pmk

Refrencing the linked topic. In regards to the wheelbase and footpeg locations, has anyone got a reference to the front to rear weight bias on these vintage bikes. Not critical, more curious about it.

Footpegs on my buddies and my MAR have been swapped to Kawasaki footpegs. Position remained the same. My buddies MAR is going to be modded. He currently runs bar risers, guessing about 1 1/2” maybe more and slightly forward. Certainly noticable compared to my MAR with no risers. We both run the tallest Renthal bars. Lowering the footpegs is primarily to accomodate his tall height.

Feetupfun, the topic I linked, do you recall the MAR you measured. Maybe remember what year it was. I ask, since your dimensions measured a wheelbase of 51.5”, same as mine, but doing the math based on swingarm length, I came up with 27.2% vs your 26.2%. Any chance it was a typo mistake, or do you think they had different length swingarms while retaining the same wheelbase? Even though you posted that info years ago, thanks, it was very insightful.

This topic I found gave some insight into footpeg location front to rear.

The mention of setting the height based on the axle centers is great info. Easy to check, and guessing the MAR footpegs are above that reference line. For whatever reason, this IPad is not accomplishing searches here, but I plan to keep gathering more info until we start cutting.

Aftermarket footpeg location brackets and do it yourself footpeg relocating certainly is popular on vintage bikes currently used in competition. In general, how or what criteria determines the best footpeg front to rear location? Is the lowest possible position that kerps the fert safe best? While researching this, one company mentioned that going rearward with footpeg mounts is not always a benefit, it can reduce weight on the front tire and creates steering issues. Being specific, we will be modifying the setup on my riding buddies 72 OSSA MAR. The internet has many photos of these machines with footpegs anywhere from stock to 50mm x 50mm down. As a rider, he is 6’3” and about 200 pounds with gear on.

Simple report. Installed Tubliss system. Installed onto a 2.15” wide vintage Akront rim that was laced onto the existing oem OSSA MAR rear hub. As per Tubliss instruction recommendations, I went with a new rear tire to ensure no or minimal leaks possibly from a previous rim lock scarred area. Even following instructions, the Dunlop 803 was a tough challenge to seat the bead of the tire onto the rim. Even once seated, I deflated the tire, and the Tubliss to allow the Tubliss bladder to settle into position. Immediately, the Dunlop fell off the rim bead seat area on both sides with simply being deflated. Reinflated, bead seated and Tubliss inflated. Wheel was reinstalled and tested at 3 psi in the yard. Bead stayed seated. Had an event Sunday. Rode the entire event at 3 1/2 psi, tire never dropped off the rim towards the center. Being a lower class rider, with far less experience than all of you, the lines I rode were mostly rolling with no hops. The rear certainly found more than enough grip, and felt more stable. After the event, I rode my buddies MAR, same rear tire and pressure. Granted, his rear damping is firmer, but it did seems my bike had more grip. Advertising mentions it is the added ability of the tire to flex because of no tube. Maybe, but honestly, it could be we used two different gauges when setting up, or me running the 2.15 and him the 1.85 rim.

My riding buddy and I had a discussion about the Twinshock vs Vintage topic riding home from the event yesterday. Our local group runs the classes of Vintage B and Vintage C. We both have OSSA MARs. Mine a 73 and his a 72. As others posted, we ride for fun. We are honest with our score and winning is not the most important thing. In regards to the Hondas, obviously, the TL series is vintage, but what is the opinion on the later Honda twinshock bikes. I asked, based on curiousity. How much better are the 80s Honda Twinshocks.

I doubted this was possible as did my friend with the issue on his MAR. He drilled the rim and installed screws. A bit upset that the screws apparently were not holding the tire, he removed the wheel, and unseated one bead to reposition the tube. He noted there was no torn or elongated rubber on the tires bead, simply the spots where the screws had held the tire.

Guessing, probably order two Tubliss setups, and install them, one in each MAR. My MAR has so much rear grip it sometimes catches me off guard. If I run the rear with Tubliss and no tube then it can seriously mess with my head... Who knows, maybe I should polish that 2.15” rim, lace it up, run Tubliss in it with no tube and a Dunlop. Just is a tight fit already between the swingarm with 1.85”, but it would be cool to do and simply adds to my resto-mod built MAR.

I suppose, but for $95, the Tubliss setup seems pretty cost effective and retains the vintage look of the rim while adding a level of safety and reliability. FWIW, my riding buddy was having issues with what was thought to be the Dunlop tire slipping on his MAR with an Akront rim. For whatever reason, his tire does not drop towards the center, but constantly he would see the valve stem getting that lean to it. He added screws to the rim in tne bead area to stop the tire from slipping. The ironic part, even with screws securing the tire, the valve stem still tilts with use of the bike. He removed the tire to correct the tilted valve stem, and found the screws marks were not stretched or elongated. He determined, with the low pressure, he runs, the tube is walking about inside the tire casing and over time, with the tire flexing the tube moves enough to tilt the valve stem tight against the edge of the hole and is trying to tear the valve stem out.

