Mito 443 Project

[Yazza54]

jason61c said:

Yazza54 said:

443 non pv cheetah cub 68mm bore with 7mm crank. Toying with trying lectron flat slides, I'm hoping the extra stroke and 36mm carbs instead of 38mm might make it less peaky than the other I've seen, also will run a digital ignition. Yes it'll need a billet basket and will run straight cut primaries. Going to keep messing with the rolling chassis for a bit first as there's still plenty of jobs to do but in essence that's the idea engine wise.

Thats doing it properly! What sort of weight will it be?

I'll have to sit down and actually try and add stuff up but I'm hoping around 120kg, I've thought a little about it but not to the extent of working it out yet. There's some bits about this bike that will be heavier and some lighter plus a lot of gubbins removed. Was surprised to find out that the rd motor isnt much different weight wise, the little mito engine is a right lump for its size.

[bass gt3]

Yazza54 said:

Yeah that is conservative, at that spec I'd be disappointed with 85! Will see how it goes, not planning on porting the cub cylinders just a clean up and transfer to case match as they're bloody wild as is!

Indeed, but i think the unknown here will be pipes and their design and efficiency in relation to YOUR engine. I've got a stonking book at home that lays ou the exact science of 2T design, tuning and especially pipe design, right down to stinger diameter and length of insertion into the belly. Things like cone ratio from ex port to belly as well makes a huge difference to overall performance. I'll try and get the title/ISBN number and maybe you can sort yourslf a copy. Well worth having the maths behind it all rather than someone fobbing you off that these or those pipes are the dogs danglies etc, meanwhile you're chasing your tail.
I guess with the +7mm crank you'll be pegging the rpm limit around 10-10500 so area under the curve is vital rather than a peaky top end with faff all below. By comparison, my RS250 has very little below 8k but once the PV's open she really zings up to 12k and is surprisingly quick!.
She's goingto be a superb little thing, good luck and enjoy.

[Yazza54]

Agree mate, since I'm going to this extent I'll be getting TSA to make pipes specifically for the bike, will be another rather large expense but simply not something to skimp on!!

[bass gt3]

Cool. Kenny has a good reputation it seems. But let me get you the books details and you can do your own calcs to be 100%

[Yazza54]

Cool this is the one I have http://www.amazon.co.uk/gp/aw/d/1859606199?pc_redi...

[bass gt3]

Nope, not the same book. The one i have is A5 sized and very very science based. It's from the 70's or early 80's, reddish cover. I'll dig it out.
The section on exhaust design alone is frightening at first but incredibly detailed in terms or dimensions and volumes based on port dimensions and such. It's so good you could actualy design your own pipes down to the last mm based on your cylinders characteristics & measurements and the formulae in the book.
I'll get back to you.

Edit it's this one. The cover looks right from memory. Bugger me, $139 s/h or $246 new, i'd better show it some love....

http://www.amazon.com/Two-stroke-Tuners-Handbook-G...

Some of the reviews....

http://www.amazon.com/Two-stroke-Tuners-Handbook-G...

Edited by bass gt3 on Wednesday 9th April 00:04

[Yazza54]

Thanks Steve

[RumpleFugly]

There's a CD-Rom copy of it on ebay for a fiver if that helps. Seems like the printed book is going for crazy money nowadays!

[theshrew]

Yazza54 said:

Just ordered some titanium bolts for calipers cos I'm bored .

Titanium bolts

I still amazes me at how much weight you save with just by swapping 1 bolt to titanium, and how something so strong can snap so easy.

They look great to

[bass gt3]

RumpleFugly said:

There's a CD-Rom copy of it on ebay for a fiver if that helps. Seems like the printed book is going for crazy money nowadays!

Ryan,
Get a copy. I promise it'll be one of the best ways of spending 5 quid you could find. It really will be worth it for cutting through the BS that abounds in the 2T world.

[13aines]

I sent him a PDF copy I read in the past last night Steve

Ryan, lets do the calculations and design an optimum pipe - if only I could weld, let alone weld spannies.

[Yazza54]

13aines said:

I sent him a PDF copy I read in the past last night Steve

Ryan, lets do the calculations and design an optimum pipe - if only I could weld, let alone weld spannies.

Haha that's an entire project in itself, the thing is it's one thing spitting out a calculation that gives you a good straight pipe design, you've then got to actually fit it to the bike hence why it's something that requires a lot of skill to find the best compromise between design and actually fitting. That's why I'll be getting someone to do it who's proven and will make the pipe specifically for the motor and bike.

[13aines]

Probably wise! I hadn't really considered the weight of that... Definitely easy to do the calculations, but it's clearly far more involved than that!

[Yazza54]

It is something I've always wondered about having a go at, the software packages now even print out cone templates for you to cut out of steel sheet. But this won't be the test bed for that!!!

[bass gt3]

Ryan,

Have a read. I totally agree that making or calculating the optimum pipe design is one thing, then fitting it to the bike is quite another. But there's some very useful info about things like stinger ID and how if it's too small it raises piston temps etc. There are certain factors that you can determine and incorporate into a known design that may make a huge difference.
The pipe design section takes a lot of data from the port windows and timing, so it becomes apparent that a pipe thats good for a 485 motor may not be much cop on anything else. The devil is in the details mate!!

