305 top end questions

[kartsport]

I'm currently building up a 305 Scrambler motor to use in a street tracker style bike out of a couple of parts bikes I have laying around, and I have a couple of questions on the top end I intend to use.<br /><br />I pulled apart two motors to try and make one good one out of them (one motor had a bad head, but good pistons/cylinders, and one had a good head, and lower end, but the left piston was frozen in the cylinder from sitting) and I noticed that the intake valves on the bad head had a &quot;B&quot; stamped on them, while the other head did not. I tried to fit the &quot;B&quot; intakes to the good head , since they were in much better shape than the ones that came out of it, but they don't seem to want to fit. I know that Honda made &quot;A&quot; and &quot;B&quot; pistons/cylinders for their CR125's, so I'm wondering if that was the case here? Did Honda have two different spec intake valves/guides on the 305s?<br /><br />Also, on the head I intend to use, the cam end for the ignition has a lot of play in it, while the end on the bad head has none. I'd pull the cam out of the bad head, but it's junk due to being run without any oil by an unknown previous owner. I'd just go and buy NOS parts or take it to an engine builder to take care of, but I'm in college and money isn't something that I have right now. Any ideas? I don't know what kind of play to expect on that, but I'm reasonably sure that what I have is too much to use. I'd rather not spend all winter building this thing to have it fail to fire, or worse yet do damage to it due to a bad part.<br /><br />Thanks!<br /><br /><br />-------------------------<br />'67 305 Scrambler (stock and original)<br />305 Street Tracker

[georGe]

I dont know of there being 2 different valve sizes for the CB/CL 305 series. It is possible that different size valves were installed by a previous owner for what ever reason.<br />As for the ign. end of the cam having play that is not uncommon and is not good. What kinda play are you getting in/out(thrust) or advance/retard (rotational) or up/down/side/side ?<br /><br />georGe

[kartsport]

The reason I asked about the &quot;B&quot; intake valves was the fact that the exhaust valves from both heads had the same stamping on them, and they fit either head.<br /><br />As far as the play goes, I'm getting a lot of play in thrust and rotational, but none as far as up and down goes. I figured that the thrust wouldn't effect the timing, but that the rotational sure would. Is it possible to take the end off of the bad crank, or am I looking at buying a cam half?

[georGe]

The rotational is probably due to sprung springs @ the advancer mounted on the cam sprocket . These 2 springs allow the advancer to return @ low rpm, they can be replaced or &quot;adjusted&quot; yer choice.<br />As for end play it is just as crucial as rotational when it comes to yer ignition operating properly. There is minimal contact area when it comes to the points,if the thrust is to great contact area decreases and the points cant do their job properly.<br />It is possible to to take parts from the bad head and swap over to the good one. <br />It would also be a good idea to click the &quot;marketplace&quot; link @ the left of the page and pick up Bill Silver's manuals they have alot of info and also try to finda Clymer manual(M331).<br /><br />good luck !<br />georGe

[kartsport]

Thanks for your help so far George! I went ahead and swapped out the point shaft, seems to be a much tighter fit. I'll have to adjust those springs to get rid of the rotation, and I should be set. <br /><br />I'm having a bit of a problem getting the two halves put back together at the moment, and the old CL72 Clymer manual I got with some of the parts isn't helping much. I have the marks lined up, but the whole deal just doesn't seem to want to go back together. I'd just pop out the left cam half and heat the whole deal in my oven (the joys of single life!), but the cam sprocket seems to be stuck on the end, and heating both the cam/bearings and the head probably isn't too great of an idea. It could be me being too worn out to figure out the easy solution, but just thought I'd see if there were any tricks to getting the cam sprocket out of there.

[kartsport]

Nevermind, solved my own problem. The little &quot;H&quot; that retains the point shaft wasn't in the right spot. Felt like the prize idiot after I figured that one out, only took an hour of fiddling with it, and it just fell together. Ah well, a bad day spent working on a bike is better than a good day working!

[georGe]

Glad ta here yer making some progress !!<br /><br />georGe