Vintage Dirt Bike Q & A

After months of messing about Ive finally given up on the steering head bearings and instead refitted the (still good) originals, sigh... seems no one had bearings that fitted my MT who knows why?! So since i had most of the other parts, I spent a few days building up what i had and then had to clean up and lube old cables and make up a throttle cable from parts of other dead MT ones i have in my spares. I kept surprising myself at what i did have which made the missing parts all the more annoying LOL

The engine is in, but it needs painting and has been fully rebuilt with new seals and bearings, just need the small end and i can fit the CR top end and Bassani pipe. Need to source a carb and an inlet manifold still...

Wiring was a mess that took a day to sort out adding the missing connectors or swapping better ones in after a huge clean up and re-taping session, and also work out what went where when i got it back on the bike.

not too much needed now tho... new bars (the ones fitted are twisted and only there to work stuff out), front turn signal stems, levers (just bought a set), small end and carb... wow, for a long time it was just a frame, its funny to see a second MT in the garage now! LOL

Its got a mismatch of wheels on it right now as i have two sets of rims and the alloy rims with the dirt tyres were on my other MT but the front end was borrowed from this bike, so the front wheel got moved over but the back ive still to do. more work! LOL

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

That's a good looking roller you have there! I like the rear shocks. Are they from a CR?

~JM~

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WWW.CADDY500.COM
The High Performance
Big Block Cadillac Forum

Thanks!

Shocks are NOS vintage Red Wing Hammerheads and are the longest ones they did. Really nice kit, all alloy and made in Japan. Needed to grind down the rearmost chain guard fixing to get the reservoirs to fit, but worth it.

From Omars on the web:

These beautiful cast aluminum RedWing shocks are period right for street trackers, cafe bikes, vintage flat trackers and vintage MX racers. They add a novel, vintage look to your project bike. These are NOS (new old stock) products made 25 years ago in Japan. And yes, the price is for a pair. The damper rods are a thick, 1/2" in diameter to handle abuse. These eye-to-eye shocks are re-buildable. The supply of some components is now exhausted so we purchased contemporary parts to keep these old shocks available. At some point in the future, we will no longer be able to sell these shocks because the supply will just run out. Shocks come with spacers.

The reservoir on hammer head shocks is at the bottom, not the top. You need to see if your chain guard will allow clearance for this shock. The body of the shock is 2" wide and the springs are 2 1/4" wide. So measure 1" in from the center line of your existing shock-is your chain guard within that dimension? If it is, modify your chain guard or order our Street Tracker shocks.

Another little warning-some swing arms with long tapered shock mounts (like Maico) may contact the bottom of the reservoir. In this situation you must relieve the swing arm for clearance.


14 1/4" NOS RedWing eye-to-eye Hammerheads $205.00

Built-in reservoirs on the bottom hold 4.71 oz or 157cc of oil. The travel is 4.13" which makes them technically AHRMA cheaters, okay in Evo classes. Current spring choices (at this time) are;

* 60/90 lb chrome progressive springs
* 75 lb black single rate springs
* 70/100 lb white progressive springs
* 80/110 lb yellow progressive springs
* 110 lb black single rate springs

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Finally got hold of a small end bearing that fits, a generic Wiseco... Why on earth did honda mess with the multiple bearing thing?!??

Anyway, now i can put the CR250M top end on the bike... phew!

An update with some pics tomorrow I hope.... Since these pics were taken ive added some new levers, new bars and turn signals and a bunch of other bits n bobs like the rear wheel that matches the front etc etc... its really been a labour of love to clean up and reuse parts, but its looking great!

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

CR250M top end on and the Bassani pipe sort of fits (see the other thread on that - viewtopic.php?f=21&t=3118&start=30 ), so rolled the bike out into the open so it could see some daylight...

Just needs the carb and the manifold and its a runner... eek!

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Jon,

The bike really looks great! It'll be done before you know it ...

