Barrel back from an extended stay getting honed, this time of year & all, but the good news was a light lick and its all straight, so the extra support is working well.
Barrel back from an extended stay getting honed, this time of year & all, but the good news was a light lick and its all straight, so the extra support is working well.
Don't you look at my accountant.
He's the only one I've got.
The limiting factor on the big MB would appear to be the transfers...when you go as big as 54mm in the bore the top angles change - and not for the better. Passage volume is pretty much optimised for 100cc, not really enough room for the bigger ports needed for bigger displacement. that's why i was going to put a DT125 barrel on one...everything is optimised for 125 already.
just how far do you ride the scooter anyway ? looks like plenty of thinking time but a tad dodgy posting while riding...
Kart tracks are different and most need spread of power over peak but I think on the balance of it the watercooled 100 is the way to go for an MB.
This 54.5mm barrel is watercooled so I won't compete with it but I think I will give it a try on my road MB100 sometime, just for giggles.
Heinz Varieties
Well here's my attempt at trying to get a reasonable curvature to the MB transfers. Clearly I've just stuck some inserts in & glued them in place. Next step is about 1/2 doz gluing iterations with grinding in between to get a finished job. I'll also have to look at the outside curve & match to the inner, but it was a bit naff before. Then there is the twist, but I'll try this first.
This should pull it kicking & screaming into the 80s. Wish there was a 100cc MC18 or newer to be starting with.
Last edited by F5 Dave; 24th December 2014 at 08:31. Reason: rotate photo
Don't you look at my accountant.
He's the only one I've got.
Is this a fresh barrel without the water jacket ? if so at least you're free from the constraints of finning and can add material to the outside of the transfers to get a better curve...If not, it's been welded on once, pull it off again if you have to.
I like your work, curving the transfer duct walls and eyebrow exhaust ports, very interesting.
Factual Facts are based on real Fact and Universal Truths. Alternative Facts by definition are not based on Truth.
Its the same WC barrel I brought down to Chch Bob. I hate weld into Honda barrels, despite the LC jacket, but that caused enough issues.
Don't you look at my accountant.
He's the only one I've got.
Hi Dave
I use an Pratley steel putty to fill and shape the transfer ducts. The putty allows the shape to be roughly formed by jamming into the duct with a small spatula then using a pre-formed tool to mash into final shape (as Mike also mentioned)
Hmm that might be easier for the bottom bit, might try some. Repco it seems. The inserts gave me some consistent shape if I got them in the same place. Jolly hard this stuff in such small places.
Don't you look at my accountant.
He's the only one I've got.
Well I've been tickling any tickling these transfers as
One, I didn't do a very good job initially. So hard to see up there
Two, the MB is a bit lop sided from std.
Anyway enough obsessing and just time to sew it all back together. I'd have liked to do a leakdown test but my new slip manifold means making an expanding mandril dodah.
Engine goes in frame tomorrow and dyno sometime after.
Don't you look at my accountant.
He's the only one I've got.
Really I was close to crying when I got home.
People seem to sling things together and get great results. But I have to find new problems. So I started with getting the woodruff key off but sorted that out.
First run full of hope and trepidation. I go to sleep every night thinking about my transfers or ex port. So I was hoping for some more spread. Heck even some more power.
What I got was 5hp less and 500 less rpm than the already peaky spread. Some jet changes reduced that to about 2.5 less but the spread is still gone.
Worse still is it jerks really violently on decell. Tried new plug and huge pilot. But I'm concerned to ride it like that.
Don't you look at my accountant.
He's the only one I've got.
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