FurryOnTheInside's first build: The Night Fur(r)y

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Like the name? :cool: Night Furry hehehe! pronounced "Night Fury", after the dragon species from the movie How To Train Your Dragon. It's characteristics are lightning speed, deadly stealth, awesome firepower, and an appetite for fresh fish! :D
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Anyway I actually wanted to start a build thread after the first engine start so it's a running bike first.. but never mind. :oops:

I mainly built this single speed Night Furry (motorised Specialized Sirrus 2012) because I thought this will be a faster way to get a running bike before summer ends. Far too late for that now but never mind. :oops:
I wanted to have two motorised bikes anyway. I'll always be riding solo if I don't build two bikes, haha. :rolleyes:

The Sirrus has been a touring bicycle work in progress for a while. I was fitting it with a more aerodynamic cargo system, trying to improve on the typical square shaped panniers and bar bag, to help with the headwinds I face on the coast. I wanted to have room for the things I need during the ride, and a modular system so I can just carry some of the bags when I only need certain items. I wanted plenty of room in the handlebar bag for my things. This is as far as I had got with that idea
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However I had stuck with the stem and bars that came with the bike, the straight fork, V brakes and the 32 spoke wheels.
I have been carrying more and more stuff on cycling trips. I wanted easier/better equipped camping, fishing and snorkeling but weight had become a problem already. Then the bulk became a problem, too.
Then I added a single wheel trailer for the bulk, and that increased the weight even more.
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All the water, food and stove fuel, clothing and personal comforts needed for the journey was growing exponentially as the weight slowed me. Trips to the nice places were taking too long and leaving me too saddle sore. :(
This bike needed an engine!

So this build is intended for long distance, up to 80 miles, but further than that when it has proved itself. :)
It needs to be pedallable if it isn't possible to fix on the road.

It has to carry shore fishing rods and rod rests along the top tube, which is why the rear rack is so high up.
I will try to carry all of my fishing equipment on the bike, so that I can camp in one place and make little trips out to the surrounding areas without always bringing the trailer with me. :)

So yeah that's basically what the bike is for and why it is this type of build on a so-called "hybrid" bicycle.


For the motorisation I have upgraded the wheels and the fork using the parts left over from the Dawes Galaxy Cross, and I have upgraded the brakes to hydraulics which I bought used on fleaBay.
I just got the front brake working without dragging on the caliper body (it wasn't meant to take a 220mm rotor!) by removing some material from the caliper body.
I also put better cranks/chainset on it, I have bigger chainrings again since I will be going faster.
Used different pedals too, because I want to keep the Shimano Saints for the D.G.C. mountain bike style build, but these are still awesome with their two sealed cartridge bearings per pedal and with replaceable steel pins.

I have tried to make it a stealthy bike by using the noise moderation techniques that are mentioned in the forum. I probably have some more work to do there.

I have been trying to build a reliable drivetrain too. I hope I have done a good job.

I have added a better head for cooling and reliability, and made a "head steady" to relieve the stress on the two lower engine mounts.
I have done some crank balancing work, done some port widening but no changes to port timing, retarded the ignition timing, improved the air filter and lengthened the intake.

I didn't want to use the rag joint sprocket mount but the top hat adapters are expensive to get shipped overseas. So I made my own double sprocket mount for standard mountain bike chainrings.
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I got the single speed drivetrain set up without burning my bridges so I will test it like this, and then look into setting up the two speed system later.


I took the bike out once and couldn't get a spark. It has an upgraded spark plug wire, NGK boot and NGK iridium plug but I managed to break the thin wire coming out of the CDI. I'm 99% sure the problem is fixed now but I can't try out it due to a recent injury.

I had to fix a leak from around the fuel tank nipple when I found fuel actually dripping from it.

I have to fix some other faults I found during my first outing before I can get it out again anyway:

The plastic front fender keeps touching the tyre and dragging noisily (when will they invent lightweight plastic fenders that actually stay straight?)
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The chain is never going to be quiet without a toothed tensioner pulley; but I needed to try out this "double" tensioner in readiness for my attempt at making a two speed shaftless shifter.

I should have got around to shortening the idle screw on the carburetor, it does catch on my trouser leg as predicted. I'll get to that soon.
The >29" wide handlebars are going to take some getting used to. I hope the width proves useful when I actually load the bike up with some heavy cargo for a camping & fishing expedition.
My inverted gripshifter was confusing me on my first ride. I'll have to relearn which way to twist. At least I was pleasantly surprised with the front and rear gears' function having never tried this particular combination of components before (except when I tested indoors on the trainer).
I have a better rear derailleur on the way: 9 speed Shimano SLX (shadow) so I'll have to change that sometime soon, although the Acera I have is working.
Oh, and it still needs the new updated handlebar bag and side panniers.. And some good bright headlamps preferably with a bit of a bluish tint!
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Second test ride today! :D

I loaded up the Night Furry with a moderate/ half load of fishing gear and supplies for an afternoon of flinging the tinsel at the mackerel. :)


Only went about the same distance as the first test ride. I knew I could get there and back easily on one litre of fuel. It was again a sunny day after a storm so the paths were a bit busy. I did plenty of pedalling with the engine turned off. I love how well it pedals! It's even better when I get a boost up to speed using the engine haha. I loved it, and the bikey loved it. I'm enjoying exercise which is so not normal for me lol. I think it's pretty cool. :cool:


The engine handled the increased load very well. I noticed it isn't 4-stroking at full throttle very much at all, I think it may be tuned too well for breaking in. o_O
The short steep hills slowed the bike a bit more this time. That's understandable. It still gave me a huge grin going up those little very steep hills without dropping down to the smallest front chainring. :D
It sounds cleaner on the steep uphills than flat ground, but as I said it barely 4-stroked at full throttle today anyway.

