Something to think about.

[Minesbetter86]

Hey guys there is something you need to know, I have previously been looking for a head for my 350X, because the cam runners locked up, and there impossible to find. So i did some searching and guess what? An 81/82 xr500r top end will work on a 350X, the only thing is that a 350x has the oil injected cam runners and this head doesn't, so what I did was get the same thread bolt put alittle thread sealer on it and blocked it off, at the base of the motor. You also must configure a new top motor mount, because this one is set back farther than the 350X's. So pressto A 500X!!! The only thing I did was run good oil in it, since its not an oil injected head, I dont want to mess these cam runners up like in the past, SO, Can you imagine the possibilities of a 500X???? OOPS, i already have, cause I did it, and let me tell you, it scares me. ITS ALMOST UNSAFE!!!

[ATCnut]

Cool, Ive got to save this somewhere so I don't forget

[mudfreak99]

are you saying the xr500 head and vavles worked or the intire cylinder? if it isjust head and valves then it is NOT a 500x, sorry
josh

[250sx]

what we need here are details and PICS.

[Minesbetter86]

Yes I did use the whole top end, including, Piston, cylinder, head, etc. So it does make it a 500X. I guess I should have clarified that for you, SORRY.

[Minesbetter86]

OK,

I have explained everything in the best detail I can. All I can tell you is that its a direct fit, up until you get to the oil injection hole that you must plug, and the motor mount. That is all I know, sorry I have no pics, cause I have no camera. Any questions just ask.:headbang:

[250sx]

we gotta see some pics dude...go rent a digicam from walmart. ;)

I'm not saying I don't believe you...I just wanna see how it looks. :headbang:

[trike250cc]

u can rent cameras??:eek:

[da_catt]

how do you make a 350x into a 500 by just changing the bore. the 500 kit powroll use to sell had a big bore piston and a stroked crank. that kit you had to do major case grinding to get the cylinder to fit. the xr500 cylinder could fit but i am sure the 350x and xr500 do not have the same stroke. that would have to be a big piston.

[Rocketman]

So how does this xr500 top end oil the cam? You say you blocked off the oil passage on the 350x lower end. You are talking about the one for the external metal oil line that runs up to the head. Are you sure you are getting oil up to the top end? If this works I'm surprised it hasn't been done before. Hope it works out long turn for you. :)

[gpracing1]

I would love to see some pics also!!:headbang:

You can rent a digital camera at rent a center for a day or two. ;)

[ATCRYDER]

Thats rather interesting. I see no reason to go out & rent a camera jsut for that, people have imaginations-they can use them. But If you ever acquire one, you know where to post pics. ;)

Rob

[250sx]

you can rent a camera from walmart for free. :rolleyes: :lala: :lala: :lala:

[Minesbetter86]

Well, you guys have beat me down to my socks with questions already, but I posted it and I will answer them. O.K. I always thought that the size of the boar determined the cc of the motor, which the side of the xr500 cylinder says 467cm3, I really had know idea that the stoke had a say in whether it was a 500 or not. The xr cylinder sat right in the case, very snug. I used the stock 350x rod, the xr piston, cylinder, head, cam, rockers, rocker cover, etc. So I dont know what it makes it then, except for
BAD A$$. Also, if you guys didnt know, oil also shoots up through the stud passeges to the head, and also through the cases in the motor. Thats how it is getting its oil to the cam. The 200X is the same way, you dont see no metal line on it do you? That is how it oils its cam runners. So my 350X is doing it that way now. I thought you guys would have knew this stuff??? :thmbsdwn: It hasnt locked up, or started making any funny noises, so I imagine its working good. But thats it for today, anymore questions just ask. Thanks.

Lance:wtf:

[gpracing1]

Wonder how (or what it would be like) that engine that you have there in a 250x or 300ex frame... Hmmm:shocked:

[gpracing1]

Sorry that I can't make a readable sentence.:D

[250sx]

what we need to find out now is what the borexstroke is for a 350x vs an xr500 to find out what size motor you really have. 467 is the actual displacement even though they call it a 500 for marketing sake.

Anyone got the specs?

