How To Train Your Night Furry

FurryOnTheInside's first build, part deux:
Dawn Of A New Error

There was me thinking I would be working on the second build shifter mountain bike by now haha. I'm just getting the Night Furry tuned up to hopefully take it on a proper long distance trip. I can hear the beaches calling me from the west.
I have collected a few parts to hopefully improve the performance and reliability of the Night Furry (touring MB) while it was winter and while I was busy with boring non bike stuff. I have started getting the bike together again in the last week or two, though.
So here's a few of the things I have been working on..

Firstly I needed to upgrade my front brake. Awesome stopping power just wasn't enough. I needed a black lever and caliper haha. No but seriously, I wanted a similar shape lever to the rear brake, so I got this Magura MT2 which is not too dissimilar to the Magura HS33 rear lever.
View media item 61342And the caliper is quite nice too. A bit chunky perhaps but seems to be good quality. I fitted it to the adapter that I had previously had to cut down for the Shimano Deore caliper to fit properly with the 220mm Hope rotor. The MT2 is different though so I needed washers to get it spaced out enough.
View media item 61311I thought I might as well buy a new adapter, that hasn't been cut down, so I won't need the washers. But then I checked how wide the pads actually are and the MT2 has a wider pad surface, needs a wider brake track on the rotor than the Deore, so I had to get a new rotor too. Not that it wouldn't have worked, but it's best to do things correctly. :)
So I got this Hope rotor that is newer and wider, but it is also a floating rotor and slightly larger diameter at 225mm
View media item 61319It really is quite huge. I'm used to seeing the 220 now so it looks normal to me but everything else looks puny!
View media item 61313
So that's brakes sorted, next thing is I got a new narrower handlebar because I really wasn't getting used to the 720mm mountain bike bar. The new one is 610mm but it still has room for all my controls, just doesn't have a load of unused space and I can put my hands more under my shoulders so I am more comfortable on the bike for long periods of time, which is what this build is all about after all.
I really need to have music when I'm riding for hours, too. A bit of kickass neuro or some thumping goa to smother the engine noise lol. :p There was room for my little 10W Bluetooth stereo speaker with a "handlebar extension" to support it. I could add lights to that extension too if I don't put them elsewhere.
View media item 61318
I want to be able to choose/ change to the best gear ratio while I'm out on the road, and so I need to have multiple sprockets mounted together on the left side and some kind of system for chain tensioning that will allow bump starting. I have not got that up and running yet but I have made a start..
I saw that there was probably room to squeeze two sprockets in behind the spider that I put behind the rear rotor mount, meaning that I should be able to get the second largest sprocket to line up with the engine output sprocket (10T).
View media item 61314It was tricky getting them to fit.
View media item 61317I had to change the M10 bolts and nuts to proper chainring nuts that are thinner and source some M8x0.75 bolts, then shorten them as there was only one size (40mm) and make some 15mm long 10mm OD spacers. I was able to get these parts all in stainless steel. Took ages to do it neatly.
View media item 61316I did have to use a few shim washers to get the sprocket stack spaced just right, hopefully I will keep them oiled enough to not rust a lot. Most of the washers I used are stainless though, but those only come in 1.25mm which is a bit limiting.
View media item 61334Anyway I managed to get four sprockets mounted. 38T(steel) 40T(Al 6061) 42T(steel) 44T(steel)
