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New guy - CRF50 140cc motor swap with pics

29K views 71 replies 36 participants last post by  PitRacerVince  
#1 ·
Hello everyone, I just picked up a NEW 08 crf50. I dreamed of having one of these as a kid but my parents were anti-powersports. I turn 30 in a couple months so I said what the hell and went out and bought my childhood dream bike. I'm 180 pounds and I knew the motor would be lacking so I had a Piranha 140cc waiting. As soon as I brought the bike home I didnt bother to start the Honda motor and just began the swap. This is my first time working on an off road vehicle and I found it to be pretty fun.

The bike fired right up on the first try, which was good news. The exhaust doesnt line up perfectly so i had to drill a new hole in the exhaust mount. I think this little exhaust is bogging down the 140, however it still screams!



Now to the immediate issues; The foot pegs are too short now, they barely stick out enough to put any size foot on.

Also my rear brake pedal doesnt stick out far enough anymore, is there a longer replacement part somewhere?



I have read to replace springs in the forks and completely replace the rear shock. Will this give me more room (I'm 5'10" 180).



Thanks a bunch!



Bike brand new when I brought it home yesterday AM:

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Engine removed:

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New engine in later that pm:

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Original Honda Motor:

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I'm considering selling this motor, any ideas on what I should ask?
 
#4 ·
youre going to need a complete big bar setup, being you have the stock bar setup now (smaller than 7/8"), the clamps you linked were for 7/8" bars.

You should be able to pick up a bigbar kit fairly cheap in the classifieds section, youd need top clamp, bars, throttle, extended cables



btw nice bike, theres not a scratch on it;)
 
#5 ·
Nice bike! Stock Honda 50s look so cool!!!



You'd get a good chunk of money for a brand new Honda motor. It could definitely be used to fund a bunch of new parts for this thing. So either sell it or use Trail Bike parts to build up this motor (117cc) and build another bike!
 
#11 ·
Don't buy any cheap no name parts off ebay they may break and you could get hurt its not worth the chance. Oversized footpegs and extended brake pedal are what you need big bars kit is also a must. Extended fork legs and HD springs in front and a heavy duty spring in the rear shock is a good start. Check out the companies advertising on this site and the classifieds.
 
#12 ·
IMO get a used Big bar set up, leave the tall seat till you really had enough of the stock seat, find a used shock an get rid of that stock swinger an get a +2 in the back your goin to need it pretty soon..New tires front an back/starcrosses, shinko, NEVER get millvilles they blow an wear in like a day, and forsure get rid of that stock throttle assmbly............an yeeah keep the stock motor say if that china motor craps out on u in like a season or two ha, u can build up a nice TB 88-117 w/e ur style an how much power u want, an always get a race head if ur goin a BBK
 
#13 ·
How much are you wanting to spend??



Must haves, IMO: Fastway pegs. BBR tall bar kit. New throttle (Joker if you can swing it).



With that motor you're going to be riding way over the suspension, so I'd recommend at least a bigger swinger and new forks (sp 5's, Zokes, etc.). I guess it's a matter of how much you want to stay kinda stock, which, with a 140, you've already blown that out of the water, and how much you want to spend. My favorite ride is a 10/12 BBR primmy with a Zoke/Elka setup, Protaper mini bars, 88cc.





enjoy!!!
 
#15 ·
My intent is just to play with the bike. It wont be raced or anything like that. However I need it to be more suitable for someone my size. I dont have an unlimited budget so cheap and solid is what im looking for. I cannot believe how expensive the tall bars are!



Also, I see you can increase to a longer travel rear shock. Is this accomplished with the factory frame?



As I said before im very new to all of this and dont quite understand all of the terminology. So if you have a suggestion please post a link where I could possibly order from so i can compare prices.



Again, I just need this bike to be able to fit me (5'10") comfortably....



Thanks again guys!:p
 
#19 ·
best way to go on a big bar kit is to find some one selling a triple clamp on the crf 50 sale forums for bout 50 bucks hit a local bike store for a good set of bars then find a throttle and cable in the crf 50 sale forum for another twenty its way cheaper.. and as for a shock if your gonna keep the front end stock springs and legs just put a stiff spring unless your jumping twenty footers.. I have two bikes one just pretty much stock with a bigger motor and one with suspension and a motor and the stock one is way more fun by far.. and i would keep your stock motor its worth more than the one you bought and by putting a 140 in the bike you bring down its value.
 
#21 ·
Welcome to the wonderful world of pitbikes!:D. First off,clean bike! good choice. As everyone else has been saying, definately get a big bar kit. On my 50, I dont even have the name brand kit. I bought a cheap top clamp off of ebay for 40 bucks. Im jumping 25 foot gaps and it hasnt broke yet! I put a pair of bicycle bars on there and a KX65 throttle cable and tube. This was about 20 dollars so now your at a total of 60$. Next your going to need the longer front brake cable which BBR sells for $20. ($80 total). Then your going to need to get a good set of grips for 10-12$. Your only looking at about $90 in all. Which is very cheap. Who knows,I see the big bar clamps on ebay now for $20-$30. so that shaves off $10. Ill post links for you ASAP. For suspension, I See alot of people going with high end shocks that are way out of (my) range. ($250-$400). Some of the aftermarket Heavy Duty springs dont hold up to well, But some do. For the fork springs, mine are now very sloppy and worn because I didnt buy the heavy duty bushings and all that good stuff. So a good choice is to go with bigger forks such as crf70 or Aftermarket racing ones. There are alot of people on this site that give good deals on parts and are in very good condition. Just look around often and you'll usually see what your looking for. Any more questions dont hesitate to ask!
 
#22 ·
Here is the Big Bar clamp-> XR50 XR 50 CRF50 CRF 50 BAR CLAMP:eBay Motors (item 350267655955 end time Nov-19-09 14:42:46 PST)



Here is a good throttle assembly with a cable KAWASAKI KX65 RM65 KX RM 65 THROTTLE ASSEMBLY:eBay Motors (item 390041832444 end time Oct-30-09 17:36:17 PDT)



I also forgot to mention to get a different front brake setup like a perch and lever. You can find one of those easily. Im running a standard clutch perch with the clutch lever upside down :cool: Haha. there are some links for now!
 
#25 ·
Oh the dilema... Let me explain;



I just got a mid $400 offer on Ebay and a local guy on Craigslist who is willing to give me my $500 asking price cash (for the stock 50 motor). I'm really torn. I bought this to play with, something I could easily store and easily throw in the back of the suv and go. However after taking it around the yard tonight i realize just how small it is. I realize I could make it more suitable for someone my size, however that wont come cheap. I spent my budget on the bike and motor. So do I sell the motor to mod more? After looking at parts I realize I will need more then the money I get from the motor to make it the way I want. A buddy told me just sell it and take the money and buy something bigger. However I hav no where to ride something bigger. The whole point was small. I have small with rediculous power but little control. I just dont know where to go from here...



Your thoughts?
 
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