1985 ATC 250R Rebuild Nearly Complete....Now....The MOTOR???

[DSW85ATC250R]

So after seventeen years in a trailer I pulled my bone stock 1985 ATC 250R out to get it running again. As the original owner I have only ridden the bike at Galmis so it was still in great shape. The brake mater cylinders needed rebuilding, I flushed the cooling system, changed the oil, and cleaned the varnish out of the tank. Third KICK!!!! Started right up!!! I was having so much fun I decided to put all new plastic on the bike. Then I wanted a new seat cover...decals. I remembered how weak the stock light was so I figured out how to add a battery behind the now plasitcoated headlight so I could add the 10" KC HiLite combo LED. The gold wheels were not doing it for me any more since the 80's were a long time ago I decided to do a set of polished wheels, a mohawk front and the stock tires on polished and a set of shat-trak haulers as well. I added an FMF pipe and silencer before doing any research here. Mistake...I can always spend more...right!!! I then did a set Boyesen Rad Valves. So the stock swinger looked weak so I decided to do a Chrome +6 swing arm from Lonestar. I thought I was done.......WRONG!!! The MOTOR???

Now my dilemma!!! I do not need anything crazy. The motor is a Virgin and I do not think I want to do a bolt on kit. I understand Carlos at BDTM is the man when it comes to motors (Carlos PM me PLEASE)!

1) If I keep the stock Jug can I do a 300cc Sphynx and port work??? What kind of $$$$ am I talking (ballpark)
2) Do I really need to touch the bottom end?
3) For now can I leave the FMF pipe until I step up to a BDTM Wurks setup?
4) Is the Keihin 39MM PWK, New cable and UPP Intake a good fit?
5) Is the ESR Airbox delete / K&N a good option?

What am I missing. I want to keep the bike more on the reliable side but give it that extra punch that it's new looks deserve for the Dunes!

Thank you in advance for your help!!!!

Pics:

[DohcBikes]

Holy crap dude that bike is gorgeous. I'm sure you'll get many engine tips from the smoker guys. My advice for the beast you built there would be GO BIG OR GO HOME.

[Billy Golightly]

Wow, clean clean bike!

You probably want something like a bolt-on 330 kit (New cylinder), with some porting. Probably $7-$800 by the time you're done. Every one rags on the FMF pipe but I have rode and tried a ton of them (not the BDT wurks pipe, but pretty much everything else) and I still love the way the power is distributed on the FMF, its not too peaky, and it has a nice broad high RPM pull that just works for me. If you decide to sell it, PM me

The 39pwk is a great carb, run whatever intake and reed cage you want, I've had good luck porting a stock one before actually (most of mine have that actually, one rad valve). Unless they've released a new model, the ESR airbox delete kit is for the TRX and will not fit on the ATC. You can just run a UNI pod filter with a 65mm opening and clamp onto the back of the carb, it nestles in neatly between the shock and the resivior canister next to the frame.

[DSW85ATC250R]

Holy crap dude that bike is gorgeous. I'm sure you'll get many engine tips from the smoker guys. My advice for the beast you built there would be GO BIG OR GO HOME.

DoHcBikes, thank you so very much for th Kudos!! I love it! G.B.O.G.H. No replacement for displacement.....right!

[yaegerb]

So after seventeen years in a trailer I pulled my bone stock 1985 ATC 250R out to get it running again. As the original owner I have only ridden the bike at Galmis so it was still in great shape. The brake mater cylinders needed rebuilding, I flushed the cooling system, changed the oil, and cleaned the varnish out of the tank. Third KICK!!!! Started right up!!! I was having so much fun I decided to put all new plastic on the bike. Then I wanted a new seat cover...decals. I remembered how weak the stock light was so I figured out how to add a battery behind the now plasitcoated headlight so I could add the 10" KC HiLite combo LED. The gold wheels were not doing it for me any more since the 80's were a long time ago I decided to do a set of polished wheels, a mohawk front and the stock tires on polished and a set of shat-trak haulers as well. I added an FMF pipe and silencer before doing any research here. Mistake...I can always spend more...right!!! I then did a set Boyesen Rad Valves. So the stock swinger looked weak so I decided to do a Chrome +6 swing arm from Lonestar. I thought I was done.......WRONG!!! The MOTOR???