[Minesbetter86]

Yep, that sounds good 250sx, After all this has been brought up I would actually like to know what size motor Im running. But what im saying is that the swap is a simple process, If you have any mechanic experience at all on trikes, its a breeze. I ripped the complete top end off an 82 XR500R, and bolted it directly to my bottom end, easy as pie. It makes one heck of a difference. Just today I went to my local track, and some dude on a RAPTOR, said my trike was junk. Well my bike might not look the best right now, due to bad plastic, but it is very, very mechanically sound. All his headlights seen was my racing # 69. Compared to my trike, his piped Raptor was a TURD. LOL. Thanks for the response you guys, and if anyone has those specs, post them please.

Lance

[ATCnut]

I did a little research, and found someone that had posted a brochrue for a 83xr500r. It stated that the bore and stroke are 92mm and 75mm. From my 350x brochure its bore and stroke are 81mm and 68 mm. Calculating the xr500r piston (92mm) and the 350X stroke (68 mm) I get that you built a 452 cc machine.

The other thing to note is that the 83 xr500r was 9:1 compression where the 350x is 8.5:1

Sounds like you built a killer machine.

Are you running the 350x carb? if so, how did you jet it?

Or are you running the xr500r dual carbs?

I would love to see pics

****, after reducing the pic size and compression, it is not readable

[Mr. Richard]

wait a minute!!!! 68mm stroke on the 350x and 75mm stroke on the 500 ,,, pin height on the piston don't jive,,,,,

[ATCRYDER]

A moderator Breaking the posting rules! *GASP*

ANyways: You bring up the good info--specs! Now Im interested in what seems like the simplest big bore in the world......

[250sx]

Originally posted by ATCRYDER
A moderator Breaking the posting rules! *GASP*


:doh: :cry: now do I put a donating member on pic probation??? :ugh: :shrug: :yup: :yup: :yup:


Back to the thread...this sounds almost too good to be true. What all years will interchange for this mod?

[ATCRYDER]

Read what Kasey said---he bring sup a very valid point.

Im sure HONDATC (bill) from 3ww has knowledge of all this, he is building the XR pwoered 350X as most know....im sure he weighed this option.

Rob

[Mr. Richard]

ok now my book says that a 79-82 xr500 bore is 89mm stroke is 80mm for 497cc's thats 12 mm longer stroke than a 350x

a 83-84 xr500 bore 92mm stroke is 75mm for 498 cc's

so where do you get 467cc???? so now you have to figure out what the head and cylinder are really off of,and what the bore of the cylinder you are using is,,,, ,,,

[mudfreak99]

correct me if I am wrong but the stroke distance is determined by the piston rod, and crank shaft size. If this is correcet wouldn't he be going down in compression because of the short stroke of the 350 crank???:rolleyes:

[da_catt]

the 350x could be a long rod motor and the xr500 a short rod. this could even out the compression. What are the rod lengths for both engines? it wolud be nice to cc the head and cylinder to find out the compression of this setup.

[ATCnut]

I apologise if the data was not considered "trike related". I thought we were trying to figure out what the motor was in the modified 350x. Dan, if you would put someone else on probabtion for that post, then you have to do me. Rules are rules.

[Minesbetter86]

Ok fellas, your all getting in a huff about abunch of crap. I redid all my info and this is what I found. The boar size on my xr500r cylinder is 88.6mm. I used the 500 flat top piston, which has no vavle reliefs in it. Also 467cm3 was a misprint, the side of my cylinder said 497cm3. Sorry about the confusion. I used the stock, I repeat stock 350X rod. (Note) When in the process of building this machine, I thought of what you guys said, because I new it would be an issue.When I put the cylinder on the bottom end, i turned the motor over to see if the piston came up higher than the cylinder, cause I didnt want to go any farther if it did. The piston came about 1cm from being flush witht the cylinder deck. So you guys read all this, and do some more posting.

P.S. If any of you guys are planning on doing this swap, I am not responsible for anything that gets broke, or damaged. I did this swap and it worked for me, so if someone else does it, and something gets messed up, im not responsible. Thanks

[Unregistered]

there was a guy in portland ore in the early 80,s that did the same thing. he built around 10 of them. they all had single tube swings ( 12"over) chrome frame, swing arm axle ect. sold as a drag trike. he did some thing else to the engine? they where sold as a 550cc. last one i saw was 2yrs ago. ran alcohol, he dropped a valve. sold for 3800 the same day

[Mr. Richard]

we are just very curious becauce this is a real easy big bore swap for the 350x and i have one!!! thats why we want picts,,, i know where there are two xr500's but need to know for sure what year,,,, sorry about all the questions but this is great exciting news here!!!!

