CR500 Cafe project

[Pony]

Ok heres what I got, what I wanna do and why I wanna do it. I am looking to build a nasty 2 stroke "cafe" style bike. (I hate that term, its been basterdized as much as "bobber") Have seen one guy have something kinda like what im looking to build on here. Main reason I wanna build something like this is

A. it would be badass and
B. It would give me a chance to really mess and experiment with porting, building an expansion chamber, and even getting diffent ratio gears machined for the transmission. Where horsepower and whitenuckle fun are more important than it being super easy to ride and spin good lap times.

I have an 85cr500. I want to take the motor which is very fresh despite needing a clutch cover, and set it aside to put in a beer can later on down the road. I dont wanna waste a perfectly good MX motor

I want to find an 83 cr480 to put in this frame because from what I have read, it is the aircooled motor to go with if you want a 5 speed. Aircooled motors look more awesome, getting rid of the radiators is a must, and with this being a street bike I dont see overheating being a problem.

I have a CB750 frontend on it right now for mock up, but I will need to get new forks. I think The stance will handle well, the CB triple clamps move the front end out a bit. If any of you guy see a potenial problems let me know!

The rear section will be built into the frame, not a bolt on. I have a shorter shock off some street bike I might try and run but the twin shock idea i had in the picture is a no go. so the rear shock mount is probably going to get relocated

The tank is also off of the CB750, but will probably use a CB350 tank or something similiar. that tank is way too big looking.

So some questions I have are: What should I do for lights? Could I go a rewind on the 480 like the thread in this section?

What would be the best ignition to use?

Is a 39mm or a 38mm lektron a better choice?

Does anyone have a lead on an 83cr480 motor? I plan on rebuilding it, so locked up ect is a ok.

Has anyone ever cut custom gears for a transmission before? I am a CAD operator for an electrical company by trade and I am wanting to carry this shit over to engineering parts. The idea of figuring out the right ratios to work with my HP and torque curve and then desiging them and handing specs over to a machinist and getting back something that no one has gives me a hard on. The only thing better would be someday being able to machine the parts myself. Boner time.

Does anyone else think this sound like a kinda cool project? Any feed back would be rad.

[Pony]

Ok dudes, after getting on here wide open pumped on my new build idea I can see coming off like a dumbass after doing some research. I apologize for that.

First there is no stator on a CR480/500. I have had many a cases split and dont know why that though even came out. I guess because the XR650 thread in this section my dumbass mind just threw that out while sitting behind my desk at work. So I am going to go ahead and assume that something like those ELINE generators will be the only thing to make some juice. If not inform me. Im here to learn.

After researching the aircooled big bore hondas the 83 CR480 was the best motor I figured I could make it work. Well as I'm sure all of you know putting a left kick, right side countershaft motor in an 85' frame would be getting into the "why the hell did you do that?" category.

so now I am to assume that I need to find an 84 cr500. Remember, I am doing this because I have a bunch of parts I wanna make into something, so I dont really wanna buy an 84 and start from there. It appears that an 84 rear engine mount is different than the 85. I am not scared of doing some mount relocating but wanted to make sure I wasnt still out in left field picking daises like I was with the 480 idea.

When I get paid I have found some new 750 forks I am going to pick up, since the ones pictured are pitted and toast. I have not decided on what to do for the triple clamps but I am leaning towards having a new steering stem machined that will press into the CB clamps but run CR500 bearings and races.

Also in looking for a motor to build I have noticed people parting these things out. is it a bad idea to buy a motor in increments such as, cylinder, head, cases, tranny, lower hardware, ect? I know that that is not uncommon when building an older hard to find HD motor but I guess it might get a little pricey for this project.

Come one dudes, give me some feedback. Im actually a little disapointed I didnt catch some shit for my ignorant first post. Thought you guys were hardasses...



Edit: I copied this from the DS section. Couldnt figure out how to move it. Sorry for the double post.

[blownbillybob]

Would be cheaper to buy a complete engine off e-bay then piece one together?????

