Topic: STROKER project, keep your children away

[mec]

nice work mec...

....but also have to ask: why did you have to go for this solution where the hinge of the tensioner puts a bending load on the adjuster plate through the "L" beam that you built? Why couldnt you attach the hinge somewhere directly to the head and just press the blade in the middle?

BTW, we have a UEM vintage Endurance race in Franciacorta, in the north at the end of october, you might want to come to that one....

TG

hi,
i decided to go this way, because i didn´t found any place to mount the hinge. there is not enough room, not enough material for threads (exept M3,M4). the good side is, that there is not enough room for bending either.
more i am concerned about damage by vibrations. the stock parts are more or less all mounted in rubber.

today i found +12 stripped threads on the K2 cylhead.
to eliminate the thread issue on the camtower screws, i replaced all 4 (middle) M6 screws with studs. the studs do have a M8 thread screwed in the aluhead, and on the other end do have a M6 thread. the camtowers are the modern ones with holes for fixation of the rocker arms. to mount these shafts it was necessary to cut the shafts in two and to take care that the inner half will be possible to be mounted from the camchainsprocket side.
i like this way of strengthening the fixation of the camtowers much more than welding and drilling the camcover. there are no valve springs on this earth to strip the 8mm threads. mounting camshaft, chain, rocker arms is more tricky, however.

mec

@TG: can you give me more infos on the endurance race, link, please?

[turboguzzi]

yep, some project..... on the other hand, it's nice that you can check your cam timing with the cover off,

in the 500's you cant!

sent you some details on the race to your email

TG

[MRieck]

Mec....please tell me you will be replacing the guides....especially the exhaust

[mec]

Mec....please tell me you will be replacing the guides....especially the exhaust

 

[MRieck]

Mec....please tell me you will be replacing the guides....especially the exhaust

 

The cylinder head in the previous pictures has the old style exhaust guides with no seals.....I would change them ti the new style that uses a seal. Considering all the work you have done I'd actually go with the 5mm valve conversion kit with the 34mm intake valve.

[mec]

thx for clarification.

i have two cyl heads to choose from. this one seems to have not too much miles on it. definitely valve stem to guide play near zero (or as new).

ad valve seal: i am happy to reduce friction were ever it is possible. for a racing engine i think its ok not to use the valve seals on the exhaust valves. i am not sure, but didnt have the first K models no valve seals at the inlet valves even??

valves with 5mm stems are the nonplusultra (eventually in my next engine).
34mm in valves are compatible with a high duration cam (without deforming a proper combustion chamber too much)?

mec

[MRieck]

thx for clarification.

i have two cyl heads to choose from. this one seems to have not too much miles on it. definitely valve stem to guide play near zero (or as new).

ad valve seal: i am happy to reduce friction were ever it is possible. for a racing engine i think its ok not to use the valve seals on the exhaust valves. i am not sure, but didnt have the first K models no valve seals at the inlet valves even??

valves with 5mm stems are the nonplusultra (eventually in my next engine).
34mm in valves are compatible with a high duration cam (without deforming a proper combustion chamber too much)?

mec

Right...the first K models did not run seals but all the later models did. Friction between the seal and valve stem is almost immeasurable.....I wouldn't worry about that. The no seal exhaust guides are tall which can interfere with high lift camshafts.
 The 34mm 5mm stem valve is very nice....it weighs 36.6 grams as oppossed to 47.4 for the OEM 32mm intake valve. The 5mm titanium retainer only weighs 4.2 grams!
 I run the 34 intake and 28 exhaust valves with a Megacycle 125-75 in a 67.5mm bore with no problems. It is advertised at .400 intake lift and .375 exhaust lift. Duration at .040 is 262 and 257 respectively. It is a very nice cam.

[bucky katt]

[/quote]


hi,
i decided to go this way, because i didn´t found any place to mount the hinge. there is not enough room, not enough material for threads (exept M3,M4). the good side is, that there is not enough room for bending either.
more i am concerned about damage by vibrations. the stock parts are more or less all mounted in rubber.

today i found +12 stripped threads on the K2 cylhead.
to eliminate the thread issue on the camtower screws, i replaced all 4 (middle) M6 screws with studs. the studs do have a M8 thread screwed in the aluhead, and on the other end do have a M6 thread. the camtowers are the modern ones with holes for fixation of the rocker arms. to mount these shafts it was necessary to cut the shafts in two and to take care that the inner half will be possible to be mounted from the camchainsprocket side.
i like this way of strengthening the fixation of the camtowers much more than welding and drilling the camcover. there are no valve springs on this earth to strip the 8mm threads. mounting camshaft, chain, rocker arms is more tricky, however.

mec

@TG: can you give me more infos on the endurance race, link, please?

