[secretariat]

Hi, new member here.
I am wondering if anyone has replaced the RE GT 535 engine with 4 or 2 strokes, looking to build a track bike with improved engine performance. Experiences? dos? do nots?
Thank you!

[gizzo]

Haven't had to do it yet but if the time comes my plan is to swap out for a Suzuki LS650 or DR650 engine.  I had a Savage a while back and measured up to see if it'll fit. Looks like no worries and that being the case, the DR mill ought to fit, too.

Welcome aboard.

[UncleBuck82]

I've have thoughts about the XS650, which is pretty close to the right size.

Someone did it for an earlier Bullet

[gizzo]

That's a GOOD idea. 

[GlennF]

https://www.youtube.com/watch?v=0l0Inn1YmGE

[gizzo]

Nice. Too bad the XS650 is almost unaffordable now. I just saw a Himalayan with a KTM RC390 transplant. That's a big power increase. Too bad it's a sucky engine with no grunt and sounds like a Briggs & Stratton.

[ace.cafe]

Nice. Too bad the XS650 is almost unaffordable now. I just saw a Himalayan with a KTM RC390 transplant. That's a big power increase. Too bad it's a sucky engine with no grunt and sounds like a Briggs & Stratton.

At the risk of sounding self-serving, there are mods for the GT535(from 3 different sources, not just me) which can provide peak hp about the same as a KTM 390 Duke and still offer plenty of torquey grunt down low.

The reason that these smaller displacement lumps are weak down low is because they have inherently lower torque from their smaller displacement. They get their higher hp figures by revving that smaller tq to higher rpms, where the smaller tq gets multiplied by enough rpms to be strong in the upper revs.

Hp = tq x rpm/5252.
Simple as that. If you have low tq, just rev it to the moon to get your hp.

However, this is why people lament that kind of power curve as "no grunt".

The 535 has some grunt from tq, but it needs some revs for more hp. That's what we modders are giving it.

It doesn't need an engine swap.

[KC1961]

I'm happy with my bike as is, but I always thought that an air-cooled Rotax 600 as was fitted to my CCM 604e would have been a good transplant for our bikes. And the chain is on the same side, might make it a bit easier. Possibly might even vibrate as much if not more than the RE lump too!

[gizzo]

I hear you,  ace.  But sometimes engine swaps are just for fun.  Like my mate who put the T500 Titan engine in the monkey bike, the other one who did a LS1 swapin his Nissan Sylvia or my old VT250 with a XL500 lump.
I will only consider it if the 535 destructs. I don't have much faith in RE being able to supply parts and it might work out less expensive. I'm mostly content with the power for now.
A friend rides a rc390. She thinks it's awesome but I loath that engine. It's a single, but no thumper.

[ace.cafe]

I hear you,  ace.  But sometimes engine swaps are just for fun.  Like my mate who put the T500 Titan engine in the monkey bike, the other one who did a LS1 swapin his Nissan Sylvia or my old VT250 with a XL500 lump.
I will only consider it if the 535 destructs. I don't have much faith in RE being able to supply parts and it might work out less expensive. I'm mostly content with the power for now.
A friend rides a rc390. She thinks it's awesome but I loath that engine. It's a single, but no thumper.

How about the Kawi 650 twin that they are using in this Paton?
https://www.bennetts.co.uk/bikesocial/news-and-views/news/archive/2014/february/patons-kawasaki-650-street-legal-racer

[gizzo]

I'd ride that! It's good that the engine is hidden away though. It's not a good looking engine. E-R 6 is a commuter, but there's a guy here racing one and he's ridiculously fast on it.

[Bert Remington]

gizzo -- this is what you go with an LS (https://www.flyinmiata.com/V8/turnkey.php).  I almost went down this path but I bought a neighbor's Integra so he could visit his sick mother.  Huge huge mistake.  I would have been better off just giving him the money without taking the car.  On the other hand, that V8 Miata would have been fatal to my drivers license.

A Flyin' Miata story: as I was setting up for a 100mph T1 at Thunderhill, I checked my mirrors and I saw this small Blue-Red thing a half-mile back.  As I was proceeding with classic line at T2 that Blue-Red thing, all wings, flew by me on the inside.  I visited them later -- they were running the Miata I4.  Engineering and workmanship were outstanding. What they say they can do -- they can do.

[gizzo]

That's cool. But I would rather this:
https://en.m.wikipedia.org/wiki/Giocattolo
There's one in our local motoring museum.

[GlennF]

gizzo -- this is what you go with an LS (https://www.flyinmiata.com/V8/turnkey.php).  I almost went down this path but I bought a neighbor's Integra so he could visit his sick mother.  Huge huge mistake.  I would have been better off just giving him the money without taking the car.  On the other hand, that V8 Miata would have been fatal to my drivers license.

A Flyin' Miata story: as I was setting up for a 100mph T1 at Thunderhill, I checked my mirrors and I saw this small Blue-Red thing a half-mile back.  As I was proceeding with classic line at T2 that Blue-Red thing, all wings, flew by me on the inside.  I visited them later -- they were running the Miata I4.  Engineering and workmanship were outstanding. What they say they can do -- they can do.

The standard go-fast Miata mod here is a cosworth blower kit:

https://www.mx5mania.com.au/Cosworth-Supercharger-Kit-NC-2006-2014

They had a lot of early teething issues and blown engines but it all seem well sorted these days.

[Bert Remington]

Yep that'll get the job done.  Very tidy like a factory option.  Much less intrusive than an LS.  But I'm still an NA guy.