There is apparently no steel 40T available in the 104mm BCD standard.
View media item 61331To make the chain bend to all four sprockets (actually three of them probably wouldn't be a problem anyway, the way I've lined it up) meant switching from the 1/8" (#410) bmx single speed chain to a 3/32" multi speed chain. Actually what I chose was the KMC X9-93 which is an even narrower 11/124" nine speed chain.
Such narrow chain means that the front sprocket had to be even thinner, but that gave me the opportunity to grind it on the right hand side again, and thereby move the chain line further left. I had ground it down to 3.2mm (0.120") for the bmx chain. This time I went to 2.2mm with the teeth slightly tapered to 2.0mm to help ensure that they engage smoothly.
View media item 61322In order to do this safely without burning or ripping off fingers I mounted the 10T on a bamboo cane and secured it with a softwood wedge hammered in. This meant I could hold it against the bench grinder and rotate it easily.
This technique was even more helpful for the second stage, though. I put the cane through a hole in my little folding workbench and was able to rotate the cane from underneath the table top with one hand while using the rotary tool with my other hand. Total control and safe too. :)
View media item 61321While I had the sprocket off I relubed the bearing on that side of the clutch shaft (it didn't need it but best to do it now) and took a photo of the epoxy chain retainer I made during the initial build.
View media item 61320
I'll have to see if I can make the four ratios system work with an automatically adjusting tensioner too. It would be quicker to change ratios if I don't need tools or even really touch the tensioner/s at all. I'm hoping this Shimano Zee (Shadow Plus) derailleur will do the trick. As this is Shadow Plus technology it has the one way clutch drag system, meaning the resistance to allowing chain slack is much greater than the tension it applies. Science! :p
View media item 61339
While I was working on the drivetrain I thought I would upgrade the rear derailleur for the pedal chain. Acera is okay, functional but not great, old tech. I had this Shimano SLX Shadow derailleur for a while now. Fitted it to the bike today and I'll dial it in when I have the chains back on.
View media item 61341
Lets see what else am I doing? Okay next is the exhaust muffler. It is nice and quiet with the long soft silicone hose added behind the muffler, but I worry that it adds restriction to the flow of exhaust gasses. So today I cut half an inch off the internal side of the stinger and I drilled the lower baffle in the muffler even more to flow faster. I stuffed a steel scourer inside just so it hopefully isn't any louder. I had already opened the baffle a bit, but this time I went further and drilled five 8mm holes.
View media item 61338View media item 61337
When I took the muffler off the engine the exhaust gasket crumbled and left a rough layer on the exhaust flange and the rest on the cylinder. I was expecting trouble but not quite this.
View media item 61335I'm wondering what to replace it with. Could I just wet it with oil and clamp it back together for now? I expect not.
I have a silicone brownie baking tray, hoping that will work. Idk.
I probably have a spare stock gasket but I would like this problem to not happen again so I'll give the silicone a try.
View media item 61336The other thing was the RED Loctite completely disappeared from the threads of the left stud hole in the cylinder. Somehow. That one is puzzling because I know that I put plenty in the hole and on the stud. I might try the blue when I put it back together but this means I can't trust any of the red loctite I have used on the engine, so I can expect to be pulling out the wrong parts when I unbolt things that have red one end and blue the other, like my exhaust studs did. :/

