Building my Trail BIke!

Discussion in 'Engine Mods and Swaps' started by mike96, Apr 25, 2017.

  1. mike96

    mike96 Member

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    Well it has been a while since I have been on here. To be honest it has been a while since the last time I have ridden my blaster, partly due to the fact that I dont have a title and cant register it/have not had the time to go to the DMV to get one issued, and partly due to the fact that I really do not enjoy riding a quad as much as I thought I would. So I decided that maybe it was time to find a trail bike, So I started looking around for something short enough for my inseam with good suspension and light weight... Needless to say I was having a hard time finding exactly what I was looking for. Then as it happened I ran across a killer deal on a bike I figured if nothing else part it out and make a little cash. Then I remembered I saw a post involving a Blaster and a YZ http://advrider.com/index.php?threads/built-a-wr200-because-i-didnt-know-they-existed.911735/ and that got me thinking...

    At first I didn't think there would be any compatibility between the two but the more I looked at the frame. but the more I looked the more it looked like it would fit. so today I took the plunge and made it official. All I have to say is WOW... I didn't think it would be that close, and I mean it is really close. So far the only modifications I have made so far was cut the lower center mount from the frame and in she went. I had no idea that the baster motor would fit so well in a KX frame.

    1991 KX125 frame BTW... the first few shots are of the motor just sitting in place with the swing arm bolt ran thru it. one thing I didn't get was a good shot of how close the front mount is to just sliding in place.

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    After manipulating the front mount tabs on the frame Just a little. All it took was to slide a punch thru the mount hole on the frame and tap it with a hammer a couple of times to get the motor to start sliding down.

    [​IMG]

    So close... So close........

    [​IMG]

    Looks like I need to trim down the lower mount on the motor just a little to get the front of the motor to drop just a tad.

    [​IMG]

    now the only two concerns are how the motor looks with the bike assembled and will I need to manufacture a 3rd mount for this monstrosity... The bike is going to be mostly light trail riding, I am a bit to heavy and dont really have any desire for fast technical stuff or getting air so... As of right now there will be two bolts holding it in. I was thinking of spinning the head around backwards, drilling out the lug on the head and making a couple of brackets to the front down tube... Dont know yet... Gotta figure that out.
     
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  2. Awk08

    Awk08 Administrator Staff Member Technician

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    the blaster engine only needs those 2 mounts, I think that's due to it being counter balanced, which most bike engines are not ?

    have you checked sprocket alignment with the rear tire/sprocket ?
     
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  3. mike96

    mike96 Member

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    I haven't checked it officially, just looked "line of sight" about where the sprocket lines up with where the swingarm lines up. It looks like it will be pretty close, it might just have to be bumped over a tad. I need to get the rest of the parts out of storage and put it back together. All I have with me right now are the engine, frame, swingarm/shock. and subframe. The rest of the bike is in storage.

    I am hoping that with the low impact riding I will likely be doing, only two mounts will be enough. I will work on setting up a third mount just be give me piece of mind. The only thing that concerns me with only having two mounts is if one of them were to brake under high load, I know highly unlikely that will happen but still.... One thing that gives me a tad bit of worry on the mounts is that the swing arm bolt feals a tiny loose like the KX swingarm bolt may be 1mm smaller diameter than the blaster bolt. I will have to figure out something to take up the slack...

    Sprocket lines up pretty well with where the swing arm sits. As of this picture the only thing holding the engine in is the swing arm bolt and the front motor mount pinched between the frame mounts, no bolt.

    [​IMG]
     
  4. Awk08

    Awk08 Administrator Staff Member Technician

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    So use the blaster bolt ?
    Enlarge the frame tab holes to fit it
     
  5. mike96

    mike96 Member

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    I did a little research this morning and from the looks of it the FX swing arm bolt is 2mm smaller in diameter than the blaster bolt. I could enlarge the flame holes but the size difference means that the blaster bolt wont fit the KX swingarm unless I can find replacement bearings for the swingarm. It will probably be easier to find a small piece of thin wall tubing or have a custom bushing made to fill the gap in the blaster engine mount lug.

