Wildguzzi.com
General Category => Bike Builds, Rebuilds And Restorations Only => Topic started by: pete roper on June 09, 2017, 01:39:49 AM
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Didn't even know this section existed until now. Yes, I'm not overly bright.
Anyway, I'm starting a 'Bare Case' engine build of the 1400, single spark 8V. If there is any interest I'll document it. If not I won't bother. Let me know.
Pete
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I'm in!!!!
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I like all the build threads. Something always to be learned even if you don't have that particular model.
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I'm interested!!
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Please proceed... :popcorn:
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What is this engine from?
The only 1400 8v I know is twin spark
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Please do.
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I'm in too! Would love to follow the build
-Ulrik
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What is this engine from?
The only 1400 8v I know is twin spark
It's an oversized version of the 1200 I'm building for Beetle's bike. I've been accumulating parts for it for a while. The biggest issue will be the compression ratio. A quick dummy-up would suggest the stock 1400 pistons might give too high a CR but I haven't done a full assembly yet. I'm hoping it will be reasonable but I've never actually seen a Cali head on the bench so I don't know what differences, (Apart from the extra plug.) there are to its shape and volume. I suspect not a lot though.
I'm hoping I don't have to modify the pistons too radically as I have a 1400 crank and the factory actually does a very good job of balancing them so I'd prefer to keep everything ridgey-didge. If the CR is too high I'll just have to get some new pistons forged, not a big deal but I'll have to ensure they weigh identical to the originals from Gilardoni if I don't want to frig about with a crank balancer unless I have to and it would make my purchase of the Cali crank a bit redundant.
Rods have already been closed and ground to a 2 thou clearance, crank is brand new, got a Cali 14 light-pull clutch on the way and all the guff I need for a 'D' kit for the top end. I'll be using the case from Ralf's original motor that ran its big ends after rollerisation as it's front main still measures up and looks fine. I've got a super low mile rear main from a leaky 1200 Sport to modify for the back of it and I'll pull a gearbox out of the alp of 8V boxes under the bench. Once it's built we'll chuck it into Mark's Griso one weekend, then the mapping is his job! :D
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Sounds terrific
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Heck yeah!
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Another alternative if the CR is too high, less ideal but it will depend on how much extra volume is needed, would be a compression plate under the barrel. This would cause a problem with the camchains but providing it was 1mm or less I reckon I could get away with milling a similar amount off the rocker support base.
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Looking forward to the project.
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Me, too. I'd sorta forgotten about this section. :rolleyes:
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Well, here's some good news! While this project is going slowly, mainly because my hands seize up in the cold weather and it's been sub-zero in the mornings for the last week, I today finally got round to installing the crank and cc'ing the chambers.
Now all of the aftermarket 1400 conversions use different Pistons and I'd at first thought that this would have to be because of radical differences in the combustion chamber volume to deal with the extra swept volume. I'd done a rough dummy up with just a piston filled with oil and flat-surfacing the head and was a bit worried that that was the case a s the CR did calc out as too high butI wasn't willing to just 'Guestimate' it in such an amateurish way so today I did the full dummy up.
CCV came in at 78cc. Bore is 104mm, stroke is 81.2mm
To calculate the CR you use the formula SV+CCV divided by CCV
So.
Swept volume is 52x52x3.412x81.2=749.156 cu/mm
Divide that by 1,000 to convert to cc's and add 78=827.2cc
Divide by 78=10.6.
Winner, winner! Chicken dinner!
It would seem that the reason the AM kits all use different pistons is down to correcting the balance factor, not because of a different combustion chamber design! Now this makes sense if you want to simply offer a 'Bolt On' kit that doesn't require disassembly of the bottom end but since we're using a 1400 crank as well as the B&P kits it's a complete non-issue. The 1400's are balanced really nicely at the factory so to my mind it's actually easier and probably not a lot more expensive to just buy a crank and do the bloody job nicely!
Oh, a 10.6 CR is right on the money for this project :thumb:
Pete
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Well that's certainly good news! Then you can get on to assembling the thing! :grin: :bike-037:
-Ulrik
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Well I just learnt something, and I enjoy mathematical explanations when I have time just to work through it.
Like most things that seem complicated, once you understand them they're actually simple concepts.
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Hi Pete
When I went to school pi was 3.1412 ......
In your figures above I see 3.412 , I might be wrong, was it pi you were using ? or was this some other dimension ? I hope so
Anyway good luck with it, keep us posted, I think most of us enjoy the progress
cheers
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Hi Pete
When I went to school pi was 3.1412 ......
In your figures above I see 3.412 , I might be wrong, was it pi you were using ? or was this some other dimension ? I hope so
Anyway good luck with it, keep us posted, I think most of us enjoy the progress
cheers
Yeah that's what he's shooting for with that formula.
Pie x R squared x stroke = swept cylinder volume if R = 1/2 bore diameter.
When I correct pie in his numbers I get 689.7cc which sounds closer to the 1400cc target than his first calculation which sounds like 1600c.
Anyway using that I get CR of 9.8:1
But check me, it's early and I've got a febrile 3 y/o on my lap.
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Hi Pete
When I went to school pi was 3.1412 ......
In your figures above I see 3.412 , I might be wrong, was it pi you were using ? or was this some other dimension ? I hope so
Anyway good luck with it, keep us posted, I think most of us enjoy the progress
cheers
Yes, you're right, and that's because I was drunk! Sue me! :grin:
Oh, and while less than I'd like CR wise 10 to 1, (Close enough will do and we can probably run 91 RON safely. Note we are NOT chasing peak HP but we hope to build something with enough bottom end and midrange to pull down a barn. Top end will hopefully remain about the same as what we have with the best of the 1200's.
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Thanks Pete,
Watching this post with interest.
Craig.