Sumotrack rebuild

[Ratranger]

So this bike has basically sat since it broke on the dyno. I ended up moving from WA to OK and lost motivation on it. I did pull and replace the top end with a Hoo's 700cc kit, but then found the throttle bodies locked up. While it sat neglected I worked on a few other bikes, including my DRZ400 that now has a 462cc big bore stroker with a FCR41, cams and ported head.

Coming back to the XS I started by pulling the front end to fix a few things I wasn't happy with. I'm modifying a new set of throttle bodies for it. And biggest change will be a JEMCO style exhaust. I ordered the cones and pipe to start that build today. I also plan on making a better license plate holder while I'm at it.

So here's a picture from before it broke, and a picture from today, years later.

 

[Jim]

Always knew you'd get back around to this.

 

[Ratranger]

Always knew you'd get back around to this.

I never planned on it sitting this long. Initially I was saving forthe new top end, but that didn't happen until after I moved. Got it on and found the throttle bodies frozen, and just lost any motivation.
Then I spent time on dirtbikes, cr80 powered by an xr100 engine, yz125 with xr200 engine, a couple 4 wheelers, and then hopping up the DRZ.
The other day I just randomly decided to start back on this bike. Doing the front end work, and modding the gsxr throttle bodies right now. Once I get parts I think I'll start from the opposite ends of the exhaust. Build the muffler end, and start the header end and meet in the middle.

 

[RC4MAN]

Sorry to hear about the Dyno mishap, looking forward to the resurrection

 

[Ratranger]

Sorry to hear about the Dyno mishap, looking forward to the resurrection

A wrist pin circlip failed on the right cylinder, which gouged the wall and caused the rings to stick. Still made 45hp with the damage.

Here's what motivated me to get back on it. I bought a motoscope mini for a good price and was thinking I'd put it on the DRZ. Once I made a mount for it I didn't think it would be great on the DRZ, possibly too fragile for a real supermoto. But it would be a great replacement for the cheap gps speedo that was on the XS. The GPS speedo worked, but was slow to get signal and too many trees would cause it to lose signal.

 

[Adamc]

A wrist pin circlip failed on the right cylinder, which gouged the wall and caused the rings to stick. Still made 45hp with the damage.

Here's what motivated me to get back on it. I bought a motoscope mini for a good price and was thinking I'd put it on the DRZ. Once I made a mount for it I didn't think it would be great on the DRZ, possibly too fragile for a real supermoto. But it would be a great replacement for the cheap gps speedo that was on the XS. The GPS speedo worked, but was slow to get signal and too many trees would cause it to lose signal.View attachment 257893

Its a great looking bike and one worthy of finishing. I hope you continue to keep us all informed with plenty of pictures.

 

[Ratranger]

Got the new throttle bodies done. Added a second air nipple after the butterflies, 1 is for MAP sensor, other will be for the idle control valve. A significantly improved linkage between the throttle bodies. The basic connector I had before just had too much flex and caused balance problems.

I'll probably just get new injectors, cheaper and easier than cleaning the ones I have.

Haven't started on the new exhaust yet, but have everything except the cones. I'm doing a stepped header again. 1 1/2 at the head, then it'll step up to 1 5/8 to the cones leading to the mufflers. I'm sorta copying the Jemco pipes. So it'll be about a 16" cone from the 1 5/8 up to 3 1/2 for the muffler bodies and a reverse cone on the end.

 

[Ratranger]

Looks like I have something to work on over the next few days off. Mail man dropped off what I need to do the exhaust.

 

[halfmile]

Where did you get your tubing and cones??

 

[Ratranger]

Cones came from cone engineering, mandrel bends and 3 1/2 tube came from summit, and baffle tube was from ebay, but made by LA choppers.

The cones showed up fast. I ordered them on the 19th. https://www.coneeng.com/

I have used mandrelbends.com in the past, but summit was the lowest price this time around

 

[Ratranger]

I'm debating having the mufflers more level, or following the frame angle. I'm thinking following the frame angle will look better. Top picture is following frame, bottom is more level.

 

[Adamc]

I'm debating having the mufflers more level, or following the frame angle. I'm thinking following the frame angle will look better. Top picture is following frame, bottom is more level.
View attachment 258138View attachment 258139

Frame line version looks good to me. Better balance with the swing arm.

 

[halfmile]

Is everything Stainless to be brushed or polished?

 

[Ratranger]

Is everything Stainless to be brushed or polished?

Mild steel, it'll get something like the jet hot coating once it's done. If I really like it I can rebuild it with stainless, but it'll cost almost twice as much.

 

[Ratranger]

Making an exhaust is a baffling experience.

 

[Ratranger]

Now the question is staggered a little, or even?

 

[Kevin Werner]

Staggered...

 

[Jim]

Staggered.

 

[GLJ]

Staggered with a little more stagger.

 

[Ratranger]

Ok, mufflers are done, next up is the headers. So far I have to say I'm pretty happy with the harbor freight protig 205 welder. Much easier to weld thin stuff than mig, and being able to do aluminum is nice. Also the milwaukee m12 die grinder is amazingly useful when doing something like this.