    Blaster swingarm bearing 22ID x 28OD x 20W
    KX swingarm bearing 20ID x 27OD x 30W
    according to pivot works website.
     
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  6. mike96

    mike96 Member

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    I did a little more "internet fabrication" on the swingarm bolt issue. So as per info found on pivot works website the Blaster swingarm bushing has a 16mm bore and the KX swingarm has a 15mm bore, confirming that there is a 1mm gap in the swingarm/engine mount. AWK suggested boring/drilling out the KX frame to accept the blaster bolt. My concern here was that the bolt wouldn't fit the swing arm. I think I have found an easy solution for that problem. After digging around the web I have found a swing arm bushing that matches the blasters OD with the KX ID, it is just a bit longer that necessary, which is fine. It should be easier to cut down a bushing than bore out the center of it.

    So now the only hang up is the swing arm nut. The blaster has basically a plain locking nut while the KX has what looks like a short auto lug nut with the matching taper in the frame... I have the blaster swingarm bolt with me today and am going to compair them side by side. If the blasters bolt has the same thread pitch/diameter thread and is close enough to the same length I will be placing an order for a couple of bushings when I get home tonight.

    We shall see.
     
  7. mike96

    mike96 Member

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    The more this bike gets closer to being complete the more I think this combination was meant to be... Motor is in and the front mount bolt is lined up and in place. Swingarm/rear mount is in place and the rear suspension on. next step will be to trim down the rear of the head to clear the fuel tank and mount the the subframe/air box and see how the carb lines up.

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  8. mike96

    mike96 Member

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    Sorry I have been off the band wagon for a bit and it has been a while so here are a couple of updates. I registered on a KX forum to get info and have posted a couple of updated there so I am basically copying and pasting from there. Everything that is there has been done in the last month or so.

    Post 1...

    As the bike sits, the engine in on its way back in for hopefully the second to the last time. The frame has been painted black mostly to keep it from rusting after welding so there wasn't a lot of concern in making it look good right now. after it is together and running maybe even ridden a bit, it will come apart again and the frame stripped and powder coated. I am waiting on a swingarm bearing kit to come in so I can mount it and get it mack on it own to feet. Then I can start working on the next big part, the pipe.

    So here it is, my KX125/Blaster combo. Sorry the pictures are a bit small and this is the first time I have used Google picture storage over photo bucket so they are hyper links rather than pictures themselves.

    https://photos.app.goo.gl/JzFa9WScCb7ibXhS8

    https://photos.app.goo.gl/K9jgotVYKxxB8iTJ9

    Here you can see the notch in the frame to clear the engine. In the picture it looks like the engine is sitting on the frame but it doesn't once the swing arm bolt is in.

    https://photos.app.goo.gl/qJH8FpGbAfqKsZnr5
    [​IMG]


    Post 2

    Just want to throw a few pics up real quick. It might be a bit before the next update. I have a couple of things to do on the house and I need to clean off the lathe to make a couple of spacers. With all the other projects going on right now making parts for this is a little low on the priority. I might get to it this week...

    Chain alignment looks pretty good from here. It is a tad to the left but not by much based off of the existing marks on the chain guide.

    https://photos.app.goo.gl/ryiTrfgcF5nic5tU7


    There is still a small gap in the washers I am using for the engine spacers so when I take measurements for the spacers I will compensate for the chain alignment also.

    https://photos.app.goo.gl/G2u99jWJ6eQUhXTE7

    So I have a couple of options when it comes to pipes. This is the pipe from my blaster, It is a right hand bend which it pretty unusual for this quad, so if I can help it I would rather not cut this pipe. But I was thinking a pipe set up like this will give the bike kind of an old school KDX look with the air cooled engine. I would have to make a custom or loose the right side rad shroud.

    https://photos.app.goo.gl/wgDz4UWxkFS71qzQ6

    https://photos.app.goo.gl/8v9DbceiuTzAykzZ7

    The KX125 pipe actually lines up pretty well also. It is more than likely going to be on the small side for the engine so I dont plan on actually using it but just to get an idea of what it would look like with a newer style 2 stroke pipe on it.