Now my dilemma!!! I do not need anything crazy. The motor is a Virgin and I do not think I want to do a bolt on kit. I understand Carlos at BDTM is the man when it comes to motors (Carlos PM me PLEASE)!

1) If I keep the stock Jug can I do a 300cc Sphynx and port work??? What kind of $$$$ am I talking (ballpark)
2) Do I really need to touch the bottom end?
3) For now can I leave the FMF pipe until I step up to a BDTM Wurks setup?
4) Is the Keihin 39MM PWK, New cable and UPP Intake a good fit?
5) Is the ESR Airbox delete / K&N a good option?

What am I missing. I want to keep the bike more on the reliable side but give it that extra punch that it's new looks deserve for the Dunes!

Thank you in advance for your help!!!!

Pics:

1) BDT has quoted me an approximate price on "my" sphynx package. The whole top end with port work and +4MM crank is approximately 2500. My CC need (More $$) is different than yours and I don't know if you want a +4 crank, so you may be able to take that price down to approx 1800.
2) Na, only if its slipping, not engaging, etc....unless you want to put in a set of yukon gears or update your seals/bearings
3) I agree with Billy, FMF is a good all around pipe. The nice thing about the wurks pipes is that Kenny Robertson and Carlos collaborate and each wurks pipe is made for your application (Thus the high sticker tag). I too would like to have a BDT wurks pipe....saving my pennies.
4) 38 or 39 PWK are great! and can be bored up to 40, 41.5. Personally though, my next carb will be a APT smartcarb.
5) Heard a lot of good things about them, but I don't use one, so nothing to add.

[DSW85ATC250R]

Wow, clean clean bike!

You probably want something like a bolt-on 330 kit (New cylinder), with some porting. Probably $7-$800 by the time you're done. Every one rags on the FMF pipe but I have rode and tried a ton of them (not the BDT wurks pipe, but pretty much everything else) and I still love the way the power is distributed on the FMF, its not too peaky, and it has a nice broad high RPM pull that just works for me. If you decide to sell it, PM me

The 39pwk is a great carb, run whatever intake and reed cage you want, I've had good luck porting a stock one before actually (most of mine have that actually, one rad valve). Unless they've released a new model, the ESR airbox delete kit is for the TRX and will not fit on the ATC. You can just run a UNI pod filter with a 65mm opening and clamp onto the back of the carb, it nestles in neatly between the shock and the resivior canister next to the frame.

Billy thank you for the input....I truly appreciate it. Depending on cost I might take and do the BDTM 261cc David Ham approach that Carlos built. Stock sleeper!!!!

[DSW85ATC250R]

1) BDT has quoted me an approximate price on "my" sphynx package. The whole top end with port work and +4MM crank is approximately 2500. My CC need (More $$) is different than yours and I don't know if you want a +4 crank, so you may be able to take that price down to approx 1800.
2) Na, only if its slipping, not engaging, etc....unless you want to put in a set of yukon gears or update your seals/bearings
3) I agree with Billy, FMF is a good all around pipe. The nice thing about the wurks pipes is that Kenny Robertson and Carlos collaborate and each wurks pipe is made for your application (Thus the high sticker tag). I too would like to have a BDT wurks pipe....saving my pennies.
4) 38 or 39 PWK are great! and can be bored up to 40, 41.5. Personally though, my next carb will be a APT smartcarb.
5) Heard a lot of good things about them, but I don't use one, so nothing to add.

Yaegerb, Thank you for responding and for the input. I like the FMF pipe but unlike you I have no comparison other than stock. I am now thinking about the LED intake. Bigger diameter and larger filter for less restrictive flow than the ESR intake set up. I have not spoken to him but I am seriously considering the setup Carlos at BDTM did for David Ham. 261cc Sleeper with a BDTM Wurks pipe. Dyno of 57HP and 40 Torque.

All depends on cost.

[RIDE-RED 250r]

Just to address one of the component questions in your initial post about using the stock jug for a Sphynx build: Cannot be done. The Sphynx is a whole new top end.

