Dellorto PHBH

[nelson pk]

How on earth did we get by before dyno`s?
If it cheeses you off,stop reading and replying.
Im glad i couldnt afford dynos years ago as i learnt much more by doing it the long winded way.
Only ever holed one piston.

I dunno mate. How on earth did we get by before mobile phones.......technoligy is s**t isn't it.
Dunno why you bothered to get yours dyno'd by reedspeed either.
See ya!

Because i can afford to do that now

I must agree with that!
Somethings do get better with age and earning more money then!

[Special X]

I know a famous tuner, well respected, gets results. He has access to a dyno, but when he builds an engine for someone he jets it on the road with plug chops.

If anyones got an AV268 and an X2 needle in their box and runs a 200 kit. I'd like to ask them to try it in their PHBH and then post the results. You can put a stupidly small main jet in if yuo want to see if that tames the AV268/X2 if you want but for goodness sake don't run WOT for any length of time or blame me for the results.

No need, i'll tell you. If someone tries it and they are running a 40 slide like a lot do it'll run like a bag of shite but it wont go pop.
Also that cam lamb jetting example is running a clubman type exhaust (which i have already mentioned, yawn )not an expansion so dont go telling people to try it when they might have an expansion on their bike because that will kill it as you do need to up the mains sinificantly if running an expansion compared to clubman style. 2 stroke exhausts have a lot of control where your bike makes power and how much power it makes and how hard it pulls, for the second time, they can make a huge difference to fuel supply!

No . . . with a 40 slide (why bring the slide into it, but you have so I'll include it) it'll run a little rich on progression (the area wher you've just cracked the throttle from tickover up to around 1/8th throttle and with less effect up to 1/4 throttle) then with the 268/X2 it'll be four stroking and spluttering to way above 1/2 throttle then get better as the main jet takes over. With a 45/50 slide it will be progressivly weaker in the progression area as the slide number goes up. If you try to tame the overich mixture by using a small main jet it will be rich until the main jet area and then be catastrophically weak at WOT.

Whats this about box pipes and expansions. I suggested that someone could fit a 268/X2 combo to a properly set up engine and report on what happens. This will only cause a hugely rich mixture in the needle/atomiser area. It won't blow anyones engine up.

Read my lips 105 main jet on a 30PHBH is very very weak. Your engine will blow up with a box pipe, and even quicker with an expansion.

Don't try this with a super monza . . . they work in a different way to other engines and I wouldn't have a clue how to begin jetting one.

[Darrell Taylor]

not read the whole lot of this but one thing to come out on few posts i have is that variables will always exist
running different compression advance,retard ignition systems will have a big effect also on jetting requirements

for example a 35 mikuni with low comp and std ignition will be fine on a 20 / 22.5 pilot but runs up to 35 clean as with hi comp and advanced ign

[nelson pk]

not read the whole lot of this but one thing to come out on few posts i have is that variables will always exist
running different compression advance,retard ignition systems will have a big effect also on jetting requirements

for example a 35 mikuni with low comp and std ignition will be fine on a 20 / 22.5 pilot but runs up to 35 clean as with hi comp and advanced ign

Exactly my point and what i've been trying to say all along. There is no one setting you can use for the huge amount of motors and kits that were first mentioned weather piston port or not.
There are just too many variables on engine to engine to say well your running a muggy 186 so you'll be fine with this and this combo will work with all these other kits.....its just not wise advice.

Special X, listen, you obviously haven't experimented with different slides. Try it and you will see the biggest effect with a weaker slide is between 1/8 and 1/4 throttle but it will also make a substantial difference up to 1/2 throttle and a little beyond so will make a difference on cleaning up the mid range. Try it and see!
All the carb parts have to work in harmony and "cross over correctly".
It's like saying the main jet only effects 3/4 to full throttle, which is misleading. The mains BIGGEST effect will be in the 3/4 to full throttle area but it will effect the throttle range all the way down to 1/4 throttle on a decreasing scale. This is on the basis of how an adjustable power jet works. You lean your main jet to either use richer needle combos or to clean up the mid range when using a power jet.
Same with atomiser and needle......Biggest effect is in the mid range 1/4 to 3/4 throttle however the bigger needle and atomiser used will have a slight effect on main jet size too, maybe in some cases not huge but it will effect it! Think about it.....the final metering on the main jet stack is the space between needle and atomiser. If your needle/atomiser combo was way too small, it wouldn't matter if you used a 200 main jet or took the main out it would still run (but very lean) because it's still the atomiser/needle thats metering the fuel in the end.
The reason i brought reed valves in the mix was to show examples of how the main jet size is affected by richer atomiser/needle combos in my personal experience. That is carb theory weather your using reed valve or piston port.
Hope this makes some sense.

[soosh]

Maybe the carb spec pages should be removed from this forum.They may be misleading.

[soosh]

Anyone tried these? Seems like a good price....

http://www.wasp-performance.co.uk/onlin ... 30-BS.html

So.....did you buy this in the end?

[corrado]

And more importantly, did it blow up your engine? :shocking:

[paulnobodyimportant]

Just to give feedback to some of my earlier comments in this thread, spent last weekend dabbling with the jets on the 30PHBH then riding and plug chops. Massive difference as it hits the power band, so I'm well pleased.
But I'm thinking of taking off the 30PHBH and putting on a spare 28PHBH, but you may ask why.

Well, from reading some of Nelson and Special's comments on this thread, it got me thinking and wanting to learn more. So reaching for the Dellorto manual, which at one point shows a graph of carb size to Peak HP. Now I'm assuming that my reedvalve 200 classic may be peaking at 14 - 15 HP and if so, the carb size should be between 25-28. The benifits of a smaller matched carb, so the book says, is better throttle pick up, balance of power and more efficeint use of fuel. The down side may be a slight drop in top speed, which I can live with.

In addition, as I have mainly been getting to understand carbs and jetting this year, it gives me a further oppertunity to meddle and learn. As a starter, I would swop over all jets, needle and slide and see what the ride and plug chops tell me.

Now some of you may say that I'm wasting my time, but are there any votes for going down this route.

Thanks


Paul

[corrado]

PHBH 26 might be better suited then as it's much closer to ideal spec out of the box and you can just about run it through the airbox if you wanted to retain standard looks.
Factory jetting on the 26 is 110 main, 50 pilot, X7 needle, AV266 atomiser, 40 slide.

[paulnobodyimportant]

Forgot to say, I've a spare 28 phbh so I thought it may be worth experimenting or would it be a waste if time