Donor Gearboxes

[el chupacabra]

More Progress, I have drawn the reed cage housings and started looking at where the studs will go to join the halves. Do you reckon m8 would be enough? I am also tossing up using cap heads and recoils as they will make less of an obstruction in the transfer port feeders on the case vs a flange washer. Does anyone have any objections or bad experiences with recoils vs studs?

Also look at how much room I have for carbs now with a 1370mm wheelbase, hopefully a 62mm main bearing will be enough on the lay shaft seeing as that's what a Yamaha banshee uses and they can make some big HP. A cylindrical N305 ECP has 4x the load rating and can take axial loads in each direction, are there any major downsides to this style of bearing vs the 6305 deep groove ball bearing?

[jato]

This design has evolved very nicely imo - it looks real pretty and purposeful! - I'm also a fan of cylindrical roller bearings but i have seen wear patterns on the races showing the effects of "unrestrained" crank flex in high power/rev engines, so great for the layshaft and maybe adjacent to the crank primary if the cranks are pretty rigid.

[pete376403]

This design has evolved very nicely imo - it looks real pretty and purposeful! - I'm also a fan of cylindrical roller bearings but i have seen wear patterns on the races showing the effects of "unrestrained" crank flex in high power/rev engines, so great for the layshaft and maybe adjacent to the crank primary if the cranks are pretty rigid.

Norton had issues with commando cranks flexing and they went to barrel shaped (?) Superblend rollers to fix that

[el chupacabra]

I think I will stick to the ball bearings on the crank and use only the rollers on the Lay shaft.

[el chupacabra]

Not related to the V4 but has anyone made their own air cooled 4 stroke head gaskets before?

[jato]

40 thou copper bought from E Hayes in invercargill. prior to fitting heated to red then dropped into salt water. i understand that the salt has a hand in removing surface oxidation as it goes into the water - the gasket comes out immaculately clean like its been bead basted.

[el chupacabra]

I'll probably give that a try, I'm having trouble with the little V twin I made as there is no aftermarket head gasket so I have to conjure something up.

Here is some more V4 progress, I decided to render the model for some extra motivation. You can see I've added ribs in between the Vee to strengthen it up a bit.

[husaberg]

I'll probably give that a try, I'm having trouble with the little V twin I made as there is no aftermarket head gasket so I have to conjure something up.

Here is some more V4 progress, I decided to render the model for some extra motivation. You can see I've added ribs in between the Vee to strengthen it up a bit.

What bore i think i have A 54mm one here small hemisphere? pitbike

[el chupacabra]

What bore i think i have A 54mm one here small hemisphere? pitbike

It is a pit bike head, it's a 47mm bore but having widened the cam chain tunnel 14mm it proves hard to seal. I might lap the head/cylinder in the morning and use some of that copper head gasket spray on the lapped surfaces, I could add O rings to the oil galleries too. but all this requires a 2+mm base gasket to account for the lost head gasket. I have a feeling that the thick (2.5mm) gasket material I have will crush over time, maybe I should make a 1mm steel shim and run 2 thinner gaskets. The race is on sunday and I would like to test the engine out properly.

hmmmmm.

[husaberg]

i bought these years ago not sure where they are though.
http://dratv.com/nealbainth.html
http://dratv.com/cohega54bofi.html

for a race motor i would oring and steel oring it.

[el chupacabra]

I haven't made much progress lately as I've been working on the bucket. It finished every race and didn't explode, not bad for an engine cast at home.

I have however finished modifying the case to accept the GSXR water pump and designed a small adapter to mount it on. The next steps will be to model the lay-shaft and finalize bearing locations. I'll get some foam cut to cast the forward crankcase or the cassette. I'll start with some of the smaller parts.

[el chupacabra]

It's time. . . something clicked and I've decided it's time to make some parts. So I cocked up this pattern as the piece of foam was too small, tomorrow I am picking up some more XPS foam and am hoping to have some patterns ready before the end of the year. I'll hunt around to get them cast and heat treated by someone professional or I can just cast/heat treat myself although I don't have a good supply of virgin aluminium and would likely recycle something.

[el chupacabra]

I've cut the foam and now it is time to get to casting, hopefully sometime in the new year as life has thrown me a curve ball. Does anyone have a good supply or know where I can get some LM25 or a quality heat treatable casting alloy? I'm wanting to avoid mostly recycled material of questionable quality. Also on the off chance does anyone know someone who will cast something this small for me? It might be less hassle to get someone else to pour it if it is cheap enough, otherwise I'll get around to it sometime in February at the earliest.

Thanks in advance.

[el chupacabra]

I've gotten a local foundry to agree to pour these castings for me and they are only 20 minutes from home. As of now I am finishing the front crankcase half, I am a third of the way there (2/6 pieces). This and the Cassette plate will be cast on the same day before moving onto the rear crankcase half. The front pattern is made of 6 pieces of 50mm thick XPS foam.

[el chupacabra]

Ready to cast, well kind of, it could be all go next Friday. I seem to have over looked the front engine mounts when double checking everything after the full redesign from before. Now what's the best solution, bolt a laser cut plate onto some raised bosses (with a solid bush in between) or glue on some lugs (will also have bush in between)? It seems like it done many different ways, the TZ250 seems to use a bolted on plate with no problems.