Ftwelder

I removed the base gasket (.5mm) and it made a noticeable improvement. I am thinking about removing 1.5mm from the bottom of the barrel and using the gasket for a 1.0mm difference. My squish band is 1.75mm at the outer edge so I will likely cut 1mm from the head, I need some help with the calculations to make sure I don't increase the compression too much. The kicker has horrible geometry. The pipe is fairly easy to make but wouldn't fit the stock cylinder or frame. I am a rookie at sheet metal work and it took a very long time to make the tank and it's not even very good. The airbox is a fibreglass unit but also useless as the rear tubes are different. The bike came with a sock (like on your foot) for an air filter.

The skinny pipe seems to work really well. It pulls better off idle and the high RPM hit is completely gone. Old pipe. New pipe.

Thanks! Toward the top of that climb, at that RPM the engine is ready to accelerate suddenly. Below that RPM it is weak, compared to my OSSA MAR. I ended up cutting the cones out of my pipe and rolling new ones that were very gradual with a 65mm diameter mid section about 100mm long and hope to test it Saturday. I have the stock pipe but I lowered the seat support tubes of the frame when I reworked it and and changed the exhaust port to use a normal MX type steel double wall flange. The original exhaust port was severely worn so it probably wouldn't fit. Ill keep you posted.

I am using a 24mm OKO (PWK) currently. I have been up and down the scale with jetting and carb size and the current combo runs well and idles down even when really hot. It's not building up any carbon and rarely if ever stalls. It does get a little fat at the bottom of a steep grade but runs very clean under any acceleration. I have a video to share that has good sound quality.

I have both a very long head pipe and a poorly designed expansion chamber! The belly is probably too large and baffle cone too steep. I found a great series of Youtube videos by "AU mechanic" explaining pipe design that I have begun watching. The power down low is pretty good but I find myself slipping the clutch on steep grades in sections and carefully avoiding getting "on the pipe" which hits quite suddenly. I am learning quite a bit and love the way the bike handles, Thanks much for your input! I have lowered the cylinder .5mm by removing base gasket and it seemed to help. Compression is a low 6.5:1 in stock form. Ill make a new pipe before tampering withthe port timing any more. Frank

Greetings, I altered a Suzuki 185 trail bike for trials service and it's coming along pretty well. The motor is stock and I made a pipe to get it going and now want to make improvements with pipe and port timing. Most of what I need can be found in factory data or engine measurements except engine RPM range typical in amateur trials. I would guess 800~6000 with peak around 4K? Does anyone know better? Thanks!

At my next outing I kept having fuel delivery issues along with gear box oil making it into the crank case. The red disc type filters are useless. I probably could have done a better job cleaning out the tank after switching to a bigger filler. I think I have the bugs worked out. i removed the base gasket (.5mm) and found an improvement. I have another cylinder/head combo and am thinking planning a 2mm skim on the bottom of the cylinder and weld/rework the head to correct squish space and raise compression slightly. Here is how it looks now. More later, thanks for looking

Quick update! I have had a number of small setbacks. At one point in the process I bonded in an aluminum bushing to support the shift shaft after the case had been damaged, I don't remember hitting the shifter on anything but by the end of the second loop the gear shaft was flopping around and the oil had been let out. When I got back to the shop I pulled out my "arc-less" resolution, ground out the goo and filled it with a high-zinc filler. I then machined the weld away and reamed to 12mm

If you are in a position to do so, have both bikes around for him to ride.

Wow! That Panther is cool!!!

It sounds like a great event, have a great ride! We have a two day event on our schedule that I hope to ride this year. I checked last season on the first day then rode the next. This is my second season competing in motorcycle trials but my 50th of 2 wheel amateur dirt racing. Let me know how the weekend goes.

Yikes, that is a lot of money. It's good you found a cheaper option. I have a buddy with a TY250 and I rode a TY 175 for the first time yesterday. Very nice bikes! Where is the three day event? Frank

Heading out for my second "first ride" tomorrow. I sealed the head pipe, repacked the muffler, modded the front damper rods so they hopefully won't blow their oil out the vent holes, tested almost every possible jetting and carb size combo, adjusted timing and I am really happy with handling. I need lower bars but it feels great otherwise. I am running a 12T on the front now and an still a little tall in the gearing. I ordered a 10T and 11T from two different sources over the past couple weeks and neither has shipped yet. I have some slight clutch drag that is annoying and makes finding neutral challenging. The TS clutch has some interesting springs that "thread" into the clutch hub and I left them pretty loose. The issue may be all new friction materials so if it doesn't clean up tomorrow ill adjust the springs to a shorter length in the hope it will take up some cable slack. Clutch pull is very light compared to what I am used to. I have till noon tomorrow to get it together! (sorry about crappy links.)