I kept the RPM lower on average today, using mostly 1/4-3/4 throttle (the needle), but I gave it one little speed test on the way home. Only one quick test and I backed off before the bike had stopped accelerating. 6500 RPM, calculated as 30mph. I'm happy with that. :)

The engine did seem to sound slightly louder today. I don't know if that was just how I perceived it, or an actual thing. Is it possible that the engine really is louder since beginning the break in? o_O
I definitely want to get around to making a shroud around the air filter. It should be a priority now. :oops:


I received the third triangle frame bag this morning just as I was about to leave. I need to lengthen the bottom Velcro strap but it is a good fit for the front of the frame. I think the bags do a good job of utilising the space around the engine without getting in the way of air flow. Not bad for a cheap set of bags anyway and I think they look pretty cool too, not that that matters lol. :)
 
Third test ride today! :D

Stealth on the seafront (again). :cool:

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I had a brief chance to go fishing again before the rain comes back and before the temperature drops, so headed out again with my beautiful Night Furry. Carrying a half load of cargo again, just enough stuff for an enjoyable afternoon of fishing on the seafront. :)
There was a bit of a headwind on the way out, just like the first ride. The bike loved it. Pulled well and sounded a little smoother with the added load on the engine. I pedalled basically all the time anyway because I like it and it feels unnatural to not pedal! :oops:

I have to use the bicycle cover to keep the salty sea spray off the bike when I'm fishing but I am glad I have it for stealth purposes too. There was a bit of splashing of the waves on the seafront wall, and there was a dreaded PCSO walked right past me; but neither could find a way to harm my beloved Night Furry. :p

On the way home the wind had dropped considerably, but I still managed to get a new top speed so far, and I am very happy with it! :D
8000 RPM (calculated as 37.27mph) while pedalling in my top gear 52:11 :cool:
Then I had to shut off because I ran out of path. :eek: Very nearly didn't make the corner haha. :oops:
RPM climbed quickly up until about 7.7k and then it was increasing a bit slower but I know 8k was not the top speed. I wasn't even tucked, just leaned into the wind and pedalling.
I know that I shouldn't push the RPM so much just yet but omg it's so fun! :D

Anyway I am mostly keeping the engine in the 4.5k to 5.5k range and using the needle where it's a bit more 4-strokey. I could hear the uneven spluttery sound even at wide open throttle on the way home. It only clears up a bit on steep hills. I should probably pedal less so the engine gets to do more of the work, but that's not my natural/habitual riding style. :oops:
At least I'm getting used to the inverted gripshifter now. :)

Oh and the right fish species (tasty ones) weren't hungry so I didn't bring home anything to put on my toast, but I still had a great day out in the sunshine with my bikey. :cool:
 
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Fourth test ride. :)

I tried something different this time, resisting the urge to pedal and letting the engine bear the full load to get the rings seated (like I should have been doing all along, lol).
Using lower RPM than ever, trying to keep it below 5.5k as much of the time as possible and pedalling as little as possible, I found out just how bad the acceleration is below 4.5k.

I tried to find the lowest limit of RPM. The engine will just about keep turning at 3250 RPM (15mph). It won't keep turning over lower than this without being helped by my pedalling. The 4-stroking is awful at this sort of speed "blub blub blub" and produces very little power; but with a little help from the pedals it can get back up to a smoother RPM and start pulling again quite quickly.

Hopefully, when break in is finished and I lower the needle to its lowest setting in the clip, the engine will perform better at very low RPM. :)
 
Furry:
You really do get it don't you!. I love the way you've made your bike so useful and practical, and that you care enough to be careful with the break-in. - - Especially when it's so damn temping to give it the beans.
 
Furry:
You really do get it don't you!. I love the way you've made your bike so useful and practical, and that you care enough to be careful with the break-in. - - Especially when it's so damn temping to give it the beans.
Thanks! :)
Haha I certainly hope I am doing justice to the great wealth of information, knowledge, experience and sound advice I have been given on this forum. :)

I wanted a bike that can do long distances reliably and comfortably, and I think I will have that! :)
I'm just so looking forward to next summer, when I can take the bike out on some real adventures, to some much nicer places that are impractical to get to/from under pedal power alone (especially with the amount of camping, fishing and snorkeling equipment I like to carry!).

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It looks like I'm going to have to cover up the sweet looking engine though.
For stealth looks and sound I am going to start working on a cover made from Teflon oven protector, some aluminised bubble wrap and 2mm correx board. Air filter first and then something at the sides of the cylinder. I'm hoping to reduce noise but keep the airflow.. we'll see how it works out. :)
I must be responsible to our sport by not being a noisy nuisance, and be respectful to the public who just want to use the bike paths to have a nice peaceful pedal around on a sunny day. :)
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Still, the moments when I do get to give it the beans are really quite a thrill. 37mph+ isn't too bad for a four-strokingly rich, not even broken in, eBay generic no-name engine, pushing my heavy butt and a pair of rear panniers. :D
 
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