Topic: STROKER project, keep your children away

[voxonda]

and voila,

at least it looks way better, however far away from being perfect.
most importantly however, I do not know nothing about the strenght of the repair.

the cases had been sandblasted anyway, the ugly welds had been removed. the missing alu had been tig welded.

conclusion: doable, but the honda cast is of very poor quality making all welds full of debris. this is a recognition i made many times all the years ago.

mec

A lot of zinc in the castings I've been told.

Correct zinc makes it easier to cast.

[mec]

waiting for bored and honed cylinders many ideas are coming up as this new, old cb1100r completes my bikecollection since 10 days. i do not know what to do with this bike in the near future, but i feel that it is a good insurance when more power is needed on the racetrack one day. 
in this stock configuration it is even more something like a tank from the army than a race replika, what honda wanted us to make believe.
256kg dry, that says all.
but what i know from earlier, the engine gives a good base for racing, however expensive and not as relieable as the 1000er kawas.

today i got a call, crankshaft is balanced, cylinders ready for assembling the engine. unfortunately the headwork will take some more time. i will use this time to think over my modified camchaintensioner one more time.

i will keep you updated.

mec

[turboguzzi]

nice one!

classic bike had a big feature on them in a recent issue.

i think the tank is supposed to be aluminum, check it out.

guess they'll start ob e relevant to classic racing in two years time or so. they started in 81'

TG

[mec]

you are right, the fuel tank is made from aluminium.
nevertheless, the bike is heavy metal

these days i did some work on the engine again.
first, i couldn´t live with the camshaft hub made from steel. i manufactured another one made from aluminium..........sh..,....1mm out of alignement. another one, this one, the third one works fine.

working on the pistons: i managed to save some weight (-3gr from the pins) and brought all 4 pistons (including pins and rings) to the same weight: 222gr complete (71.25mm diameter!)

plastigauging the bearings

mec

[mec]

with the carillos and the 69mm crank i run into clearance problems near the starter motor (inside the upper case). so i had to remove 0.5mm material. heavy duty studs installed.

another problem waited to be solved: as seen in the second picture at cyl2, there was only a small amount of material round the sleeve near the venting holes (in direction to the fins). similar problem on cyl 3. eventually the base gasket in combination with a liquid seal could do the job, but i decided to go a safer way and glued some prefabricated 5mm alu piece into these slots so that the gasket can find more surface to make a good seal.

this time i am waiting for my cyl head to be done. a friend of mine, robert, is doing the port job, i did not want to do it another time. it is much time consuming, i am tired of this work.

mec

[Terry in Australia]

That is beautiful metal art Mec, keep up the good work mate, you are an inspiration to all of us engineering "wannabees". Cheers, Terry.

[MRieck]

you are right, the fuel tank is made from aluminium.
nevertheless, the bike is heavy metal

these days i did some work on the engine again.
first, i couldn´t live with the camshaft hub made from steel. i manufactured another one made from aluminium..........sh..,....1mm out of alignement. another one, this one, the third one works fine.

working on the pistons: i managed to save some weight (-3gr from the pins) and brought all 4 pistons (including pins and rings) to the same weight: 222gr complete (71.25mm diameter!)

plastigauging the bearings

mec

Mec
  What color connecting rod bearings are you using?

[mec]

con rod bearings are yellow ones.

mec

[MRieck]

con rod bearings are yellow ones.

mec

I knew that would be the case as Carrillo always bores the big end to the minimum factory ID.

[mec]

what has been done so far?

i determined the combustion chamber volume: 32.5ccm (would give approx a compression ratio of 1:9)
this value was determined after the cylinder heigth was decreased by 0.4mm (ex valves had been set deeper by 2mm to clear valve to valve distance, 0.5 base gasket, 1.3 head gasket).
the camchain is too long at the moment. now i will decrease cylinder heigth by another 0.5mm, dito cylinderhead heigth. this will give 1:10 compr ratio, hoping a reduction of the camchain length will make it fit properly (from what i feel, it will take another 0.5mm heigth reduction, resulting in <1:11). next investigations will come soon.
the cyl head is half done. the pics show the eliminated inlet tubes(?), which will be replaced by bigger ones, suiting better to my 34er flat slide carbs.

the upper crankcase has got a primary chain guide (from cb900f), hoping this will reduce primary chain slack.

mec

[Terry in Australia]

Once again Mec, I'm kneeling at the alter of the Church of Engineering Excellence, brilliant!

Regarding your beautifully machined larger inlet tubes, as they're screwed into the head like the OEM ones, how will you connect the 34mm flatslide carbs? Will you use a curved rubber adapter like the OEM Honda items? If so, where will you get some that big?

Let me know mate, I've got some 34mm Mikuni flatslides here but I was going to weld some tubes directly onto the ports with flanges so I could use Suzuki GSXR rubber stubs? Cheers, Terry.

[Retro Rocket]

Hi Terry, there's a guy close to me that has anodized replacement inlet tubes for our bikes, not to sure if they are bigger than stock but he has them made locally. If interested send an email and i willcheck them out for you..

Mick

[turboguzzi]

which leads me to ask:

hei 750 gurus, isnt there a way to straighten the inlet tract in those 750's?

 looking from above, the elbows that the air has to deal with always look painful.

[MRieck]

which leads me to ask:

hei 750 gurus, isnt there a way to straighten the inlet tract in those 750's?

 looking from above, the elbows that the air has to deal with always look painful.

