YZF600 engine stuffed into a 90 blaster

[rshutchinson]

Hey guys, joined here to have a place to show my progress as I make it on this project. I'll use it as an intro as well I guess.

This project has been probably nearly 20 years in the making. I remember going to the Norm Carr Classic when I was a kid and there was always this one badass quad that had a streetbike engine in it that would destroy the other bikes there. Ever since then I've always wanted to do this. Even if it's not going to function the best, I want to do it simply for the fun of it and unique-ness.

Now that I'm much older and have some experience with cars/motorcycles, modifying, cutting, welding, cursing and all that goes on with these projects I have been keeping an eye out for deals on a cheap frame and engine. Well I've found them finally. Didn't want to spend much on this project just yet. Anyway, I picked up a blaster frame in good shape with everything that I needed from it for $225. Then I found a running yzf600 engine that had been put in a sled for $175. Now the fun begins.....

Shoving this

Into this

I'm just about to lift the motor out of the sled and get some measurements.

So far I know I'm going to have to cut, re-weld, gusset and strengthen the braces running from the front suspension to the lower frame tubes and extend the frame a few inches to make room for the head to clear the steering shaft. I'm hoping to lengthen the frame as little as possible as I also want to lengthen the swing arm a bit and I don't want this to be a 20' boat. I'll be strenghtening the whole frame as much as possible as well.

 

[jvb]

Welcome to the forum, going to be a nice build to watch!
Good luck

 

[pudvah]

I'm tuned in for sure.

 

[rshutchinson]

Thanks guys. Get to cutting tomorrow, measure to see what size tubing I need and hope to have the motor sitting in the frame.

 

[dirtysquared]

Welcome. Take pics!

 

[deeeebeeeeee]

I have seen bikes like these sitting on display and in pictures. I always wanted to see one in action.
Hope it turns out as sweet as it sounds.

 

[rshutchinson]

If I have it running this year I'll post up some video from some trails around here.

 

[79 bronco]

Welcome, we love pics!

 

[rshutchinson]

Didn't get as much time as I wanted to today but got some work done. Cut a piece out of the frame so I could take a section to the local metal suppliers.

In case anyone is wondering the stock frame tube is 1.15" OD and 0.97" ID. I ended up getting 1" OD .120 wall DOM tubing for slug. I used a sanding disc on an angle grinder to remove some material for a tight fit into the stock tubing. I am using some 1.25" OD .120 DOM tubing to fit over the slug.

I'm lengthening the frame 4".

Started by cutting the frame in two. Doing the lower rails first, since they are straight I'll be able to keep the frame square by lengthening both sides exactly the same.

Bent the two lower tubes to be parallel with each other so I can slide the rear half of the frame onto the slugs in the front half. I will be changing up the top tubes slightly to make room for the carbs and airbox.

Lower slug. Bent part at the top slides into front half of frame so that I can just slide the whole rear half onto it.

This is just the slug, don't have the main tube over it. I'm using one continuous slug rather than two separate slugs like you would normally just due to the fact that I'm only lengthening the frame a few inches and to help keep everything straight. Anyway, drilled holes for rosette welds into slug. Chamfer the edges of the slug to remove stress risers in those areas. Also chamfered the stock frame and will chamfer the new tubing for better penetration.

 

[rshutchinson]

Thinking now I'm going to only lengthen it 2-2.5" if possible instead of 4". I'll set the engine in and see how much room I've got for exhaust and head clearances. I'd like to only lengthen the frame as little as needed since I'm also going to lengthen the swing arm 2-3" as well.

 

[jvb]

Thinking now I'm going to only lengthen it 2-2.5" if possible instead of 4". I'll set the engine in and see how much room I've got for exhaust and head clearances. I'd like to only lengthen the frame as little as needed since I'm also going to lengthen the swing arm 2-3" as well.

