Otis' Hot Rod Blaster build

[YZ Otis]

Otis' Hot Rod Blaster
It began as a 89 Blaster. We've owned it about 20 yrs. Played with brakes, suspension & engine stuff from the start. Put a YZ250WR engine in it around 07. Bf BOTM August 09. Switched to methanol at some point. That was entertaining. Took it apart to reconfigure the suspension and never got around to finishing it. Bare frame hung on the tap room wall for years with all front suspension mounts cut off as a constant reminder. I'm gettin pretty old so figured I could part it or put it together one more time. So here ya go, lol ... Burpp!
-------- * --------
"1989 Blaster"

Goal = Fun to build, fun to look at, fun to BS about and really fun to ride.
Inspired & encouraged by my Friends at Blasterforum.com & E2S

Otis' YZFS 250+ Blaster build
"1989 Blaster"
> Remains of Original plastics
> Fresh 1989 YZ250WR engine (wide ratio trans)
> Ohlins 360 kit w/additional porting to Ohlins' specs. ( Cylinder replated by Millennium Technologies )
> Crank rebuilt, weight added & balanced by Crank Works
> 89 Mikuni VM38 round slide ( bored to 39.25mm )
> Engine isolated from frame on magic rubber pads ( impossible, right! )
> 89 YZ250 Pro Circuit Pipe & Spark Arrestor
> 12/50 sprocket set
> CR250 anti-vibe bar mounts
> Fox Podium shocks
> A-arms +5 1/4" -.5" (actually out 2.625" and 1" in toward bike centerline by relocating a-arm mounts) each a-arm extended 3 5/8" and moved to rear 1/2".
> New A-arm bushings, seal caps, ball joints, tie rod ends and wheel bearings.
> +4 1/2" swingarm, eccentric carrier chain adjust. ( long travel, built for Fox shock length & travel )
> Amp Link chain guide ( negative reviews but I wanna try it at the dunes for awhile )
> Hand lever brakes all 3 disks & foot brakes rear only. Dual calipers on rear rotor.
> 12v battery, rewound lighting coil & TrailTech rectifier/regulator
> Headlight, tail & brake lights are led.
> Radiator fan
> ( *DIMWIT ) Stainless Bumper, tow ring, Grab bar & Heal guards.
> Silly fun stuff
Low fuel warning light, volt meter, usb charging ports, coolant temp guage, a really loud horn and Yamaha hubcaps!
* (Did It Myself With Inferior Tools)

No hurry .. finishing up the motor mounts while waiting for the crank to get back. Nothing pretty about it yet. It's just a bare frame so ya prolly don't need pictures

 

[YZ Otis]

Set some parts together to check clearances and finalize exhaust, rezzi & expansion tank locations. Lotsa final welds & cleanup to do before paint.

 

[RIDE-RED350r]

Very cool build Sir! Love it

 

[YZ Otis]

Thank you! Forgot how much I enjoyed tinkering with these things .. also forgot how much I forgot

 

[YZ Otis]

Came across this old thread.

Retro Graphics

Got started with my Retro HotRod Graphics last night. I'm no artist so I can't do skulls or naked chicks so I have to stick with the simple stuff. Used some chrome & yellow vinyl. Been layin out ideas on the puter for awhile and decided it's time to get'er done. I got a vinyl cutter years ago...

blasterforum.com

Can hardly believe it took me 13yrs to save enough $mall change to send the 360 cylinder & crank to the pros ..
Most of the diy parts on this build where made over 10 yrs ago. Another old thread.

DIMWIT parts

Freeform stainless or DIMWIT Otis parts (Did It Myself With Inferior Technology) ... figured I couldn't present a ATV for BF approval without a bit of homemade bling (only kind I can afford) and heel guards ( ya know how Awk is :) ) ... LOL ... Here's a couple pics so ya know I'm still workin on...

blasterforum.com

Anyhow, welding's done & got some paint on the frame to keep the rust away.

 

[Blaster200_117]

Came across this old thread.

