Vintage Dirt Bike Q & A

Hi,

This may be a stupid question but I am racking my brain trying to get it to work out. I am trying to time my 79 Cr 125R after a rebuild. I have not heard this bike run in 15 years and it's a treat to hear it run. However, I am trying to set the timing with the book, but it shows that I should have an "F" mark, but it doesn't exsist on the rotor. I have tried to set it at the 2.44 millimeters BTDC, but there is just not enough movement on the stator. It just looks all wrong too. Do I just set it to TDC and line up my stator with that? All I have is a "T" mark. I lined up the stator with the center of the stator mounting bolt hole as shown in the manual, but it still doesn't seem right. Any ideas? As well, I have read that alot of riders are leaning out their mixture to 32:1. Would you recommend this on this bike. It is smoking like a bugger, so I'm willing to give it a try if it would be deemed safe. Thanks in advance for any answers.

Cant help with the timing.

Would certainly recoment running 32:1 high quality synthetic or racing oil.
This is ample lubrication and safe.


You may want to check your crankshaft seal on clutch side for another possible cause of smoking exhaust.

You did not say what your present fuel mix is.

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'84 Honda CR500
'84 CR125
'85 KX125
'83 IT490
'82 Maico 490
'80 YZ465
'75 Husky CR360 GP Mikkola
'75 CR250
'72 DT2MX
'91 XR200

Thanks for the oul mix help. It's currently at 20:1. I did check the crank seal (3 times), and I am quite sure that it is OK. Thanks for the help.

I have a couple of '79 CR125R's and I feed them premium gas with 40:1 synthetic oil with no problems.

Hey Czechman.....just wondering how you checked the crankseal, I have a motor that I need to check, was planning on draining the oil and pulling the clutch cover, starting it up and shooting some carb cleaner to see if she misses a beat. ????? How the rest of you guys do it?

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Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007

I didn't shoot carb cleaner or anything like that. I just did more of the visual inspection. The seal seems to sit on the bushing quite tight so I thus assumed that it is fine. Maybe thats the wrong way to go about it, but it's pretty much all I know. I'm just starting to learn some tricks. Sorry I couldn't be of more help. Let me know if you succeed.

Go to the Suzuki RM, TM & PE forum on this site and look at the topic "Leakdown Tester" by pursang. This is the best way to check bottom end seals. I don't think a visual inspection is too accurate. Good luck.

Thanks MD. I'll give it a try