[Minesbetter86]

The XR500R topend that I used was an 1982

[350xhilaration]

I'm unfamiliar with the exhaust setup on the XR. does it have 2 pipes coming from head? what about timing chain 350X or XR? Single carb or dual? This might be a cheap project with massive improvements. And still remain reliable. You got some people interested big time... Post as much info about the whole deal as you can. Nobody is gonna try to hold anyone responsible for anything, just great to hear of a different avenue for performance than $1,500 Powroll big bore and stroker kit.

[SpeedBump]

Can you say 500ex QUAD, on the cheap. BTW, i don;t need the top motor mount anyway! :D

[jenndnn3]

We are incredibly interested too!! Showed this to the hubby...there goes my 350x...

[SpeedBump]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1873890075 lmao now the man's engine just got a boost. look at this one too, pipes look real close as well. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=34284&item=1873891435

[350xhilaration]

I just sent an email to Winston "Boss" McKannick at Dirt Wheels asking about this, I wonder if he'll reply?? Hell it might get published:rolleyes:

[Minesbetter86]

The exaust outlet on the XR is the same as a 350X,(Dual). I used the 350x cam gear and timing chain. And the engine I removed the topend from only had a single carb, but I have heard word of these having dual carbs, im thinking about upgrading my already kicka$$ system. As you can see someone has already located an engine. But here is some imporant news, I have got alot of questions about how the cam is getting oil, so as usual I had to go all out and fix this little problem. Heres what i did. I took off my rocker cover, and removed the rockers. Took it down to my local machine shop, and had him drill a 5/16 hole in each one off the cam runners, all the way through the rocker cover. Then I had him tap half of the holes and thread it to fit little brass fittings. These fittings were in the shape of an L one end had threads on it, the other had a nipple for a little hose to slide on. I had him do this to both sides of the rocker cover where the cam rides. Then what I did was unplug the hole at the base of the motor where the origional oil feed came from, and put my line back on. I cut the line at the top off the head about 4 inches from where it bolts on the rocker cover. I then slid a small piece of hose on it and then clamped it with a small clamp. Then I put a Y fitting on it, so it could go from 1 into 2. then ran 2 pieces of hose from the Y to the fittings and clamped them. So now your origional oil line feeds both of the runners just like it did before. Now no worrying about oil control. What do you think of that, am I the man or am I the man?????

[Mr. Richard]

yep you r the man!!! great job we have figured out that your engine is 423cc's thats very kool...

[HondaATC500X]

I have some questions and then I'll post some pictures from MY findings and projects.

Where does the cylinder bolt down onto the 350X case?

How does it fit in the frame?

How does the bottom of the sleeve go into the 350X case?

What carb are you using, what intake boot, and what reed cage?

[84200s/m]

350x doesn't have a reed cage

[HondaATC500X]

I'm very aware of that...I have a pallet full of 350X engine parts. I was asking what reed cage the 500 was using.

[SpeedBump]

why would the 500 use a reed cage? Not being a wisen-a s s, honest question.

[HondaATC500X]

Thats one of Honda's ingenious ideas and no one will believe me but yes, the 500's do have Reeds, and Reed cages even though their 4 strokes. The early 79-80 model used a standard intake setup but the 81-82's did not. Also the 83-84's are a completely different bike. Like going from a 83-85 200X to an 86-87

[Caterpillar]

BUMP

[SpeedBump]

We need more info!!!!!!

[HondaATC500X]

I'll be glad to post some pictures of the XR500 topend on a 350X as soon as I learn how Minesbetter86 did his conversion, I'd like to do it too.

[Minesbetter86]

What do you want to know about the conversion? If you read the whole thing it tells you how to do it. Just go through the whole forum and it will tell you how to do the whole setup. To answer your questions.

Well i imagine the cylinder bolts down the same place the 350X does, it uses the studs, and the two little bolts on the side. Down a the bottom on the clutch side.

