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Restoring my old Himalayan: Slapped on a 470cc big bore kit & more

22nd December 2022, 15:58 by Utkarsh Chaudhary

Even with a bigger rear sprocket, the top speed of the motorcycle has increased by 25 km/h.

BHPian ambarkhan recently shared this with other enthusiasts.

The Himalayan 470

In the 6th year of ownership, I was getting confused between keeping the bike or letting it go. There were spy shots of the Himalayan 450, the new KTM 390 Adventure/Enduro and the Xpulse 420 floating around. On the launch of any of these, my bike's resale surely gonna take a hit. So I had to make the decision to sell the bike now or give it a new life and drop the plan of selling it ever. A carburated dual sport bike is surely gonna be a rare thing in the future. After a lot of thought and discussion with a few bhpians, Rajeev and Shubendra, I decided it's gonna be a permanent member of the garage.

Now time for upgrades.

The Restoration

The first thing I wanted to upgrade was the suspension. Luckily on one offroad ride, a fellow rider, who was on the new Himalayan, wanted to ride my Xpulse with the rally kit. We swapped the bikes and I was pleasantly surprised with the suspension on his Himalayan. That moment helped me decide to replace the existing suspensions with the stock ones and then decide on upgrading.

The bike had the battle scars of the years gone by, both rims were bent, the suspension was worn out, T stem was not in the perfect state. I decided it's gonna be a one-time affair let's swap everything in one go.

I was practically living in my hometown instead of Pune, so I decided to restore the bike in Pune and bring it to my hometown. I had 45+ days in hand and ordered all the parts in one dealership in Pune and to my surprise when I reached there the order was not even placed. I was extremely pissed, and decided will get it done in my hometown.

At a dealership in my home town, I preordered all parts and got them there in approx a week's time. This was the first time they were changing all these parts on a non-accidental bike. The owner and manager both are enthusiasts and gave me a 5% discount and waived the labour charge for everything except getting spokes on the rims which is an external charge.

Also Installed MRF Mocross tyres in front and Ralco motocross tyres in the back.

List of all the elements replaced.

The Bigger Heart (Big Bore Kit)

There is not enough power in the world to keep us enthusiasts satisfied. The same happened to me, I got bored of the stock Himalayan 411.

I figured out about the big bore kit for Himalayan. There was one from NMW Racing which is a trusted name for its rally and racing circle. There were 3 kits; 450cc, 470cc and 500cc. The last one needed the boring in the crankcase and needed a special drill. I couldn't source any trusted guys for the job even in my extended circle. So 470cc kit was ordered. It came with forged pistons (83.5mm) and extra gas kits and a couple of main jets, eventually the 125mm stock jets turned out to be the best fit even for the bigger bore.

The installation took mere 4 hours at my trusted mechanic's shop. I wish I had more pics taken while installing. I also installed a big sprocket for the rear.

Just to please my eyes, I removed the stock headlight setup and installed led lights on custom-made brackets.

How's the performance?

There's a 25kph extra on the top speed even with a bigger rear sprocket. I expect it to be in the order of 165kmph+ with the stock sprocket. The revs for an extra 1000rpms which is way beyond my expectations. The setup seems to be reliable.

Planned upgrades

The Himalayan's brakes were never good to start with, now the excess power is too much for them. So exploring better options. I don't want too much bite as it will end up front-end washing out.

I am planning to upgrade the bike to dyno before doing further upgrades on the engine. The things in my mind are High lift cams and a ported head to make out more of the new bigger heart.

Attaching some pics of her in the sand dunes