    https://photos.app.goo.gl/RVbkh8pwe66M6Hsw5

    And the KX pipe in the other orientation. Just to see what it would look like.

    https://photos.app.goo.gl/U2C2q9L4MHPKmPm86

    Somethings make me question the engineers... The more I play with this project the more I wonder it it was intentionally done with this swap in mind. So I turned the KX pipe up like in this position like the blaster pipe would be just to see what it would look like and after taking the last pic. I noticed that there is a manufactured dent in the pipe to clear the engine cases (or frame possibly, I dont remember which) and I found that the dent aligned pretty well with the shape of the blaster head... Kind of weird... Just saying...

    https://photos.app.goo.gl/yoAj61jr1DFicRhU9

    And the most recient. Post 3..

    Quick little update. Got a bunch done in the last couple of weeks. Once the engine spacers were made and in it all went together very quick for what will be the last mock up build. Spacers came out nice and pretty much put the engine right where it needed to be. It might still be just a tad to the left, but that is something that I can change a little later if need be. I think I have even figured out what I am going to do for a pipe.

    A friend of mine races moto as well as he and his dad own a small machine shop dealing with motorcycle and ATV/UTV engine work. The last time I spoke with him he told me that he knows someone that builds expansion chambers for two strokes, so at some point I will be getting in contact with him for a proper pipe for this beast. In the mean time I have purchased some 2-stroke pipe software and ran a few numbers... The 125 pipe is a bit on the fat side surprisingly for the power output I am looking for, but the biggest problem with it is that it it too short both in the head pipe and stinger. I managed to get my hands on another pipe, one that has the same size head pipe KX. So I used it to lengthen out the KX125's pipe on the head side. The stinger on the other hand is a tad bigger in diameter but it should work well enough for now. So what I am ending up with is something a tad shorter and a bit fatter than it should be. I think a re-tune on the carb should do well enough to get me a few miles down the road so I can see if i like riding this monstrosity.

    https://photos.app.goo.gl/ehZJXw6AZ2cQ9UVe7

    https://photos.app.goo.gl/paCXJcqGCXatRtRo6

    https://photos.app.goo.gl/uiE1xtZWx5fN2ZPu8

    https://photos.app.goo.gl/nyzs8LUL1X6eWHfy7
     
  9. mike96

    mike96 Member

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    Quick little update. Just some pictures of the pipe flange and head pipe fitting in the cylinder.

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  10. mike96

    mike96 Member

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    Just a quick update....

    IT"S ALIVE.....

    It is ugly and I need to get some pictures but it runs and moves under it's own power, sort of...

    I have the carb out of it right now because I believe it is running lean. It idles fine but as soon as you give it gas it falls on its face and tries to die. I am gonna throw a larger main in it tomorrow morning and see how she does.

    Will post pictures as soon as I get them on the laptop...
     
  11. mike96

    mike96 Member

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    Well sorry it has taken a couple of days but here are a few pics. It runs and rides. I need to take care of title so I can register it. I still need to swap out the main jet and go retest to see how it runs. The setup I have on it for air intake isn't ideal but it will work until I can figure out something else. I have an idea on what I want to do to make a flexible rubber like boot but it will be something that needs time to figure out the best process to use to make it. The pipe that is on it now is definitely not right for the engine and it hangs down a bit low. I will need to make something different eventually. For not it is at least ride-able and I can put a few miles on it and see if I enjoy riding this monstrosity. Also there is a crack in the rear rim that needs to be taken care of...

    O-yea... and it is UGLY....... I am thinking of stripping the red off the tail and side plates, temporary back to green. Then if I keep the bike and tear it down to paint I might go with a blue frame and dye the plastics black.

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    Last edited: Jun 2, 2019
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  12. Larry's Shee

    Larry's Shee Active Member

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    So how does it work with the KX pipe?
     
