Vintage Dirt Bike Q & A

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PostPosted: Sun May 12, 2013 8:15 pm 
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Joined: Thu Jan 03, 2013 6:30 pm
Posts: 89
Don't sweat the tubes being out just a touch, be sure mark both high points in the bends and make sure the are both facing the same way (to prevent binding) I fixed mine by overbending them in a press. USED to be Forking by Frank was a source for legs but I think Frank died a few years back, so I don't know what they offer now.
2 fddy forks are much better to keep up than the toothpick 125's. I prolly have 10 sets of 125 forks to this day sitting in my shop.

As for tires I always was super worried about how heavy they were vs which type they were, but then I was a 125 specialist. Unless you are traveling to places where sand tires are a must (Southwick) or a mud race then good intermediate to hard tire should do the trick. I of corse had several sets of wheels/tire types at my disposal.
The sizes you mentioned sound okeedokee.

I remember my first time to one track in Florida and thought Id need sand tires....couldn't be farther from that.. it was super hard pack blue groove....whoda thunk.

Go for it!

_________________
1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.


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PostPosted: Mon May 13, 2013 12:22 pm 
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Joined: Sat Dec 01, 2007 3:03 pm
Posts: 265
Hey Ohio, whats the grease gonna hurt? I was taught to always grease new seals, maybe I was taught wrong.


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PostPosted: Mon May 13, 2013 9:42 pm 
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Joined: Tue Apr 02, 2013 4:09 pm
Posts: 19
There maybe confusion on the whole greasing seals thing. It's ok to grease the outer diameter of the seal slightly prior to inserting it into the lower leg or sliders. I use we-40, but have used grease. I do not however put grease in the inner diameter or lipped side. This wil trap dirt and degree defeating the new seal in a matter of seconds on a sandy track. My two cents.

I really enjoy the input guys thank you for the advise on these old bikes. I'm having a blast getting mine to run past my buddies taco with a 370 motor.


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PostPosted: Mon Oct 07, 2013 8:21 pm 
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Joined: Tue Apr 02, 2013 4:09 pm
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Guys, Maybe I'm stating the obvious here, but I want to talk about the importance of correctly setting the stock ignition timing. Had my 73 Elsinore for just over a year now and have not been impressed with how it has performed. I have complained early in this thread about gearing, clutch, to much octane,pipe, carburetor etc. I thought I had the ignition set correctly before as I've tried several times in the past to get it just right using the manual and a dial indicator. I recently replaced my points plate with another and spent some time really working the points making sure everything operated correctly and smoothly. Pulled the motor from the frame and put it up on the bench... Eye level. Set the points gap as instructed then the ignition timing at 1.5-2 degrees. I'm telling anybody struggling in this area that my bike today was completely transformed. It ran like a raped ape! No more clutch problems, starting issues, gearing problems. I got the true Elsinore experience. Diligent timing is a must on these points bikes. PVLers need not read this. I'm excited because now I can spend money on suspension and not on a motor rebuild.


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PostPosted: Sat Dec 28, 2013 8:36 pm 
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Joined: Tue Apr 02, 2013 4:09 pm
Posts: 19
Been awhile since I posted anything. Gave up on the points and recently replaced them with a PvL ignition. We'll worth the money. Not much of a noticeable performance upgrade, but what it does do is give reliability and consistency. I'm still very much struggling with the front end. So much so Im now using a lightly used 73 MT front end. Same as CR front end except for a couple extra ears on the sliders and the dampening rods. Seems the orifices are different. MT front end is softer even with heavy spring and heavy oil. At least it's keeping the fluids in now. I think my cr sliders might have been worn out. I'm gonna try using the cr dampness with the MT sliders next. Out back I'm using a set of series 12 progressive shocks. Didn't think I needed them until I rode with them. Huge performance increase from stock. I imagine works performance or race techs are even better. I found that my intake boot was allowing air in after the carb and believe this contributed to a recent seize. Wosner piston along with a new boot and she is running real good now. Next up will be a back up frame that I will gusset myself along with plastics and wheels. BTW, found an original CR GP seat. Love the look and feel. It allows me to grip the bike with my knees now. My CR is still out performing my buddies tacos, but not by much as they are starting to get their stuff working real nice now too.