Check out "Chop Cult" web site look under " birtbag challenge" 2010 lots of crazy shit third pic down is of a yz490 in a custom chopper build

You can google and you tube the challenge also

[cr5moto]

I don't think you can put an air-cooled motor in a water cooled frame...and how do you plan on getting a licence plate for this?

[Pony]

I dont know why you couldnt? I dont expect it to bolt up, I plan on fabbing mounts ect. I thought cramming motors into shit it is not supposed to be in was the hoon way. Maybe I signed up for the wrong forum jk.

But as far as plating it goes, that probably wont happen. I would like to, but I dont wanna build a bike around the governments laws. I want to build something radical and fun. Not something that has to fall into a class to race, and not something that has a bunch or dorky mirrors and shit hanging off it. I guess Ill let this bike go the direction it wants to and then see if I can get it registerd.

[blownbillybob]

There's a 84 cr500 engine for sale on e-bay buy it know for $449.99 complete check it out?????

[Pony]

Ok I have been gathering more parts but I need to ask some people who know what they are talking before I keep spending. Should have asked before I assumed. After talking to hillclimb Jim and at the suggestion of some other guys I am going to run a finned cylinder and head on my 85' bottom end. I decided to run the 83' cr480 topend because I could find the parts cheaper and have read how good of a motor it was. I got the head in today. But before I order the cylinder and see what this little project is going to require I wanted to make sure that there is nothing that would keep me from matching these components any more than 84 cr500 parts. I assumed the 480 would work no one said any different, but my pops has always told me what assuming something will get ya.

So if someone in the know will give me the go ahead
I will go ahead and order my 480 cylinder tomorrow. Also if you have seen one of these swaps done before what kind of hurdles will I have to overcome? I figured stud placement might be a but anything else?

Right now I am doing working on fitting the cb750 triple clamps to the cr's steering head. Look like I just have to shorten the steering stem. Also I will post up some pics tomorrow to try and keep this thread interesting. Thanks for your help.

Note: I have been trolling the "other site" just because there is lots of info. But I won't be posting there. Seems like this place had a higher concentration of dudes that know whY they are talking about. I'm trying to learn so I don't have time to sift through uneducated opinions. The BANNED site is where it's at.

[Pony]

Here are some pics of the head. I have not seen an aircooled motor set up with a decompression unit. No reason why you couldnt, right? I figured if I trimmed a minimal amount of fin to make a little spot for one, it would be no problem. Wouldnt have to worry about dodging a water jacket.

[Pony]

Here is the CB350 tank I picked up off egay. It is about 2 1/2" shorter, it's skinnier and not quit as tall as the 750 tank. Plus the cap is offset, and I think it looks better.



Here is another pic of the roller with the shock back on and the old tank on it. This tank towerd over the frame and I hope the smaller one looks right. Ill see this weekend.



And if anyone knows anything about the 480 vs 500 ac cylinder swap, let me know. I ready to move on buying that cylinder if running the 480 cylinder is possible. Thanks in advance.

[Roostius_Maximus]

i've done decompressors on a few 500 finners and a husky now. no problem.

[Pony]

i've done decompressors on a few 500 finners and a husky now. no problem.

Sweet! I understand you know these motors about as well as anyone does. Can you tell me what I might be possibly getting into with putting a 1983 CR480 cylinder/head on a 1985 CR500 bottom end? Thank you for the reply.

[Roostius_Maximus]

i havnet had one of those here to see what its like. Do you have measurements of the stud spacing?

[Pony]

I sure dont. After hearing that it had been done, I figured my best bet would be just to troll around ebay until I came up on some good deals and see first hand what the problems might be. I came up on a cheap head so I picked it up, and have my sights set on a cylinder. Stud placement will be an issue I am sure, but I was hoping that that would be my only hurdle as far as matching the cylinder to the cases.

I hope I am not biting off way more than I can chew, but best way to find out is to get the components and start measuring and figuring it out. I will be documenting it here, so I guess we can all see what this swap entails.