Your pipe fits the opposite way the MT125 pipe fit my MR; yours is low and kind of points down, and mine was high and pointed up. It's probably from the exhaust exit angle of the CR cylinder (the MX cylinders were more of a straight shot from the exhaust port, with less down angle). You could heat and bend (or cut and weld) the header - I've done both - or just live with it.

I think I spent more time on exhaust work than any other single item, but I really need the pipe tucked in tight.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Thanks Ray, well I do need to order a carb and manifold and work out how best to feed the air. Id like to run the old airbox, but i know everyone will frown on that... just dont tell them, it can be our secret

I think the pipe would fit better if i have the ground fins on the head like the MT head is. The CR had a down pipe and as such had full height fins. Its a simple fix with a dremel, i just didnt want to mess with the head unless I really liked the pipe.

Whatever happens I will improve the fit of the pipe and sort out a better bracket if i keep it, else it will get sold onto an MT rider and i will get a different pipe i guess... the price of progress perhaps?!

Anyway, its getting closer and it looks clean and cute, i just hope it sounds mean as its a bit too cute right now LOL!

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Jon,

I would use the MT airbox too - it might need a bit of work, though. I'[m using the MR's original airbox, but without the top and submarine snorkel; I also ground off the top lip to allow air all round the element. It works great.

Does the MT head fit the CR cylinder? I used an MT125 head on my CR for a while. There's also the '76 CR250 head, but nearly half the fins were removed to make room for the up pipe.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Yes the mt250 head fits the cr250m cylinder. The only problem is that the mt dosnt use as many studs as the cr so one of the studs will have to come out of the cylinder. Its not hard I had to remove my studs and put them in my new cylinder. I have heard the mt wont seal as well as its not got as many studs. It was designed for the up pipe tho so its fins are shorter on one side.

Ray, the MT filter is a sort of donut and needs a lid so as you say I might have to snip it down so it is just the middle part to form the lid on the filter, that would allow a huge volume of air to come in, so is probably the ticket with this, good thinking! I have a spare lid so no problem giving it a go either. not much good for riding through water tho, not that i expect this bike to do much of that LOL!

The MT head will go on the CR with the mods Woosh says, or i could just grind off the fins... 73/74 CR heads are rare but hey its just a head right?! The 76 CR250 head i dont think fits, as they have different studs.

Woosh, Agreed, I dont want the higher compression to pop the old MT head and cause a leak so will stick with the CR head. I could redrill an MT head to add the studs, and i have looked, but it means milling off parts of the fin and getting a flat surface for the nuts, not ideal and not cheap to have done.

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Jon,

I used an MT250 filter element in my MR for the first year or so, as it was the only thing I could find at the time. It was about 1/2" taller than the frame and stuck out of the airbox a little, but worked OK. I never realized the MT element's plastic bottom ring had an inner lip that snapped onto the bottom edge of the frame, until after I stopped using it. I recently replaced the foam gasket on the airbox floor with a new one, now it seals perfectly instead of leaking grit into the carb throat.

I modified a '73 CR250M head to fit the MR (definitely NOT easy) and then found another one as a spare, so they do turn up on eBay now and then. I wouldn't feel too bad about grinding on it if necessary. I borrowed a woodworking belt/disc sander from a buddy, and I'm amazed how well it works on metal - something similar would probably do a great job on your head. I have yet to sand any wood with it.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Ive seen those MT filter bottom lip/floor things and have a few here from old filter setups. The new aftermarket filters dont have them, and I will have to see if i need one, the same thing with the top, as they have foam that will squash a little to fit so im hopeful i dont need anything else for the fit once the lid rests on and squashes it all down tight.

Ahh yes, well i have a secret weapon for grinding, its called a black and decker powerfile. i bought it years ago and it eats steel and alloy really well, just like the tool you mention. I also could use burrs on the dremel as well i guess... lots of options when i get a few mins i'll have a look

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

I have the same shocks on mine! And the same pipe!!! Very nice job!

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I drink your milkshake!

Thanks Danny, glad you liked... you have good taste with those parts

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Hey what tire do you have on the back of your bike? It looks like a rally raid but I cant tell for sure.