1969 T100c Rubber Mounting Engine?

So Iv been using my T100 as a daily driver for a few months now, finally got new tires and wheel bearings on it and it seems to be happy to ride. Starts up every time with little effort, sometimes none. Very minute oil leak, hardly even noticable over hundreds of miles. Gets 60mpg, basically it seems to be a great daily driver in my opinion.

But, my trip is 20-30 miles per day mostly rural roads where speed limit is 65mph. Iv had the bike upto 70mph just to see what the vibration was like at that speed vs the 45-50mph I typically ride. Didnt seem to improve much.

I run 90 octane non ethonal fuel, so I retarded the ignition timing a tad to try and smooth things out and that helped a little, mostly at lower speeds. But at 50mph it looks like Im sitting somewhere around 4k rpms, maybe a few hundred less than with stock ignition timing. And 70mph looked maybe 5500rpm or so. Tach isnt fully reliable.

Before I takle this endeavor I thought it worth asking if anyone has ever considered or done this successfully? As far as rubber mounting the engine. I know anything is possible with the right tools, and I might get alot of flack for "ruining" the feel of a classic.

But at the end of the day, Im really looking for a way to PRESERVE the bike while using it as a daily driver. The vibration is such that over time I have had to replace numerous bolts throughtout the bike due to the threads being stripped smooth. These near 60 year old parts I feel cant handle the raw beating of this motor much longer, so Id like to find a way to stop beating them up so bad.

 

Been lookin at that....but what I want, I cant really afford to drop $7k on a new one and leary about buying a newer used bike I know how most of them are treated haha.

But I had to replace some parts on the T100 anyway so while I was putting everything back together I decided I had some thick rubber washers so I stuck one on each side of where the top brackets mount the from the rocker box to the frame. That small change did make a noticable decrease in vibration.

So up next Im going to buy new rubber washer and put one between each solid motor mount to the frame and see how much smoother that makes things.

 

So a little update now that I have had time to work on this idea again. Every now and then, while out and about I would look around for more rubber washers like the ones I had but couldnt seem to find anything like what I wanted. So eventually, came up with this idea to make my own using an old tire I had laying around the yard. So I did just that, with the outside of the tire measuring about 1/4 inch thick of rubber I had to buy a new bolt for the front motor mount in order to do it the way I wanted having a rubber barrier both against the frame mount and the large metal frame that bolts to it. Unfortunately could not find another through bolt like the original just an inch and half longer, so had to settle for a regular bolt. Doesnt look the best, no.

The rear engine mount I had to get more creative, as I could not fit a longer bolt there even though I bought one due to the chain being on the other side there just isnt room for that. And 1/4 inch was too much on both sides for the stock bolt thats there so I instead cut some pieces out of the sidewall which turned out to be about 1/8 inch thick and those seemed to fit good enough. Couldnt get 2 on each side like I wanted, but best I could do given the circumstances.

The bottom mount, same deal I used 3x 1/4 pieces with 2 of them replacing that solid spacer and the other on the outside. I did not put anything on the other side of the bolt, standard bolt wasnt long enough and at the time I wasnt sure if that was a through bolt or not until I took it fully out.




All in all, I would say I dont think this 2 day endeavor was really worth the time haha. It may have made a minor difference overall, but anything over 50mph really does start to vibrate the bike to pieces after a while. So 50mph is its limit, but it will do it all day long.

After installing all these mounts, I took it on a test run riding between 60-65mph for an hour straight and I can honestly say I wouldnt recommend it. I was still vibrating hours after, and the vibration has loosened 2 bolts and one bolt on the top motor mount came off completely but somehow just rested on the head so it didnt go anywhere.

Everything is back together and all tightened and secure with new lock washers in places that needed it. I do all of this because the recent hurricane down here took my job away temporarily, and since we live so far from civilization out here its about an hour and half to any other normal job so I really need a reliable economical form of transportation my only other vehicle aside from the wifes suv that she uses for work is a truck that gets 18mpg. I was hoping to reduce the vibration enough to make 60mph doable for long trips, but looks like no matter what that wont be the case. And even on rural roads down here, people seem to think they need to do 90mph everywhere.

 

Unfortunately for me, I think you may be right. I took it on a trip today after double checking everything was tight, fluids were good and chain was slacked right cleaned and lubed. The trip was 35 miles one way through 2 small towns with stop lights during rush hour. The first 15-20 miles or so were fine, but after going through the first town the vibration seemed to be getting worse. The motorcycle itself performed excellent, handled great ride itself was smooth (as far as the road goes) and the engine ran smooth as butter even idling in hot traffic.

The 35 miles back was unbearable. I had let the engine cool before heading back, but the whole ride was just too much to handle really. Even dropping down to 40mph occasionally to slack off the vibration didnt do a whole lot.

So you may be right, I may have actually somehow made things worse. Either that or Im missing something here, Im no expert in harmonics by any means. But I have come to the conclusion that its going to take more than 1/4 inch rubber tire washers to have any real dampening effect if any on this engine. So tomorrow Im returning it all to stock, and Ill take it on that same trip and see if its any different. Either way, giving up on the idea haha.

I guess at the end of the day, I have to remember Im riding an ancient relic at this point.

 

I dont know if I wanna do all that as far as the gearing goes, seems like alot of work. I may one day look into getting the crank balanced if all else fails, but honestly it is much better now that I returned it back to stock. I guess I didnt realize how much worse I made it haha.

My last 70 mile trip I did at 50mph and it wasnt too bad. It was buzzy, but at the end didnt really leave me feeling numb or anything. I did manage to loose one side of my front tank mounts that were all new, so theres another $30 I have to drop. I do almost daily inspections on the nuts and bolts out of habit but I always glossed over the front tank mounts. Guess I wont let that slip next time, maybe some locktite. The other side was solid. Other than that, no other bolt came loose on that ride at all.

So id say, although its still pretty buzzy at 50mph and up, maybe its not so bad if I can keep the bolts tight and prevent them from coming loose. Iv only ever had a few come loose the entire time Iv owned the bike, so thats not so bad I guess. Im having my friend loan me his grom so I can compare it to a newer motorcycle in terms of vibration. I figure a single cylinder grom should be on the higher end of newer bikes that are buzzy at highway speeds.

But yes, right now Im looking more into the handlebar and maybe foot pegs now. The seat actually isnt bad at all, its mainly the bar and pegs.