Hey guys! new to the forum. Ive owned 3 blasters so far. Figured i'd post my new project. my buddy gave me a blaster frame. motor was blown. And i just happened to have a 75 Honda CB400 twin streetbike layin round gatherin dust. The 400 is a monster in a blaster frame. I had it in the quad last summer but everytime you cracked the throttle too hard on hard pack or pavement it would either rip the front end in the air or rip the front motor mount apart or (usually) both lol. I half assed the project the 1st time cuz i just wanted to ride. plus the valves needed adjusted on the 400 and i couldnt get the valve cover off when it was in the quad frame and i couldnt snake the motor back out of the wheeler without cutting the entire thing in half so it sat in my scrap pile for some time and i am just now bringing it back to life. Im doing alot more frame modifications and extending the wheelbase this time in hopes of curing previous problems. Posting some pics now just got started on it about a couple hours ago. If you guys like the project lemme know and i will update this thread regularly! I:I BTW ive only had to spend 50 bucks so far and that was for my argon welding shielding gas. im a scraphead project builder and LOVE IT!
My Yamahonda Blaster CB400 Take Two
- Thread starter dave.s3693
- Start date
Haha agreed. give me bout a week and it will move under its own power. last summer it was a beast. was just sick of rewelding the front motor mount so i wanted to redo it completely. plus the valves were ticking like crazy so as i said i had to remove motor in the worst of ways to adjust valves lol. i just got the frame back to one piece again lol then my MIG ran out of argon and ive been searchin all over for my CO2 regulator cuz all i got left is a CO2 tank. as soon as i find the regulator i will be back in business.
Forgot to add.. Had to extend frame a bit cuz first time the engine was in, the carbs had absolutely NO clearance between engine and rear shock mount. its gonna be an adventure fitting the plastic, gas tank, and seat again. thinkin bout keeping it a "naked" quad meaning no plastic just seat and tank and MAYBE very small custom fenders just to keep the mud,snow,etc.. off of me. Opinions??
Hey, it's always good to see someone who isn't scared to do a little cutting! May I give you a few tips? First, are you sure the frame has to be so wide? I think the widest parts of the motor cases may end up being above your frame tubes anyways. Second, I would make your new frame long enough to extend all the way to the stock rear frame tube. It would give you a good 1.5 feet or so of contact to weld on. I went under the rear tube on mine. (see the pic below)
Thanks for the tip. tomorrow i will extend the new piece i made to under the original frame like yours is. The frame you built looks AWESOME man. that DOHC yamaha engine looks killer. i put one of those in a Warrior before. It was a 400 DOHC. the one downside to my materials is all i have is old projects that didnt turn out that i have been cutting up for the frankenblaster project so i have limited metal to work with. The new piece prolly doesnt have to be quite that wide but the CB400 twin is pretty tall and the oil pan is actually very deep and wide so i just wanted to be safe. the frame can be part of the foot pegs probably too tho so im not too worried. once the thing is strong enough to move around safely again im gonna flip it upside down and do some more welding and bracing. i dont wanna have to continously bring it to the garage to weld on it like last time. Ive done alot of these projects now actually. my cousin bought a blaster from me and we put a Tri-Z 250 liquid in it. That thing was INSANE! lol Ive done 4 Warrior frames now. starting with a Honda CB360 swap then we upgraded to a CB500 4-cyl and the guy said it still wasnt enough so we threw a CB750 4cyl in it. It was a hell of a ride to say the least but so damn heavy that it was only good for nice trails and paved roads. Next frame i get im putting a Honda CBR750 V4 i got from a junkyard in it. Havent seen a crotch rocket motor in a wheeler yet. Hybrid custom sh*t is what i love. i have to mess around with any new thing i get. No other way lol
Also as tall as the 400 engine is the oil pan sits in if not partially below the frame tubes so once everything is together and i test run it im gonna fab up a skid plate probably.
I bet you could still fit. It will be a lot stronger if its not so wide. If you want to make it easy you could just make it as wide as the rear frame tube like mine. Plus you won't have to go so far to connect in the motor mounts.
I know you have done this a few times, but i'll share how I do my frames. I made my frame by screwing the blaster frame down to a sheet of plywood. Then I was able to have the motor sit where I wanted it (a flat oil pan helps a lot but you can use shims or foam). I then drew my new lower frame on the plywood. I used that as my steel template. If your motor sprocket ends up too low or high you can use wood to shim the frame or the motor. I don't think about anything else until the rear motor mount is 100% perfect. Once that rear mount is locked it's all down hill.
I don't want to highjack your thread with pictures so here are links to extra pictures that may help you.
