Part 4: building the prototype frame (continued)
My design process includes building an accurate CAD model of the frame and other bits that I'll be fabricating. However, existing parts aren't always accurately represented in the CAD model. The most obvious is the engine. I do enter the mounting points into CAD. I also include a side-view photo that is scaled very close to 100% that I can use for side profile reference. Other than that, I don't have an accurate 3D representation of the engine, so this leaves some guess work and many small details can be overlooked.
With the initial engine fitment (above photo) I discover a few areas of interference. First, the large round holders for the swingarm cups are extremely close to the cases. I kinda expected they would be close, but maybe not as close. Then at the front of the engine there are several areas of interference. First being the right side radiator hose. This would require machining a pocket into the front mounting plate. Next, the support bosses behind the mounting plates interfere with the engine cases because of draft on the case castings which I didn't account for. So these will also need to have some material machined away. All in all, not too bad. I carefully mark the areas that need to be trimmed with a Sharpie and prepare to do so minor modifications to these parts. Not really a big deal in the grand scheme of things.
I feel comfortable that I can proceed with the frame construction as designed and only need minor adjusting of the smaller CNC machined parts. Next steps are to get the frame on wheels and begin on the rear sub-frame. I also want to verify that both rear suspension configurations are fitting properly. There is a configuration for a single shock using a TZR250 3XV swingarm, and a more custom dual shock version using my own swingarm and dual Ohlins shocks from a Yamaha snowmobile.
20200927_110958 by
andbike, on Flickr
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andbike, on Flickr
Both rear suspension configurations fit well, so I move on to the sub-frame. The main frame is accurately modeled in CAD, but the rear sub-frame is modeled very rough. There are too many complex existing parts that need to fit to it, so construction the the sub-frame is mostly figured out on the fly. I start with fitting the tank, then moving rearward adding seat mounts, battery box, brackets for electrical component, and ending at the tail light. Oh, and one other detail... since Dirtbag is now a 3-day event with two nights of camping I'll need some provision for securing a tent and sleeping bag to the bike. So a utility rack will be integrated into the sub-frame. Its likely to be fugly, but I'll plan to remove it and add a proper race tail later.
20200929_143559 by
andbike, on Flickr
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andbike, on Flickr
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andbike, on Flickr
Wait, there is one more process that I almost forgot about. This bike still needs to get a VIN and DMV title. So here's what needs to happen... the tail light I plan to use doesn't have the little white license plate light that is required by the vehicle code. I also don't plan to use turn signals (I know, I'm a bad boy). However I will need these items to pass a "brake and lamp inspection". If you look close you'll see temporary brackets welded to the end of the sub-frame. These are for mounting the stock OEM tail light (which has the required license plate light) and turn signals.
20201005_102553 by
andbike, on Flickr
First stop on the list is CHP for an initial inspection and assignment of a CA VIN "blue tag". The blue tag is what the state of California requires on all home built vehicles to act as the VIN. These tags are applied by a qualified inspection officer at the CHP.
The first complication in this process is getting an appointment with the CHP. It is now late August. Time is running out on my build window and my local CHP inspector has been temporarily re-assigned to traffic duty in one of the fire areas. CHP policy is that you are first required to use the field office closest to your home. For me this is the Dublin office... but my inspection officer isn't available and no one knows when he'll be back. At the time I was helping a friend in Tracy with a project so I stop at the Tracy CHP office and explain the situation. The inspection officer there is very sympathetic, but stalls so that he has a few days to get an okay from the Dublin office to look at my bike. This takes up another week or so. By then the Dublin inspection officer is back in and I'm able to make an appointment. Yeh, finally!
I have six or seven other motorcycles that have been "blue tagged" for various reasons. The actual tag is a thin aluminum foil with super strong adhesive on the back. It also has a small hole at each end for the option of adding rivets. Ive always opted to not use the rivets. I arrive for my inspection and all goes well. The bike doesn't need to run, it just needs to have the appearance of a complete vehicle. We discuss placement of the blue tag and I suggest a location forward on the frame near the steering head as where you'd normally find the VIN location. We have a brief discussion about the use of rivets (or not) and the officer goes inside to complete the paperwork. After a longer than normal duration he comes out and says that he's decided that he's NOT going to put a tag on my motorcycle since I don't want to drill holes in the frame for rivets. He suggests that I add an "extra plate" somewhere that I can safely drill holes into. Oh, and by the way, he's taking a medical leave for 5 weeks. Fuck! He must have felt my frustration and offers to re-inspect the bike and apply the tag if I can return the next day.
Back home, I add the plate which is larger than I visualized and in an area where I had planned to add some diagonal bracing later on. So I decide to put in the diagonals at the same time to make sure everything fits and I still have space for the plate.
20201007_112655 by
andbike, on Flickr
Bike is back together and off to the CHP again...
20201007_173250 by
andbike, on Flickr
Success! I get the blue tag!
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andbike, on Flickr
Next step is to get the bike running and off to an inspection station for the brake and lamp inspection. There is some gray area to this part of the process. Several years ago you could go to any moto mechanic and have him verify that the lights and brakes are working and they would sign a simple statement of facts. Now DMV wants official certificates which most moto repair shops don't have. The only exception is if there isn't a repair shop in your area with the proper certificates. The closest shop is in Castro Valley and I'm in Livermore. According to the DMV this IS in my area.
I've used the shop in Castro Valley before and the tech there is SUPER picky about details. One time he failed me because the earlier mentioned license plate light was visible from the rear. Apparently that is not acceptable. Another time he failed me because my rear brake was slightly spongy (he wants the pedal to be rock hard). So what would go wrong this time I thought? Both brakes were rock hard. No white lights were visible from the rear. Everything worked including a horn (which isn't checked).
The inspection goes perfect... till we get inside to do the paperwork. Crap, now what? On the CHP paperwork they list the model year as "0000". The tech says this isn't correct. He wants a specific year. I mention that I have two other bikes titled as SPCN (special construction) and that those vehicles also show the model year as four zeros. The owner of the shop jumps into the conversation and suggests that he do the same. At this point he is getting very agitated and suggests that I go to DMV to have them confirm the year then come back and get the certificates. Time is running out. If I'm going to make Dirtbag I don't have time to do that. Extremely reluctantly he fills out the certificates with the "0000" year and I'm off to DMV.
By some strange act of God, I'm in and out of the DMV in about 20 minutes with NO APPOINTMENT! This isn't my first beauty pageant so I have everything in order and the process goes perfectly! The next day I call the owner of the shop in Castro Valley just as a courtesy to let him know that DMV also recorded the year as "0000". He is much appreciative.
I can now cut off the temporary tail light brackets and finish the back of the sub-frame.
to be continued...