250 shifter

Bob Monday · Joined: 21 May 2004 Posts: 91

A friend wants to assemble a shifter just to keep himself in shape for other forms of racing. All he's going to do is run laps, and frankly, he's not much for "maintenance"... even basic stuff. He's also 230#+, so wants more "umph" than a stock 125.

What 4-cycle engines seem to work well on a 125 shifter chassis? We don't want to have to fabricate a lot of parts (motor mounts, J arms, etc.) if we can avoid it. This kart will not be used for any racing, so doesn't have to meet any particular rules.

I have a chassis, so all we need is to put a motor on it. Suggestions, especially if you've done it? If you're speculating, pls say so!

Bob Monday

Ted Long · Joined: 08 Nov 2005 Posts: 29

CR450F!!!!!! Got the oomph and plenty more. Plus its very similar to mounting a 125, so not a whole lot of mods needed.

Larry Andrews · Posted: Thu Nov 24, 2005 9:39 am Post subject:

I'm pretty sure that the guys at PSR have built a mount for the 450. The CRF engines have a big advantage of not needing an external oil tank like the Yamaha 4/S's do. Exhaust might have to be a custom job...probably do-able with a length of flex stainless following the stock headpipe, and a custom bent tube running to a supertrapp on the back bumper.

Brendan Wales · Joined: 28 Nov 2005 Posts: 111

^ He said he DOESN'T want a lot of maintence.

A 450 would be a bad choice in that case.

Danny Lerner · Posted: Thu Dec 01, 2005 5:38 pm Post subject:

Check out the kawasaki ninja thread. I have been doing some research on the topic. The EX250 Anderson combination is slightly faster than cr125s on a long track - from what I have heard so far.

Scroll to the next to last post on the kawasaki thread (should be mine). The link in that post has pictures of the EX250 kart. Tooling will definately need to be done to build this kart. I have searched hi and low for a 4 stroke 250 motor that is reliable and will fit on the kart. This is the only compromise I have seen yet. AND, it IS a compromise because of its size...

If he wants more umph, he should really consider a stock cr250. I don't like 2 strokes because of the maintenance level, and because I have reliability issues with them, but a stock cr250 is about as reliable as 2 strokes can get, and have tons of power. No matter what your friend does, he is going to have to do basic maintenance. There are no real shifter karting specific engines that are even slightly maintenance free.

Danny

Bob Monday · Joined: 21 May 2004 Posts: 91

What's the weakness(es) of the CRF450?

A 4-stroke would have to be less maintenance than a 2-stroke, and easier to fabricate an exhaust system.

Danny Lerner · Posted: Thu Dec 01, 2005 6:34 pm Post subject:

From what I understand, the crf needs somewhat constant valve attention?

Danny

Ted Long · Joined: 08 Nov 2005 Posts: 29

Put your friend on a diet!! lol
I agree with Danny about the cr250, its a good motor and it will go for a while before it needs anything. You won't find a "maintnance free package" anywhere though, so he'll just have to learn to work on whatever he ends up with.

Josh Schultz · Joined: 07 Nov 2004 Posts: 122

How about an XR400? They are air cooled so you don't have to screw with the radiator, very reliable on a bike. They only make 35hp but how much power do you need just to keep in shape for other motorsports?

Bob Monday · Joined: 21 May 2004 Posts: 91

He wants to keep up with me. It's no fun to run "with" someone if they can leave you without notice. I saw a couple 450s sell on ebay last week. Combining that with a fairly stiff CRF chassis I already have would make an affordable toy.

Bob

Danny Lerner · Posted: Sun Dec 04, 2005 4:39 pm Post subject:

Bob Monday · Joined: 21 May 2004 Posts: 91

It would seem that a 2 stroke is going to be a lot more sensitive to pipe and jetting than a 4 stroke. He wants to unload and run some laps, not hunt for the right jet for 45 minutes.

It always seemed like a bad design idea to mix fuel and oil and call it "lubrication". Wink

If anyone runs across a stock 450 that seems affordable, let me know. A totaled bike would probably be ideal as we'd get all the ignition stuff, too.

Bob