Retro Graphics

Got started with my Retro HotRod Graphics last night. I'm no artist so I can't do skulls or naked chicks so I have to stick with the simple stuff. Used some chrome & yellow vinyl. Been layin out ideas on the puter for awhile and decided it's time to get'er done. I got a vinyl cutter years ago...

blasterforum.com

Can hardly believe it took me 13yrs to save enough $mall change to send the 360 cylinder & crank to the pros ..
Most of the diy parts on this build where made over 10 yrs ago. Another old thread.

DIMWIT parts

Freeform stainless or DIMWIT Otis parts (Did It Myself With Inferior Technology) ... figured I couldn't present a ATV for BF approval without a bit of homemade bling (only kind I can afford) and heel guards ( ya know how Awk is :) ) ... LOL ... Here's a couple pics so ya know I'm still workin on...

blasterforum.com

Anyhow, welding's done & got some paint on the frame to keep the rust away.

View attachment 36038

Couple of questions Otis. First off this is badass but I thought you got your yz swap blaster running a while ago?? Like a long f*cking time ago. Or is this just a refresh?

Anyway, Im curious what you did with the exhaust, or did it just fit? If you modified the expansion chamber then you just have a big bore dog with no power but I didn’t think it would fit without modifications? If it did just bolt up, what pipe are you running?


Also those bike motors have a mount on the head. Did you not put a mount there or did you weld up a mount for it right there?


Also super curious on the travel of this thing. Looks badass.


I plan on getting a long travel 450r dual rate elka for the rear end of the yfs250r when I get that far along and just cutting the shock mount and moving it back for more travel and down for a longer shock as well as lowering the rear end (I like a quad with a high front and low rear end, like the trx250r)

Also on a blaster Facebook group I did encounter a guy who has a rear linkeage suspension that phragle apparently built him back in the day. Something to think about.

Nice build!

 

[YZ Otis]

Yes you can call this a refresh. My son rode it almost daily for a few years.

I put this methanol carb on and it got scary.

Useless on trails. Exciting but dangerous at the dunes where you could open it up. Stock front suspension had to go so I cut off all a-arm mounts. Sat around in pieces for a long f*ucking time. Was gonna dump the Blaster stuff but I really want to hear those 360cc's sing. Hope this thread leads to that.

If I was to modify an expansion chamber it doesn't mean I would have a big bore dog. If it it didn't work (and it will work) I would build one. I usually do things wrong but it's fun and I learn more than talkin bout it. Here's a link to an adventure a few years ago. Had fun & put it back to stock before the Granddaughter ever rode it. (Boring)

LT50 to reed valve (rambling) - ATVConnection.com ATV Enthusiast Community

Kids Quads - LT50 to reed valve (rambling) - Picked up a 2003 Suzuki LTA50 for my Granddaughter. https://cimg6.ibsrv.net/gimg/atvconnection.com-vbulletin/2000x1504/20200724_102431_c121c86b4c91d7c5415f9214d4965ff4b8309f13.jpg She's not as ready as she thinks she is so I have the Winter to tinker...

atvconnection.com

Ya, this build will have decent travel. Our old guest Blaster has close 12" in back, a hand me down from the YZ bike.

I wanted to rake the front suspension back like the trx250r but it became to complicated. Will still be a sound platform for the 360.
Oh, never used the headstay on the kart or quad.

 

[RIDE-RED350r]

Yeah, head stays are a debated topic in the 250R world as well. Many TRX guys don't run em, particularly with big bore cylinders.

 

[YZ Otis]

Figured the head stay was not there for the engine but to help the integrity of the bike frame.

 

[YZ Otis]

A little progress.
The most important change is the front suspension. I'm anxious to see how it goes together so I start there

I had no idea how simply complicated a-arm geometry is till I had only the bottom front pivot point to reference from. Locating the other mounts and achieving the desired shock location, travel, track & caster was all the geometry my beer brain could handle

 

[YZ Otis]

Got the engine in. Happy with the motor mounts. Need to build the carb & wiring harness plus endless little details.

