ATC 250RF project under way...Still at it!!!

[SYKO]

Hi there SYKO. Well, heatings is the alternative I'll be using on the next tank. I've already cut one up, hoping to weld it, but with the experience had by 250Rfan and Jason, I'll be heating one very ugly tank I have left and make it work, since there is not much that needed to be cut to make it fit. Do you have any advise for me in this fuel tank heating mod. endeavor? I've never done this before.
BTW, thanks for the suggestion.

TORKER.

just heat it up till the part you want to move is plaiable wear some gloves you can heat the plastic up quite a bit in fact untill its smokin and move it around and have a spray bottle of cold water so you can move it and set it. you can almost turn the outward parts inside out if you heat it enough.

[torker]

That's what I thought.
Thanks Big guy.

TORKER.

[OZQUAD44]

How do the stock 250r radiators compare to the KX250F radiators? I would have thought the 250 two stroke radiators were bigger than the four stroke radiators as it was?

Great project you have got going there. I'm not a real fan of two strokes and I've had nothing but trouble out of my KXT250B motor. Fouling plugs at the worst possible moment, an intermittent high speed miss, and at times the dreaded powerful hookup at completely the wrong moment. I've always wanted to put a four stoke donk into it, but I didn't want to molest the frame too much as 87 Tecates are as rare as rocking horse poo!

The other thing holding back was the power drop. I raced 450 fourstroke quads for a few years and I think going down to a 250 may dampen my enthusiasm a bit. The KXT has heaps of power but its just too much work after getting off a fourstroke quad. I'll be interested to see how your project turns out. If its got a fair bit of stick, I may be hunting for a second hand Kx250F. Good luck.

[torker]

How do the stock 250r radiators compare to the KX250F radiators? I would have thought the 250 two stroke radiators were bigger than the four stroke radiators as it was?

Great project you have got going there. I'm not a real fan of two strokes and I've had nothing but trouble out of my KXT250B motor. Fouling plugs at the worst possible moment, an intermittent high speed miss, and at times the dreaded powerful hookup at completely the wrong moment. I've always wanted to put a four stoke donk into it, but I didn't want to molest the frame too much as 87 Tecates are as rare as rocking horse poo!

The other thing holding back was the power drop. I raced 450 fourstroke quads for a few years and I think going down to a 250 may dampen my enthusiasm a bit. The KXT has heaps of power but its just too much work after getting off a fourstroke quad. I'll be interested to see how your project turns out. If its got a fair bit of stick, I may be hunting for a second hand Kx250F. Good luck.

Check page 3 of this biuld for side by side radiator pics. Those are FLUDYNE, I don't really know about the stock KX rads. They are however bigger than the stockers and I do know for a fact those engines run hot and don't like to be trail ridden. 2 strokes are not bad if done for its intended purpose. Don't try to go trail riding with a drag engine. It will be horrible and will suck.
I'm sure the 250F will not have the get-up and go or torque of the 450's (that's why I'm getting the biggest, heaviest flywheel I can use). Those 450's engines are bigger (and a lot more expensive) and require a lot more fabrication, plus there was a lot of talk of the 250's and nobody doing it. Until now that is!!! And, if you've been reading this, you know the 250f engine is more than 10 pounds lighter than the 250R's !!!!!!!!!!! I'm just going to finsh this and report back to you guys. Still waiting on some parts and the welding. If my friend doesn't show up next saturday I'm going to another friend. But this one will charge me. Everything can't be free. Oh well. Bottom line is...
I WILL GET THIS DONE.
Thanks you and all those that had reply for your good wishes, help and support for this project.

TORKER.

[torker]

Pics??? Let's see it. All of a sudden there's a few 250F's in the works. I think that's pretty cool.
I would be even cooler if we could all make it to TF 2010.
TORKER.

[OZQUAD44]

I absolutely love these 4 stroke conversions. The work some of you boys have put into the 450 Three wheelers is awesome, but I've got to say this conversion has made up my mind.

Just think of this boys. The 1986 and 1987 KXT250 weight was in the vicinity of 280 lbs. Given the weight savings made by modern design and materials of the 250 four-stroke KX250F motor compared to the 86 R motor. It is not unreasonable to suggest that a KX250F motor in a 86/7 T3 chassis will equate to a 270 pound, fully suspended, low centre of gravity, corner carving machine.

Hurry up torker... Two ride reports please... and Make them snappy!

I'm off to look for a doner Bike.


Ahh.... nothing better than killing of a two wheeler to resurrect a three wheeler :-)

[torker]

Guys, there's not much to report. Progress has been slowed due to not having someone to do the welding available. As soon as my good friend (AKA the welder) gets untangled from some problems I'll kidnap him for at least 1 day of welding. The reason: He'll weld everything for free and there's a lot of welding to do. The frame will get some gussets and will be "stitched", just the same way we used to do with the race cars, plus some other miscelaneous welding here and there. Radiators are almost completly done (need some aluminum welding finished), pics will be coming soon. The kickstarter problem is almost done too (waiting for the welder to be finished) and last but certainly not least is the exhaust. I'll be buying that next, but I can't decide between a CRF250R LEXX slip-on or a TRX 450R stock silencer. I'm thinking the LEXX (read, more expensive) I'm almost certain it will need some modding to be fitted. Which it's very OK with me. Pics to come.

TORKER.