Mid Atlantic trials may have them here in the states.

One of the two things I can do with a multi-meter is check continuity so I started by testing the stator wires to ground and none were. Bingo! The wire that goes to the coil frame had a soldered joint fail. I made some improvements in the wire routing while I was under the tank.

Thanks, I have a 12T front sprocket and it's a little tall. I can get 10 and 11T here in the states but it's perky for sure. I was surprised how quick it is. Your comment about the ground has the thinking. The CDI box is rubber mounted and probably gets it's ground on the stator plate. I really like the platform so far. The clutch is heavy but works good. I think the case covers are probably fragile.

I was mistaken the extra throttle is an Amal T80/200. Electrex is backed up?

I love the Domino levers for feel and leverage but I am having an interference issue with the throttle I am using, preventing me from sliding the brake perch inwards. I have a Domino throttle to try.

Sorry for the long delay. I was waiting for parts and a 1988 KX250 caught my eye but I am back on track now. The first event of the season was today so for the past week I was super busy completing the build. By Friday I had it together, oil in the gearbox and figured I should give it a whack and see if it would light. To my surprise it started on the first kick! I warmed it up a bit and set off the the carb still choked. I did a minimal amount of tuning, made fork brace and mounted fender and headed to the venue for a preview loop before setting up camp. The bike was running great! I messed around near the parking lot, EVERYTHING FINE! so I head off for a three mile loop. Long about section four at the bottom of the ravine the bike goes quiet 10meters from the bottom of the grade. No sputter, just silence. I had no spark. I changed plug and still nothing. I pushed it back up the hill and on to camp where I tore it down and with no spares or test equipment I was able to make nothing better but I am pretty sure it's the CDI module. This is what it looks like. Ill get some detailed shots when I have unpacked. Thanks for looking. Relaxing with my OSSA Ill have updates this week.

I made more progress this week. I spliced my rear brake cam so it now has Honda spline count. I also made arbors to hold my brake backing plates so I could true my brake shoes. It's amazing how many challenges one encounters when messing around with parts from several sources being used outside original purpose. I wanted to make good use of the long brake arm but it makes contact with the forks pinch bolts. I couldn't rotate the backing plate as the anchor feature on the backing plate was making contact with the fork leg due to using a wide MX hub and narrow TLR fork crowns. The only victim was a less then ideal cable angle. Next thing was to get some chain management pieces going. I wanted something that was up out of harms way and made a plastic sandwich with some material engineered for impact resistance and free machining wrapped in 6.1mm thick 2024 aluminum. Ill bolt it up with flatheads which need to be ordered. I made a bracket weeks ago before painting the swing arm and it's position worked out fine except for one small issue. The bolt heads contact the tube by a little bit. Ill need to turn them down a little before the final assembly but I am happy with the result. Next thing will be the spring loaded tensioner which will be located just rearward of the swing arm pivot.

Thanks for that info. Friends have mentioned my levers are hard to pull. Ill take your advice and try something else. I have a variable ratio lever on my OSSA but it's a POS. I have considered making my own with hardened perch and malleable lever.

We had our first ride of the year after a rare burst of reasonable weather generally called "the January thaw" (before five more weeks of snow) and got motivated to get back to work. The I found a longer brake arm for the front and had to alter the cable fixing point. The original one came right off and I made a new one and located it so the stock brake cable still worked. Here you can see the angle is way off. Here is a beefier piece (for welding) tacked on to test It's welded on and still work. (this is good) i machined a new anchor arm and almost have it done. More tomorrow,

Interesting you mention the stock bike. At our last event of the season a young couple showed up to follow the loop and watch. She had an old TS and he had a Matador. 10 degrees of head angle makes a huge difference!

Thank you. Our annual awards banquet is the weekend and I have been invited with others to display the bike at the venue! It should be done except brakes. Untitled by barnstormerbikes, on Flickr

I think you are right but it's going to take time and possibly taking the bike apart a few times before it works right. Ill get stevec to shoot a clip since he has the volunteer spirit.