The only other real change was that I got around to changing the jet size in my NTTC stock carb. I got a Delorto DO style 5mm jet kit from KMT (English company, Swiss machines) in sizes from .65 through to .74 so I have put the .68 in for now. I noticed that the new KMT jets are 1mm shorter than the stock jet, so I have bent the prongs on the carb's needle valve (fuel inlet valve) upwards by 1mm to make up for the difference. I'll be testing soon.
View media item 61323

Well that's it for now. I might take a photo of my temporary air filter box tomorrow. It's super junky, but hopefully will increase my stealth a little bit. :)
 
Last edited:

FurryOnTheInside

Well-Known Member
Joined
Sep 23, 2013
Messages
3,926
I have filled the sprocket cover with about a stick and a half of hot melt glue, then filled up the space around the chain in the case side even closer to the chain. I wrapped the chain with a piece of Teflon coated oven liner which was easily removed (compared to the cereal box!) after the glue had cooled and hardened. The chain should be unable to escape from the drive sprocket now.

I also made a new chain slider very close to the drive sprocket so that the chain feeds onto the sprocket more reliably.
I used some pvc pipe, flared one end slightly with a knife, and attached loosely with a cable tie. I then carefully filled the space between the slider and the support beam with hot melt glue before tightening the cable tie and adding another large cable tie to secure it. Hopefully this will prevent another derailment.
View media item 61366Edit: I just added a second fixed chain slider so now there are three sliders on the top run of chain. I don't actually like the way the RSP is working now. It seems like everything has changed slightly. :rolleyes:
View media item 61367


I'm also trying out the silicone baking tray exhaust gasket when I take the bike out later. I don't want to try to predict the results of that lol, but I have to try stuff out to gain knowledge, right? :D
 
Last edited:

FurryOnTheInside

Well-Known Member
Joined
Sep 23, 2013
Messages
3,926
I just did another scientific test. Some interesting results again. :)

The good news first lol, the silicone baking tray exhaust gasket sealed in all the exhaust gasses. No signs of oily leakage. Although the engine did not get up to full temperature during the short test run.
View media item 61370Unfortunately the double muffled exhaust is no quieter than the one with only the stock muffler lol. All the noise seems like it comes from the exhaust header. I can't tell whether the intake is quietened by the filter box. I just hear the header. I guess I will have to try wrapping it closer to the cylinder.

The results of the drive train test were not particularly encouraging. On the first start attempt at a low speed, the engine started fine but there was a metallic "ping!" as something fell off. I later discovered that was the lower section of one side of the Zee cage. The part that had been flexed out when the chain somehow escaped the cage yesterday.
View media item 61371
View media item 61369The bump start worked though. I bump started a few times at slow speed and then it didn't work and the RSP chain slider has popped out of its mount and was hanging loose on the chain being rattled around.
I can't see exactly how it occurred but the chain was running on the largest sprocket (44T) and somehow the chain got between the sprocket and the spokes during the bump start. The chain bent at least one spoke and knocked the wheel out of true very slightly but that was enough that I had to readjust the rear brake because these Magura HS33 rim brakes run so close.

My conclusions are there is much doubt about the future of the Zee automatic tensioner! I might have to try using two fixed position pulleys and getting the Allen keys out every time I want to switch sprockets. I think I will persist in using the 11/124" chain for a while and see if I can get it reliable.
For now I must retrue my rear wheel and order a mountain bike chain retainer pulley wheel and some more 6082 T6 flat bar. :)
 
Last edited:

Spare_Parts

Well-Known Member
Joined
Nov 29, 2017
Messages
2,017
Think it's time to simplify your chain line. To many points of failure as you have seen. Maybe do one mod at a time.
 

FurryOnTheInside

Well-Known Member
Joined
Sep 23, 2013
Messages
3,926
Think it's time to simplify your chain line. To many points of failure as you have seen. Maybe do one mod at a time.
I'm definitely going to be removing the Zee tomorrow.
I think the whole thing had too much flex, being a derailleur it has too many links.. The B pivot, the parallelogram, and the tensioner, when I really only wanted the tensioner.
If only it was possible to separate that part to use on its own. But then, I think it would really be best if the ratchet and band brake were about twice the size. The Zee was only made to prevent chain slap on mountain bikes, not bump start bloody engines. :rolleyes:
Still, it had to be tried and tested. :)

Pity it didn't hold up, because it means there's zero chance of a bump start left side shifter now. :confused:

Now I get to make a whole new system for tensioning and controlling the chain while allowing me to switch between rear sprockets mid-ride. :D
I thought about using two KMC "missing links" and adding and removing short sections of two/four/six links to keep the chain as straight as possible and not have to move tensioner pulleys at all. But then there would be some links in the chain getting less worn than others, and my "missing links" would wear out too. The Kmc "missing link" doesn't like to be reused over and over again.

So I'll probably just have a second pulley and a few different holes to bolt it to. That's the most practical way I think.
And until the new pulley and alloy flat bar arrive I will just make a single speed on the 42T, like it was last year. :)

Oh and I'm adding some kind of spoke protector because although I enjoyed the experimental stuff (and it was successful in that it improved my understanding of the possibilities and limitations of the avaliable technology), damaging the spokes was really disappointing. :confused:
 
Top