MB100 development

[datfreak]

hi guys -
I'm not too worried about the jetting as yet - ill do the porting then sort the pipe THEN re-jet it . I just wanted to hear her run again.


The carb is on a bit of a angle - but is that a prob? Under throttle (and the bikes nose comes up) the angle wouldnt be too much.... I might look for a RD inlet just to be sure.

I'm unsure on which pipe as yet i was thinking of butchering a rv125 aprilla expansion chamber - or using a premade one like this one
http://www.josdijkman.nl/shop/index....productId=4468

I was recommended tthe above pipe by a euro pipe guru see his website here:
http://honda80ccracing.weebly.com/

Id really like a stainless "welded" -like the arrow branded ones- pipe but i think it will blow the budget.

ill update when ive got some porting done.
cheers

[datfreak]

some porting done ..After making one inlet side larger, I tried to copy it on the otherside and......... went thru into the barrel stud channel.

Would have looked ok if I hadn't screwed that up. Maybe the bridges are a little skinny (esp when I take the edge off them) - i have seen a few like this on online porting pics - piston life may not be the best


I did bell rules with the inlet and exhaust port ., ex width ,floor height, piston bottom to top of inlet port
-- and if I did the maths correctly, increased ex timing to 194 degrees. Which isn't too wild, but I can take more off later.

I need to do alot of smoothing, but this can wait until I fix the hole.

looking into devcon now - but seems it is only sold in big amounts.. Is there a another brand "metal fill" epoxy that is good enough? Something I can buy from suercheap/repco?

[Grumph]

Instead of Devcon, it may be safer to bore the stud hole say 1mm bigger over a short distance and press in a piece of thin wall tube.
From memory, the stud holes have a generous clearance to the stud so it should be possible to use 1mm wall tube.

This is a common fix for cracked 60's triumph heads....

[speedpro]

I simply would not worry about it. It's all sealed top and bottom so who cares.

[Ocean1]

Instead of Devcon, it may be safer to bore the stud hole say 1mm bigger over a short distance and press in a piece of thin wall tube.
From memory, the stud holes have a generous clearance to the stud so it should be possible to use 1mm wall tube.

This is a common fix for cracked 60's triumph heads....

I used to port 1275 mini heads completely ignoring a pair of pushrod holes, which I'd ream oversize beforehand to take 5/8" hydraulic tube. I'd break into the holes by a good 5-6mm but with the tubes pressed lightly in with Loctite the ports flowed better than the traditional conservative shape.

I did the same with some stud holes once, machined up a tube with a top-hat to fit a register in the hole to feed the compression into the head. Worked OK.

[F5 Dave]

I agree with speedpoo. But JB weld is pretty good and should find on ebay in packs of a few s,mall tubes.

[datfreak]

thanks guys for your ideas... I like the idea with the thin walled tube, ill have to see it iI can get some locally.
Otherwise ill give the jb weld a go( i did a search and a local electronics dealer stocks it - Jaycar).

And its true, speedpro's "do nothing" would be fine but im being anal retentive and want a flat smooth surface for flow ------ i know it would probably makes no difference, but i stuffed up and want to fix it... ( i do change my mind alot-- maybe tomorrow do nothing will sound like a very good idea)

edit: If i do the "do nothing" approach, then i could open that side port even more (like the otherside),making the hole even bigger..... and the worst thing that could happen is that the head stud maybe in the side of the inlet as a ridge... this may effect flow but this would be countered by the port, being bigger and having a otherwise better line... decisions

[datfreak]

Hi, I did the alloy tube idea to fix the hole, it worked great. As the pic, the wall isn't perfectly smooth but close enough.

Also , see the other pic - One of the foot pegs has snapped off, so ive got the x member off for welding. The alloy rim is a high lip 18" D.I.D, I'll be putting these on when I get new spokes (stainless unless they are too expensive, if so ill get chromed thai ones).

Just took it for a little run, and had to move the needle up to the highest point to remove mid range bog down, so I may have to go up a main jet size.

And she has now a lot more grunt - front comes up nicely.. Kinda feels like a older cr125 that I had before - just the h100 has terrible brakes and suspension Will be great when I get a better exhaust and tune the carb,.

I was going to keep the original drum front as it is only going to be a street bike but now after riding it, maybe a disc front end is a good idea.


I'm surprised how easy it is to ride, I expected it to be more pipey(like cammie on a 4 stroke)- but it feels quite flexible.

This bike has no tacho or tacho drive, so is there a tacho that runs off the cdi OR would I be better off getting a h100 side cover that has the drive?

EDIT: ok there seems to be a few universal tachos that should run from cdi but they use 12v - is there a 12v conversion for the h100? like the yamaha one http://www.youtube.com/watch?v=ljDFwVgvELI

[koba]

EDIT: ok there seems to be a few universal tachos that should run from cdi but they use 12v - is there a 12v conversion for the h100? like the yamaha one http://www.youtube.com/watch?v=ljDFwVgvELI

There are heaps of options, for a rod bike the best bet would be to get a (Much) lighter Stator/Rotor setup of something else.

The standard MB/H one is shit for performance work.

As racers we don't have to worry about lights and indicators but I'm sure there is plenty out there.

For the tacho you could run a small battery for tuning work, when you need to know the revs, after that just unhook it all and get to know the bike.

[datfreak]

....best bet would be to get a (Much) lighter Stator/Rotor setup of something else.
.

So Im back to searching for more cr80/85 parts ?I should buy a bent cr for parts Do any year flywheel and ignition fit? does the cr stator coil fit on the h100 stator plate (as the cr on is a 2 vs h00 3 hole)?
\I'm on holidays now (yay!) so I can do a build thread and stop hasselling you chaps in the mb100 dev one - but saying that, your knowledge and 2 stroke experiences have been so very helpful.

[koba]

So Im back to searching for more cr80/85 parts ?I should buy a bent cr for parts Do any year flywheel and ignition fit? does the cr stator coil fit on the h100 stator plate (as the cr on is a 2 vs h00 3 hole)?
\I'm on holidays now (yay!) so I can do a build thread and stop hasselling you chaps in the mb100 dev one - but saying that, your knowledge and 2 stroke experiences have been so very helpful.

Older CR 80's bolt on.
Will try find a link.

No good for a road bike if you want lights though, really you will need to shop around for something that has lighting coils too, if it is already made for 12v just graft the whole lot on.

[speedpro]

I've made mistakes with what I'm using but pretty sure a CRF150 generator and rotor fits with an adaptor plate. Use the whole rectifier/regulator and capacitor and you end up with 12V supply and trigger for a CDI. The rotor is a direct bolt on to the MB/H crankshaft.

[F5 Dave]

I keep telling you that is not crf. They have inside out arrangements. CR125 or 250 03 ish. 40w of power. Suit a baby light at most. Getting harder to find. Can get 50w after mkt but $+

[datfreak]

anyone tried
http://www.mh-aerotools.de/airfoils/javapipe_en.htm

?
(you have to install java for it to work).
Is the sizes correct ? pity the exhaust size only goes to 1000 m2. Curious to what you guys think..( Im still sussing out a nice exhaust for my h100)

[F5 Dave]

Are you intending to cut and weld them? I can send you pdfs of cones that should do the trick