Vintage Dirt Racing on a 350 Honda Twin

I enjoyed your adventure thoroughly. My son was on #5 so I tried to follow as many as I could, but especially the two Honda twins. Congrats to everybody who built and brought that baby home in style.

-P

Your son is Gus? Didn't he finish the race with a broken wrist?? Pretty gutsy and a class win to boot!

It is sitting in my garage

OK, cool! I'm sure you will want me to get it out of there ASAP, will talk to you this week and work it out. Thanks!

Went for a country cruise today with my wife and best friend Jan, all back roads, 5 hours of riding, 180 miles and lunch in Astoria. A really nice day for a slow putt.

Bike and wife all shined up for a cruise;



At Astoria's Sunday Market;

It looks like it was a great day for you two!! Laura and I also enjoyed ourselves today, walking the beach and cleaning the garage so I can fit the bike back in there!

It seems like a long long time since I've actually worked on the old twin and have still been catching up on months of honey-do's and projects. Before launching into the SL350 update, here's a brief recap of our latest adventures;

A few weeks ago, with Luke and Jan's help the Austin Healey was finally driven for the first time since bringing it home almost two years ago. Carbs rebuilt, tuned up, new brake hoses and several minor repairs here & there, and she ran better than expected and sounded exactly like a sports car ought to! Next up for that project is a new water pump, cooling hoses and fan belt. After that we are taking it to a detailer for a clean and polish.

Here is a pic right before we took it off the jackstands and drove it;



The next weekend we put 850 miles on our Shadow, riding to Hells Canyon and back for the "other" Hells Canyon Rally (not Lady Bug's event), despite a very cold and wet ride over, we were rewarded with decent weather there and great weather on the return trip home. Here is the bike at Hells Canyon Inn, just a few miles from the Idaho border;



Upon returning home and after completing a few more items on my domestic list, I announced that if we were going to make it to Chehalis VMX Nationals this year, we would need to devote some time to the old twin, so this weekend we actually started in on SL350 T98 2.0. Part of the plan for this year was to lighten the bike as much as possible, the other was to add some much needed power. I have been doing a lot of reading about the old 350's (as well as getting advice from Mr Fast) and was somewhat hopeful that the big bore kit in the old parts bike I brought home last year (reputed to be my original Powroll "400" kit installed in that motor back in 1985) was (A) Still in good condition and useable and (B) 67.5 mm, as from what I've learned this is the largest bore possible without sleeving and is also AHRMA legal.

Here is the old parts bike, ready for tear down;



Motor out and ready for disassembly;



First look inside, hmmmm, appears nice and clean;



Next layer, still clean;



Still looking good, no apparent damage yet;



Would I get lucky on the bore size? Yep!



Hardly a mark on the pistons and cylinders, the only problem found was one of the wrist pin clips was missing the curled ends, but could not determine when that happened and there are no markings to indicate it had broken off when running;



"Powroll"



Camshaft (two views), numbers on cam are 0 &1 and 8 & 11;





So now the search starts for piston rings & gaskets (hoping Bore-Tech can help on these), a variety of smaller pieces and identifying the cam and head. The ports in the head appear to be stock (aside from minor flash clean-up ) and the intake bores are approx 29.8 mm. If anyone has info on cam and head identification, I'd appreciate any guidance possible.

Once parts are on the way, next step is to clean, prep and paint the frame (powder coating is out for version 2.0, not enough time or money right now) and going through the many boxes of parts looking for the best pieces and grinding, drilling and otherwise lightening anything possible before reassembly. It should be a busy July!

Didn't realize you were into old British cars. I've got a real nice TR-3A & Jrs. got a TR-250. Looking at that motor of the SL it looks really good. With the Powroll conversion I don't imagine it's got a stock cam. Any idea what it is?

[QUOTE With the Powroll conversion I don't imagine it's got a stock cam. Any idea what it is?[/QUOTE]

I was hoping you (or one of the other CB350 aficiandos) would know! :huh

I was hoping you (or one of the other CB350 aficiandos) would know! :huh[/QUOTE]

Go to megacycles website. They list the different cams with lift, duration, etc.

While waiting to find the various pieces needed to build the motor, I decided to get a jump on the chassis and spent about 3 hours today, cutting, drilling and grinding. The net weight savings as a result of all that work? Maybe a pound, maybe less...

Before;


After;


Every mount, flange or bracket was ground, reduced or minimized and 22 more holes were drilled. The triple clamp also got a good massage. One more evening of grinding and sanding and then a few coats of paint and it will be ready for reassembly. I will be pulling the swingarm and steering bearings to service (or replace) as needed. Every piece that goes back on the bike will be reduced as much as possible. Nothing can stop me but fear or common sense!

You better weigh that paint before you put it on the frame, you don't want to undo all your hard work

Talked to Owen our mechanic. Those numbers are just casting numbers for a stock cam. When a cam is reground it is welded up & reground. Look on the side of the lobes for any weld build up. If none there it is probably stock. Take a caliper & measure the lift. Then compare it to stock specs & Megacycles specs. Should be able to tell just from the lift what it is.

Will do, thanks for the help!

This ^^^

You know how much I enjoy watching this weight-reducing process.....or madness.....same-same....lol

Finally found piston rings from a guy called "The Greek" The closest I could find were 68 mm but with the correct thickness (1.5 1.5 3.0), I will carefully file the end gaps and should be okay. Will order most of the rest of parts from Bore-Tech next week.

Happy 4th of July and thank you to all our veterans and service people!