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New Project! CR 80/xr 100 conversion

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#21 ·
I was thinking about a conversion myself, but I was thinking CRF150R chassis with an XR100 or CRF150F motor. The 150R has a ton more room under the tank to clear the head than a CR85 has.



I got sick of monkeying with KLX110's, and parts that you have to make fit, so I built a KX65 pit bike with just a Fox shock set up by PR2, a set of Cannon Racecraft front springs, and some Moose rearset (1/2 inch) pegs. The bike is cheap and fast, but it takes a bit of practice to get it down at first. I love it! Now I'm working on a small wheeled KX100 pit bike.



The only advantage to the conversions is that they are quieter than a two stroke MX bike if that matters to you, the four stroke may be able to get a green sticker where applicable, and you can sometimes get the four stroke into the pit bike races, although I'm working on getting my 65 into tthe local races. I can't stand fooling around with the builds-- I just want to get the thing together and ride the bike with the engine that belongs in it-- a conversion is a huge pain in the neck IMO. --L*64
 
Discussion starter · #22 ·
Yes a custom project takes awhile and sometimes gets frustrating but its worth it and in the end its supposed to be fun working on it. Got a full mod 110, 70 and a trick mod ttr 90 to ride so yeah this is a long term project. Even got a reeg 70 frame kit sitting in my garage that I am going to see if I can get a kx 65 rear wheel and brake setup to work and finish my custom shortend 85 front end that I have laying around. LOL



Had a 01 kx 65 that I was going to use all the suspension off of for my 110. Bought it without a topend for $350! Ended up getting it running and selling it for a very nice profit.



Yep thats why I am going to run a crf 70/80/100 tank or the crf 150R or a 150F tank. The 150R tank is not cheap at all to buy used so may lean towards the others. A 85 tank fits but is tight though and may run into problems.
 
#23 ·
That 150R tank won't simply just bolt up I'd imagine-- and I can't weld. I've been seeing 150R rollers for about $1500. I'm sure Dave Miller could easily do something to get the 150F motor into it. I'd hate to do anything with an XR100 motor, because it's so expensive to get any decent power out of it, and when you do-- it becomes unreliable.



If you want to race the bike in the pit bike races, then a conversion makes sense as they won't let a 150R in. If you are just goofing off at ride days, or backyard riding, then I'd do a 150R, or in my case-- the KX100 pit bike. I'd rather have the 150R, but I don't want to part with that much cashola. I hope you do get it together, and it comes out awesome. --L*64
 
Discussion starter · #24 ·
Your are correct on the gas tank as all of those other tanks I said will directly not bolt up. Either move or make new gas tank mounts on the frame or just make brackets to bolt the gas tank to the frame which is easy. I can weld and fab some stuff so not a problem for me. Just got a new hobart mig welder so this is why I got the project. LOL



Here is a pic of the bike and pic of the motor. It will be getting a new tank and plastics with graphics after motor is in. Once the frame work is done may be getting it powdercoated white or whatever I come up with for free and if not I will just paint it myself.



I got the motor and one of the rear mounts on the case has a peice cracked off. So I am getting a refund hopefully from the ebay person since he gave no info on that being like that and no pics of it. It should still be okay since the bolt to hold the motor would still have about a 1/2 to 3/4 of the case to hold onto. But yeah would rather have a good case and be stronger. LOL At least I got everything like electrical, carb and etc for the motor.



Project may be sitting like this till fall since got other stuff to work on. May pick up some stuff I need for it along the way.



I love having something different then everybody else and love to get questions from people when they say who built it and stuff like that.
 

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#25 ·
I saw that roller before-- I think Firepower had it for sale about a month ago. I was thinking about swooping it up to use the wheels for the BBR framed TTR125 that I bought off of Ebay. ( I sent it back because it looked nice in the pics, but it was a total toilet when it got here!)



You know what you could do-- is get a cheap CR85 frame off of Ebay to chop up for the conversion, and put a CR85 engine back into the roller to ride it for the time being. Once you get the conversion done, you can switch all the running gear from the 85 to the conversion, then you could still ride while you're chopping and welding. I was going to get a 150R, then an Ebay 150R frame, and a 150F motor. I was going to send the 150R frame and the 150F motor to Dave Miller and then just ride the 150R. Once I got the conversion back from Dave, I was going to put the 150R parts onto the conversion, and start riding that.



