Best of NX250 / AX1 / XL250 Degree built

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scrambler
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Registriert: Fr Sep 14, 2012 8:50 am

Re: Best of NX250 / AX1 / XL250 Degree built

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I hope if you read this you will have done a shake down ride and come back with a big smile: D.
To be honest - after I turned off the engine after the first test run, I noticed the smell of gasoline. And wouldn't you know it - the carb was leaking. Looks like I screwed up. Oh well, metabolic end product happens :roll: .
I'm surprised the XL headlamp isn't DOT approved since it was sold in the UK for Orad use, but they have a different deflector
Honda has used these small headlights on many off-road bikes, e.g. also on the CRM250 https://www.cmsnl.com/honda-crm250r-199 ... vGUTudS9_I. But like the XL250 Degree, it was never officially imported to England. I don't know how that was done with the missing DOT. In any case, I couldn't find a DOT headlight even after an intensive search.

CRM250 headlight.jpg
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scrambler
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Re: Best of NX250 / AX1 / XL250 Degree built

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One totally unnecessary carburetor removal later :roll: . The seal in the float chamber had hardened shortly after I overhauled the carb :)

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Add brake fluid and bleed

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No time for bolting on the tank shrouds - enavant to the first test drive. Of course, only across the fields - it still has no road approval.
Nothing drives as easily as a nixie :D

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Voilà - my first NX250 with a rear disc brake. It requires however a lot of force and gets hot - lets see if that can be remedied by cleaning the brake piston.

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jonathan
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Registriert: Fr Sep 13, 2019 12:11 am

Re: Best of NX250 / AX1 / XL250 Degree built

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great to see it finally up and running :D There's always a few teething troubles with a new build but the main thing is it starts, runs and rides OK. I usually throw a load of water on the disc and pads and do a couple of hard stops from low speed, then repeat the process about five times going a bit faster each time. The water stops the pads and rotor from glazing up if either has been replaced. Having said that, if it's running hot it does sound like it's dragging

Looks like you have some fine countryside to do your shakedown :D

I've ordered some rims for my AX1 but there's a five week lead time :( , plus the water pump oil seal and circlip I ordered from honda is on hold as the honda servers have been hijacked, apparently, so its now resting under a dust sheet until further notice :cry:
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scrambler
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Re: Best of NX250 / AX1 / XL250 Degree built

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Yes, everything is taking longer at the moment. If I can help with the spare parts let me know - I owe you a lower chain slider anyway ;) .
Speaking of overdue - finally the special screws for the shrouds have arrived. They are XL250 degree specific parts, M5 with 20mm head and only 5mm long thread. Couldn't find them anywhere until I found similar from the FMX650. On this occasion, I also ordered replacement turn signal glasses and rubber holders for the degree turn signals, as long as they are still available.

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When the brake piston was pushed out, parts of the dust seal were also pressed out - therefore cleaning the brake piston was not enough.

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The grooves of the seals must be cleaned, a lot of dirt collects there - which pushes the dust seal outwards and destroys it. Same problem as with the front brake. Thank god the same brake piston / seals as in the front brake of the NX250 are installed in the rear AX1 brake caliper. The procurement of spare parts was therefore not a problem.

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Off to the next test drive. The brake disc now runs smoothly and does not get hot anymore. However, the braking performance is still insufficient.

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Perhaps the brake pads still have to adapt to the used brake disc. Or the sintered metal gear pads are too hard. Since I am too impatient I have ordered a new EBC brake disc and organic EBC brake pads, let's see if that solves the problem. In any case, my AX1 decelerates much better.

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jonathan
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Re: Best of NX250 / AX1 / XL250 Degree built

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pads are a funny one. I've tried organics on the transalp and they felt like cheese, but they work really well on the CB500 X. The Alp is quite a bit heavier so I reckon this is the reason. The other thing I noticed, on the KTM hub, I think the brake disc is normally on the left so the slots run back to front when fitted on the AX1. Can't see it making a great deal of difference, but you never know. Some KTM discs are just drilled so no directional slots.
If I spot any Degree bits and pieces, I'll let you know
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scrambler
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Re: Best of NX250 / AX1 / XL250 Degree built

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jonathan hat geschrieben: Mo Jul 06, 2020 1:43 am on the KTM hub, I think the brake disc is normally on the left so the slots run back to front when fitted on the AX1. Can't see it making a great deal of difference, but you never know. Some KTM discs are just drilled so no directional slots.

Dang, you are right. How could I overlook that (how can one overlook a mountain - it's huge)? Unfortunately I had already ordered the brake disc - again with asymmetrical slots. At least the new EBC brake disc has a KBA number for the TüV (which the KTM disc didn't have). The first brake pads turned out to be semi-sintered - because that would likely only semi-solve my problem, I ordered pads again - from the UK. I couldn't find the organic ones in Germany.

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On the first test drive, the braking performance was almost zero - again. After a few violent attempts, the performance increased. It's still not great but decent. Possibly I have to buy a disk with symmetric holes. Or what else could be the reason? The brake caliper is overhauled, leaving only the foot brake cylinder that I could also take care of.

