards I decided to do it myself (…again). The SW Motech crashguards have the big disadvantage that they actually do not guard a lot and are bulky. But everyone wants to have them – so they were quickly sold !
I found these as main disadvantages of their design ( and this is not only valid for SW Motech ):
- Their tubes go too close around the engine block / accessability of engine
- They are not saving your feet as they are too close to the engine,
- They are a pain to mount on the bike, especially the connecting tubes behind the cylinder
- They are heavy
- You can’t mount anything on them
I found Moto Guzzi 850T5 carabinieri crashguards in eBay which looked nice and did not cost a lot, the losses if they would not fit was low.
Some weiding to be done. What I liked was the squared design and the connecting tubes which are plugged into with an inner tube. All latches were useless and had to be done by myself.
Sandblasted and powdercoated they really look nice ! And there are thread inserts which could be used for fixing useful stuff.
Steering head bearings
It is known that the Himalayan has some issues around the steering head bearings. First of all there seems to be that within the asssembly process the bearings are adjusted too tight which gives extra and unnecessary load on them. Therefore it is recommended to untighten the adjustment screw by 1/4 turns which still will keep the bearing without any play. the chances that this is done during the 1st inspection at the deaklership is close to zero if not extra asked for.
Another issue is the insufficient sealing of the lower bearing, there is a metal/rubber ring but this is more decoration than sealing ring.
parts needed:
- 2 x SKF 30205 J2 / Q .
- 1x NILOS Ring 30205 AV – which replace the lower sealing
- A good quality of grease, rather HT grease than Marine Quality
- Approx. 2 hours time and the equipment to do it
Be careful that you use the bearings with the suffixes:
J2 tells you the version of cage for the rollers
Q is the higher surface quality
There are also bearings without suffixes but you would rather use them on your trailer as wheel bearings or sililar. Here I will not explain how to change the bearings but enjoy the pictures, see what I found without really feeling any marks when turning the handlebar.
Hydraulic clutch activation
Finally I got all parts to build my own hydraulic clutch activation. I always love to have a look as close as stock or at least how the OEM could have designed it. The master cylinder fortunately looks very similar to the brake cylinder, like mirrored.
At the end it was not a plug and play experience. Most important points:
- The original levers did not fit, fortunately I could combine the aftermarket ones I had with a different basis. Mechanical re work nedded to be done to have satisfying results
- Length of the clutch hose is 1000mm. Choose a teflon one with screwable ends.
- The slave cylinder is an easy install. Make sure the bleeding screw points straight upwards while bleeding to remove trapped air.
- Use Loctite on the nipple thread of the activation rod plus secure with a 2nd nut. Before install a rubber gaiter to avoid any dust getting into your hydraulics.
- For best results use DOT4LV, less viscosity gives you a superior response.
- The brake switch is different, the original will not fit. You will have unpin the block connector to connect just 2 connectors to the new switch. You will now have to pull the clutch whenever you start the engine.
- You need to exchange the clamping part of the master cylinder for one with a thread for your left mirror.
- Advice: carefully flush master – and slave cylinder. These parts seem not to be properly clean . After my test rides I found dirty dark brake fluid in the reservoir – I could have avoided with flushing the parts.
Parts list:
- Master cylinder
https://a.aliexpress.com/_EJ9wR3F
- Clamp with thread for left mirror
https://a.aliexpress.com/_EHv1l37
- Slave cylinder
https://a.aliexpress.com/_Ex6cahL
- Hydraulic hose 1000mm
https://a.aliexpress.com/_EwS1VCV
Final experience on the road: The force needed with the left hand is slightly reduced. The accuracy to operate the clutch is well improved. The system works nicely, is an improvement even against the Venhill cable ( which I think is already a huge step ). Cost is actually compareable with a Venhill cable if shipping cost and customs clearance are added ( UK purchases being as expensive and complex as shopping in Uganda )
Disassembly of the fuel pump / cleaning of internal filter
As sparepart I recently got a used but running fuel pump for my Himalayan. Seems that this pump model is also used in the Classic series, but I have to verify. ( please comment if you know better than me )
The pumps used have the disadvantage that the very important fuel filter is incorporated in the pump, you need to disassemble the pump to clean it. In the petrol feeding pipe / between pump and throttle body / there is no filter and this is actually not possible because this is a pressure pipe.
As seen in the pictures the filter is somehow folded into the assembly body.
The filter can be removed, but you have to know how. Don’t try to turn but use a screwdriver to lift gently from the stub. A little oilspray before might help. Filters are readily available from a small Yamaha bike at low cost:
Yamaha xtz 150
https://a.aliexpress.com/_EG6ttsz
Yamaha xtz 150
https://a.aliexpress.com/_EG6ttsz
Take care that you do not reuse the O Rings and that you use precise and dedicated FKM ( Viton ) Rings with correct softness.
Replacement for the rear hub / sprocket rubbers
Project wear-resistant absorber rubbers for the Himalayan rear wheel.
Anyone who knows PU (polyurethane) from the automotive sector as a replacement for rubber chassis bushings can understand the enthusiasm for this material. The wear resistance is enormous, PU basically doesn’t age, mech. resilience is very high. After I had exchanged ideas with a friend / a well educated automotuve specialis and also a fan of PU in the automotive sector, the enthusiasm was there immediately – and off we went:
The Shore D value (elasticity) was measured on a new stoc part and liquid PU of the appropriate hardness plus hardener was ordered. Molding the original geometry of the rubbers seemed too complicated due to the undercuts and would have required a two-part silicone mold – so simplify it! A spare wheel without a brake disc was aligned horizontally crosswise on a hot plate and the volume was determined with water. Then carefully coated with release agent, mix PU and quickly pour it into the warmed hub, insert the chain wheel carrier in exact alignment, insert the axle for centering and let it rest.
Finally, the experiment resulted in a part shaped like a donut that could be removed from the mold easily and was installed today. The first 1.5 hour test was successful – now it’s time for the long-term test, which I’m quite calm about.
Note: PU is not really cheap, the pot life is somewhere around 3 – 4 minutes (….uuuh) and if on any spot release agent was forgotten you have an issue (you know construction foam – is it the same thing only unfoamed) Gloves, mask and good Ventilation is mandatory because you will not like to inhale superglue!
Petrol Pump – some „insights“
This chapter is not based on own experience with my bike but with a bike of a fiend who regularly encountered problems with the engine idling and spontaneous cut off of the engine. It seemed that nothing really helped: We thoroughly cleaned the throttle body and we checked the ignition side – without any real improvement or cure of the problem.
What you see here is a totally blocked filter of the petrol pump. Even worse: The debris was magnetic and passed through the filter as seen on the picture of the housing bottom.
This was not from a bike which made a world tour – was ridden in Germany, France, Spain and Italy, neither Congo nor Cote Ivoire.
Very unlikely that the injector survived undamaged – so we exchanged it and here we go: what a different engine: Runs like new.
My advice: Service your petrol pump at least after 30000km or even less – and if you are unable to find out why your engine stalls, does not run as expected – at least check the injection pattern of your injector or better exchange. Easy job and worth doing!
Royal Enfield Himalayan 