Kurlon has a dirt project

[Kurlon]

Stimilon 2012?

I'm banking on 2010, my only limiting factor at this point is shop time. Fortunately I have the week off before Stimilon, and if I have to I'll skip LAPS on Tuesday to get it done.

[Kurlon]

On the radiator front, given that my units seem to be water tight, but beat to crap... would it make sense to just make a metal frame ala radiator guards to go around them, bolt the shrouds to the frame, and let the radiators hide inside the guard?

[Paul_E_D]

Wirelessly posted (Mozilla/5.0 (webOS/1.4.1.1; U; en-US) AppleWebKit/532.2 (KHTML, like Gecko) Version/1.0 Safari/532.2 Pre/1.0)

guards are good.

[Paul_E_D]

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guards are good.

[seth399]

On the radiator front, given that my units seem to be water tight, but beat to crap... would it make sense to just make a metal frame ala radiator guards to go around them, bolt the shrouds to the frame, and let the radiators hide inside the guard?

sure, I rock radiator braces

[Kurlon]

Just figured out my current 'yz250' radiators are yz125 units, which is why none of the mounts/plumbing makes sense. I'm trying to score a radiator setup cheap off eBay, if that goes through I found a set of Devol guards for $30 for that year bike.

[Kurlon]

And... just scored a set of proper, 92 YZ250 radiators and associated plumbing on the cheap. Engine is coming out tonight, hopefully can deal with it and the frame R&R I need to get done this weekend, possibly even have it assembled for a shakedown run Sunday sans new radiators?

[Kurlon]

Heh, even mo-bettah... I spotted amongst the various flood of chinese aluminum radiators for modern YZFs a listing for a pair sized for 86-88 YZ250s. Odd bike to target, and I thought at the time I had an 88 YZ250 radiator on one side... so I asked for additional pics so I could see the mounts clearer. Turns out the frame mounts are way off, but the rest of the radiator setup is spot on. I thanked the seller for the pics and let him know they confirmed the radiator setup was close but not quite right for my machine.

He's now asking for my radiators to make a pattern off of, he'll sell me the resulting set for $50. : ) One off custom aluminum radiators for my roach... this could work. No way to get it done in time for Similon but... : )

On the topic of radiators, the parts fiche doesn't quite make it clear how the plastic mounts to them. If I'm not running radiator guards, the louvers appear to slot into the side near the frame, and they have threaded clips on the shroud side, you bolt through the shroud, through the tab on the radiator into the clip? It looks like there may not be enough room to run the louvers inside the radiator guards, but the guards don't have anything to take the place of the threaded clips the louvers provide so... what do the shrouds bolt to at that point?

[Kurlon]

Engine out, all that's left on the frame are the wrong radiators and a front end sans headlight. New radiators won't arrive till next thursday which sucks, but it gives me time to make some repairs to the frame before then I suppose.

That friggin engine MIGHT weight as much as some of my pitbike motors. I have some BAAAD ideas now. : )

[lrrs313]

That friggin engine MIGHT weight as much as some of my pitbike motors. I have some BAAAD ideas now. : )

What do you mean, now? You've probably had those (or similar) ideas since before you even bought the bike!

You can do enough to that 250 motor to make it have more than enough power......

[Kurlon]

That 250 stock should have way more power than I can utilize as a dirt bike... strapped into my CRF70 frame however... : )

So, changed out my linkage/shock bearings and bushings today. I'm never changing the shock upper again as it's a mess up there. Bushing is in, it now has seals (which it didn't before) I'm just calling it good and running it...

Discovered my swingarm has been welded on, got a bit of a crack forming on one side... didn't bother putting new bearings in it as I'm hopefully getting a better one in the mail Tuesday. I did pull the rollers, pack'em in new grease and reassemble though. BTW, I now HATE open roller bearing designs. What a raunchy PITA!

Motor is going to the shop with me Wed for a clean/teardown/new seals/gaskets/assembly session. I'll start reassembly of the bike that night and hope to finish it all (including a touch of welding on the subframe) Thursday so I can head to Southwick Friday. Still waiting on some Yamaha parts, and some ebay parts... but I have enough to bodge it into working order one way or another.