I finally just said the heck with it, and decided on a cheap KX100 project... --L*64
 
Discussion starter · #26 ·
Yeah I bought it off firepower on here. Great guy to deal with and yeah for the price I could not pass it up. I could buy a frame and a 85 motor but thats spending more money that I could be putting into getting the conversion done. Was going to buy a complete running cr 85 and just use the motor in a shifter kart chassis project later down the road but ended up picking up the 80 roller instead.



Good idea on the idea with the 150R project but yeah your kx100 is turning out cool

though.



Right now I got $1075 into the whole project with the complete roller and complete motor shipped to me. May get some money back from the ebay seller on the motor cause of the cracked case. Has a brand new bbr 120 big bore kit on it already so its set for now but wanna go bigger down the road after its running. LOL



My wishfull plan is to get it done for around 2 grand but more like maybe $2500 tops. Making some stuff on my own and getting deals overtime will help.
 
#27 ·
Your budget sounds reasonable if you do the work. I have about $1900 into mine initially including both bikes, BBR 120kit, BBR conversion pipe and Fatt boy springs! (little more now with some performance upgrades) I had a $550 return selling the CR engine, puts my roller at $400 just like yours.



Is your cracked engine mount the upper or lower rear? If it's the lower? You won't need it anyways. We all cut the mount off to get the engine as far back as possible.





Lucky,

I was think'n that BBR/TTR must'a not of work'd out, cuz of your lil wheel KX 100 build...





BTW, BBR has brand new 150R frames, tanks, pipes, etc. Take offs for the custom Perimeter frame builds. I their garage sell items.
 
#28 ·
Oh Gawd! In the pics-- that BBR bike looked sweet, but when I finally got it-- it was awful. The people took a grinder to the frame in order to use the stock CR85 airbox boot... the res was supposed to mount to the left on that bike, but they ground into the frame to allow it to run on the right! The rear hub wasn't spaced right, so the sprocket mounts were grinding into the swingarm... there was 3/8ths of an inch of play in the rear linkage-- I could go on and on. I sent the bike back and had them credit my credit card. I'm still fighting over the $300 that it took to ship it to me in the first place.



I can't deal with conversions anymore, so for now-- I'm just doing the two stroke thing, and I still have a stocker 110, and a mildly modded 110. I'm gonna try running my 65 in the pit bike races and see how it works. I love riding it, it's cheap, and I can ride it pretty well even though it doesn't have the torque that a 4 stroke has. The suspension is super plush too. I'm anticipating the 100 to have some low end and mid range though. ---L*64
 
Discussion starter · #31 ·
Yeah the bottom motor mount was cracked on the 100 motor. So you just cut or grind most of it of anyway then?



I contacted the seller and he said he would give me a $100 back so of course I said yes. LOL So the motor ended up only costing about a bit over $600 shipped to my door. Took the spark plug out and shined a light down in and the bore kit is brand new and the spark plug is.



Sounds like that bbr bike was a mess.
 
#32 ·
What part do you grind off? Part of the engine cases? You may find a case on Ebay or whatever if you watch. I think the hot setup is an XR80 tranny-- the ratios are a little closer.



That BBR bike was a total dump! The really strange thing is that the bike was the owner of the dealerships' own personal backyard bike. When I was arguing with the guy about it on the phone-- he kept yelling "If you wanted a bike that was perfect, then why in the hell did you buy a 16 year old bike?"... When I told him that the TTR motor that came in it wasn't even out until around 2000, and BBR never did any aluminum frames until around that same time-- the guy just kept telling me that he had had it for 16 years, and never had a problem with it. It was a bizarre conversation to say the least. I ended up getting screwed out of the $320 that I paid for shipping too. The credit card company wouldn't credit me that-- I did get the purchase price credited back though..



I had two XR100 motors sitting aound here last year. I was going to do a DMC bike at one time-- but I looked at one before, and I thought the airbox-carb snorkel was hokey, along with the way that the rear brake pedal interferes with the kickstarter. The rear shock res came really close to the frame spar too which I didn't really care for. So then I got a KLX140. I ended up not being able to get the Fox shock for it that I needed- so I sold it off to do the 65 and now the 100. If you could get the shock made for that KLX140 that it needs-- that bike would be a whole lot easier than a conversion to work with. --L*64
 
#33 ·
Yup, the low mount is removed to get the engine as far back as possible. When you start to moc up the engine in the CR chassis you'll see why.





Keep in mind the XR 80 inner engine cases won't interchange with the 100.
 
#34 ·
Keep in mind the XR 80 inner engine cases won't interchange with the 100.



I didn't know that-- can you use the 80 tranny gears in the 100? I think that's the only advantage anyways. What's different-- the crank journals? --L*64
 
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