Alot of people have good things to say about a well built OEM cylinder. I cannot comment on it because I have yet to do one. It's on my list of things to do to my second '85. But what I CAN say is being that I own an ESR 350 big bore with good supporting mods on the other '85, it's hard to imagine any OEM cylinder really being able to run with the big bore no matter how it is worked. I'm not saying it's impossible, I do not have the first hand experience to make a statement like that.. What I am saying is it would have to be one heck of a built OEM!

Welcome to 3ww! There are quite a few of us 2-stroke nuts in here, and a fair bit of us have some big bore experience too.

Nice R man! How many people can say they bought their trike brand new these days??!!

[DSW85ATC250R]

Just to address one of the component questions in your initial post about using the stock jug for a Sphynx build: Cannot be done. The Sphynx is a whole new top end.

Alot of people have good things to say about a well built OEM cylinder. I cannot comment on it because I have yet to do one. It's on my list of things to do to my second '85. But what I CAN say is being that I own an ESR 350 big bore with good supporting mods on the other '85, it's hard to imagine any OEM cylinder really being able to run with the big bore no matter how it is worked. I'm not saying it's impossible, I do not have the first hand experience to make a statement like that.. What I am saying is it would have to be one heck of a built OEM!

Welcome to 3ww! There are quite a few of us 2-stroke nuts in here, and a fair bit of us have some big bore experience too.

Nice R man! How many people can say they bought their trike brand new these days??!!

Ride-Red, thank you for the knowledge and feedback! It is greatly appreciated. I am leaning toward Doing a port of the stock jug and cylinder. I keeping hearing great things about what can be done. Seems like a great place to start. The worst that can happen is I go bigger and Bigger and BIGGER.

[aldochina]

your R is lookin slick! the red/blk/polish looks great together. Glad to see you dusting off the old girl and letting her put that grin on your face again after all these years.

[BOB MARLIN]

Anything Sphinx is going to be big bucks, if you go that rout go BIG. If you are just going up to 300 I would just stay with a ported stock cyl. It wont be 300cc but will be just as fast. If you are going big bore jump up to at least the 330, it will give you a better hp and torque combo. If you go with ESR it will be a bunch cheaper than a Sphinx but will also run hotter, ESR cooling is a tad marginal. I don't know if you know David Ham, but I do. He is a big guy, if that BDT 265 hauls ass with him on it you can bet it's making a bunch of HP. I've done quite a bit of business with BDT. I doubt I'll ever meet someone with more experience with the 250R engines than those 3 guys there. The BDT works pipes are a work of art. I have held one in my hand but I have not tried one. The craftsmanship is awsome. But honestly it would ruin the look of your trike. If you care about that. And it looks like you do.

[DSW85ATC250R]

your R is lookin slick! the red/blk/polish looks great together. Glad to see you dusting off the old girl and letting her put that grin on your face again after all these years.

aldochina, Thank you! Had I known it would make me this happy I would have let go of the "Wallet Death Grip" a long time ago. Cant wait to get some real seat time.

[DSW85ATC250R]

Anything Sphinx is going to be big bucks, if you go that rout go BIG. If you are just going up to 300 i would just stay with a ported stock cyl. It wont be 300cc but will be just as fast. If you are going big bore jump up to at least the 330, it give you a better hp and torque combo. If you go with ESR it will be a bunch cheaper than a Sphinx but will also run hotter, ESR cooling is a tad marginal. I don't know if you know David Ham, but I do. He is a big guy, if that BDT 265 hauls ass with him on it you can bet it's making a bunch of HP. I've done quite a bit of business with BDT. I doubt I'll ever meet someone with more experience with the 250R engines than those 3 guys there.

Bob, Thank you so much for the feedback. I am getting a bit nostalgic and would love to go the ported stock cyl. route! I weigh 178 after a 3x3 Animal Style from In-N-Out!!! Now if I could only ride like him!!!

[BOB MARLIN]

If you can imagine Howie Long on a trike, that's Ham!

[BOB MARLIN]

This is what it will look like if you went with the full BDT big bore. It's a tight fit.