Topic: First Bike, First Build

[ER70S-6]

I picked up this 1973 CB500 a couple of weeks ago. Before this i have never owned or ridden a motorcycle; however, i have been in to cars and motorcycles. In the last couple of months I've been drooling over Japanese cafe racers and bobbers that appear on Iron and Air Magazines site. So i decided to take the plunge.

It isn't in the best cosmetic shape, there are several dents on the tank. There very little rust on the frame however. I managed to start the bike up two weeks ago and take it for a spin. I found a small gas leak at the petcock and an oil leak at the gear shift seal. Once these are fixed it will be road worthy.

When it comes to cars i'm a big fan of rat-rods so i think i'm going to leave it in it's current condition, minus the luggage rack, front fender, rear fender, and turn signals. I think i will only change the seat and possibly the handle bars.

Other than those things i just want to make it a reliable rider for summer cruises along Lake Michigan.

[ER70S-6]

With an oil change, new spark plugs, fresh gas, and a new oil seal i was cruising on the road today  . The bike seems to run great for not having been tuned yet. The only real issue i found was at wide open throttle in first,second, and third. When i open the throttle up the engine bogs for a second or two then suddenly it kicks in and starts pulling hard. Any thoughts on the adjustments i should look into?

P.S. I'd like to get some more pictures up, but my internet connection is way to slow  . I will post some once i'm in town this week.
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[cmonSTART]

It probably just needs a good carb job.  I'll bet they're a bit gummed up and some of the rubber parts are dried/shrunk a bit. 

Have fun with the bike!

[PurduePete]

Hey bud,

I just got a very similar bike though mine hasn't ridden in 20 years. I'm doing a restore. From my experience with dirt bikes I'd say that the above is true and you need to tune the carb. Try cleaning (or replacing) your current jets and if you still notice the same thing try some new size jets. Go up though, most of the time you won't need smaller jets.

These bikes have petcocks that you can rebuild. So pull it apart and replace the insides and that should help with your gas leak. I believe there are kits. I'm about to purchase a new one for my bike as the old one can't be repaired. Sat in a tank with fuel for too long (they thankfully turned off the petcocks though so no bad gas in cylinders).

Good luck!


PurduePete

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[PurduePete]

Also double check it is the shifter seal, that's where I was told mine was leaking too by the previous. Turns out it was the oil pump, little odd but the cap with a spring on the other side was leaking. Popped it off and pulled the o-ring from the pump (was stuck) cleaned the dirt from it all and oiled the o-ring. It doesn't leak now.

If it is the shifter seal buy a couple because I've read you'll tear one or two up before getting it right on install. Also use an impact screw driver to remove those screws. They typically have better heads and those screws are always stuck.


PurduePete

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[ER70S-6]

Well I've finally got the bike to into a good driving condition. I picked up two Bridgestone Spitfire Tires, 110/90/18 Rear, 90/90/19 Front. I'm running a UNI air filter and it seams to have improved my bogging issue, since before when i was running no air filter at all. I've got a deal on some 20-50 RP motor oil (3$/quart) and it seems to have smoothed out the idle a bit.

I still however have some noise at lower idle speeds coming from the cylinder/timing chain area. I've listened all over the place with a screw driver and i can't pin-point it. Is it just a normal noise that i'm thinking is abnormal, it does go away at above idle speed. Here is a video , if you have an equalizer on your computer try to remove any frequency above 250 Hz, this will eliminate a lot of the static and you will hear the noise i'm talking about.

[GK]

Mate it could be a couple of things, firstly cam chain adjustment, you will get a rattle out of these little hondas if you dont keep the chain tensioned properly.


The other thing is if your carbs are out of sync they will create a rattling sound in your engine.
otherwise it could be your big end bearings and you need a complete rebuild