KRR150 - 68mm racing block for 200cc

[Smithson]

My mate had a KR250 back in the 80s, a real beast it was. I've always been interested in the KRs. It's nice to see them return to popularity, shows the benefits of 2 strokes -  you don't see the older 4 stroke 150s getting round much.

 

There's a racing block that can be bought for around 4k (I think), this is 68mm, which makes it bore x stroke 68mm x 54.4, which is similar to the KDX200 (66.0 x 58.0 mm) and makes it 200cc. I used to own a KDX220, but the 200 got better reviews, it had a great engine a great engine. The KR is based on the KX125 engine, both bikes share parts with the KDX200 (which may also have been based on the KX125).

 

Service Honda puts a KDX engine in a KXF frame  and sells it for $12k. The new 4 stroke motocrosses are difficult work on, so there are chassis around. Would be an interesting project, a KR200 engine in a modern dirt bike frame.

 

What would be possible disadvantages? Any thoughts?

[Kwasaki]

1 hour ago, Smithson said:

What would be possible disadvantages? Any thoughts?

If you want power why mess with silly little 2 strokes engines with wam bam stupid little surge of speed power when you can have a full on continuous power from a 4 stroke.

Don't you think motogp would be racing 2 stokes if they were better than 4 stoke.

[BenDeCosta]

37 minutes ago, Kwasaki said:

 Don't you think motogp would be racing 2 stokes if they were better than 4 stoke.

 

 

I'm sure you know this but 2-strokes make a lot more power per cc than a 4-stroke, with the obvious downside of requiring more maintenance and the hassle of having to add oil to the gasoline. 

 

Considering the condition of Thai roads and the way that Thai people drive, you should just get a Honda Wave and be done with it. I'd never drive a litre sportsbike here, I'm pretty sure that I would be dead within a year or two.

 

I had a 400cc 2-stroke Italian off-road bike in the UK, I spent more time fixing the thing than riding it.

Edited May 31, 2021 by BenDeCosta

[Smithson]

35 minutes ago, Kwasaki said:

Don't you think motogp would be racing 2 stokes if they were better than 4 stoke.

They used to be 2T 500cc. The 2T engines are light, powerful and easy to work on, but they blow smoke. 

[In the jungle]

1 hour ago, Kwasaki said:

If you want power why mess with silly little 2 strokes engines with wam bam stupid little surge of speed power when you can have a full on continuous power from a 4 stroke.

Don't you think motogp would be racing 2 stokes if they were better than 4 stoke.

 

2 strokes don't race in MotoGP because they are banned.  Manufacturers switched to 4 strokes because they were compelled to.

 

That said I accept that a 4 stroke is a better choice than a high performance 2 stroke for road use.

[canthai55]

Know which I would rather ride - dirt or street

[Kwasaki]

2 hours ago, BenDeCosta said:

I'm sure you know this but 2-strokes make a lot more power per cc than a 4-stroke, with the obvious downside of requiring more maintenance and the hassle of having to add oil to the gasoline. 

 

Considering the condition of Thai roads and the way that Thai people drive, you should just get a Honda Wave and be done with it. I'd never drive a litre sportsbike here, I'm pretty sure that I would be dead within a year or two.

 

I had a 400cc 2-stroke Italian off-road bike in the UK, I spent more time fixing the thing than riding it.

Fair call buddy 2T's had a great day, I did use to fix em for my son using them in Minimoto and later Motocross.

4T Technology caught up on them thats all.

My Honda Fireblade serves me with what I like acceleration and speed.

In my time riding here I have found Thailand safer than riding in UK.

 

 

Polini 49cc race 2T.

 

First pix my son 2T Motocross bike.

[Kwasaki]

2 hours ago, Smithson said:

They used to be 2T 500cc. The 2T engines are light, powerful and easy to work on, but they blow smoke. 