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But the test drives were fun anyway ;) Over 100km/h the Nixie got previously quite nervous, so I reduced the sag of the front fork with small additional springs.

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jonathan
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Re: Best of NX250 / AX1 / XL250 Degree built

Beitrag von jonathan »

When I owned a Honda CRF 250L, the front brake (nissin) felt like I was squeezing on a piece of wood. It was a common issue. the brake worked but had zero feel. fitting a stainless braided line made the problem more pronounced. Eventually, I did some research and found a master cylinder with the same volume and stroke (off a Husqvarna/KTM but which had a smaller piston diameter. this was the culprit. have a look at the specs on the cylinder you bought and compare the piston diameter to the stock nissin. Other than that I'd just try breaking the rotor and pads in together doing the old water procedure....when fitting new discs/pads on MTBs I always recommend the owner rides through as many muddy puddles as possible before doing any big descents! I can't imagine the direction of the slots has much effect on braking performance unless it's marginal. It may help to shed a bit of weight and present less surface area to deliver dirt onto the pads off road but I doubt it would make the braking force less efficient if the slots were one way or another. I could be wrong. If I manage find out, I'll post it up. On cars with vented discs the slots are usually in the opposite direction to the way the cooling vanes go, but this doesn't apply to a single leaf disc. If you google 'KTM LC4 rear disc rotor', you'll see all manner of shapes, holes and slot configurations so I think it's primarily aesthetic

If it's any consolation the rear brakes on all the bikes I ever owned have felt more like a drag anchor than a positive stopping device :lol:

the only other thing to check is whether the hose is deteriorated. I friend of mine is a pro Motor mechanic and he told me this tip: if the brakes are are draggy and the disc and pads seem ok, it's usually the hose. they collapse internally, so when you apply the brake the fluid has a hard time returning to the cylinder as the hose contracts. this means that the pistons and pads don't return fully, and your disc runs hot, making the brake less efficient. He had a motorhome in his gargage with this exact problem when he was explaining it. Sure enough, you could feel the hose swell and contract as he pressed and released the brake. Easy job to find out: just grab the hose tightly near the caliper and stand on the brake. always worth a check
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scrambler
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Re: Best of NX250 / AX1 / XL250 Degree built

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jonathan hat geschrieben: Fr Jul 17, 2020 4:37 am Other than that I'd just try breaking the rotor and pads in together doing the old water procedure....when fitting new discs/pads on MTBs I always recommend the owner rides through as many muddy puddles as possible before doing any big descents! I can't imagine the direction of the slots has much effect on braking performance unless it's marginal. It may help to shed a bit of weight and present less surface area to deliver dirt onto the pads off road but I doubt it would make the braking force less efficient if the slots were one way or another. I could be wrong. If I manage find out, I'll post it up. On cars with vented discs the slots are usually in the opposite direction to the way the cooling vanes go, but this doesn't apply to a single leaf disc. If you google 'KTM LC4 rear disc rotor', you'll see all manner of shapes, holes and slot configurations so I think it's primarily aesthetic
I guess so. In the meantime I found out that there were KTMs with chain drive on the left side. The brake discs for these models would also fit on my rear wheel and then the slots would be the right way round. But this is no longer necessary - the brake pads only had to be braked in.

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Now the rear wheel locks with relatively little effort.

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However, the rear Bridgestone AX41 is not amused :)

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Luckily - since I have to have the disc brake registered, it also has to work perfectly.

After the brake works I will dare - on August 14th I have an appointment with the TüV engineer - keep your fingers crossed that I get an OK for road approval. It will be the most difficult part of the whole built.

In front now a Michelin Anakee Adventure 90/90-21 - a bit more street-oriented than the previous AX41.

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jonathan
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Registriert: Fr Sep 13, 2019 12:11 am

Re: Best of NX250 / AX1 / XL250 Degree built

Beitrag von jonathan »

glad to hear it was 'just' the pads....best to check everything else at the same time. I can't see why a TUV engineer would have a problem with passing a disc brake. They used the same set up on the AX1 and it's essentially the same bike. If it was 100% more braking force than the original I could see why they would be concerned as the front and rear brakes are out of balance, but on a lightweight, low powered trail bike it's always easier to lock the back up than the front anyway. Fingers crossed you get a clean bill of health, next week. Otherwise, I'd be putting a letter together explaining the circumstances, your mechanical background and history, with reference to the AX1.

It's certainly looking the part now. with the shrouds back on :D

I'm still waiting on some rims to come through. The company that supplies them is based in Italy and they only do gold anodizing in batches, hence the delay. I put the original wheels back on loosely, just so I can roll it around the garage to make some space., but at least she is now off the stand and looking like a bike again.
Staubteufelchen
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Registriert: So Jun 14, 2020 4:03 pm

Re: Best of NX250 / AX1 / XL250 Degree built

Beitrag von Staubteufelchen »

Hi Michael,

could you please post the spare part numbers for the turn signal glasses and rubber holders => it looks, as if they are identical to the xlr200r.

Thanks in advance, Andreas
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