Vintage Dirt Bike Q & A

FWIW: If it runs right with the Keihin then leave it on. If you ever have carb problems then switch to a Mikuni rather then replace it with another Keihin.

If you just want a cheap quiet solution try J.C. Whitney. You will have to wait until you get your pipe in so you know what size canister to buy. I'm pretty sure they have cheapo weld on canisters for ~$10-$20. The only other one I know of one up from there is the old style Supertrap and it would be about $120.

Don't even think about pulling the cases apart w/o a manual. You should be able to pick one up for ~$25. Yes you should rebuild the bottom end but I would say no for now. What are you going to do if you put it together and find out 2nd gear is missing? Right, another $30 set of gaskets, 6 months of looking for a replacement gear, and 6 hours of tinkering with it to fix it.

For the air filter I would just go down to any local cycle shop as they all carry UNI Filters. They are a foam filter with a hard rubber/screw clamp arrangement to mount directly on the carb. You need to know the carb outside diameter to buy the right filter as they come in several sizes. They are maybe $20 but you can get one the same day instead of waiting several weeks for eBay.

Ahhh, okay thank's for clearing that up. I just went outside to check, and it came with a B9ES. The plugs in relatively new condition, but I'll keep my eye out for the B9EV since you say it's a better plug. I can always keep the old one as a spare.


Thanks for answering all those questions. I appreciate it! And yes, I was going to pick up a shop manual sooner or later. Now I've got a good reason to. I've seen a few different ones before. Do you reccomend any one over another?

And another thing I think I should ask about, where can I get a good complete gasket kit? After thinking about it, it doesn't really make much sence to have the engine bored out, buy a new piston, and all this stuff only to reuse old gaskets.

For manuals I like Clymer better then Haynes. I have never even seen a factory repair manual so maybe someone would want to comment on those.

I have bought more then a few gasket kits off eBay and make a lot of my own with the sheets of gasket material you can get at Ace Hardware. I think Vintage Elsinores may have them, worth a try.

There is also the swap meet link you can click at the top of this page to see if anyone has something you need.

7993356344. This item on eBay is a Clymer manual that covers your bike. Factory manual is best, but a manual - any manual - is better than none. I keep a search defined in My eBay that finds any motorcycle or ATV manual with "CR" in the title. Just click once in awhile to see what's come up...

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Yeah I heared about making your own gaskets, though I didn't know where to get the stuff. But I think a new head gasket is in order anyways, and I doubt you can make those with the gasket sheets.

I had a look at Vintage Elsinores and they seem to have it. 36 bucks, not bad I suppose. http://www.elsinores.com/item411281.ctlg

I'll be taking a look at the swap meet. Thanks for pointing that out!


Thanks a bunch, glad you found that. I currently don't have an ebay account, but I'll try getting my friend who does have one to buy it for me.[/url]

If you need an extra exhaust manifold let me know I have extras just pay the shipping. The DG Pipe has a built in silencer so no worrys there. You can also get a Pro-Form pipe too that has the built in silencer but more costly than the DG on E-Bay. Both pipes are excelent & pretty quiet at an Idle. I have ran both pipes & like them. I run original FMF pipes on my race bikes.

That would be great actually! Any idea what shipping would cost? And do you have an email address so I can contact you when I get to the stage of buying all my parts?

That's good to know too, that the pipe I'm looking at isn't an el-cheapo brand piece of junk.


One thing I just thought of this morning is the cylinder head. The top of it is all dented or pitted or somthing, just lots of really small dents in it. What's that all about? And more importantly, is it still usable?

Also, any guides on adjusting the timing? I guess this would be included in the service manual, I'll have to pick one up real soon.

Lastly, just gotta ask. Can I go trail riding with this dirtbike? Or would going slow like that cause it to overheat?

The dings in the cylinder head are from metal or grit passing through the engine. In theory the raised edges of the ding can become hots spots and maybe cause detonation, but in practice lots of the 2nd-hand parts circulating have this kind of minor damage. Do your best to clean any carbon off and polish them out if you can, but don't sweat the small stuff. I would expect that you can trail ride this bike, but the powerband will probably wear you out long before the motor over-heats...

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

You can contact me at mailto:frohrs@cox.net for the exhaust manifold it shouldn't be that much for such a light part, it will be the shipping I;ll have to check. I don't recomend this bike to be trail ridden it's meant to be screamed. More of a race bike than a trail bike. You can also check E-Bay for another stock head in good condition or in aftermarket head which will boost compression but you'll have to keep an eye out for your top end more often. You will be fine if you can find a stock head for your bike.

Hah dings? These are like, dents! Holes even! (well that's taking it a bit too far) I'll try smoothing all that out though, sanding them down a bit or something.


Thanks man, I appreciate that and I'll get in contact with you once I've got the rest of this engine apart and am ready to buy all my parts.

I just looked on ebay and there's a stock head from a 1978 CR125. Everything looks basically the same as far as I can see. Would it be alright to use a 1978 head on a 1976 engine? I'm probably getting ahead of myself though as I could probably just fix the head on there now.

Now both of you say somthing different when I asked about tral riding it or not. Maybe take it to the gravel pits up by my cousins and rip around there for a while. I know it's meant to be raced, but I'm much too new to go fast as all hell on this thing. Heck, I've only ridden a dirtbike once before this. I mean, I did alright. I wasn't like my brother, I didn't let go of the clutch thinking it was the brake causing the bike to jump out beneath him and spin around on the ground till my cousin stopped it.

But yeah, I just want to know is it okay for the engine to do that. I know I should have gotten a trail bike if I wanted to go trail riding, but I got this thing for 40 bucks! Doubt a deal like that is going to come around again any time soon.

Dale,

The 76-78 CR125 heads are all the same.

More of an opinion and exageration then valuble info. Imagine a bike that idles along at 20MPH in first gear, accelerates like crazy from there, and you can see the problem using it for tight trails. That is essentially what you have.

If the trail riding you do is fire trails, jeep trails, that kind of stuff where you are doing 20-40 MPH you will be fine. If you are talking about picking your way through a forest on a game trail you may have to do something like buy a bigger rear sprocket.

Haha okay, I had a feeling they were.


Ohhh wow, I see now what you mean. Hehe, this thing's gonna be some serious fun if it's anywhere near as fast as you say. Yeah I was just wondering why you said I shouldnt be trail riding with it, I doubt I'd be riding tight winding trails like that often if at all now that I think of it. I was just curious.

That really got me to thinking what I am going to do with it y'know. Probably just take it down to the floodway where all the off roaders go and ride through the mud there and whatever.


Well, I think I'm all good now. Got all my questions answered (that I can think of at the present time) and am ready to get on with working on this thing.

A huge thank you to all who helped me out these past few days, you guys helped me learn alot! Hopefully in due time I'll be in your guys' positions, helping out the newbies. Thanks again!