After dismantling the Monkey we can now dive deeper into what is needed, which parts are missing, which are faulty, which ones need to be replaced. Or as Shakespear would say: “To replace or not to replace, whether ’tis nobler in the mind to suffer and keep the original or to take arms against a sea of troubles and invest a lot of money into new parts …” I might have mixed up some things though.
Parts to always replace … no or given
What ever parts have a normal wear and tear over time will always be replace when refurbishing what ever bike or car. Having everything already easily accessible there’s no hesitation to do an extented service rather than starter over again after a few weeks or months in usage. The parts to include:
- Engine/gearbox oil and filters
- spark plug(s)
as I’m thinking of replacing the engine as such, this will automatically include these items. Only oil as such has to be added, which is not even a full liter and shouldn’t cost more than 10 €
- air filter
as always: the question of staying with the original filter housing and replace the filter or going for an open aftermarket part – I guess it will depend on the choice for the engine. Anyway, cost’s will be about 10 € for either of which.
- break pads, discs – or as for the Monkey – drums
again the question: just replace the wear and tear or upgrade to disc brakes – at least for the front. Just the pads will be about 30 € for both front and rear in total. May be I should even add the cable for the front brake as it is less than 20 €. Better safe than sorry.
- fork oil where applicable
the Monkey only has a simple spring fork, so no need here. But … there are even upside down forks available on the aftermarket … hmm … Let’s see if budget is left over. A complete fork with disc brakes goes for about 170 €
- chain and sprockets
- ball bearings for swing arm, steering and wheels
- tires and tubes
Let’s have a closer look at the last 3 items:
Chain and sprockets
As far as I could research the original ratio is 12 / 37 with a 420 chain of 78 links. Any tooth more in front (or less on the rear) will result in a higher speed, any tooth less in front (or more on the rear) will give a better acceleration.
To my surprise I found 14 on the front and the given 37 on the rear. The 107cc engine was clearly put in to place for speed. As I consider the full automatic gearbox to bit too sluggish I would have opted for the 12 and may be even 40 or 41 in the back. If you do the maths: 1 tooth in front has about the same effect on the ratio as 3 on the rear sprocket (37 divided by 12 = 3,0833). And as the bend for the chain get’s to narrow with any smaller front sprocket 12 should be the least to go for. So any measure to improve acceleration should be done on the rear sprocket from that point on. To replace or not to replace is no question if you look at the picture:
And once you replace one part of the drive chain, better replace them all. About 35 to 50 €, mainly depending on the brand of the chain, have to be added to the budget.
Bearings for the wheels and the swing arms are standard parts, therefore very easy to source and quite cheap. Not to replace them would be really a missed opportunity as the most cumbersome part is the work on it. Lot’s of stuff has to be dismantled and sometimes axles – esp. the swing arm one, Honda seems to be specialized on this – can be seized up. Or the bushes a such refuse to get out of the frame. Have every thing in handy pieces knocked down already is half the work done.
Both the upper and lower bearing shell of the steering still look good. They just have to be properly protected for the paint job on the frame. The ball bearing as such will come new.
All bearings for steering, swing arm and wheels will sum up to approx. 40 €.
Tires and tubes
Same as for the sprockets: there’s no doubt about the replacement of the tires. I’m not too sure about the DOT number as it is only a two-digit one (normally it should be at least 3 or 4 digits for the production week and year). The best I could think of would be week 2 of 1999 (because of only one digit for production years pre 2000). But what ever – the brittle look of the tire sidewall says loud enough: “Just dump it!”
The replacement will be the original pair of Bridgestone TW2 in 3.50-8″, which come for about 40 – 50 €/pc. Also the tube is a bit special. Not only in size, but to reach the valve properly it has to be in 90°. Just another 10 €/pc.
Things to replace or not to replace in total
Just the spare parts to replace wear and tear sum up to about 250 €, which is a quarter of my estimated budget. All prices stated above are based on sources in Germany, mainly monkey-racing.com and monkeypower.de. If anyone has sources to recommend in Nairobi I’ld be happy to hear about them in the comments below.