[Yazza54]

Yup I will look into it mate, but it has to be spot on so it's something I'm happy to farm out to a professional (and get a financial spanking in the process) but it'd be nice to see the method in what he's doing, especially stingers which is something that can be easily modified after the pipes have been built at a later date. There's simply nothing off the shelf that will work properly so this is the only way.

[bass gt3]

Yazza54 said:

Yup I will look into it mate, but it has to be spot on so it's something I'm happy to farm out to a professional (and get a financial spanking in the process) but it'd be nice to see the method in what he's doing, especially stingers which is something that can be easily modified after the pipes have been built at a later date. There's simply nothing off the shelf that will work properly so this is the only way.

Agree 100%

The nice thing is that the data in this book isn't conjecture or hoodoovoodoo. It's impirical and you can set about determining the ideal pipe dimensions for YOUR specific barrel without any guesswork or internet BS. As you say, the optimum may need to be altered to fit the bike, but you'll know which direction to head in when making those changes.
And with a decent set of data, you'll save yourself a ton of cash as the trial and error element should be minimised. Especially if it prevents nips or seizures due to pipe design. Considering the time & cost of changing the pipes, the a trip to the dyno, including time to re jet and try again, it can get very very expensive.
Good luck

[Yazza54]

bass gt3 said:

Yazza54 said:

Yup I will look into it mate, but it has to be spot on so it's something I'm happy to farm out to a professional (and get a financial spanking in the process) but it'd be nice to see the method in what he's doing, especially stingers which is something that can be easily modified after the pipes have been built at a later date. There's simply nothing off the shelf that will work properly so this is the only way.

Agree 100%

The nice thing is that the data in this book isn't conjecture or hoodoovoodoo. It's impirical and you can set about determining the ideal pipe dimensions for YOUR specific barrel without any guesswork or internet BS. As you say, the optimum may need to be altered to fit the bike, but you'll know which direction to head in when making those changes.
And with a decent set of data, you'll save yourself a ton of cash as the trial and error element should be minimised. Especially if it prevents nips or seizures due to pipe design. Considering the time & cost of changing the pipes, the a trip to the dyno, including time to re jet and try again, it can get very very expensive.
Good luck

The setup/jetting is one of the reasons I'm tempted by a set of lectrons, no main jet just a powerjet that can be externally altered, which must make altering the mixture a lot more user friendly. Have you looked into them at all Steve? What have you got on the RS?

[bass gt3]

Yazza54 said:

The setup/jetting is one of the reasons I'm tempted by a set of lectrons, no main jet just a powerjet that can be externally altered, which must make altering the mixture a lot more user friendly. Have you looked into them at all Steve? What have you got on the RS?

I did look at them for the RS, but there's some complications. The RS runs a funny carb set up where the RH carb is tilted like the front cylinder in such a way that you can't fit a normal carb in it's place. The OEM carb is very special internally as it's tilted so the only way to replace them is to fit a curved spacer that mounts any new carb as it should be. They are available from a company in Italy at 280 euros!!
I've read up a bit about the Lectrons and it seems that whilst they're very good at WOT, because they lack the typical jetting attangements of a conventional carb, their low and mid throttle running can be a bit sketchy and difficult to get right.
The other thing is the RS runs a power jet arrangement that supplements the main jet at WOT as well as solenoid controlled air jets that work on a PWM principle. The ecu controls them to alter the mixture at certain rpms to almost provide a constantly variable jetting arrangement. Yes, it's a fking pain but if you get the curve right, they work very very well. Maybe look at RGV/RS 250 34mm LH carbs + solenoids for yours?? If you run it with a Zeeltronic, you can alter the solenoids from a PC so no need to keep stripping them down. The main and power jet should be fairly simple to set, but altering the solenoids will adjust your midrange and low end jetting to get it spot on. Actually, the more i think about it, that could be a very good way to go. Use the Zeeltronic from the RGV/RS and reprogramme the ignition to run the 180 degree crank not the 90 degree from the RS (easy). Get a couple of Left side 34mm RS/RGV carbs (easy) and configure with their solenoids on the zeeltonic. This would give a lovely fuelling curve as there's effectively 7 or 9 jets in the 0 to 100% throttle range.
Lots of options i guess. I still want to FI the RS but thats for another day!!

Edit:

Ignore me! Just remembered you want 36/38mm carbs for a 220cc cylinder. I would get the best keihins you can. Jetting isn't hard to get right, especially as you'll be keeping it on the safe side. Plus on your bike, it isn't hard to change mains or emulsion tubes so why risk it?? Go Keihin.

Edited by bass gt3 on Wednesday 9th April 13:27

[Yazza54]

Yeah, still unsure what size to go for. The dyno graph I posted earlier in this thread was a 421 on 38s. To me 38s on a 443, 220cc a cylinder doesn't seem too wild, but his graph was mega peaky which made me think maybe 36s would be better. Thing is he may well have had some porting done and all I'm going to do is have the castings cleaned up. Plus I'd hope the longer stroke would help to make it less peaky.