SOHC Project

Chopper gods have been kind the last 2 days, I have got lots accomplished. Monday, went from motor fully install and running in the bike to out of the bike sitting on the floor in the span of about 3 hours. Oh, and managed to wash my truck too! Then yesterday, I had a marathon "head-o-thon". Pulled off the F head/cam. Pulled the springs/valves from the F head. Would not have pulled the vavles only I need the valve seals from the K head. Assembled the K head; seated it and bolted down the K head/cylinders and mounted the cam. I went steady from 5 until 9 last night. Did manage to stop for about an hour for dinner with the OL, and a scrap wood run. That is another post, but I'm collecting wood for a bike platform.

So this afternoon I'll mount the rockers, and set the valve clearance, and she'll be ready to go back into the bike. All I wanna do is check the compression on this puppy. It was anemic with the F head showing only 80psi. With the stock K head back on she should be 150+.

Very good weekend, with slightly mixed results. First things first, I got the motor running and put about 50 miles on it this weekend. Got the motor in on Wednesday, got everything hooked up Thursday/Friday, and Friday night, she came to life. Was farely easy to get the motor running. After everything was hooked up and ready to go I was not getting any spark at the plugs. I think this was due to miswiring of the points. I swapped out the points from the F model engine and she fired right up. Couple of concerns/issues:

#1 - Compression is horrible. Its no secret why though. If you remember I put an F model head on a K motor. The F model has domed pistons, and a larger compression chamber in the head to compensate for the domed pistons. The K model has regular/flat pistons, combine this with the F head which makes for more space in the compression chamber. In the end what this means is lower compression, about half what it should be. I did a compression check yesterday and got about 80psi, it should be 150+ on a freshly rebuit topend.

#2 - Leaky valve cover. Not sure about this, but I think this also has to do with the F model head. I cranked the valve cover down, even pounded on it with the empact wrench, and it still leaks. I think there are slight differences in the valve covers that causing them to leak.

So whats the verdict? All in all I'd give the motor 1 thump up and one thumb down. I think the motor is solid, and I could go put 20,000 miles on it, but the lose of power is significant enough for me to conclude the F head is simply not a good idea. I'll find a K head and install that in place of the F head.

All is not lost though. This was my first rebuild and an excellent experience. Other than a few problems I didn't run into anything I can't handle. From here as I said I'll replace the head on the donor motor. I'm also going to put new rings/gaskets in the F motor. Right now my time frame for purchasing my chopper frame is after the July 4th holiday...then the real fun begins!!!

Six weeks into this adventure I have finished the rebuilding of the donor motor. The latter part of last week I cleaned up the the head and got the valves and springs back in. I did run into a little problem with the head. After cleaning it up I inserted spark plugs into it and found one of the plug holes had some slightly stripped thread about half way down. After looking everywhere for a M12 X 1.25 tap and coming up empty handed, I used some "Lumbee" engineering and used my Dremel to cut 3 gouges in an old spark plug. After running that in and out of the plug holes a few times it was good to go. I spend the weekend bolting down the heads/jugs and mounting the cam, rockers and setting the valve clearance. Heres the finished product...

http://pg.photos.yahoo.com/ph/marklocklear/detail?.dir=8c67&.dnm=a85a.jpg&.src=ph

Now the plan is to remove the motor from my 78F stocker and replace it with this rebuilt motor. I'll drain the oil and start prepping the motor for removal this afternoon. I'm hoping it will be ready to be taken out Wednesday or Thursday, and maybe I can have the newly rebuilt motor purring by the weekend!!!

So hopfully my ongoing "head" saga is coming to an end. As you know from former posts I have a bad valve guide on my donor motor head. So Alan, a guy off hondachopper.com sent me an F model head, valve train and all for nothing! I mean, he wouldn't even let me pay him for shipping. I'll pay it forward to the next cat that needs a part. Anyway I got that UPS, got the valves/springs out of it the same day. Cleaned it up good yesterday, and will hopfully get all the valves cleaned up this evening. Hope to have it reassembled by the weekend. Had some concerns about swapping the K motor with my F motor in my stock bike. But looks like its an even swap...no worries. Maybe get the donor motor assembled by Sunday. Then I'll start work'n on getting the F motor out of the stocker next week.

Quick update...

- On saturday got juggs (lower end) on donor motor.

- Rode up to New Orleans and hung with Bud. Very cool guy...lives in a warehouse and has 8 CB750's, all stock and cafe racers.

-Changed plugs in stock 750SS and was amazed at the increase in power.

