Every Swap Dies on One Small Part
Motorcycles are built to their maker's threads and widths, and the moment you fit anything from outside that catalogue — a different mirror, a newer wheel, an aftermarket exhaust, bars from another model — the project stalls on one small machined piece nobody sells. The mirror thread turns the wrong way. The axle is 20 mm and the new hub wants 25. The sensor is M18 and the pipe has no bung at all.
EKINSUN machines those pieces. We make custom motorcycle adapters — threaded, turned and milled conversion parts sized to your exact combination — in stainless, steel, aluminium or titanium, from a sketch, a photo with a caliper, or the two parts posted to us. One piece is a normal order.
If the original part is broken or discontinued and you need it copied outright, that's our motorcycle replacement parts service; this page is for the adapters that join parts never meant to meet.
Adapters We Machine
Mirror thread adapters
Right-to-left hand conversions, M10↔M8, and riser extensions — the correct hand and pitch on each end.
Exhaust & sensor
O2 bungs (M18×1.5), extenders, gauge sender adapters and temperature probe fittings in stainless.
Axle spacers & reducers
Spacers to the exact swingarm gap; reducer sleeves when the new wheel's bearings don't match the axle.
Handlebar & riser
Bar clamp reducers (28.6→22.2 mm), riser adapters and mount plates for a different bar on your top yoke.
Footpeg & control
Peg adapters between mount patterns, shifter and brake linkage spacers for rearsets.
Accessory mounts
Threaded bosses and adapters for luggage, dampers, gauges and cameras where no mount exists.
The Threads Motorcycles Actually Use
Half of motorcycle adapter problems are thread problems. These are the combinations that come up again and again:
| Location | Common threads | The usual catch |
|---|---|---|
| Mirrors | M10×1.25, M8×1.25; Harley 5/16-24 | Right side on many Yamahas (and some Hondas/Kawasakis) is left-hand M10×1.25 — an ordinary adapter unscrews itself |
| O2 / lambda sensor | M18×1.5 | Aftermarket pipes often have no bung; wideband gauges need a second one |
| Spark plug gauge adapters | M10, M12, M14 | Compression testers and CHT senders need the plug thread of your engine |
| Axles | Ø15–25 mm shafts, fine metric axle nuts | Wheel swaps change bearing bore and spacer width at the same time |
| Bars & clamps | 22.2 mm (7/8") vs 28.6 mm (1-1/8") | Fat bars in standard clamps — or the reverse — need machined reducers |
Not sure of the thread or the hand? Photograph the part next to a rule and tell us which way it tightens — we identify the thread from the photo, or from the part itself if you post it. See thread adapters for how the identification works.
Vintage & Discontinued Bikes
On older machines the problem is sharper: the part was only ever sold as an assembly, the assembly is discontinued, and the owner's forum thread ends with "you'll have to get one made". That is precisely the order we like. Send the worn original — even broken — and we measure it, rebuild the drawing at no cost, and machine it in a material at least as good as the original. Whole-part reproduction lives on our motorcycle replacement parts page; see also obsolete & discontinued parts.
Materials
Stainless 304 / 316
Exhaust bungs, fasteners and any adapter that lives in weather and salt.
304 machining →6061 / 7075 aluminium
Spacers, clamps and mounts — light, strong, anodised in the colour you want.
7075 machining →Steel & titanium
Alloy steel for loaded axle parts; titanium where grams and looks both count.
Titanium machining →How to Order Without a Drawing
Show us the two sides
The bike-side thread or bore, and the part that must attach — photos with a caliper reading, or post the parts.
We confirm the geometry
Thread, hand, pitch, lengths and clearances on a free drawing you approve before machining. Order with no CAD →
Machined and shipped
Turned, milled, finished — anodised or polished if you want it — and checked against the drawing. More automotive work →
What to Send for a Fast Quote
- Make, model and year — thread standards often follow the maker
- Photos of both sides of the joint, with one measurement for scale
- Which way the existing thread tightens (for mirror and linkage work)
- Material or finish preference — stainless, black, anodised, polished
- Quantity and delivery country — one piece is fine
Frequently Asked Questions
Yes. Many Yamaha and some Honda/Kawasaki right-side mirror mounts use a left-hand M10×1.25 thread, and most aftermarket mirrors are right-hand M10×1.25 or M8. We machine the adapter with the correct hand and pitch on each end so the mirror tightens the right way and stays tight.
Yes — M18×1.5 is the standard O2 sensor thread, and we machine weld-in bungs, extenders and reducers in stainless, plus adapters for gauge senders and temperature probes in exhaust systems. Tell us the sensor thread and the pipe it must sit in.
That's a large share of what we do. Send the worn or broken part — or the two parts that must join — and we measure it, rebuild the drawing free, and machine the piece. For complete reproduction of discontinued parts, see motorcycle replacement parts.
Yes — axle spacers, reducers and captive collars machined to your axle diameter and the exact width your swingarm or fork gap needs, in aluminium, stainless or steel. A wheel swap between models usually comes down to a pair of these made to measure.
No CAD needed. A photo with a caliper reading, a sketch with the two threads, or the parts themselves in the post — we rebuild the drawing, confirm it with you, then machine. MOQ is one piece.
Get a Motorcycle Adapter Quoted
Bike model + photos of the two sides — that's enough to start. Engineers reply in 24h.
// Qty & price
1 pc
Sample price
Fit your bike first
3–10
Unit price drops
Setup cost shared
10+
Best price
All tiers quoted upfront
- →No distributor — you pay the maker directly
- →CAD saved after first order — reorder anytime at lower unit price