Blaster swap.
Index of /xj
Buddy's swap
Index of /f4i
I know you have done this a few times, but i'll share how I do my frames. I made my frame by screwing the blaster frame down to a sheet of plywood. Then I was able to have the motor sit where I wanted it (a flat oil pan helps a lot but you can use shims or foam). I then drew my new lower frame on the plywood. I used that as my steel template. If your motor sprocket ends up too low or high you can use wood to shim the frame or the motor. I don't think about anything else until the rear motor mount is 100% perfect. Once that rear mount is locked it's all down hill.
I don't want to highjack your thread with pictures so here are links to extra pictures that may help you.
Blaster swap.
Index of /xj
Buddy's swap
Index of /f4i
Well im very stubborn and didnt narrow the frame but i cut it and rewelded it under the rear half as you did and yes it is WAY stronger that way. been out there for a couple hours this morning and got ALOT done actually. gotta run off to work but figured id update the build with some pics. i am very pleased with how its turning out this time lol..
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You need to use bigger tube steel for the top. That is going to snap. Also add some gussets. Other than that, can't wait to see it moving.
Its not tube steel its solid hexagonal stock. its not gonna snap lol. ran out of round and square tubing so i used that. looks pretty sharp actually. got the rear motor mount tacked before i went to work. gonna do the front mount and take more pics tomorrow. i built a dual exhaust that comes together on the right side that looks and sounds SWEET. its true dual its just the two pipes run along side each other on the right side. I think its sharp. will post a pic of it tomorrow also.
There will also be pklenty of gussets and reinforcement i just wanna mock everything up before i finish all the welding and reinforcement
Well gotta go to work so i cant do much on the build today but i figured id throw a couple pics of the exhaust in. i built it out of an old trampoline frame and random pipe i found layin around. im pretty proud lol its gonna need a bit of re working tho now that i redid the frame.
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That actually looks pretty good for just some old random pipe that was laying around.... Are you going to silence it at all?
Ya eventually when i find something. probably going to throw a giant fart can on it lol. it sounds sweet right now but you can hear it 5 miles away lol.. LOUD PIPES SAVE LIVES! why doesnt the law enforcement understand? haha
I do not want to rain on your parade, but I have never been an avid supporter of mixing bar stock and fine wall tubing.
I fear the rigidity of the bar stock may cause weld failures in the area of the zone of thermal disturbance in the tubing.
I also can invisage distortion and cracking wher the bar stock meets the RHS near the headstock.
No matter how much you gusset bar stock to tubing there will always be problems with cracks/breaks at the thermal disturbance zone.
Another downfall in using bar stock is that the strength of framework is in its flexibility, if a frame cannot flex to relieve the stresses applied to it, it may just break.
Another area of concern is the area where the frame meets the suqare RHS directly below the swing arm mounting, this is an area which is subjected to massive stresses.
Removal of the straight through members and replacing them with a box made from RHS has weakened the bottom of the structure. The engine mounts are going to be subject to most of the stresses applied in this area, that is not something you need.
I fear the rigidity of the bar stock may cause weld failures in the area of the zone of thermal disturbance in the tubing.
I also can invisage distortion and cracking wher the bar stock meets the RHS near the headstock.
No matter how much you gusset bar stock to tubing there will always be problems with cracks/breaks at the thermal disturbance zone.
Another downfall in using bar stock is that the strength of framework is in its flexibility, if a frame cannot flex to relieve the stresses applied to it, it may just break.
Another area of concern is the area where the frame meets the suqare RHS directly below the swing arm mounting, this is an area which is subjected to massive stresses.
Removal of the straight through members and replacing them with a box made from RHS has weakened the bottom of the structure. The engine mounts are going to be subject to most of the stresses applied in this area, that is not something you need.
Thank you for the info. I dont have any other materials to use so im just gonna have to pray it works i guess. i still believe the frame will take the 30 hp or whatever the engine puts out. the first time i put this engine in the frame i did a horse sh*t job and didnt even have a lower frame at all. it was just the top tubes and the motor holding the wheeler together and the only problem that came about was the front motor mount kept snapping and i rode it HARD!! lol. i think this way will strengthen the weak spots that ocurred previously enough to keep it all together without problems. it is not a bulletproof design by any means but i think it will hold up to my demands just fine. I guess i will just have to see what happens when all is said and done. BTW heres an update on the build. havent been doing much but almost got the gas tank mounted where it fits. probably gonna take some sheet metal to fill in the gaps eventually. i tried multiple gas tanks i had layin around and the stock one fits the best. Improvise, compromise, deal with it, it's all i can do..
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