 

[RIDE-RED350r]

Looking great!!

 

[YZ Otis]

 

[YZ Otis]

Yikes! Prolly should've made a wiring diagram ..

A little more progress. The wiring is done. The 12v all works. Hope I got the ignition correct. Waiting for a better length rear brake line and a uni filter. Picture is for fun, posing with rims reversed (47 1/2" rear - 47" front). With rims mounted correctly it's perfect for our steep, narrow trails with some tight turns.

A little clean up for air flow

Got this pic before the pipe goes back on.

 

[YZ Otis]

Guess that's about it. I'll try to get some video when I get to the dunes.

 

[RIDE-RED350r]

Love it!! Nice work!

 

[Blaster200_117]

Guess that's about it. I'll try to get some video when I get to the dunes.
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Badass. What length swingarm?? Also what shocks?


Just started on mine. Finally picked up a clean roller (has a motor but she’s blown). Just looking for a 250 bike now.

From what I can tell she has a 250r shock which seems to have added some good travel but it is blown and pogo sticks so I’ll be looking for a new shock. I plan on using yours and phragles info to create a long travel rear end. Just trying to figure out the best shock for the rear. Thinking 250r but am definitely trying to find something longer. From my understanding ( correct me if I’m wrong) to gain more travel on these blasted rear ends the shock mount on the swing arm gets moved closer to the quad?? As well as down so it doesn’t sit so tall?? Definitely want the longest shock possible as moving the shock mount like this adds more leverage and stress on the shock and the bigger the shock the more fine tuning you can do.

I’ll be interested to see how that thing corners as the rear end sits so high. Let me know how she does. Full ride report… whoops, corners, hillshoots, etc.

Pretty soon yours will have a twin hopefully. Assuming I don’t mess the 250 swap up

 

[YZ Otis]

Nice lookin Blaster ya got there! Are ya sure ya wanna change its motor mounts.
What I know about suspension is what I read from Phragle and my own imagination. Not too scientific. If I read too much I might just build someone else's opinion. Don't care what it looks like sitting around without a rider. This quad has nearly as much sag as a stock Blaster has travel. It also looks tall cuz of it's narrow track for our tight trails. I believe sag is critical, keep the power on the ground as much as possible. I like a +4 swing arm, just a personal preference. This one is +4 1/2 cuz I moved the spindles back 1/2 in. Shocks are Fox Podiums, cheap, I can rebuild them myself under $50 and the rear has 3" of preload adjustment. For me the small secondary spring just keeps the spring seated when fully extended. You are correct about the leverage change when relocating shock mounts. Handling stress is a shocks job. Look for a quality shock with a lot of preload adjustment to play with. You need to find a spring/spring set that suits your needs. I've tried 3 spring sets on this build and not really riden it yet.
I'm setting it up for grandkids (90 - 130 lbs) so it will need tweaking.
(Boring info below)

Phragles long travel explanation.

Suspension Geometry 101

it's really not that difficult, and you can do most of it without math. Say you want to create a long travel rear end. (desireable, since yamaha claims 7.1" of travel, take the spring off the shock and cycle the rear end thru the shock travel and your lucky if you see 5") to really...

blasterforum.com

My interpretation of Phragle (old pix with 400ex shock extended & compressed somewhere in this thread)

Another homemade swingarm

looks awesome and love that sticker, haha. I have been thinking about doing something similar, but reading through phragles posts just seems to overwhelm me for some reason and I'm a little skiddish to try it, and I'm not actually super confident in my welding yet, but then again you never...

blasterforum.com

The pipe takes a buncha homework or a professional custom build. When you go through the engine make a template of the ports, base & top. I put a tube of paper in the cylinder & trace everything, just remember to figure in cylinder radius when measuring the trace. Record port timing, double check all port timing . One way or the other you'll need this to do it right. I intentionally added 4mm to the PC pipe when I put in the connector and added a buncha weight to the crank for inertia hoping to make it more user friendly on trails. Not necessary if you live in the powerband, haha!
Blaster has a giant flywheel & a counter ballance. Light weight usually equals performance but I'm looking to inertia for smooth bottom to top rpm.

