I Hate to Admit It....But I Might Have Overlooked Something...

I went back to a more conservative jetting setting and within 5-6 kicks. I took a short video for Julian to show him that the bike was actually running and to demonstrate the popping that I told him the bike was experiencing. When I reviewed the clip, I noticed that some of the popping was coming from the head gasket, that puffs of smoke were coming out when it popped! I suspected that maybe the head bolts needed a little tightening. Indeed they did!

I checked the bolts and some were so loose that I could unscrew them by my finger strength! I guess it's my fault that I didn't think of this earlier, since the motor was freshly built. But I would have thought that Paul should have told me that after heat cycling the motor a number of times, I should tighten up the head bolts!! Details, Paul!

I tightened the bolts to 17 ft/lbs. in a criss-cross pattern across the entire head, since it's a one-piece head. Amazingly afterwards, the bike started on 2 kicks! And that's when the engine was dead cold from a sit overnight!! I heat cycled and cooled the engine 4 or 5 times and retorqued the bolts over and over again. Funny thing- the popping went away!! as well as the puffs of smoke!

So the loose head could explain a bunch of things going wrong. First of all, the engine wasn't getting good compression, which would make it hard to start the bike. Also it made it harder to reach the top end, running out of power. Secondly, the fuel ratio in the combustion chamber was more lean, because every time the piston moved downward to do a filling cycle, it would be pulling in additional air through the head gasket leak! So suddenly my A/F mixture was all off and all the testing I did has to be done all over again!

After a little testing, I calculated that I would be able to move down to a smaller pilot again. So I popped in the 30 pilots and I put in smaller mains, moving to 250's. I took the bike out on a run and it ran nicely on the low end. (I still have to work on the mid-range.) I took her down Isabel and yanked on the throttle WOT. The bike actually pulled up to 8500 rpm, that's the redline!! It probably could have gone into the red, but I didn't want to hurt the motor just yet. Just after that, the bike died, running on one cylinder. At first I thought that maybe I seized the engine, but after testing I believe that I just fouled one of the plugs. I looked at both the plugs and they were a pretty nice tan. I think maybe one of those old spark plugs just gave out. I'll pop some newer ones in and do more testing tomorrow.

The 2T Shuffle

It's been a couple of weeks now that I've been fiddling with the jetting off and on. There was a point where I had the low end cracking pretty nicely into the mid-range, but when I tried to hit the open throttle, the bike would just bog, never really getting past 6500 rpm. Making the change to a larger pilot jet really helped the low end, plus I raised the needle just a bit.

In my quest to perhaps still take the bike to someone for tuning, I called and left messages with a couple of parties- Roland Cushway, a well-known internationally famous 2-stroke tuner who worked with Erv Kanemoto, and has won 5 national titles! The other was BRG Racing. I wasn't even sure that it was Roland's phone number, but I left a message anyway. To my surprise later the next evening, I got a call back! He told me a little about his history, but he's very modest about it. He told me that he's more of a machinist. I told him what I've got and he gave me an education in 2T theory! He did have some very good suggestions, some that might be a little over my skill set. The conversation lasted about an hour- I was very surprised that he was that engaged! I really felt honored to have even been able to speak to this man of such greatness!

I also got a call back from BRG Racing. KC called me. He's the owner of the shop. He told me that it would probably be about $400 to do the job, which included about 4.5 hours of labor and dyno runs. They would change the timing, gaps and needles as needed- everything was included in the price. I told him that I would give him a shout in about a month when I've got more miles on the new motor.

Meanwhile I answered a Facebook post to someone who was looking for an RD400 engine case. Turns out that he actually lives in Livermore, so I replied that I've got one. He messaged me and the next day he came by the house. A nice fellow by the name of Julian. I've seen his pictures on the Internet- he's built quite a few bikes and he really knows his way around the Yamaha 2-strokes. I showed him what I've got cooking in my shop. He brought me an assortment of larger Mikuni main jets for me to try out. When he asked me how much I wanted for the case, ti told him that I was going to give it to him- that stopped him dead in his tracks. I really feel like this Yamaha 2-stroke thing is a community. I've met so many helpful people over the decades all having to do with this bike, if he could use the case, he can have it. But I did ask in return that he help me get my bike running and that I may need to borrow some tools. We agreed it was a deal!

A couple of days passed. I tried making some more changes to my carbs, going BIG, but the bike didn't want to start. That's when Julian came over, while my carbs were all over the place. He brought over a couple of timing dial gauges and asked if I wanted to do my timing change to 2mm BTDC now. I said sure!

I showed him a new method that I just pinched off the Internet where you actually use the spark of the spark plug to see when the points were opening. We got the left side set up and found that my original timing wasn't 1.8mm like I thought I had it set- it was more like 1.3mm. That could've definitely had an affect on my top end not going so well. He set it to 2.0mm BTDC. The other side was even worse! It was reading 1.1mm!!! Man, I suck! So he dialed that one in to 2.0mm also.

Then he asked if I want to try and start her up. Oh, shit! I have to assemble the bike under the watchful eye of this 2T stud!? Ooohh, the pressure! Plus I can hardly even breathe with this N95 mask on with all this Covid shit going on! I was sweating and panting! But I did get it back together. And wouldn't you know it? it wouldn't start! I kicked and kicked. We threw a spot of fuel down the right cylinder. Still nothing. Maybe the battery needed more of a charge? Perhaps. He suggested pushing the bike down the street to compression start it, but I said no, because we would just have to push it back. I'll leave it till Sunday. But now I'm just dying to see how the bike pulls with the timing set correctly!!