[OZQUAD44]

Torker
I think that you may have chosen the best 250 fourstroke out there for this conversion. Heres what the media had to say about the 2005 KX250F motor when it came out:

" On the track, the motor gives an abundance of confidence. The power hits hard off the bottom, pulls hard through a strong midrange to the top-end and revs out well before hitting the rev-limiter. This personality caters to all skill levels; it is super-rider-friendly as it offers healthy roll-on power with minimal clutch required to get the rpm up."

Of all the 250 four stokes, I think this sounds like the most capable to lug around and extra wheel. Its reported to have about 18.1 lb-ft of torque. I'm not sure how that compares to a 350X for example?

[torker]

Torker
I think that you may have chosen the best 250 fourstroke out there for this conversion. Heres what the media had to say about the 2005 KX250F motor when it came out:

" On the track, the motor gives an abundance of confidence. The power hits hard off the bottom, pulls hard through a strong midrange to the top-end and revs out well before hitting the rev-limiter. This personality caters to all skill levels; it is super-rider-friendly as it offers healthy roll-on power with minimal clutch required to get the rpm up."

Of all the 250 four stokes, I think this sounds like the most capable to lug around and extra wheel. Its reported to have about 18.1 lb-ft of torque. I'm not sure how that compares to a 350X for example?

Yes, before i bought the engine I did a ton of research and even suscribed to a few moto X mags. Then I went to my local riding spot and exchanged rides on my old ATC 250r for a YZF250, CRF250R, KTM250SX and a KX250F.
Out of all those bikes the KX250F had the best power characteristics. Good thing they were afraid of the trike, none rode it and all let me ride their bikes with total confidence, even tho I knew none of the guys. That tells you, Us, trike riders, command respect!!!
I was lucky enough to find a good, complete 2007 KX250F engine on e-bay for $815, cheap as these engine are in the $1500 range. I then bought a complete bottom end that included the kick start, titanium exhaust header and complete electronics.
The 350X motor has around 27 h.p. and 21 ft/lb of torque -vs- the KX250F 35 h.p. and 18 ft/lb. With the flywheel weight and Lexx slip-on, I read, should pick up around 1.7 h.p. and 3 ft/lb of torque (mainly due to the flywheel effect) across the rev range and also tamming the engines' explosive nature a bit, as well as, and very important, help with the stalling at slow speed / RPM of these motors. There's not much more h.p. to be found on these engines (even if you sink $1000's into them) and the reliability will decrease exponentially, specially the valves.
The 350X engine produces its power and its torque from down low and it's very broad, plus, it will last forever even if not taken care for. Unlike the 250F motors, but that is to be expected. Besides, the 350X engine is more than twice the weight. I'm hoping light weight will help enough to offset the differences a little bit. I'll put it like (to a much lesser degree) comparing a Raptor 660 -vs- a YFZ 450. They both produce great power and torque, but at very different RPM's.
I'll just have to wait and see.

TORKER.

[audioworks04]

Personally I would use the stock trx450r pipe, atleast to start with. The Pipe however is rather large and heavy, buy with the HRC endcap it will flow plenty and not be overly loud. Also it is set up kind of like a flowmaster muffler for a car is, meaning it does not use packing so you will never have to worry about water getting it or having to repack it. It is made out of stainless, so if you have to modify it much you will need a tig or build brackets to bolt to it. Me and Jason both used the stock TRX450R pipe with the HRC endcap on our 450 conversions I love the way mine looks and sounds.

[rdlsz24]

Wow they are getting 35 ponies out of that 250 four-stroke? My wife's cousin has the Suzuki version and I didn't realize it was that fast. That has to be around the same power output (or more) of my KFX 400 quad.

Rob

[250rfan]

This is a real nice project.

keep up the good work.

[torker]

Personally I would use the stock trx450r pipe, atleast to start with. The Pipe however is rather large and heavy, buy with the HRC endcap it will flow plenty and not be overly loud. Also it is set up kind of like a flowmaster muffler for a car is, meaning it does not use packing so you will never have to worry about water getting it or having to repack it. It is made out of stainless, so if you have to modify it much you will need a tig or build brackets to bolt to it. Me and Jason both used the stock TRX450R pipe with the HRC endcap on our 450 conversions I love the way mine looks and sounds.

Thanks, that's exactly the info I was looking for as I also thought about the end cap. I've found a brand new 450R exhaust, cheap. I just have to bid on it! I'm just wondering how it would work with the 250 motor?

TORKER.

[torker]

Wow they are getting 35 ponies out of that 250 four-stroke? My wife's cousin has the Suzuki version and I didn't realize it was that fast. That has to be around the same power output (or more) of my KFX 400 quad.

Rob

Yes, those are the numbers. But, I still don't know how fast, I would not talk about fast just yet. I am hopeful tho. The RMZ engine, depending on the year, was made by Kawasaki (the complete bike was, just as the KFX 400 was made by Suzuki) The KFX can be made to be pretty quick with bolt ons alone, I know from personal experience, trust me. The thing about them is that they are a bit heavy, even if they don't look like it. Very reliable too.
If it's as fast as the KFX I built 3 years ago, it will be fast, no doubt! The trike is about 130 pound lighter than the KFX 400! That should help a bit.

TORKER.

[torker]

This is a real nice project.

keep up the good work.

Thanks for the good words. I too think it will come out very good.

TORKER.