  Yes...build a billet head TG

[mec]

Once again Mec, I'm kneeling at the alter of the Church of Engineering Excellence, brilliant!

 


all parts back home again. its like xmas, birthday and eastern all together.

there had been some questions.
yes, i will use the oem rubber adapters. they fit perfect. only the curve is not on my wishlist.
this leads us to TG´s question. eliminating the elbow is a hard way to go. as MRieck mentioned, building a billet head is one way, or milling and welding from morning to evening for some days will solve the problem.

a little off topic, what have I done in the meantime:
made from 8mm 7075 alu I CNCed two rear sprokets 43 and 45 teeth. the rest of the aluminium was used for two spare gear levers.

mec

[mec]

for comparison, oem head and K2 head prepared for the larger bore, bigger inlets, ex valves set 2mm deeper for valve to valve clearance, in valves 33.5mm

mec

[mec]

at this time the combustion chamber volume was in the 24ccm range, resulting in a compr ratio of over 1:11. a little bit too much for my feeling.
the next photo shows removing some material for the o-rings (cause the cylinder has been milled by 0.5mm, as the cyl head was).
next step was to determine the lenght of the valve springs. measurements showed, that i had to fabricate some shims in the 3-4mm range to get the correct valve spring heigth of 34mm.
picture 3: preparing for determining the combustion chamber volume (first one of three)
picture 4: measurements for combustion chamber volume with head on

mec

[mec]

here is some strange find.
this is my K2 head (same as in the pictures above), camshaft holders from a newer modell,K7(?).
I marked the point of interest in red. underneath the camtowers you can see the oiljets for lubrication of the cambearings and camrockers. the oiljets are o-ring sealed. but from what I remember, there has never been seen the oiljets nor the o-rings when camtowers installed. i know, there are different camtowers, different oiljets, different o-ring sizes coming with newer models.
i do not have a good feeling when i can see the oil pressurized o-ring.
my solution: I can do a small little ring on my lathe to hold the o-ring in place to prevent the o-ring rupture and coming out of the small gap.
what do the sohc cyl head gurus suggest?

mec

[mec]

tools help you doing it right.
machined two washers, one for the in valveseat, one for the exhaust.
this disks help to prevent damage done to the valve seat when removing material from the combustion chamber one more time.

another time determining combustion chamber volume

last picture you can see the 3.5mm shims for correct valvespring length

mec

[mec]

another tools helping you going your way:
in order to adapt the oem rubber adapters, i machined a clon of the aluminium tube glued in the intake port.
the same thing i have done accordingly to the carbs.
in addition to this i machined a 33.5mm disk, mounted to a M4 screw. this was used as a gauge, helping to increase the inner surface of the rubber adapters in a smooth way.
with this little tools it was easy to make a proper fit of all matching parts.

mec

[turboguzzi]

just when i was going to ask: why dont you use a plexiglass plate to measure the chamber.....

by the way, dont think 11:1 is that high, but then again, I am not a 750 stroker guy. my 500 is 12.5:1.....

current two valve air cooled ducatis are up to 11:1 STOCK, and that's with 88mm + bore (the HM 796 motor). their chamber geometry is not that much better than our sohcs, 60 degrees included valve angle.

TG

[mec]

some numbers:
cyl heigth 84mm
cyl head heigth 72.1mm
head gasket 1.3mm
base gasket 0.5mm
comb chamber 27ccm
bol d´or camchain shortened to 118 bolts  



the crankcase again to be washed, i do not know how often till now  
ready for assembling.

mec

[bucky katt]

here is some strange find.
this is my K2 head (same as in the pictures above), camshaft holders from a newer modell,K7(?).
I marked the point of interest in red. underneath the camtowers you can see the oiljets for lubrication of the cambearings and camrockers. the oiljets are o-ring sealed. but from what I remember, there has never been seen the oiljets nor the o-rings when camtowers installed. i know, there are different camtowers, different oiljets, different o-ring sizes coming with newer models.
i do not have a good feeling when i can see the oil pressurized o-ring.
my solution: I can do a small little ring on my lathe to hold the o-ring in place to prevent the o-ring rupture and coming out of the small gap.
what do the sohc cyl head gurus suggest?

mec

i learned the hard way that ALL of those recesses have to have an o-ring to maintain the pressure in the cam oiling system. i wiped out a cam and set of holders finding out

[Flying J]

your work is amazing. Thank you for taking the time to photograph it all and post it on here. Inspirational.

[mystic_1]

here is some strange find.
this is my K2 head (same as in the pictures above), camshaft holders from a newer modell,K7(?).
I marked the point of interest in red. underneath the camtowers you can see the oiljets for lubrication of the cambearings and camrockers. the oiljets are o-ring sealed. but from what I remember, there has never been seen the oiljets nor the o-rings when camtowers installed. i know, there are different camtowers, different oiljets, different o-ring sizes coming with newer models.
i do not have a good feeling when i can see the oil pressurized o-ring.
my solution: I can do a small little ring on my lathe to hold the o-ring in place to prevent the o-ring rupture and coming out of the small gap.
what do the sohc cyl head gurus suggest?

mec

Yeah I don't like the looks of that o-ring peeking out like that.  I just looked at my K0 and the cam holder completely covers that o-ring recess.  Are the K2 cam holders not usable?

Perhaps a small bead of weld in that spot, then machined down, would do what you need?

mystic_1