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PostPosted: Sun Dec 29, 2013 6:06 pm 
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Joined: Fri Jun 02, 2006 11:12 pm
Posts: 159
Location: Salinas, CA
A minor bend can be straightened using your machinist's press. I've done that both working as a mechanic back in the day, and on my own bikes too. I did this on my own cr250m and those forks worked great for several years after that. I am no pro or anything, and ride more like a 50 year old than like an 18 year old.

I drilled a 1 1/2" or so hole in short length of a 2x4, then cut it in half in line with the grain to make cradles to set the fork tube on. Use another 2x4 cradle between the press ram and the fork tube to prevent denting the tube. Roll the tube until you identify the high spot. Put the tube in the press laying it on the 2x4 cradles with about 10" to 12" spacing between those cradles. Press down on the high spot to straighten. Do just a little at a time and check for straightness between attempts. You should be able to get it to where you don't have any perceptible bend and no ripples in the metal.

That's just my own personal experience though. Every set of forks is different and this may or may not work for your forks and your riding style.

Good luck,
Jon


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PostPosted: Tue Dec 31, 2013 5:39 pm 
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Joined: Tue Jul 29, 2008 11:02 am
Posts: 47
Location: Nashville, TN
I'm getting a PVL for my MR as well. Also getting Race Tech to rebuild the stock forks with emulators and springs. Matt Wiley gives a good deal to racers on these, it's worth it. I also have the same shocks. Hoping to have mine ready in the next few months for racing Cross Country with AHRMA this year.


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PostPosted: Thu Jan 09, 2014 12:13 pm 
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Joined: Thu Jan 03, 2013 6:30 pm
Posts: 89
IF you take the time you CAN graft a 125 ignition on the 2 fiddy.
You will need to make a backing plate and change the taper on the rotor to match the 250 crank.
I did this before PVL or Motosplat's were offered.

_________________
1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.


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PostPosted: Tue Jan 14, 2014 3:02 am 
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Joined: Thu Oct 14, 2004 7:25 am
Posts: 68
Location: Sydney, Australia
i run an internal rotor yz250 yamaha ignition in my methenol burning dirt track cr250 champion.it has a reed valve as well.it goes way faster than i can ride it.38mm mikuni big down pipe.have a std elsie as well in bits must build it one day
jim
australia :D :D :D :D :D :D

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Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig


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PostPosted: Thu Apr 10, 2014 9:37 pm 
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Joined: Tue Apr 02, 2013 4:09 pm
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Here's mine finished.


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PostPosted: Fri Apr 11, 2014 10:24 pm 
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Posts: 19
More pics from milestone today.


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PostPosted: Fri Apr 11, 2014 10:24 pm 
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1 more


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PostPosted: Wed Apr 16, 2014 11:51 am 
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Joined: Thu Jan 03, 2013 6:30 pm
Posts: 89
SANO !!!

_________________
1994 AHRMA National Champion Sportsman 125 Intermediate.
1996 AHRMA National Champion Classic 125 Expert.


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PostPosted: Mon Jun 27, 2022 10:06 am 
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Joined: Sat Jan 04, 2014 1:07 am
Posts: 19
Hello,

Apologies for replying to this old post. I have a 73 CR250M that is undergoing a transmission rebuild due to 3rd gear shifting problems.

Can anyone please direct me to the details of the third gear mod where the gear is cut and shims used for increased dog engagement.

(Original text…” When you have the tranny apart, look up the third gear mod where you cut the face of the gear off and shim the other side to provide more dog engagement.”)

Thank you for any help,
Ben


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