You can get a pretty 3 row 450 Radiator on ebay for about $50 but I've been using this ugly old one for so long it's like an old friend.
Have patience (let the loctite dry!) and Fun ... lotsa fun!

 

[Blaster200_117]

Nice lookin Blaster ya got there! Are ya sure ya wanna change its motor mounts.
What I know about suspension is what I read from Phragle and my own imagination. Not too scientific. If I read too much I might just build someone else's opinion. Don't care what it looks like sitting around without a rider. This quad has nearly as much sag as a stock Blaster has travel. It also looks tall cuz of it's narrow track for our tight trails. I believe sag is critical, keep the power on the ground as much as possible. I like a +4 swing arm, just a personal preference. This one is +4 1/2 cuz I moved the spindles back 1/2 in. Shocks are Fox Podiums, cheap, I can rebuild them myself under $50 and the rear has 3" of preload adjustment. For me the small secondary spring just keeps the spring seated when fully extended. You are correct about the leverage change when relocating shock mounts. Handling stress is a shocks job. Look for a quality shock with a lot of preload adjustment to play with. You need to find a spring/spring set that suits your needs. I've tried 3 spring sets on this build and not really riden it yet.
I'm setting it up for grandkids (90 - 130 lbs) so it will need tweaking.
(Boring info below)

Phragles long travel explanation.

Suspension Geometry 101

it's really not that difficult, and you can do most of it without math. Say you want to create a long travel rear end. (desireable, since yamaha claims 7.1" of travel, take the spring off the shock and cycle the rear end thru the shock travel and your lucky if you see 5") to really...

blasterforum.com

My interpretation of Phragle (old pix with 400ex shock extended & compressed somewhere in this thread)

Another homemade swingarm

looks awesome and love that sticker, haha. I have been thinking about doing something similar, but reading through phragles posts just seems to overwhelm me for some reason and I'm a little skiddish to try it, and I'm not actually super confident in my welding yet, but then again you never...

blasterforum.com

The pipe takes a buncha homework or a professional custom build. When you go through the engine make a template of the ports, base & top. I put a tube of paper in the cylinder & trace everything, just remember to figure in cylinder radius when measuring the trace. Record port timing, double check all port timing . One way or the other you'll need this to do it right. I intentionally added 4mm to the PC pipe when I put in the connector and added a buncha weight to the crank for inertia hoping to make it more user friendly on trails. Not necessary if you live in the powerband, haha!
Blaster has a giant flywheel & a counter ballance. Light weight usually equals performance but I'm looking to inertia for smooth bottom to top rpm.
View attachment 36121
You can get a pretty 3 row 450 Radiator on ebay for about $50 but I've been using this ugly old one for so long it's like an old friend.
Have patience (let the loctite dry!) and Fun ... lotsa fun!

Thanks for the info. Still deciding on shock I think I’ll run a 250r shock or a 400ex. I’d love a longer shock but I don’t want to move the shock mount on the frame.

Thinking 250r just cause it already has one on it (it’s blown) and I’d probably just send it to rocket Ron racing and have him valve it for me and put dual rate spring on it… or maybe I’ll get the spring and revalue/respring myself.

yah my biggest concerns doing the swap are radiator mounts, rear swing arm mount, and the pipe. I can weld basic motor mounts in my sleep so I bet the radiotor mounts are the same process so not too worried there.

Two biggest problems I foresee is the swing arm engine mount and the pipe although I know of one other member that kx250 swapped and he said an fmf gnarly fit without modification to the expansion chamber but he had about a mm of clearance and when it idled it vibrated into the frame…. Nothing a little dent with a mallet can’t fix.

 

[YZ Otis]

Oh, it runs! 2nd heat cycle. I'm too old to kick over that extra 120cc's but my son can do it without a problem. Short video. I don't have a editor yet so it is what it was. He's a bit heavy for the suspension.