It fits in the frame exactly the same, except for the top motor mount. The one on the 500, the top mount usits back alittle farther towards the seat, I made a new one to fit it. I think that the top mount is important, some dont. It keeps the top end from shaking and vibrating so much.

The clinder fit in mine but it might not yours.

I used the 500 Intake boot, carb and reeds.

Thats should do it for you

[HondaATC500X]

I've read the entire thread, its just a few things werent too clear to me.

So the engine still fits in the 350x frame? What about the top of the XR500 carb hitting the bottom of the gas tank since the 350x carb is flat on top? Are you using a thumb or twist throttle? What about the airbox and the airbox boot? Or are you just running a clamp on filter? Does the XR500 exhaust bend right into the 350X silencer? And the cylinder fit right down into the cases right? So pretty much all you had to do is the stuff you mentioned here? Just wondering.

[Minesbetter86]

Yes the engine still fits in the 350X frame, Why wouldnt it?? It almost the same topend. The carb does not hit the gas tank either, if it did would I be running it? I am using the twist throttle off the 500. You read me like a book, I am using a clamp on filter. The 500 carb is bigger on the filter end, and alittle bit longer. Due to the reed housing. I did not ust the 500 exuast. I used the 350X exuast. They are the same. And my exuast is a three piece DG, and it worked fine. Also the deal witht the cases, the 500 cylinder fit in mine, but honestly my bottom end isnt a factory sized one I dont think? My 350X cylinder fit in the case with room to spare, and I know that they normally fit in fairly snug. So im thinking that my cases had some grinding done to them and I didnt know it. It really doesnt look like you have to take all that much off to get the 500 cylinder to fit, if your cases are stock. In all honesty if I was to build another one, I would use the whole 500 motor instead of the top end. It looks like they would pretty much bolt up the same, mabey a few mods.

[ATCnut]

Biggest problem with using the 500 motor whole, is that the kicker goes the wrong way.

[HondaATC500X]

The only reason I asked about the motor still fitting is because the XR500 topend is quite a bit taller then a 350X topend. I asked about the carb because I ran into the problem with my project (complete XR500 engine in a 350X chassis, its not done yet its close but I'm wanting to do suspension upgrades before I run it). I had to raise the gas tank mounts about an inch to run the Kehien PD carb off of the XR. I'm also running a dual cable twist throttle, was just curious on what you were running.

I was wondering about the cases because the outside of a 350X sleeve will fit inside a XR500 cylinder. I was wondering how the OD of the XR sleeve was going down in the case. So your cases have probably been bored in the past.

Also, about the 350X exhaust. I'm running a 350X headpipe on mine but its moddified. The Flanges on the end of each tube where it does into the head (Where it gets larger) was too long for the other flanges to go over the exhaust studs far enough to get a nut on. So I cut the end flange on each pipe where it goes in the head in half and it worked fine. The pipe is very close to hitting the frame, but atleast its in there. Did you have to do this also?


The XR500 doesn't bolt up, by a long shot unfourtantly.. I cut and extended my 350X frame 3 inches and its still in there so tight you almost have to take the gas tank off to change the spark plug. The way I have mine sitting the kick lever lands right on the foot peg where it bolts to frame. Couldn't have put it in a better place.

One last question about the conversion, are the cylinder studs the same diameter or did you have to change those also?

[Unregistered]

Actually I ran into that problem, BUT, I just put a set of longer exuast studs in the motor, that fixed that problem. Yes I did chage the studs on the motor, the 500 topend is taller, so I had to use the longer studs to accomodate the height. you must also use the 500 cam chain. Also, I wouldnt know why your carb hit the tank, mabey just the way you mounted it, but mine did not hit.

[HondaATC500X]

OK, so to do this conversion we have to do this:

1. Get the cases bored
2. Change the exhaust studs in the 500 head or modify the head pipe.
3. Change the cylinder studs
4. Use a clamp on airfilter
5. Make a new top mount
6. Disguard half of the bottom center mounts from the cylinder to the case.
7. Route a oil line to the rocker cover




Some of these things you didn't mention before and is why I was asking about them.

The reason mine hit is because I used the entire XR500 engine and its alot taller.