Looking good, keep postin' pics pleez

 

[rshutchinson]

Looking good, keep postin' pics pleez

Will do, for sure. Should have a good chunk of the day today to work on it so I'll post some more tonight.

Are there any known weak areas in the frame design? I've seen a mention of people not gusseting the blaster frame enough but they don't say where the failures occur. Was just wondering if anyone knows where it failed (bent or broke?). I'll find out where I can strengthen the frame once the engine is in.

 

[jvb]

Will do, for sure. Should have a good chunk of the day today to work on it so I'll post some more tonight.

Are there any known weak areas in the frame design? I've seen a mention of people not gusseting the blaster frame enough but they don't say where the failures occur. Was just wondering if anyone knows where it failed (bent or broke?). I'll find out where I can strengthen the frame once the engine is in.

The yellow highlighted area is known to bend,(collisions only as far as i know) the red highlighted area is what i would gusset at least,
I'm sure other members have done something like this before, i'd wait for their input.

 

[rshutchinson]

That's great, thank you.

The yellow area is where the new down tubes will actually be going so that should help there and I'll be gusseting it all.

 

[rshutchinson]

Pieces to go over slugs

Hammering rear half onto the slugs

Hard to see but the sprockets are very close to lining up. I'll center the engine once I make up some mounts and see how much I need to space the rear sprocket.

Top tubes will need to be bent out and around the carbs.

 

[Fast6hand]

Looking great! That's a lot of motor in there!

 

[jvb]

Made some good progress!
Make some good measurements around, before you weld her completely together.
If she's welded up not correctly aligned, with THAT engine...
But I'm sure you know what you're doing!

 

[rshutchinson]

Made some good progress!
Make some good measurements around, before you weld her completely together.
If she's welded up not correctly aligned, with THAT engine...
But I'm sure you know what you're doing!

I measured from the swingarm bolt hole to the front a-arm and they're the same on both sides so I've lengthened both sides equally. I haven't fully welded yet, the top piece I tacked in to keep the top from sagging in. I will measure square to make sure its not twisted.

The top tubes will be bent out and around to make room for the carbs.

I'm going to have to come up with something so the middle 2 exhaust headers don't think interfere with the suspension braces.


Also, made a typo, it's actually an FZR600 engine, not the YZF.

 

[dose]

Cool

 

[rshutchinson]

Does anyone have a picture of the stock blaster chain tensioners?

Need some expert opinions here. In order for me to have aligned the planes of the sprocket with the swingarm pivot I would have had to drop the engine way down through the frame (which also meant widening the lower tubes to fit the pan down) which I don't want to do because I'll lose all kinds of ground clearance OR I would have to raise the swing arm pivot. Lowering the engine would make it so I couldn't take the bike on any of the trails around here and raising the pivot that much would destroy the suspension and geometry. So, I'm left with coming up with another solution for the chain routing. Now I've never owned a dirtbike so I don't know if I'm trying to reinvent the wheel here when it comes to chain tension on bikes with a lot of swingarm travel. If I am, please educate me!

I think I have two options. Which do you think is the better option?

Option 1: Routing the chain between the shift-shaft and under the swingarm pivot. I'd mount a stationary roller to the frame just below the swingarm pivot to keep the chain at the angle needed and to clear the bottom of the pivot point. I am assuming I'd need a spring-loaded tensioner to keep it all tight. However, it's like threading a needle between the shift-shaft and pivot because there isn't much room so I'm worried that if the chain is slapping around in there it'll damage or snap off the shift-shaft. I'd have to make sure there isn't any slap in that area.

Option 2: Routing the chain above the pivot entirely. The stationary roller would be right behind the pivot point just high enough to keep the chain from dragging on the swing arm pivot. I'd likely also need a tensioner in this scenario as well. The difference I think with this option though is that I'm thinking the chain would get looser rather than tighter as the swingarm moves up which may cause issues.

Using my hand to simulate the stationary roller in this scenario.