The last few weeks all I've been doing is cleaning up the head and jugs. I got all my parts I was waiting on this week - complete gasket set and piston rings. Got the rings on last night with no problems. Now to the head. Last week, while cleaning up the head I found a chipped valve guide. The is the small cylinder that the valve runs through. I had two choices. One was to just fix the SOB. This would cost about 200 bills, thats including having the honda place replace and ream the new valve guide. The other was to just say F' it and put the head back together and just hope for the best. I don't think this was as risky as it sounds. I had pretty much made up my mind I wasn't spend'n $200 to fix it...not when their are complete donor bikes out there for that much. Besides, the chip in the valve was pretty small, and the valve still seated OK, so I think I would have been OK with it. However, you are taking a change, and u never know when u'r barreling down the interstate at 80 mph when u'r gonna here a "POP!" and there goes u'r engine. I posted this on hondachopper.com and a brother in Texas has a complete head hes gonna give me for shipping. So for $20 its worth the peice of mind. The only concern I have is this head is for an F model, whereas the motor I'm rebuilding is a K model. There were some slight differences, but the guys on hondachop seem to feel it will work OK, so thats what I'm go'n with. At least I'm gonna give it a try. The head should be here middle of next week. I'll get my jugs on this weekend, and maybe I can have the thing put together by next weekend.

I'm really wavering on the route I want to take with my rear wheel setup. Here is the delema. I have two options with what to do with my rear wheel (really three), either the stock Honda CB750 wheel or a wider tire in the 175-200cm range. Option 1 is the cheapest and easiest route. That is to simply use a stock honda CB rear wheel. These wheels are plentiful and cheap. The DesignCycle frame I'm planning on using will accept this wheel with no problems. Options 2/3 are to go with a wide tire rear wheel setup. This is purly asthetic, but gives the bike a hard edge like no skinny/whimpy wheel can. Of the wide tire options are using a Harley Davidson (HD) setup or a metric sport bike wheel. If I go with an HD wheel, the setup is pretty easy and I simply make sure DesignCycle knows I want to go with a wide tire and they will deliver the appropriate frame to handle it. The problem here is cost. An HD wide tire setup will be in the 500-700 dollar range. Ouch!!! Thats the whole reason I got into metric bikes, the parts are cheap. Even looking for stuff on Ebay I'm still in the 500+ range. The cheap wide tire option is to go with a sport bike wheel. This would be somthing like a CBR or Yamaha R1/6 wheel and tire. These are resonable plentiful and can be aquired for around $200 on Ebay. The challenge here is application. The wheels and brakes don't just bolt on out of the box. While the wheels are plentiful all the little washers/parts and axles are not. There are alot of the wheels on Ebay because guys replace there stock wheels with customs. So when they go to sell them, thats all u get is the wheel...you don't get the other stuff you need to run/mount the wheel.

The more I think about it the more I think I will go the KISS (keep it simple stupid!) route and use the stock honda wheels. Success is important in a project like this. I'm already starting to feel the pressure of the build just with the problems I've ran into with the motor (bad valve guide). Its important that I complete this project. I hope this will not be the only project I will ever do. So I think its important to be realistic and stay within my budget goals for this project. Once I get through this one, I can sell it on ebay an tackle a new project next year and challenge myself a little more next time. And the beat goes on...

...patiently waiting on parts. Everything is on order, and if I'm lucky will be here by the weekend. I'm just hoping I can get my gaskets in this week. If I can get the gaskets in, I can put the head back together. Hopfully my search for an exhaust valve is over. I noticed some CB750 stuff for sale on Ebay from a guy in New Orleans. I sent him an email and this guy has like 8 CB750s! No choppers...all stockers and Cafe Racers. Anyway, I sent him an email and he says he thinks he has an exhaust valve that will work. I'm planning on rolling up there Saturday. I'm anxious to check out his collection too.

So all the time off has given me time to work on my polishing skills. I was just planning on cleaning the aluminum up nice, but then I see this on Ebay:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4545643998

Oh my God! I didn't know aluminum could look that good. So I'm think'n minds gotta look like that. I pulled by gear cover and stator cover off and went to work with my dremel tool. Well, I found out real quick the dremel tool just ain't cut'n it. It does a good job, but it just doesn't have the surface coverage...would take months just to do the gear cover. I went out this weekend and bought a 10,000 RPM grider/buffer. This sped this up enormously. Heres some pics of progress:

This is before using the dremel:
http://pg.photos.yahoo.com/ph/marklocklear/detail?.dir=8c67&.dnm=49b9.jpg&.src=ph

...now with the grinder/polisher:
http://pg.photos.yahoo.com/ph/marklocklear/detail?.dir=8c67&.dnm=944b.jpg&.src=ph