[Kurlon]

May have found a show stopper for now... cases are busted out around the bottom of the clutch pull arm. I'm going to epoxy it up and see what happens while I try and track down a set of cases to transfer everything to. Otherwise, the motor is mint. Top end is new, as is the rod, crank seals, etc. Transmission shows very little wear, clutch is new from the basket up. The motor would be mint if wasn't for the trashed clutch rod area on one case, and boogered up drain bolt boss on the other.

Motor is dead nuts simple to work on, I'm quite enjoying the design so far.

[seth399]

nice, good luck with it my man

[Paul_E_D]

Jeezus, You have really stepped in it. I think anyone tempted to by an old dirtbike on the cheap should be forced to read this thread before leaving the house with any money in hand.

[Fast_Eddie]

I've had good luck repairing r/c engines with the slow setting JB Weld. If new cases can't be found, it's worth a shot. The fast set JB is more like regular epoxy, don't use it.

[BLACK SQUIRREL]

tick tick tick tick tick

[Kurlon]

JB Weld in progress. Initial application looks good, going to beef it up tomorrow with a second application. I'm on the verge of collapsing though, been pushing WAY too hard since Tues, never took time to recover and am paying the price for it. I'm not making Similon, and I'm not even going to try for MX207 Saturday. My body is telling me in no uncertain terms to slow the fuck down NOW.

In the mean time, I've found a second set of cases, complete with a motor in them sans cylinder, and the crank is seized, so even if the JB Weld job fails, I'm all set.

[seth399]

dude, you probably will have enough parts for 6 half done bikes!

[BLACK SQUIRREL]

Wow good deal

[Kurlon]

I'm sending my 1992 WR250's top end out to Eric Gorr for his magic touch, and a slightly bigger piston... This in one shot covers the replate and piston I need anyways, repairs one of my two heads as well as drops the CR to make running on pump gas viable and cleans up a slightly abused powervalve in one shot.

As part of the 265 kit I get to choose how I want the powerband to be. More 'low to mid' which he suggests for stadium MX, offroad, or novices. I'm a massive novice when it comes to dirt so that's where I'm leaning. I'll be riding on trails occasionally, big outdoor MX tracks mostly. The other option is more 'mid range to top end' which is suggested for outdoor MX, intermediate to expert riders.

I was all set to tick off the low to mid option when I got to the next sentence that points out big bore kits give more low end just from the displacement bump... so now I'm not so sure if I should opt for the mild route or trust that my motard experience will transfer and I can handle a proper big two stroke hit like a big boy? (I've got a big flywheel to help with that too thanks to it being a WR...) So far I haven't killed myself on Brian's 250?

Suggestions?

Other than the top end the motor is ready to bolt back in. I have the correct radiators finally, and a rear brake master that is in MUCH better shape. New swingarm has arrived as well, only part I don't have is a pair of radiator louvers but I know where to source them. Chassis will be sorted while I wait for the top end to get back to me.

[seth399]

my suggestion get the low/mid. I almost guarantee that you will be doing more luggy riding/midrange than wringing the piss out of that thing

O and PS- I think you are crazy for doing this work to a 92 aha

[Kurlon]

my suggestion get the low/mid. I almost guarantee that you will be doing more luggy riding/midrange than wringing the piss out of that thing

O and PS- I think you are crazy for doing this work to a 92 aha

The cost really isn't that much more than me sending the cylinder out to Milenium for a replate and buying a new piston retail, and I get repairs and ride ability improvements to boot so what the hell? I got the crappy end of the stick when I bought the wreck, I've scored big on ebay for repair parts, might as well top this polished turd with a proper capstone, right?

[seth399]

word, once you have it together I assume you will have a strong runner for a while

[Fast_Eddie]

My favorite 2 strokes in the woods seem to be the ones setup for low end torque. New England style single track is usually ridden between 3000~7000 RPM.

[lrrs313]

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Definitely low to mid motor. Top end screamers are lots of fun for fast guys. Bottom end power is a lot more fun for mortals. All it means is that you will be a gear higher and easier on the clutch.