Topic: Yoshimura Exhaust, Cam, and Carbs

[754]

Yeah I think 2600 carbs are going to give the least bang for the bucks..

[scottly]

They’re gonna be about $2600. There are cheaper options for sure, but these aren’t vintage options. Head work may definitely be in the cards!

TMR's are not vintage; Webers and VM smooth-bores are vintage.

[PeWe]

My bike had 836, ported head with 34mm IN valves (F2 valves), cam Action Fours SS-1 (9.14mm lift).
It had first Mikuni Smoothbore VM29.
Carb boots cracked too easy.
Back to stock carbs.

It did not run slower with stock same top speed and good acceleration. The loss was throttle response in the mid range.

Same bike, with same head, cam, 836 29 years later.
Started with VM29 2014.
2015 it got TMR32.
Much better response, especially midrange.
Not higher top speed.
Dyno 81hp, a hotter cam gave 83hp. 4-1 all the time.

2017 1000cc. Head had got 5mm stem valves the year before.
NOW a huge power difference!
The displacement give good torque early, start at 3000 rpm something.
First years 4-4 ( open type) 93hp, hotter cam DP315.

2018 another cam with better torque, RC295.
Exh Hindle 4-2-1 this open up for more power, need more fuel.
This year TMR properly jetted for low speed and midrange.
No Dyno yet, I guess over 100 whp.
Again, bike run not much faster, but it accelerate rather quick to 200 kmh.

More cc and CR
Ported head and hotter cam.
Good exhaust
Carbs
Orient spark plugs equally, all gaps facing In valves made a difference too!

Important to see where the restriction is and modify there first.

When my last setup had 4-4 it could max have 137.5 mains.
With Hindle 4-2-1 it runs best on 145. I tested all steps between and more. Needles richer.
I think all extra fuel transforms to rear wheel power too.

Dual brakes on my bike was a must, stock was not working well.

There is a thread about Dyno results and setups.
This has no bike with modest tuning, but TMR-MJN.
Maybe it will?

[scottly]

My bike had 836, ported head with 34mm IN valves (F2 valves), cam Action Fours SS-1 (9.14mm lift).


Same bike, with same head, cam, 836 29 years later.
Started with VM29 2014.
2015 it got TMR32.

Dyno 81hp, a hotter cam gave 83hp. 4-1 all the time.

My 836 with high compression, a "mystery" cam with relatively low lift, Weber carbs with 30mm chokes, Winning exhaust, and a STOCK un-ported K1 head produced about 71 HP on the dyno. Switching to 32mm chokes added maybe 1 HP at the peak. With porting as described in the Branch porting article, I would expect the output to increase to 80HP, with no other changes. 

[PeWe]

This thread start to look like a very informative " Tuning Confessions"
Just a few bikes more what done and the outcome of it.

Can add another bike:
392 0.5mm oversize pistons in K2 stock engine made it happier. K7 cam and Kpmi springs just for sure.

Edit: before I ordered the TMR, I looked around if MJN should be worth the difference. The answer was no.
A racing bike can probably have use for a different transition in the needle area, get the short time enough out from the corners for better result.

It would be perfect if anyone has used TMR, then added the MJN needles and noticed the difference.

No way the top power will give any extra. Only the size of 32mm if the engine can make use of it.

+1000cc and lower priced RS34 will probably produce better on dyno.