Yeah MotoGP and the animal 2T's bikes but not my thing but watched Mick Doohan many a time, such a skilled rider.

My favorite was the Honda RC 900's that retired the 2T 500's.

 

The RC211V a rare thing of beauty.

[Kwasaki]

1 hour ago, In the jungle said:

2 strokes don't race in MotoGP because they are banned.  Manufacturers switched to 4 strokes because they were compelled to.

 

That said I accept that a 4 stroke is a better choice than a high performance 2 stroke for road use.

They weren't exactly banned in 2002 in fact the 500 cc two-stroke or 990 cc four-stroke bikes were specified to race in MotoGP.

 

 

[Kwasaki]

1 hour ago, canthai55 said:

Know which I would rather ride - dirt or street

 

I know what I luv to ride road or track. ????

I'd dump that ugly exhaust though and convert to an underseat one like the 2004 to 2007 models..

 

 

[Damrongsak]

Honda NSR500 was a beast.  Mick Doohan won 5 world championships in a row, 1994 - 1998. 

 

[VocalNeal]

Top Enduro riders still use two-strokes like 300 Husqvarna. Horror of horrors they are fuel injected.

Why? Because they are lighter and run cooler than 4 strokes.

 

I looked but didn't find a 68mm Kawasaki piston.

Edited June 1, 2021 by VocalNeal

[Smithson]

55 minutes ago, VocalNeal said:

I looked but didn't find a 68mm Kawasaki piston.

Here it is, not sure of availability here though. https://shopee.com.my/Zx150-kr150-rr150-RACING-BLOCK-59MM-68MM-i.48210694.1765141824

 

It's strange it isn't talked about more, 200cc is a decent size engine for a 2T. As time gones on there will be more rolling chassis for dirt bikes because the 4 strokes are too complicated and prone to blow up or be ruined by a bad mechanic. I remember a KXF rolling chassis going for B45k. Here's the KDX motor in a KXF chassis.

[Kwasaki]

1 hour ago, Smithson said:

As time gones on there will be more rolling chassis for dirt bikes because the 4 strokes are too complicated and prone to blow up or be ruined by a bad mechanic. 

That's nonsense if you look after them the bike engine yourself.

Why is there a CRF400 crossers if 4T's are no good. 

[Smithson]

27 minutes ago, Kwasaki said:

That's nonsense if you look after them the bike engine yourself.

Why is there a CRF400 crossers if 4T's are no good. 

There's superbike tech in powerful modern 4 strokes, which doesn't like dust. I'm not much of a mechanic, but those who are claim they need a lot more knowledge and money to maintain than 2 strokes, which are much simpler.

 

The Mx 450s compete in the same class as 2T 250s would if they were still competitive. The 4T MXers are now much faster, plus less gear changes, which makes for easier riding. If you look at hard enduro the top guys are mainly on 2Ts, which are fuel injected for less smoke.

 

You may remember the cbr150 that were very common ten or so years ago? You see very few these days but the kr is still very common.

Edited June 1, 2021 by Smithson

[papa al]

1 hour ago, Smithson said:

 

You may remember the cbr150 that were very common ten or so years ago? You see very few these days but the kr is still very common.

cbr150 is still a very common street bike

the exact opposite of a dirt bike.

 

 

 

[In the jungle]

19 hours ago, Kwasaki said:

They weren't exactly banned in 2002 in fact the 500 cc two-stroke or 990 cc four-stroke bikes were specified to race in MotoGP.

 

 

Your memory of the detail is better than mine.  What I should have said was that two strokes were rendered uncompetitive by a rules change.

 

I think a two stroke 500 won one race in the season where they competed against the 990cc four strokes.  But on most circuits that season the four strokes just romped away in a straight line.

 

 

[VocalNeal]

Found a 180 kit for a KLX150.

[Smithson]

1 hour ago, VocalNeal said:

Found a 180 kit for a KLX150.

That would probably push the hp into double digits.