Nighthawk 250 to Twinstar Engine Swap?

Koestum

Coast to Coast
Will the '90s Nitghthawk 250 engine swap to the early Twinstars?

They seem to have the same mounting points and I'd be happy to swap an engine and harness to gain the 12volt electrics.

From what I've read the Rebel 250 has the same mounting points but the sprocket has the wrong offset (or something) so the Rebel is a no-go.
 

Rider52

Over 1,000 Posts
I have a 92 Nighthawk sitting here and a spare engine. I'll measure the engine mounting points if that will help. There is a difference between the Rebel and Nighthawk. The swingarms are very different and will not interchange.
 

Rider52

Over 1,000 Posts
The rear engine mounting points are both 3.5 inches wide. They are right at 5.5 inches center to center in vertical distance from each other. They are both 5 inches from the right hand (clutch arm) case side to the mount. The front mounts are 2" wide. The distance between the front and rear top mounts is around 10". The engine is pretty compact. I saw a picture of a bike yesterday built out of extra parts. It had a Rebel 250 engine in a XR500 frame. The Nighthawk engine mounts solidly at the rear but had a cradle in the front that mounts engine to the frame.
 

Koestum

Coast to Coast
Awesome, thanks for that.

Both engines use the same bottom end so the Twinstar also uses the cradle front mount. I'm guessing a swap will likely work out.

I'll check the Twinstar dimensions and report back.
 

Koestum

Coast to Coast
It looks like the Twinstar 185 engine mounts pretty much match your Nighthawk measurements... it's still mounted in the bike but it looks like my crude measuerments are very close to yours Rider52.

I was looking at an early '90s no title 250 Nighthawk for the engine, but since then I found a nearly complete but rough '81 XS1100 with title for $300 that I'll be picking up on Saturday.
 

ex119x

Been Around the Block
The XS1100 engine won't fit in the 185 frame unless you make some spacers and a mounting plate,:D
 

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