Agree on not quite following the modified rim idea. According to the Tubliss website, the 18' fits both 1.85" and 2.15" rims.

I did a search and some reading. There were some posts discussing using modern tubeless tires on vintage bikes / rims and how some owners have had issues with the tire dropping off the bead at the low pressures normal run. My 73 OSSA has an Akront rear rim. Unfortunately, probably on account of the slight ding in the rim from the previous owner, my Dunlop D803GP tire is dropping off the rims bead area. The oem Akront rear is a 1.85 width. Dunlop is suggesting a 2.15 width. I purchased a used OSSA wheel assembly from a different model than the MAR and unknowingly, it had the 2.15 wide rim. So, looking for opinions. Stay with the 1.85 wide rim and install the Tubliss setup. Install the 2.15 wide rim, and hope the spoke lengths are acceptable. The wheel was rebuilt recently with new spokes so it should disassemble easy. Then remain running a tube setup. Or go all in with the 2.15 wide rim and Tubliss setup. Consider, the Tubliss setup is specific to each rim width and does not interchage according to part numbers. Although, possibly it is only the width of the special Tubliss rim lock. It seems some have converted to Tubliss, so any info there would be good also.

Not sure which tank you purchased or from what vendor. Simply a FWIW, my buddy purchased an aluminum tank for his MAR. While it looked great, with use he found the tank had a couple of small leaks along the welded edges. The guy we use for welding is aerospace certified. He spent some time welding the tank and would smooth the edge back as it was with no bead of weld showing. Try as he might, the seam would open slighly in another spot. Point being, it appears the edge is a very thin joint after being sanded smooth. Ultimately, I asked our welder to do a nice functional but pleasing to the eye bead around every seam. Once polished the tank looks fine.

In regards to OSSA parts, I have been buying from Alex Snoop in New York. Alex has been great to get stuff from. He recently rebuilt my friends MAR crankshaft, that engine will be going together this fall.

In regards to the Preston Petty fenders, I have been talking with the current owner of Preston Petty Products for a long while now about various topics. Currently, the fenders are not available, but are on the list of things to be offered in the near future. Currently they are selling the MX Front fender which is the old Tony D, the mx rear, the enduro rear fender with light and without light, the headlight, and I believe the front fender with integral bracket to mount to the underside of the lower triple clamp. The modern day Preston Petty Products are molded by Polisport for PPP. The molds and tooling are expensive, but the quality is supposed to be very top level. If I remember, I will share when the fenders are released and ready to ship.

Typically, the resin used is Vinylester. Here in Florida, where boats are common, this resin is easily obtained locally and the cost is not expensive. Currently, I am helping my buddy repair two oem MAR tanks. He has been doing the sanding, and I have been doing and teaching him the glass work. When he returns to Florida this Fall we will finish them. No plans to coat them, but one maybe both were coated previously. To find the leaks, I used a bicycle pump on the tanks vent and sealed the cap with a section of flat rubber. Submerged in a bucket of water, I added a couple PSI slowly with the bike tire pump. As for the aluminum tanks, my buddies MAR currently has one of the Spanish aluminum tanks on it. He bought it new, and from day one it had a leak. Not bad, but it was on the upper seam. He rode it this way a while and just recently had it repaired. Our welder guy is a certified aerospace welder. Even when super cleaned, he commented that the aluminum is a bitch to weld as the original welding was kind of dirty. Ultimately, this aluminum tank was welded with the beads left and not sanded. Plan is to mirror polish it and hopefully not dent it.

Interesting, but are you certain retarded timing causes backwards running. I was always led to understand if the timing is too advanced, the engine kick back and provided the kickstart is not engaged, this is the initial engine firing that sets in motion the backwards direction. After that, the timing is firing after top center, and look out when you let the clutch out.

Photo did not post. Was this the orange bike in Missouri, USA.

Until filled to the top, then the excess will purge out the radiator cap.

Try the Fowlers website for the TYZ, that's your best bet. I assume you are referring to the letter code. Most times, if it is the first piston swap use a B, but they may go as high as D.

Thought you were selling the bike. Seemed like it was sorted out, what happened.

I agree with FeetUpFun, make certain the carb is clean. These bikes do not like any debris in the carb or jets. Next, ensure the throttle and cable are rigged correctly with a small bit of freeplay in the grip with throttle closed. I will add, my own SY recently had some weird stuff happening. Turned out to be the rubber disc in the choke plunger had fallen out of the brass plunger. Not lost, but would randomly reposition itself, the bike ran pretty good, but would die on any descent.

Reading posts here on TC, I was under the impression that one of the mods done to these bikes was replacing the cylinder studs that secure the head with bolts. This was done so the cylinder head could be removed with the engine in the chassis.

I have been looking for it, just no luck yet.