  13. mike96

    mike96 Member

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    Well it runs with it on there. I bought 2-stroke wizard software and ran the specs for my engine thru it for a couple of different engine HP ranges. The cone sizes that the program kicked out obviously dont match the KX pipe so some modifications were made. Front half (inlet) on the pipe had to be stretched a bit to try and make it at least a little closer to something close to right. I still need to add a couple of spring retainers to help keep the pipe in place.

    I haven't had a chance to really ride it yet, I just changed the main jet last night. It felt like it was breaking up in the upper RPM when I ran it in the parking at work, so we will see how it does later today. I have a bit of work to do on my master bathroom. I am in the middle of a full remodel I started back in September last year. So short of taking it for a spin up and down the block for tuning purposes, that will be about the most riding it might see for a few weeks.
     
  14. Larry's Shee

    Larry's Shee Active Member

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    Reason I asked about the pipe is because it's a critical piece for performance. Most don't realize this and just cobble it together.
    I would appreciate more info on what the actual difference between the program and the pipe, and specs of your compromise.
    Have you looked into a right bend Blaster pipe? Might be easier to fit/modify it.
    With that program, have you considered building a pipe from scratch?
    The pipes I've made I used the formula from Golden Jennings.
    If i wasn't such an old caveman I'd love to play with Wizard or Bimoto program.

    https://www.google.com/search?clien.....0j0i22i10i30j33i299j33i160j0i13.G80BSGbnY1Q
     
  15. mike96

    mike96 Member

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    I agree with you on the pipe, it is a big part of performance. I have thought about a right bend pipe. In fact I have a right bend pipe that was on my blaster. I would hate to cut up a nice pipe like this to use on this project

    [​IMG]

    The difference in dimensions between the KX pipe and the pipe that 2 stroke wiz kicked out isn't huge but enough that I am sure performance is suffering. I would have to measure the pipe to see the true difference. I know that the pipe inlet on the KX pipe is the correct diameter and the KX pipe was short hence the main reason the stretch in inlet length.

    I am planning on making a second revision of pipe. I was originally thinking of doing a custom pipe cut and welder from sheet metal, but I think that is a bit out of my abilities, So... So the next pipe will be done similar to this one only using several pipes to make one. Then plan was going to the junkyard with the print out for the pipe dimensions I need and find a few pipes with the bends and correct cone shapes that I can cut up and weld back together to make one pipe.

    We will see.
     
  16. mike96

    mike96 Member

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  17. Larry's Shee

    Larry's Shee Active Member

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    Yeah, I wouldn't cut up a $400 pipe either. I thought maybe it would fit as is. Maybe a pipe from a KX250? HELL, any pipe if you could get it cheap enough. Even Jennings admitted all pipes are a compromise.

    I couldn't find the free PDF for Jennings book, but if you do it's a good read about pipes. Explains how angles, lengths, and volumes affect things.

    Some of my comments are as much for anyone reading this, so they can gain knowledge too.
     
  18. mike96

    mike96 Member

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    I went back out last night and put the RHB pipe up on the bike just to take another look at how it fit with everything in its proper place. The first time I had the pipe up nothing was fully bolted down and it was pretty close. Now it is even closer and I mean like scary close. It sticks out to the side a ways and it would interfere with the tank I have on the bike now, but....

    All I would have to do is find a OEM tank so I could modify the rad shroud to clear the pipe (or run without one), cut the pipe in the middle of the first bend so I could turn it just a tad, trim a head fin a little and cut the outlet and rotate it about 90 degrees so it points back and not at the shock. The pipe would come out and turn up,turn back down just over the head and then it follows the frame down the side of the bike. I think a pipe like this would look really good on the bike. Maybe I will go toss it back up and have my wife take a couple of pics while I hold it in place.

    I also took a look around for Jennings book. I found it on PDF but was only able to view about the first 10 pages or so. I have a few other places I can look, maybe I will get lucky. I am curious to see what he has to say about pipes now. I have some thin cardboard at work I saved from going into the recycle bin, and the program I bought came with cone making software. Maybe I will play with it a bit and see if I can come up with a pipe that mimics the RHB pipe I have now but fits the bike a little better... Like I need anther project right now... LOL.

    Yep, knowledge is power, and in this case literary...
     

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