Z1 powered '81 Moto Martin

Yes you are right ,sory, i missed that extra outlet.
Good to hear it is working.
I just looked at some of those bikes. and all i can say is WOOOOW!!!!:woohoo:
There are some beauties there for sure.

robin congrats on your bike being accepted into the superbike meeting!
could you have someone mill your brake line splitter,so that it was square with the thread bores?or perhaps your careful filing has already squared it enough for use.i looked last night quickly and only found a single disk splitter.if you need another i am sure we can help you find one.
brake late accelerate early!!!!!!!!!!!!!!!

leon holmes

531blackbanshee wrote:

robin congrats on your bike being accepted into the superbike meeting!
could you have someone mill your brake line splitter,so that it was square with the thread bores?or perhaps your careful filing has already squared it enough for use.i looked last night quickly and only found a single disk splitter.if you need another i am sure we can help you find one.
brake late accelerate early!!!!!!!!!!!!!!!

leon holmes

Thanks, I'm pretty about it too and the splitter seems to be leakfree right now.

Clutch is back in business with a cleaned up rod and fine-adjusted worm wheel so I got to the Dyno meeting but the results were bad, 63 rwhp :blush: but I found out later that I had a disconnected HT lead on #1, possible from trying to fit the dyno's RPM sensor so interested to see what she will do on all four.

Shop owner is giving me a second chance run for free. And promised to physically punish the person responsible. :ohmy:

Treating the bike to a new set of NGK sparkplugs, the one not firing for a while has taken a beating resulting in a stumble at WOT that wsn't there before. Also read about the relay mod on the coils but the voltage drop from the battery to the coils is now negliable, four hundreds of a Volt.

Also going to wash out and oil the pod filters.

glad you have got the bugs worked out.so if it has 60+ on three,so we should probably be seein 80+ on all four eh?
give the dyno operator a sound thrashing and let us know what she turns hittin on all four.

leon holmes

Back on the Dyno today, shop owner proudly showing of the new Garret turbocharger for his personal ZX11 project "Brutus", goal is 400 HP. :woohoo: But back to my little bike...



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!

can u explain why the power went down without the pods? is it due to uncorrected jetting, making it too lean?:side:

mark1122 wrote:

can u explain why the power went down without the pods? is it due to uncorrected jetting, making it too lean?:side:

A good set of pods should be allmost the same in airflow as no filters at all, I'm thinking my old pods are pretty restrictive which should explain the #95 mains instead of the stock 112.5 [sudden brainwave]unless the #95's are bored out![/sudden brainwave] or there could be a disturbed airflow to an air jet in the intake side of the carbs but I find that less likely. I have been working on and tuning VM and BS series carbs as part of my hobby for about 8 years but there are a lot of variables.

Too bad there was no exhaust gas measurement on the Dyno today to indicate lean or rich.

You make some good point for sure. i have heard of guys drilling out jets. but what they don’t realize is the jets are made as a venturi (spell?). So when they drill them larger they get poor atomization and must run richer and waste fuel due to poor burning.
so the power went up due to a lean condition, right?
Are u planning another Dyno run?
Will there be exhaust gas testing?
What carbs are u using and what other mods are done?

mark1122 wrote:

You make some good point for sure. i have heard of guys drilling out jets. but what they don’t realize is the jets are made as a venturi (spell?). So when they drill them larger they get poor atomization and must run richer and waste fuel due to poor burning.
so the power went up due to a lean condition, right?
Are u planning another Dyno run?
Will there be exhaust gas testing?
What carbs are u using and what other mods are done?

I'm not sure if the venturi in the jet has any part in atomising or that is has a different purpose, for example in the machining of the jet, also there are other jets without venturi... I think it's pretty much raw fuel being drawn past the jet needle without any air and the atomising takes place in the carb venturi.

On the filterless run the power went down, most likely due to a lean condition, if it's waaay lean there is nothing left to combust, if it's waaaaay to rich the air/fuel mixture can't combust also dropping power so the symptoms are sometimes very similar and that's where the exhaust gas testing comes in.

There will be a new run with exhaust gas testing, I would like to test the effect of some 118 mains and no filters, ideally with a set of K&N's but it would be a waste of money if they don't have any use...

AFAIK the bike is stock internally, '73 Z1 engine. 28 mm Mikuni carbs but the kind with an extra pilot fuel circuit screw on the bottom, no accelerator pump, old unknown but cleaned and oiled pod filters. Also 4-1 header and short muffler, stock points and advancer with stock settings, stock coils and classic Lodge spark plug caps without resistors, new NGK B8ES plugs.

Also got this points cover last week. :woohoo:

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.