OzVMX Forum
Marque Remarks => Honda => Topic started by: Kev on May 19, 2013, 05:20:19 pm
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Hi Guys
I am about to look into a 74 CR250 to try and fix shifting issues. The problem is dropping out of gear , normally 3rd. I have read that this is a common problem with this model so I am thinking that there would be some logical places to look at. I have never split these cases however I have done other bikes. What special tooling will I need ,if any. Are there other later models that could be used for spares? I am hoping someone out there knows their way around these bikes that might like to give some advise.
Thanks
Kev
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check the "dogs on all the gears" male and female they round off
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Mate, raced one back in the ealy days of VMX. Their gear boxes were shit, as Bazza said check the dogs but that's only half the problem.
I worked out after many frustrating gear box inspections that when I measured everything it became evident that the problem was that the slector forks only partially engage the gears. This was not a fault of bent this and worn that, it was poor design. I did after may hours of re-spacing and shimming of the gears, fixed it and never had a problem again (did 4 years hard racing prior to sale) Another poxy thing is the kick start gear is made from barley sugar and will break in half if it kicks back, the gear from a MT250 will fit and is much stronger.
Good luck
Bill.
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See if you can get a 75 CR250 gearbox. I think they were built in a Russian tractor factory, they're as solid as a rock!!
I've been racing one for 3 years with no problems at all. Besides the up pipe im pretty sure that's all they changed on the 75 model
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The 73/74 250 Elsinore gearbox was a problem from brand new. As Bill said the dogs don't engage far enough into the gears, they need to be re shimmed to enable better engagement. The 75/76 gears are stronger but still don't engage any better until re shimmed. If any of the dogs on your gears are rounded replace them or at least have them back cut. I did these mods to my 74 CR gearbox in the early 90's and raced a few seasons with no more gearbox issues.
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Spose you could always fit a 480 in it, they had good g/boxes didn't they? ;)
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75/76 boxes will do the same thing - usnless you set them up well as mentioned - don't think just changing over will help.
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Great info , thanks very much
Kev
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That wasn't your bike at the VMXWA event on Sunday was it. If it was all the comments on the start line were, "yep 3rd gear, crap gearbox"
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That was it
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....maybe not crap, just showing the signs of 40 yrs of abuse...