I've got 2 spare 500 engines and one perfect 350x bottom (No its not forsale). Maybe I need to throw one of these together.

[SpeedBump]

HEY, YES!!! Please do toss one together. When you do, please post as many pictures as possible. I have a line on a complete bike. I already made a FRANKENSTEIN out of my 300/350 quad and trikes, so doing this is just one more small step. Please post some actual measurements of clearances. btw i found a pic of a 1983 xr500 engine, and seems it HAS an external oil line (although mounts to the head in a different place) If i can get the link to work, you can see for yourself. http://members.toast.net/rhueladams/xr500engine.jpg http://members.toast.net/rhueladams/xr500engine2.jpg

[HondaATC500X]

Thats a RFVC XR500. I wouldn't reccomend using one of those as they are completely different and you might run into more problems. Theres a few things that concern me with the topend swtich:

1. The loss of compression from a shorter rod-Now I know this could be remedied by decking either the bottom of the cylinder, or the head. BUT I'm thinking it might be better that the engine has lower compression as to not shread the rod. Which leads me to my next concern.

2. Engine life-Thats a big boost in power and alot more pressure that the rod has to withstand. Without a doubt boosting the compression back up to where it belongs will shorten it, but how long will an engine last in stock form? 350X engines and parts aren't really cheap to just sacrifice one.

[hrc200x]

This might change some minds, what does everyone think? Also, on page 3 you'll see that this guy posted a message, he didn't mention anything about him getting a machinist to work on his head, 5 hours later he comes back and says that he now has machined new oil holes. If you can prove that it is true you'll be getting an appology from me, but until then I don't see how its possible with the few mods you said you've done. I'm sure there is quite a few people from ohio on the board that could take a look at your machine and possibly take pics for you.


http://www.boreal.org/~kimball/350X-500XCases.jpg

http://www.boreal.org/~kimball/350X-500XCylinders.jpg

http://www.boreal.org/~kimball/350Xinside.jpg

http://www.boreal.org/~kimball/BotomCylinderMounts.jpg

[Minesbetter86]

You know, I dont know who the guy is that posted all the pictures. But he evidently cant read. I am pretty sure that everything he has mentioned in his pics, I have mentioned in my posts. If I remember correctly, I said I changed the case studs and the exuast studs. I also mentiond using the 500 cam chain, to accomaodate the taller top end. AND! I said that i thought my cases were previously board, and thats how it fit into my cases. I also mentioned that you have to discard half the cylinder mount bolts. Oh yeah and I also mentioned the top motor mount too!!!! And for your information, i did have the rocker cover done within five hours, it doesnt take a rocket scientist to run a drill press and a tap and die set. That is all i took to do it. DUH! I am sorry for the attitude but I cant believe this cat is trying to say it cant be done, when it has and I rode the damn thing today. It makes me sick that people have the nerve to say that type of CRAP!!!

Now somebody has to back me up. I bring you all this great information and this is what i get. WHATEVER

[250sx]

Take it easy guys. there's no need to be offended or call :bs: on anyone yet. Let's just ask questions and get answers.

He never said cases hadn't been bored. However, I am curious about how the cylinder mounts to the cases. Are those pics what yours looks like?

[Tecate performance]

You can't deck the cylinder or head too much without changing the cam timing because of the shorter distance. 1cm is a lot to take up. The tensioner will take up some slack, but to go more you'd have to get a different length chain or adjustable cam sprocket. Dirt wheels made a 500x by using a 79-81 xr500(non RFVC) head, boring the stock 350x cylinder to 97mm, machining the cases to accept it and using the stock 350's stroke but with a heavy duty rod. March 1995 Dirt Wheels

[da_catt]

look at this http://forums.atvconnection.com/messageview.cfm/catid/15/threadid/321922.cfm
another top end for the 350x the FT 500 Ascot.

[trikeaholic]

now this is a great thread!!!! We gotta see pics, and please, try to write down the conversion so us idiots can dream of doing it too! I hope this thing works, sounds too good to be true!:headbang:

[gpracing1]

Yeah that would be nice. I'm not so mechanicaly inclined, but I have friends that would do this for me. I could have gotten a 82xr500 engine right before christmas, but couldn't spend the money at that point and time.