Vintage Dirt Racing on a 350 Honda Twin

Rick, you're closing in on HP in the high 40's. I would recommend 32 mm Mikunis to go with Owen's porting on the head. Good luck amigo. If you need carbs PM me.

Mr Fast; thanks for the many words of wisdom! I've already purchased a set of VM30's, since this bike is primarily a once or twice a year mx bike and needs quick throttle response. As time allows, will eventually build a vintage flat track bike, perhaps using the 435 motor I'm picking up in May from former PowRoll rider Tom Street. That setup will definitely want the mega-carbs!

Also, you mentioned in a previous post the lack of proper chemistry in modern oils for break in and suggested some break in additives, what were those again?

Take care in Mexico, have a great time, ride fast and come home safe!

Rick,
Go to a good auto parts store like NAPA & tell them you want the oil additives for new engines. Should come in a small tube for around 10 bucks or so. If you can't find any, let me know.

valvoline has a "racing" oil that has extra zinc and other stuff. It will say not street legal or some such on the label.

-John

In between other projects, I've been carving out an hour here and there to work on the SL350. Rather than honing in on just getting it running, I've also been trying to determine what parts I have that will work and what still needs ordered. Part of that process is to "mock up" the bike with various parts and see what does or doesn't work.

The MT250 fuel tank turned out to be a bust, the cylinder head rides higher than I thought and interferes with the tank bottom.

First alternative was a plastic tank that Paul (OC) had, looked pretty good and was lighter than stock, but the rear of the tank presented a big fat wall for the family jewels to hit, not great when you are trying to motocross. :eek1


Then I went down to the other barn and pulled the tank and seat off my daughters SL100 and tried them, but no, same problem as the MT250 tank, looked great but would not ride down over the head. Tried a few more tanks and realized I was just going to have to go with the stock tank;


At this point I also had one head pipe inserted as was also trying to determine if the vintage Brit front fender would clear the exhaust, it does.

Once we knew for sure it was going to be the stock tank, I called Randy and he said he'd stop by and pick up the tank and side panels for painting in Honda red.

Time to mount the VM30 carbs;


The manifolds supplied by Boretech have a smaller bolt pattern, so after trying to file the holes out I ended up just slotting the manifolds;


Manifold on head, carefully aligned so gasket and manifold are centered over port;


Carbs on;


Checking side panel fit, just right!


Now time for exahust. Picked up the CNC head pipe retainers off of ebay, made in Portland by Ken. Nice look and much lighter than stock;


Pipes on;


Installed drive chain, but before adding side cover, a little wiring repair;


Countershaft side cover, stock other than a previous bobbing;


Cover after thoroughly cleaning and adding obligatory "lightening" holes, with a stock cover for comparison;


Sunday afternoon;


Every part going back on is first cleaned, shined, lubed, drilled, painted or anything else that can be done to make it lighter, function better or even just look better.

Next is wiring and a temporay fuel tank to get it fired up and start breaking it in, I did pick up the oil and additives as recommended by Lameco. Hopefully the next report will be about how good it sounds!

Is the lost cooling area right next to the valves not enough to matter?

because it only runs in 15 minute motos and never sits still, it should be ok

Also, You're new retainers are aluminum & will radiate heat faster than the old steel ones.

The last couple of nights, I've been sorting out the wiring, installing the ignition advance and points plate, throttle cable (a story in itself) and many other little bits and pieces. Last night I knew it was close, so buckled down and finished the wiring. Here is the old harness I made back in 2011, a little rough but with some repairs, serviceable;



Part of this project was to make the bike lighter (it's really like sanding down an anvil ) and where better to reduce weight than to eliminate the battery? Oregon Motorcycle Parts makes this nifty battery eliminator, a giant capacitor;



Planning to make an underseat electrical mounting plate, but in order to ensure everything works before investing that time, i just tie-wrapped all components into place;



All wired and ready to fire, all we need now is fuel!



