We have now pretty much completely taken the engine appart. It’s starting to feel really serious and really scary! Want to know how my Indian Scout 741 engine overhaul is going? This is part 1 which is mostly dismantling and cleaning.
Have no clue what I’m talking about? You can check the main page for my Indian Scout adventureto get clarity!
The rebuilt of the engine is now done! You can check it out in the Engine overhaul – part 2 article! It’s amazing! And we did far more than what was planned!
Engine overhaul
As I’ve mentioned in my gearbox overhaul article and the one where I explained my bike is in 1000 pieces, at first we just wanted to change the head gaskets. Well, I also wanted to change the seat gaskets but my dad seemed reluctant.
It all started when the head gaskets actually died on us when the carburetor was finally working fine. The engine was purring pretty great that day, until it wasn’t anymore… Fumes were coming out of the gaskets, it was the end of them!
Phase 1: remove the cylinder heads!
So we first removed lots of bits to gain access. That was probably the most time consuming part. The carburetor, the distributor, the gas lines, the oil lines, the tanks, the seat etc. all came out.
Then we just removed the bolts holding the heads. Nothing special here. We just created a cardboard with the cylinder heads drawn on it, to keep the bolts in place as there are different sizes (same as for the clutch really).
Tap a little, insert a thin razor like blade and the heads came apart easily.
Cleaning up the residue of 80 years old gaskets, dirt and grease was a bit annoying. But cleaning is satisfying to me so I didn’t mind too much!
We played a little with the engine and my dad showed me what it does when the engine is working. And you can see it in the below video!
I personally find it quite fascinating!
Anyway, I cleaned the cylinder heads and it was time to go back home.
I thought I did a pretty good job!
But in between my 2 trips, my brother took the cylinder heads and got them sanded. Oh god, what a difference it makes! We had to get the cylinders cleaned like this too! no choice.
I’m burning steps here but here is a picture to compare before and after sanding!
Phase 2: remove the cylinder bodies!
So on my next trip, we removed the cylinder bodies. For some reasons, my dad was now ready to do it! No clue what goes in his mind when he does that!
Just 4 bolts on each side and the manifold to unscrew. From what I understood, for most, removing the manifold can be the hardest part. For us it was actually easy. Dad had never really touched it so it was ‘normally’ screwed in, not forced.
We pulled up the cylinders very very gently and they both came out super easily. For a little while, this whole process made me start to think mechanic was fairly easy! I was giggling of happiness to see the pistons and how they go up and down.
No, I had never seen pistons in my whole life, before this!
At that point, I thought that was it. Dad said nothing seemed broken so clean and rebuilt and be one step closer to riding my bike!
For those, I didn’t even start cleaning since I knew my brother would put those in his sanding machine and voila! extra clean!
Phase 3: remove the valves
Well, actually my brother had to remove the valves to be able to put the cylinder in the sanding machine. After all was done, he gave me a course on how to put them back. Because I’m not happy when they do things in my back!!!
Phase 4: clean
So here is the result of the cleaning! It’s magical! It makes me wish I could have put the whole bike in the sand and ta da! clean!!
The manifold is less shiny than the cylinders but it’s still a big improvement. Pictures above are before and after.
Phase 4: cry
Why would you cry, you may ask? Of happiness to see all the parts so clean?
Yes, you know me a little by now. But not only…
Unfortunately the valves wiggle and have to be changed. This requires the valves guides to be changed as well and, what seems the worst of all, the valves’ seats have to be adapted. In addition I’ve just found out that the whole cylinder surface may need to be ground down 🙁 Me not happy! Me crying!!
Plus, I’ve been studying a bit. And that’s when I cry the most.
Pistons clearance, piston rings end gap… Darn, I need to look at that carefully. If there are issues, Will I need to rebore the cylinders? Just hone them? Change the pistons? How?! …
Yeah, I realized sanding the cylinders was probably not the best idea.
And cry…. 😉
In conclusion
First, I would say that, taking apart the engine, was far easier than I had imagined. The worst part that can probably happen is that something is stuck or something like the rings brake in the process. I don’t know?
Second, I have to tell you that the inside of the engine is quite fascinating! Well at least to someone as novice as I am. It is smart, precise yet simple. Well I’m starting to find out it isn’t that simple, but conceptually, it seems simple.
So this whole experience has made me realized how much I have learned so far. I come from such a long way, that it’s easy. But of course, the issues we are facing are making me realize how much more I have to learn.
And I’m scared!
I’m scared because I don’t know how to learn these things. Yes there are plenty of info available around and I make the most of it. I can learn all the technicalities but I’ll still don’t know when something goes wrong.
I don’t know how to explain this. For example, my dad is amongst those people who can identify an issue just by the sound. How in hell, can you learn such skill? Experience? Yes of course, but how do you get such experience? I’m not going to rebuilt 50 bikes!
Not sure this makes it clearer. In short, I’m feeling lost and hopeless!
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