MK3 1.5inch unbalanced header pipes

Schwany · May 31, 2021

I'd be about as concerned about running 1 5/8" pipes on my Norton motor as Ron Wood.

Fast Eddie · May 31, 2021

Schwany said:
I'd be about as concerned about running 1 5/8" pipes on my Norton motor as Ron Wood.

Did Ron run 1 5/8 pipes... on a standard motor...?

Schwany · May 31, 2021

I don't run a standard motor. I'm off topic

Schwany · May 31, 2021

seattle##gs said:
I work out of a small garage. It can get crowded. My project is a Trackmaster frame that was originally designed for a Triumph Triple. I adapted in a
P-11 motor and trans, no easy fit. I fumbled around with different pipe designs but now I want to try the original pipes.
Two days ago I finally took my Goldstar cases down to a place in South Seattle called FLAME SPRAY to get a couple of bearing holes repaired. They build up the hole by blowing in stainless steel and then boring to size. $350 and it looks like a lot of work but I can't assemble the motor with sloppy main bearings. New cases are approx $2000 + shipping from the UK. I will let everyone know how this works out. This could save a lot of motors and gearboxes.

If you have time, it would be great if you could start a thread somewhere on your Norton tracker project. I'd like to see it live and in person when finished, if possible. I'm just up the road so to speak.

seattle##gs · May 31, 2021

Correct me if I'm wrong ( CMIAW ) but I believe one reason for the small diameter exhaust pipes was to minimize reversion. I read an article in CLASSIC BIKE eons ago by Alan Cathcart who described a pipe modification consisting of slotting the exhaust pipe on the underside and welding in a small piece of sheet metal as a dam to stop reversion. I don't remember the exact distance from the head. He took the bike (a goldstar), flogged it around the track and gave it a glowing report. I always wanted to try it. Perhaps it would help on 1 5/8 Norton pipes.

Fast Eddie · May 31, 2021

seattle##gs said:
Correct me if I'm wrong ( CMIAW ) but I believe one reason for the small diameter exhaust pipes was to minimize reversion. I read an article in CLASSIC BIKE eons ago by Alan Cathcart who described a pipe modification consisting of slotting the exhaust pipe on the underside and welding in a small piece of sheet metal as a dam to stop reversion. I don't remember the exact distance from the head. He took the bike (a goldstar), flogged it around the track and gave it a glowing report. I always wanted to try it. Perhaps it would help on 1 5/8 Norton pipes.

IIRC it was just after the first bend.

I experimented on the dyno with home made anti reversion washers once. All in all, a complete failure !

seattle##gs · Jun 1, 2021

OK I won't do the pipe mod.
The trackmaster will not be a street tracker. A friend runs a 250 Yamaha DT1 at Castle Rock and the TEST&TUNE days. We are going there this Sat. to play with the Yamaha and it looks like I can put the Norton trackmaster on the same track for a very fun day. I will check out the details this Sat. From then on I will have to rely on two different friends who have trucks to get there. Looking forward to it. Sometime when you are in West Seattle you can come by and see it. It's got a set of R1 forks and a Joe Hunt magneto. Single Mikuni.

NIX · Jun 2, 2021

You need a certain gas velocity which is lost when you go too big in diameter. The famous kick-in-the-back, combined with the I-paid-a-lot-so-it-must-be-good will give the illusion of performance increase where it means a loss in low and mid range. A smooth curve doesn't feel like raw power,
but is certainly making a faster bike.

Schwany · Jun 2, 2021

seattle##gs said:
OK I won't do the pipe mod.
The trackmaster will not be a street tracker. A friend runs a 250 Yamaha DT1 at Castle Rock and the TEST&TUNE days. We are going there this Sat. to play with the Yamaha and it looks like I can put the Norton trackmaster on the same track for a very fun day. I will check out the details this Sat. From then on I will have to rely on two different friends who have trucks to get there. Looking forward to it. Sometime when you are in West Seattle you can come by and see it. It's got a set of R1 forks and a Joe Hunt magneto. Single Mikuni.

Throwing some dirt. Norton motors are good for that. Should be a great time.

1 3/8, 1 1/2, or 1 5/8 inch pipes on a tuned dirt slinging tracker won't be an issue you are going to ever notice. The motor should be wound up to where it all works in the dirt. If you wanted to go 15mph in 3rd gear and claim it makes for a faster bike, the bigger pipes might be an issue though.