Since Randy has our one really good fuel tank being painted, I first tried the plastic desert tank and SL350 petcock, but even though it appeared clean when I disassembled, it would not flow fuel to the carbs. I found that out after quite a few kicks with no response, then removed one float bowl plug and nothing came out but dust!

Grabbed the only other decent tank available, the TL125 tank with single outlet, threw on a t-fitting and hooked it up. Now with fuel to the carbs, about ten kicks later she roared to life, and sounded great! Rode it up and down the driveway and it felt pretty strong, although a lot of tuning remains to be done. Here it is after the test ride;



Next up is to find some better cables (and in a hurry), do a lot of tidying up of wiring and appearance times, rechecking valve clearance, and getting the carbs properly jetted and tuned. CRR Steel Stampede is only 10 days away.

Plenty of time

First a video of the bike on Saturday morning, wanted to ride it a little before the next tear down and fix/build session;

https://vimeo.com/64970385

At end of video, I am saying to Jani "you're being filmed right now"...she wasn't amused!

Sounds great.

So after a short ride, it was time to get back to work. Randy arrived bearing gifts, he'd painted the tank & side panels and put on numbers;


Randy got to work on the chassis;


I went to work on the fuel system, we needed a functional petcock to fit the newly painted stock tank. We had many old crusty parts to pick from;


Randy was going through and fixing and adjusting all things chassis, for instance last week when we finally found a working triple clamp, the upper was loose on the stem. Randy's solution was to make a shim;


We also agreed that the fork gaitors just looked kind of crummy, so we went back to the original fork sliders;


After sorting the chassis bits, Randy went to work on the fenders. My advice was just to clean them with scotchbrite and Randy agreed, for oh, about a minute;












Nice work Randy!

After going through three different petcocks, I found enough pieces to build one decent part...kinda. I also like to cut the stand pipes so I can run the fuel level lower in the tank and still maintain a tiny reserve;


Ready;


Randy building lower fender extension/splash shield;


Fussing with the wiring;


Randy built a nice little mount for the battery eliminator/capcitor, seen just in front of the back fender;


Getting there;


Glamor shot;


About 5 PM we decided to go on a test run and see how it worked, Randy chased on the TTR and I rode the SL350. We only got about a mile before it started running super bad, so turned around and came home. We were pretty tired and decided to call it a day. Tomorrow we would see if we could figure out what was wrong. :huh

Sunday morning, time to go find out why that @#$% bike was running so lousy yesterday!

Here is what greeted me;


I'm pretty sure gas isn't supposed to be orange! Time to tear it all apart and find out whats wrong; drained the system and stated looking at every piece and part. Disassembled the petcock (for the umpteenth time), took apart the carbs, flushed the fuel tank, etc, etc.

Besides some unidentifiable gunk in the gas tank, one of the old gaskets in the fuel valve had come apart and deposited a nice chunk right in the valveway, you can see the offending bit in the lower right;


After cleaning, removing the brass screen and opening the rubber valveway holes up with a drill;


Cleaning the carbs, while apart I lowered the needles one clip (she was fat in the middle);


And a new throttle cable from Sport Moto in Eugene, the Sudco cable was junk;


Did a lot of other little stuff, did a compression check, adjusted the idle bleeds, etc and synched up the carbs a little tighter than before. Reassembled and went for a ride. Oh mama! From bottom to mid range, runs really good, jetting is still too fat but will work on that. Getting closer.

Just to top off the day, decided to service the clutch and install the heavier springs. Cleaned the centrifigal filter, inspected all the discs, cleaned and reassembled with new springs. Would of completely finished but the side cover gasket was wrong. Torn down;


Leaving for the first vintage race Friday night, lots to do, but we will get there!

You going to make Terrebonne? Hope to see you at the races!

Dave Armstrong
President
VME
Seattle

Dave, yes we will be there! We should be rolling in Friday evening about 7:30

How about a VME sticker for my bike

Sure!

What forks are you using?