GN400 engine into a GN250 frame???

[bomba]

I was wondering whats involved in fitting a GN400 engine into a GN250 frame. Has anyone heard of this swap being done?

[NighthawkNZ]

I was wondering whats involved in fitting a GN400 engine into a GN250 frame. Has anyone heard of this swap being done?

I have seen it been done before, and as far as I am aware it should be a straight swap (again as far as I can remember)

[scumdog]

I was wondering whats involved in fitting a GN400 engine into a GN250 frame. Has anyone heard of this swap being done?

I dunno but I like your line of thought!

[FROSTY]

There is one BIG issue. As faras I recall the GN400 was kick start and 6 volt electrics.That'llmake some of ya electrics are gonna be messy--cdi etc
Otherwise its just a matter of altering some brackets

[The Lone Rider]

What a great idea.. can this be done with other bikes? Such as the Honda Magnas.. chuck a 750 motor on a 250 ride? Whats some other ones?

[NighthawkNZ]

What a great idea.. can this be done with other bikes?

depends... some can fit straight in... ie; Xj 650 to XJ750 was the same motor just different bore size. Others may fit with a minor alterations new brackets etc, and some with major alterations.

You wouldn't want to be putting a to high power motor into a frame thats not designed to take the stresses and or the sub frame not being able to handle the higher torque and power etc.

[The Lone Rider]

Well I know with some of them each version is the same except the engine size. I think with the Magnas thats the case, although slightly different read-out lay out and such on your bars on the 750

[Bren]

I have seen it done myself too....dont think too much alteration is required...there is currently an XS250 on TM with an XS400 engine....

[The Lone Rider]

I have seen it done myself too....dont think too much alteration is required...there is currently an XS250 on TM with an XS400 engine....

I bet you can guess what I'm thinking for my ride though :P

[xwhatsit]

There is one BIG issue. As faras I recall the GN400 was kick start and 6 volt electrics.That'llmake some of ya electrics are gonna be messy--cdi etc
Otherwise its just a matter of altering some brackets

Would the GN250 alternator drop into the GN400 motor? That would solve it, no?

I thought you'd have to change the CDI anyway, though, although I don't know shit.

[skidMark]

other option with gn's is change the bore piston head etc to dr350....bolts straight on.

[FROSTY]

Anything is POSSIBLE its just a case of is it worth the effort.
Some conversions are easy because of the bikes being basicly the same bike.
CB250/cb400 XS400/250 rd250/350 rz250/350 xj650/750 xv750/1000
z650/750 gsx750/1100 gb400/500
some not so easy

[xwhatsit]

CB250/cb400

Better qualify that with CB250N/CB400N, or T, or any of the Superdream variants, before GiJoe1313 tries to stuff a CB400/4 lump into his Hornet...

CB250RS/XL500/XR500 is something I briefly investigated.

With this one though, the question is why? You won't gain much horsepower (27hp as opposed to the 22hp of the 250), although you'll get an extra 50% torque. I'd imagine a relatively uncommon bike like the GN400 you wouldn't get an engine particularly cheaply.

Just found out that they made a GN400E, just like they made the GN250E -- so I'm assuming that the E, just as with the 250, means it's got an electric start and (presumably) 12V electrics. Look for a 400 with alloy wheels, that's the E model.

Exhaust system could be a pain in the arse; the 400cc engine has a single exhaust port, whereas the 250 engine does that silly one-port-for-one-valve thing so you've got a 2-into-1 system. Frame looks similar though so you might be lucky.

Quite interesting looking at a photo of the first GN400 model (1980). It's quite pretty; wire-spoke wheels like the early 250s, more normal seat, but best of all, it's got low bars. Quite tasty!

[bimotabob]

Hi

Yeh for some reason the GN400 was a complete sales failure, they are very rare here in NZ - infact I dont recall actually ever seeing one.

I wish you all the best finding one - you gonna need it.

Cheers

[koba]

I was wondering whats involved in fitting a GN400 engine into a GN250 frame. Has anyone heard of this swap being done?

Easier to get a gn 400 and swap all the gn250 id bits over, but thats Illegal so don't do it!

[koba]

What a great idea.. can this be done with other bikes? Such as the Honda Magnas.. chuck a 750 motor on a 250 ride? Whats some other ones?

old steel frame GSX-R 250 can fit an impulse (REPULSE!) GSX400 motor.
Needs electrics and everything from 400.
400 doesn't make all that much power but I'm sure It would result in lots more torques!

Ultimate 250 swap is a KLR600 into an NSR frame tho! WeeHeeHeeLies!

I have one for sale, see profile pic.

[Alexofbbulgaria]

other option with gn's is change the bore piston head etc to dr350....bolts straight on.

Hi, my GN250 engine has a terrible rattle and i want to replace it. Instead of replacing it with another GN250 engine i was thinking of doing something like this. Could you please give me a few more details as to the work that will be involved and what parts i need to search for. Does it really bolt straight in or is their a little bit of work needed.

Thanks