[/quote]


thanks for the idea of doing the studs for the cam towers mec. i finally ended up heli-coiling all the holes in my k4 head to the m6 thread but when i build the big motor next year i'm going to do the studs like you did. where did the studs come from or were those something custom made by you?

[mec]

yes the studs are custom made from old crankcase bolts.

mec

[Bill/BentON Racing]

Damn impressive,you go man,I was going to tell you about LMP,saw his Hy-Vo chain setup a couple weeks ago,this is one interesting build,I sure hope you finish it,great work and Good Luck,Bill

[bucky katt]

yes the studs are custom made from old crankcase bolts.

mec

so a lathe is going to be in my near future i think.

[mec]

wating for further spare parts I am preparing a second set of Marvic wheels.
inspector and supervisor are checking the work done so far on the engine.

mec

[bucky katt]

i love the new shop supervisors you have Mec! how old are they?

[Bill/BentON Racing]

Are those Bengal kittens or just a couple future gear heads,MR's stageIV sounds like the cats meow ,Bill

[mec]

hi,

the shop supervisors were 2 weeks at time of the fotoshooting.
during general inspection on the crankcase they adviced me to do some repairs on the case.

it seemed that the PO had minor problems to control the exorbitant power of the 55 horses giving all their energy to the rear wheel. this led to some cold deformations done to the crankcase mounts.
possibly this accident caused furthermore a brain concussion. at least this came to my mind, when I saw the repair done to the case

I decided to give it a try and gave my best

[mec]

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

[turboguzzi]

It is a well known "secret" that the japanese industry as a whole used all kinds of thinning agents to help the molten ally flow during the die casting process, these agents are known for their negative impact on weldability.

If you ever welded good ole' british castings, you'd see the difference right away.

[mystic_1]

Great work on that repair, Mec.  I'd bet a (US) dollar that your repair is way stronger than the previous work

mystic_1

[mec]

some goodies arrived:
JE pistons 71.25mm, the piston pin moved upwards 3mm to compensate for the 6mm longer stroke.
piston complete with pin and rings 226gr.

the sleeves are premachined, some work on the cylinder has to be done however.

mec

[mec]

an extra long primary chain has arrived.
this chain had to be cut for proper length, 70 bolts.
the chain arrived with two extra semi-rivet-links. this link has to be secured with two micro bolts. a solution i was not very delighted. i went another way: i had a wider primary chain from a cb1100r and disassembled the links to gain two longer bolts. with this extralong bolts i was able to rivet the primary chain so that it appeared as new.
luckily the chainslack was minor, nevertheless i decided to use an altered cb900 bol d´or primary chain tensioner.

mec

[mec]

the primary chain tensioner is spring activated (without the hydraulic force of the dohc), the spring has an extra preload of 5mm.
it is now a similar tensioner mechanism as used in the double roller chain system used in our sohcs.

mec

[MRieck]

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.

[turboguzzi]

Mec, looks like you are going to have a few long nights till the race in rijeka.....

BTW, regarding your Egli rep, Do the rules let you get away with such modern wheels? Like someone else said, not sure the suit a 70's tool, but taste is very personal thing. On another level, you seem to prefer very wide tires but all the vintage 1100-1000's that I see here run quite narrow sizes to make the steering quicker.

What tires are you going for at the end?

TG

[bikebitzofvt]

Mec~
As always your handiwork is awe inspiring.  Can't wait to hear the results of your next outing!

[mec]

Mec, looks like you are going to have a few long nights till the race in rijeka.....

BTW, regarding your Egli rep, Do the rules let you get away with such modern wheels? Like someone else said, not sure the suit a 70's tool, but taste is very personal thing. On another level, you seem to prefer very wide tires but all the vintage 1100-1000's that I see here run quite narrow sizes to make the steering quicker.

What tires are you going for at the end?

TG

TG, i think that this engine will not be race ready at the beginning of october.

i do not know much about the regulations in the GTF races ,   all i know is, that the wheels look a little bit modern in fact. but as far as i remember, it must have been in the late 70ies or beginning of the 80ies i used EPM magnesium and the three spokes dymag wheels. particularly the dymag have a similar look to the marvic. my marvic are 18", i think they are vintage wheels too. the race regulations of GTF say, that we have to use 18".

in rijeka i will give the metzeler road attack a chance. the second set of wheels will be fittes with BT45.

one word to the BT45: i think this tire is one of the best choices for overall performance. price is reasonable, grip is good (maybe the avons are better?), durability is good. my BT45 are appox 5-6 track days old and they are good for another 5 track days.

mec