Z1 powered '81 Moto Martin

Great progress on the bike Robin.

One thing bugs me... The dyno testing... What good are HP numbers if there are no other variables provided to benchmark/diagnose? You can start going down the wrong rat hole quickly.

Good epiphany about the possible drilling of your jets...

kzr750r1 wrote:

Great progress on the bike Robin.

One thing bugs me... The dyno testing... What good are HP numbers if there are no other variables provided to benchmark/diagnose? You can start going down the wrong rat hole quickly.

Sorry i dont get what u are tring to say? Is'nt the idea to get a base line so u can compare it to future changes.

That side cover is Killer.:woohoo: can u still buy them new, or did u ebay it?

mark1122 wrote:

It make sense to me that there is atomization starting at exit of the main jet . the main jet screws into the the needle jet. there are 2 types, bleed and primary. the bleed type have holes in them to bleed air into the fuel as it exits from the main. this starts the atomization before it reaches the carbs throat. Some carbs (smoothbores) also have an air jet that feeds this area . It can be changed out like a main jet to adjust the fuel ratio.

Good point, the needle jets on these carbs have the holes in them but I don't understand where the air should be coming from, from the venturi? I checked an extra set and there is no other (air)passage in there.

You do make sense :lol: but still unsure how it should work in this case.


kzr750r1 wrote:

Great progress on the bike Robin.

One thing bugs me... The dyno testing... What good are HP numbers if there are no other variables provided to benchmark/diagnose? You can start going down the wrong rat hole quickly.

Good epiphany about the possible drilling of your jets...

As Mark1122 says, baseline data.

(And a nice picture for you guys to look at. :laugh:)

Got the cover from Ebay Germany and there was another one on Ebay Motors but that one meant losing the points... Also available on www.moriwaki.co.jp/global/product/01.html

there is often a hole at the bellmouth that leads to the needle jet.

mark1122 wrote:

there is often a hole at the bellmouth that leads to the needle jet.

But not in this case... the needle jet does have the holes just not the air passage going to it.

well, you can only work with what u have. It doesnt realy matter. when u get it back on the dyno u will get it jetted right.

mark1122 wrote:

well, you can only work with what u have. It doesnt realy matter. when u get it back on the dyno u will get it jetted right.

Indeed, and nice to have techical discussions and hear some new insights. Bike is running well as is and with some possible extra HP in the future.

Thats good to hear. keep us posted with the progress. I hope to get my bike on a Dyno some day. I will be sure to post the results.
I cant waite to see what a perfect plug color is suposed to look like. I feel it will speed up the learning curve for me.

mark1122 wrote:

kzr750r1 wrote:

Great progress on the bike Robin.

One thing bugs me... The dyno testing... What good are HP numbers if there are no other variables provided to benchmark/diagnose? You can start going down the wrong rat hole quickly.

Sorry i dont get what u are tring to say? Is'nt the idea to get a base line so u can compare it to future changes.

That side cover is Killer.:woohoo: can u still buy them new, or did u ebay it?

Sorry I didn't make my point. HP is one criterion. Exaust gas output is another veriable that will tell you where the issues may lie.

kzr750r1 wrote:

mark1122 wrote:

kzr750r1 wrote:

Great progress on the bike Robin.

One thing bugs me... The dyno testing... What good are HP numbers if there are no other variables provided to benchmark/diagnose? You can start going down the wrong rat hole quickly.

Sorry i dont get what u are tring to say? Is'nt the idea to get a base line so u can compare it to future changes.

That side cover is Killer.:woohoo: can u still buy them new, or did u ebay it?

Sorry I didn't make my point. HP is one criterion. Exaust gas output is another veriable that will tell you where the issues may lie.

Ah allright, normally there is exhaust gas measuring but there were problems with it, I agree that you can go the wrong way like this but a good Dyno operator can still diagnose some stuff from the graph like a less then perfect final drive or rich /lean running but the former method is better. But I have a healhy engine to go from.

Robinjo wrote:

Red line was last time on three cilinders.
Blue line is the good one, 74 RWHP, about 88 crank horsies.
Green line is without pod filters, there is a lot of difference :ohmy: carbs are running #95 mains, manual says 112.5 for '73?

So I'm pretty pleased with the results, I know I have a good and healthy engine but it likely could produce more with some K&N's and matched jetting instead of the old brandless filters the bike came with. Off to the search engine!

I like the fact that it has a very straight incline,no dips.
When u see dips u start to find parts that are not working together. like a header with a 5000rpm flat spot, or cam timming.
This is a good baseline.

mark1122 wrote:

Robinjo wrote:

Red line was last time on three cilinders.
Blue line is the good one, 74 RWHP, about 88 crank horsies.
Green line is without pod filters, there is a lot of difference :ohmy: carbs are running #95 mains, manual says 112.5 for '73?

So I'm pretty pleased with the results, I know I have a good and healthy engine but it likely could produce more with some K&N's and matched jetting instead of the old brandless filters the bike came with. Off to the search engine!

I like the fact that it has a very straight incline,no dips.
When u see dips u start to find parts that are not working together. like a header with a 5000rpm flat spot, or cam timming.
This is a good baseline.

Even more midrange power (3 HP at max point) without filters, would love to extend the green line higher up. Happy my short exhaust pipe works well, stock cams are pretty mild I think.

Is there a centralised Dyno result/chart topic somewhere on this site?