ESE's works engine tuner

[senso]

First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.

[F5 Dave]

First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.

I was asked to fix a mates foul stroke running one at a race.

It was running out of gas in the race. We'd fooled around raising float levels & bending floats so they didn't rub against the sides (evidence they did). But it still did it.

Maybe this is what fixed it.

There apeared to be a burr on the inside of the float needle brass housing where they cross drill it. I sanded it out with some sand paper over a drill bit & problem solved. Well at least so far. Chinese crap.

[senso]

I usually either add two extra holes around the float needle, as the stock ones are very small and the clearance between the needle and the bore is to thigh and the small cuts that the needle has are way to small, or I grab my 90º hand piece with a small 1mm burr and make the stock holes oval, and set the float to close a little bit earlier so they dont mess up due to uneven terrain(forward tilting).

[F5 Dave]

I checked the PWK on my GasGas last night to see it didn't have a similar burring (sometimes running out of gas on steep inclines).

[husaberg]

Attachment 267776

My OKO float jet/needle valve had a brass washer like seat that fell out and was lost now its just a rubber tipped needle in an alloy hole like the original Keihin. It was easy to re set the float height.

I

Whoops i may not have posted the OKO vs PWK 28. It was from a Aussie pitbike thread.
I will find it again the float valve i think was smaller than the PWK28 i think but fixable.

OK here it is..........http://www.miniriders.com/tech-talk/...carb-mods.html

First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.

This explains how some pwk copies may differ in detail re the Float needle and seat.
http://www.miniriders.com/tech-talk/...carb-mods.html

I can't vouch if it holds true for all the pwk copies or all the sizes. Guess some copy carbs less equal than others maybe........

[TZ350]

OKO 24mm carb making 30 rwhp. Watch the fuel line, sometimes the restriction can be upstream at the tap maybe.



Added a fuel header tank to the system by getting a large inline filter and modifying it by gluing a air breather to the top so now when the fuel demand is heavy the is a ready supply close to the carb.

[Gazzza]

Just a quick question but I'm sure some one out there may know the answer.
With out gong into models and things is it possible to add height to a piston crown by welding? Just to head off one reply, for various reasons I can't work the head to get the required compression, really need it to be the piston being altered if possible.

[TZ350]

Can you skim the base of the cylinder.

[Gazzza]

No not really, its a fairly rare engine I'm working on and don't want to sacrifice any of its originality... Really the only option it to modify the low compression pistons I have or wait until the right ones pop up, and that's fairly unlikely.

[speedpro]

This could be a useful place for those contemplating fuel injection

http://www.efihardware.com/index.php

[husaberg]

No not really, its a fairly rare engine I'm working on and don't want to sacrifice any of its originality... Really the only option it to modify the low compression pistons I have or wait until the right ones pop up, and that's fairly unlikely.

Gazza Pm me the measurements of the piston you have and what you need.
I have had a low HP old britsh dungar piston welded when it spat a land but it was only done when the piston was truly unobtainable and i was young and impetuous. But it was not an ideal solution.

[RomeuPT]

Hello everybody.

The most powerfull Honda type exhaust duct, for the T port, that I dyno developed for a customer in Belgium, was a 41 wide by 32 high oval at the flange face.
This went out to a 41mm header diameter via an oval to round transition.
The stepped transition, with simply a round 41mm spigot ID lost around 1.5 to 2 Hp comparred to the CNC lofted shape.

I filled the spignot with high temp epoxi to try oval to round transition, the epoxi will burn slowly but give enought time to test.

First test makes me feel a bit better power before peak... The plug looks a bit leaner but still ok. Wish I have a dyno.

Thanks Wobbly.

Regards

[cotswold]

Just a quick question but I'm sure some one out there may know the answer.
With out gong into models and things is it possible to add height to a piston crown by welding? Just to head off one reply, for various reasons I can't work the head to get the required compression, really need it to be the piston being altered if possible.

You can, I had a kawasaki klr piston built up and re machined to suit a cam and valves we fitted, you do have to be careful not to over cook it though as the 1st attempt failed dismally.

[Grumph]

Just a quick question but I'm sure some one out there may know the answer.
With out gong into models and things is it possible to add height to a piston crown by welding? Just to head off one reply, for various reasons I can't work the head to get the required compression, really need it to be the piston being altered if possible.

As others have said, the answer is yes...but ! I've done it on both 2 and 4 stroke pistons. I'm going to assume that you're talking 2 stroke on this thread. First you need to find a TIG welder who knows his alloys...and has access to the right rods. Then it's done slowly and carefully to try and avoid distortion....good luck.

Can i assume you've looked at alternative pistons ? Most bore sizes have been used at some time when you include oversizes. Failing that see sketchy's thread on CNC work wanted....

[wobbly]

I did it to a piston in a world champs winning chainsaw on Alky that had an integral head.
Used high silicon rods, and preheated the piston in the oven.
Worked fine, I think only due to the fact the saw made bugger all bmep, and the Alky kept it cool.