[Roostius_Maximus]

seeing as how the guys were using the '84 500 jugs i'd have stuck with that.
As far as i know the 480 is the same platform as the 450, which was basically a 250. it used the 250 reed and flange aswell. the 84 500 was the first of its own

[Tharrell]

I have an '82 480.
Don't sweat the cylinder.
You can always sell it easily if it won't work.

http://www.vintagemx.us/cgi-bin/swapmeet.cgi

[Pony]

Well, after reading this I cruised over to ebay and stumbled onto an 84 cylinder good fins but pretty rough shape. Unfortunatly I was bidding from my phone and by the time it logged me out and I could get back in the auction was over. It went for 8 bucks. I was fucking livid.

I have good basic mechanical knowledge but not the CR500 specific intimate knowledge many of you have. Where Could I find information that would let me see the differences between the 480 and the 500 cylinder?

so now I am back to where I was before. I have an 83 head in good shape. I guess my best plan of attack now is to pick up a cheap 83 cylinder because they seem to be so much more available. If I have the cylinder then I can take measurements and see what the swap will entail.

Im probably going to post on the other site just to try and get some more imput before I piss money away on something that someone knows will not work and know some facts as to why it wouldnt. Thanks for the imput and keep it coming!

[Pony]

Ok, I think I have just enough info to really get in trouble now. I know these are just pictures that are not to scale but they make me feel better about using the 480 cylinder.

The base gasket part numbers are only one number off from the 84-84. Its a lot different from the 84-85 (I know this really means nothing but thought it was worth noting). The base gasket looks very similiar between the aircooled models and the major difference is in the switch to liquid cooled. Finally, they all seem to have the stock bore of 89mm. If any of this info is incorrect, please let me know.

So my conclusion based off this very limited information is that an 83 swap wouldnt be any harder than an 84 swap. I know this is a pretty flimsy conclusion, but I am not as reluctant to drop some cash to find out.

[Roostius_Maximus]

get in that list and check a few things, see if the exh gaskets and reed gaskets are the same

[Pony]

83 CR480:

intake: 14132KAE000 exhaust: 18291430306 reed cage: 14100KA5770

84 CR500:

intake: 14132KA5740 exhaust: 18291KA5307 reed cage: 14100KA5741

85 CR500:

intake: 14132KA5306 exhaust: 18291KA5306 reed cage: 14100KA5691


I dont see any real shared part #'s. Anything else I should check? I really appreciate the help Roost.

[Roostius_Maximus]

get asking the guys witht he fins i guess

[100hp honda]

all 3 years base gaskets are 12191-KA5 originally at time of manufacture

the KA5 has been superceeeded by ML3 and MAC. ML3 originated on the '86-'88 500. 450, 480, 500 can all use the ML3 base gasket. so you now have your answer to whether the studs are the same

have to know what the part numbers meen then you can get a idea what parts work.

[Roostius_Maximus]

i'll have to bring the 450 engine out of storage and look. i swear its smaller

[Pony]

Dang man, where do you get your info? Ya'll are pretty savvy. Thats awesome to hear. I will go ahead and order the cylinder.

I have to order some OEM honda o rings for another motor, and I figure might as well start getting some gaskets for this jug swap. I usually use bike bandit, but this last time it took over a month for me to get some damn circlips. Any suggestions?

[100hp honda]

i'll have to bring the 450 engine out of storage and look. i swear its smaller

i went through this same part number deal before. im not sure theres any 100% way to tell from just the numbers but if you use some logical judgment i think you can get a darn good idea what parts interchange. i know for certain just from the parts fisch that 450/480 were identical base gaskets. the '85 also used a KA5 number, i cant say for certain its a identical gasket but i believe the studs would be the same and in general i think the gasket would be similar or possibly nearly exact. if there is differences they may be slight variations in shape like the rear boost port area shape or wider transfer mating surface area etc etc. my belief is that all big hondas from '81-'01 could use the same base gasket.

[Roostius_Maximus]

knowing that the big hondas started out as big 250s, used the 250 exh flange and reed assembly doesnt make me real confident that the studs are the same either.